Postoperative Visual Loss and Informed Consent

NEWSLETTERVolume 23, No. 1, 1-20 Circulation 83,045 Spring 2008

www.apsf.org The Official Journal of the Anesthesia Patient Safety Foundation

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Inside: POVL Update ..............................................................................................................................Page 3

Informed Consent ......................................................................................................................Page 4

Machine Checkout Guidelines ................................................................................................Page 6

OR Fire ........................................................................................................................................Page 8

Dear SIRS: Flow Sensors........................................................................................................Page 10

Q&A: Reuse of Syringe Pump Supplies ..............................................................................Page 14

I’m a retired anesthesiologist. I was asked by Dr.Lorri Lee to write a brief article from the patient’s per-spective about posterior ischemic optic neuropathy(PION). I should know about it. It happened to me. I’vebeen slow to write this. It’s a rather painful subject.

Following my fifth back operation in September2006 (a prone, redo 3-level lumbar fusion), I had somuch swelling I was unable to open my eyes at alluntil about noon the next day. I at first thought I hadLacri-lube in my right upper eye, but soon becameaware of the pulsating colors of scintillating sco-tomata in the upper 80% of the field of my right eye.(It was interesting in that, at least in the lower portionof the affected area, I could see through the flashingcolors.) Having given a lecture on PION, I was prettysure what the problem was. I called the surgeon’soffice and somehow impressed upon them that Ineeded to see an ophthalmologist right away. Fun-doscopic exam was normal. Over the next 3 to 4 days,the scintillations diminished and were graduallyreplaced by gray with some improvement of the fieldcut to about 70%. I’ve been followed by a neuro-oph-thalmologist with minimal improvement. Pallor inthe infero-medial right optic disc was first noted onday 20, confirming the diagnosis of PION and rulingout anterior ischemic optic neuropathy (AION). I canstill read normally, albeit a little bit slower, and mybinocular vision is intact so I can drive; this doesn’taffect daily life too much. I’m told my left eye is notquite normal, but I can’t tell that because I have noth-ing to compare it to.

time. But this was not a problem to be expected. Infact, it is a complication for which there is currentlyno way to monitor, no way to prevent, and no wayto treat. I’m really quite fortunate, because 68% ofthe 83 cases (recorded at the time) woke up com-pletely bilaterally blind and improved very little.Very probably, with another 20 or 30 minutes ofsurgery, I would have been in that 68%.

I knew about this complication. I had been to lec-tures about it, and I had lectured about it. I had dis-cussed it at great length with my anesthesiologist. Iwill say that it was never mentioned by my surgeon,and when it happened, he tried to blame it on the anes-thesiologist. Later, he told me he had seen one case as afellow but thought it was a fluke. His office still reas-sures me this never happens. That’s comforting. I’m

See “Blind,” Page 3

I practiced anesthesiology for 28 years, both inacademic and private practice. I have not returnedbecause I don’t think someone with a significantvisual field defect should be routinely responsible forintubating patients. I don’t want to hurt somebody. Ithink I could probably intubate someone right nowwithout difficulty, but the day that I didn’t everyonein that room who knew of my problem or shouldhave known would get to write a check. No oneshould want to be my partner.

I have no grudge against my surgeon or anes-thesiologist (my former partner). They did a goodjob. My surgery lasted 7-1/2 hours with blood lossaround 700 ml, less than the average of 9.8 hoursand 2010 ml for PION cases. All of the recordedPION cases had either an anesthetic time >5 hours ora blood loss >1000 ml, so I was at risk on the basis of

If my spine surgery went fine, why can’t I see?Postoperative Visual Loss and Informed ConsentThis issue of the APSF Newsletter opens with a personal and tragic account of postoperativevisual loss (POVL) in an anesthesiologist and follows with an update on POVL, a compre-hensive review of informed consent, and a spine surgeon’s perspective. We hope that thesetimely articles will increase awareness of POVL and encourage appropriate preoperativeinformed consent.

by Anthony D. Lehner, MD

APSF NEWSLETTER Spring 2008 PAGE 2

NEWSLETTERThe Official Journal of the Anesthesia Patient Safety Foundation

The Anesthesia Patient Safety FoundationNewsletter is the official publication of the nonprofitAnesthesia Patient Safety Foundation and is pub-lished quarterly at Wilmington, Delaware. Annualcontributor status: Individual–$100, Corporate–$500.This and any additional contributions to the Founda-tion are tax deductible. © Copyright, AnesthesiaPatient Safety Foundation, 2008.

The opinions expressed in this Newsletter are notnecessarily those of the Anesthesia Patient SafetyFoundation. The APSF neither writes nor promulgatesstandards, and the opinions expressed herein shouldnot be construed to constitute practice standards orpractice parameters. Validity of opinions presented,drug dosages, accuracy, and completeness of contentare not guaranteed by the APSF.

APSF Executive Committee:Robert K. Stoelting, MD, President; Nassib G.

Chamoun, Vice President; Jeffrey B. Cooper, PhD,Executive Vice President; George A. Schapiro,Executive Vice President; Matthew B. Weinger, MD,Secretary; Casey D. Blitt, MD, Treasurer; Sorin J. Brull,MD; Robert A. Caplan, MD; David M. Gaba, MD;Lorri A. Lee, MD; Robert C. Morell, MD; Michael A.Olympio, MD; Richard C. Prielipp, MD. Consultant tothe Executive Committee: John H. Eichhorn, MD.Newsletter Editorial Board:

Robert C. Morell, MD, Editor; Lorri A. Lee, MD,Associate Editor; Sorin J. Brull, MD; Joan Christie, MD;Jan Ehrenwerth, MD; John H. Eichhorn, MD; RodneyC. Lester, PhD, CRNA; Glenn S. Murphy, MD; DeniseO’Brien, MSN, RN; Karen Posner, PhD; Andrew F.Smith, MRCP FRCA; Wilson Somerville, PhD; JefferyVender, MD.

Address all general, contributor, and subscriptioncorrespondence to:Administrator, Deanna WalkerAnesthesia Patient Safety FoundationBuilding One, Suite Two8007 South Meridian StreetIndianapolis, IN 46217-2922e-mail address: [email protected]: (317) 888-1482

Address Newsletter editorial comments, questions, letters, and suggestions to:Robert C. Morell, MDEditor, APSF Newsletterc/o Addie Larimore, Editorial AssistantDepartment of AnesthesiologyWake Forest University School of Medicine9th Floor CSBMedical Center BoulevardWinston-Salem, NC 27157-1009e-mail: [email protected]

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In Memoriam:

The APSF wishes to express its deepest sym-

pathy at the passing of Dr. Ann S. Lofsky.

Dr. Lofsky was a consultant to the APSF

Executive Committee and a frequent contributor to

this Newsletter on important topics, including

hypoperfusion in the beach chair position, maternal

cardiac arrest, and complications of cervical epidural

blockade. She was a director emeritus of The Doc-

tor’s Company and a practicing anesthesiologist in

Santa Monica, CA. Dr. Lofsky was board certified in

both internal medicine and anesthesiology. She will

be sorely missed by all who knew her. Our condo-

lences are extended to Dr. Lofsky’s family, friends,

and colleagues at her untimely passing.

A Statement by the ExecutiveCommittee of the APSF

From time to time, the Anesthesia Patient Safety Foundation reconfirmsits commitment of working with all who devote their energies to makinganesthesia as safe as humanly possible. Thus, the Foundation invites col-laboration from all who administer anesthesia, all who supply the tools ofanesthesia, and all who provide the settings in which anesthesia is prac-ticed, all individuals and all organizations who, through their work, affectthe safety of patients receiving anesthesia. All will find us eager to listento their suggestions and to work with them toward the common goal ofsafe anesthesia for all patients.


POVL VictimEmphasizesDisclosure“Blind,” From Page 1

by Lorri A. Lee, MD

Postoperative visual loss (POVL) has receivedheightened attention in the anesthesiology, ophthal-mology, and spine literature for almost 10 years now.We have made significant progress in disseminatingthe knowledge to the anesthesiology communityregarding the different types of injuries to the visualsystem that can occur perioperatively, such as centralretinal artery occlusion (CRAO), ischemic optic neu-ropathy (ION), and cortical blindness. Data from theASA POVL Registry have clearly demonstrated thatION, the most common diagnosis in our database, hasa distinct perioperative profile from that of CRAOpatients. ION occurred with patients’ heads sus-pended in Mayfield pins without globe compression,was commonly bilateral, and was associated withlarge blood loss (median 2.0 liters) and long anes-thetic/operative times (≥6 hours anesthetic duration).1These associated features of ION are consistent withan injury caused by physiologic perturbations in sus-ceptible patients, rather than direct trauma, as canoccur with CRAO. The vast majority of patients in theASA POVL Registry who developed ION were rela-tively healthy (ASA 1-2), and it has been reported inpatients as young as 10 and 13 years of age after spinesurgery.2,3 These findings suggest that any patient maybe susceptible to developing this devastating periop-erative complication, regardless of age or health status.Whether or not these patients who develop ION peri-operatively have atypical physiology or vascularanatomy of their optic nerves remains unknown.

Though we now have a few more pieces of thepuzzle of the etiology of ION, solving this mysterywill require significantly more research in one ormore directions such as 1) clinical multicenter retro-spective case control studies or prospective multicen-

ter observational studies; 2) development of an animalmodel for ION utilizing physiologic perturbations tocreate an injury of the optic nerve; 3) development of areliable intraoperative optic nerve function monitor;and 4) studies of patients who have developed IONafter spine surgery to determine if their physiology oranatomy is unique.

Until there is definitive evidence on the etiologyand prevention of ION, the ASA Task Force on Peri-operative Blindness has issued a Practice Advisory forPerioperative Visual Loss Associated with SpineSurgery with the following recommendations formajor spine surgery cases:

1. consider consenting patients for the risk of POVL

2. use indwelling arterial catheters to monitor bloodpressure, and consider use of a central venouscatheter

3. use colloids along with crystalloids for volumereplacement

4. position the head so that it is equal or above thelevel of the heart

5. consider staging procedures.4

Because of the significant variability in the bloodpressure and transfusion management in patientswho develop ION, no recommendations could bemade for these areas.

Dr. Lee is Director of the ASA Postoperative VisualLoss Registry, Associate Editor of this Newsletter, andAssociate Professor of Anesthesiology at the University ofWashington, Seattle, WA.

References

1. Lee LA, Roth S, Posner KL, Cheney FW, Caplan RA,Newman NJ, Domino KB. The American Society of Anes-thesiologists Postoperative Visual Loss Registry: analysisof 93 spine surgery cases with postoperative visual loss.Anesthesiology 2006;105:652-9.

2. Chang SH, Miller NR. The incidence of vision loss due toperioperative ischemic optic neuropathy associated withspine surgery: the Johns Hopkins Hospital Experience.Spine 2005;30:1299-302.

3. Kim JW, Hills WL, Rizzo JF, Egan RA, Lessell S. Ischemicoptic neuropathy following spine surgery in a 16-year-oldpatient and a ten-year-old patient. J Neuroophthalmol2006;26:30-3.

4. American Society of Anesthesiologists Task Force on Peri-operative Blindness. Practice advisory for perioperativevisual loss associated with spine surgery: a report by theAmerican Society of Anesthesiologists Task Force on Peri-operative Blindness. Anesthesiology 2006;104:1319-28.

Solutions to POVL MysteryRequires Research

sure it occurs far less often in private practicebecause procedures there tend to go much fasterthan they do in teaching hospitals. But it doeshappen.

If this had occurred without my knowing of thepossibility, I would feel far differently about it.

I’m very fortunate in that when I first enteredprivate practice I had an older partner who pulledme aside and told me that since I had 4 kids Ineeded to get disability insurance that specified myoccupation as anesthesiology. He told me it wouldbe expensive and that I should never complain andalways pay the premiums. Without that advice, myfamily would be in big trouble. The amount Ireceive is far less than what I was making and I stillhave 2 kids in college, so things are a bit tougharound here. The Texas Medical Association, ofwhich I had been a member for many years, refusedme for medical insurance and that has become anongoing problem.

I was at the top of my game when this occurred.The back problem now seems to have been solved,but what else do you do when you’re a fully trainedclinical anesthesiologist and can’t practice anesthesi-ology at age 58? Pain medicine is an obvious optionbut that frequently involves a lot of bending overand the lifting and turning of patients. I really don’twant to do another residency. There are generalmedicine things out there and I had hoped someadministrative positions. But potential employersand even some of your former colleagues look at youlike you are some sort of malingerer when you tellthem this story! So far, the only thing I’ve found is asmall job examining military recruits.

This complication is a devastating one forpatients and their families, even when it does notresult in complete blindness. Disclosure on everycase needs to be done not only by the anesthesiateam, but also by the surgeon. An issue of this mag-nitude has to be presented well ahead of time inorder to be properly understood, and the surgeonis the only one who has that opportunity. In addi-tion, this is the only way it will be understood as acomplication of positioning rather than an anestheticcomplication.

Dr. Anthony D. Lehner, MD, was a practicing anes-thesiologist in Dallas, TX.

Ischemic Optic Neuropathy (late exam with optic nervepallor) (Photo courtesy of Dr. Sohan S. Hayreh, Universityof Iowa)


See “Consent,” Next Page

Informed Consent Requires Active Communicationby Colleen E. O’Leary, MD, and

Regina S. McGraw, RN, JD

The concept of informed consent is rooted in thefundamental ethical principle of the right of self-determination. This principle recognizes that patientsare autonomous; that is, that they are independentagents with the capacity to make decisions regardingtheir well-being without coercion from others. Theneed to respect an individual’s autonomy stems fromthe work of the 18th-century philosopher ImmanuelKant, but the medical-legal concept of informed con-sent was first introduced by 3 court cases in the mid20th century. Salgo v. Trustees of Leland Stanford Hospi-tal (Cal.App.2d 560, 317 P.2d 170 [Sup. Ct. Appl.]), in1957, determined that the physician is required toexplain the risks, benefits, and alternatives of a pro-posed procedure to a patient. Natanson v. Kline (186Kan. 393.350 P.2d 1093), in 1960, further specifiedwhat information should be disclosed to a patient andintroduced the “professional practice standard.” Thisstandard requires that a physician disclose to a patientwhat other physicians in the community would dis-close under similar circumstances. In 1972, Canterburyv. Spence (464 F.2d 772 D.C. Cir.) introduced the “rea-sonable person standard” which requires disclosureof information that a reasonable patient would con-sider important in making an informed decision.1

The Centers for Medicare & Medicaid Services(CMS), through their Conditions of Participation(CoP), which health care organizations must meet toparticipate in the Medicare and Medicaid programs,address the issue of informed consent. CMS grants“deemed status” to hospitals accredited by organiza-tions they recognize such as the Joint Commission,ensuring that hospitals meet or exceed the CoPs. In amemo to State Survey Agency Directors dated April13, 2007, the Center for Medicaid and StateOperations/Survey and Certification Group announcedrevisions to the Hospital Interpretive Guidelines forinformed decision making and informed consent. Inthe Patients’ Rights CoP, (42 CFR §482.13(b)(2)), theinterpretive guidelines state

Hospitals must utilize an informed consentprocess that assures patients or their represen-tatives are given the information and disclo-sures needed to make an informed decisionabout whether to consent to a procedure, inter-vention, or type of care that requires consent.

In the Surgical Services CoP (42 CFR 482.51 (b)(2)),the interpretive guidelines state

The primary purpose of the informed consentprocess for surgical services is to ensure thatthe patient, or the patient’s representative, isprovided information necessary to enablehim/her to evaluate a proposed surgery beforeagreeing to the surgery. Typically, this infor-

or other exception applies. State law will govern whowill be considered a legally authorized surrogate deci-sion maker. For example, depending on the laws, thisperson may be a designated health care proxy,spouse, or an adult next-of-kin.

Consider the following example: a healthy adultpatient who presents for elective surgery is competentand has capacity to consent for a surgical procedure.The same patient has an unexpected outcome, is in theintensive care unit, intubated and sedated, andrequires a second operation. The patient will now nothave capacity to consent for the second surgery,requiring the consent discussion to occur between thesurgeon and the patient’s authorized decision maker.

Disclosure of InformationObtaining informed consent requires active com-

munication between physician and patient. The com-munication process is an ethical obligation of thepractice of medicine and a legal requirement perstatute and case law in all 50 States.2 The goal is toprovide the patient with sufficient information toallow him or her to understand the nature of the med-ical problem; the indications for treatment; the mate-rial risks, benefits, and alternatives to treatment; andthe consequences of refusing treatment. It is only thenthat the patient can make an informed choice withrespect to suggested therapy. The informed consentdiscussion should allow a meaningful opportunity tohave questions considered and answered.

What constitutes “sufficient information”? Moststates use a “reasonable person” standard (see above),although there are some that rely on a “professionalpractice” standard. The informed consent discussionshould focus on the indications for the proposed treat-ment, a description of the procedure in terms a layper-son can understand, and an explanation of availablealternatives. A frank disclosure of material risks of therecommended and alternative treatments is impor-tant. Material risks are those that a reasonable personwould want to be made aware of before deciding toundergo or reject the recommended therapy. Materialrisks include those that occur commonly, but havelittle long-term consequence, as well as those that arerare but may result in severe, long-term morbidity ormortality. A recent informal survey of both privateand academic institutions across the country revealedthat the following “common” risks of general anes-thesia are frequently disclosed: possible oral or dentaldamage, sore throat, hoarseness, postoperativenausea and vomiting, drowsiness, and urinary reten-tion. Disclosure of more severe risks includes possibleawareness, postoperative visual loss, aspiration, neg-ative pressure pulmonary edema, organ failure,malignant hyperthermia, drug reactions, and the riskof failure to recover from the anesthetic, coma, ordeath. For regional anesthetics, common risks often

mation would include potential short andlonger term risks and benefits to the patient ofthe proposed intervention, including the like-lihood of each, based on the available clinicalevidence, as informed by the responsible prac-titioner’s professional judgment. Informedconsent must be obtained, and the informedconsent form must be placed in the patient’smedical record, prior to surgery, except in thecase of emergency surgery.

The interpretive guidelines further state

It should be noted that there is no specificrequirement for informed consent within theregulation at §482.52 governing anesthesia ser-vices. However, given that surgical proceduresgenerally entail use of anesthesia, hospitalsmay wish to consider specifically extendingtheir informed consent policies to includeobtaining informed consent for the anesthesiacomponent of the surgical procedure.

Securing a patient’s consent for medical treatmentis a process requiring effective communicationbetween doctor and patient. Increasing numbers ofpatients view the doctor-patient relationship as a part-nership and expect to be actively engaged in the deci-sion-making processes governing their health care.

There are several elements intrinsic to theinformed consent process:

Competence and CapacityA detailed discussion of the terms competence and

capacity is beyond the scope of this article. The termcompetence refers to a patient’s legal authority to makedecisions.

Adult patients, generally considered patients whoare 18 or older, are presumed legally competent tomake health care decisions unless otherwise deter-mined by a court. Consent to treat a minor must begiven by a parent or legal guardian unless state lawrecognizes certain conditions that may qualify as anexception to the general requirement for parental orguardian consent. For example, depending upon thestate law, minors may be legally authorized to consentto their own health care if the patient is a parent; ispregnant and consenting for prenatal care; is married;is otherwise emancipated; or is in the active military.

“Capacity” refers to a determination made bymedical professionals that a patient has the ability tomake a specific decision at a specific time. To havecapacity, patients must have the ability to understandand reason about their medical conditions, and toappreciate the indications, risks, benefits, and alterna-tives to proposed treatments. It is the physician’sresponsibility to determine if a patient lacks capacityto a reasonable degree of medical certainty. If apatient lacks capacity, consent must be obtained froman authorized decision maker, unless an emergency


“Consent,” From Preceding Page

Standardized Consent Process May Be Useful

disclosed encompass prolonged numbness, “spinalheadache,” backache, and failure of the regional tech-nique. Less common but severe risks frequently dis-cussed include bleeding, infection, nerve damage,persistent weakness or numbness, seizures, coma,and death.

Introduction of uncommon, but potentially devas-tating risks in the holding area, immediately preoper-atively, is suboptimal for patients and uncomfortablefor anesthesia professionals. This is especially prob-lematic if their surgical colleagues do not habituallydisclose specific risks that are known, uncommon, butsignificant sequelae of certain types of surgeries. Con-sider the risk of postoperative visual loss that has beenassociated with major reconstructive spine surgery,cardiac surgery, and extensive ENT procedures. It isconceivable that patients presented with the possibil-ity of sustaining permanent visual impairment for thefirst time immediately prior to surgery may wish toreconsider or delay their decision to proceed with theproposed treatment. A better approach may be uti-lization of a standardized, institutional consentprocess developed by the surgical and anesthesia pro-fessionals who routinely care for these patients.

In addition to discussion of risks, benefits, andalternatives, some states require disclosure of theidentity of all persons reasonably anticipated to beinvolved in the patient’s anesthetic care. Absent awritten informed consent document naming all of themembers of the anesthesiology department, this mayprove to be problematic.

Practitioner’s PersonalRecommendation

An important part of the informed consentprocess is offering the patient one’s professional opin-ion of the best options given the skill set of those pro-viding the anesthesia, knowledge of the patient'scomorbities, knowledge of the patient’s comorbidi-ties, and the surgeon’s preferences. Important to thispart of the discussion is an explanation of the prosand cons of the recommended technique as well as theback-up approach. It is important to appreciate thedifferences between persuasion, manipulation, andcoercion in presenting this information to the patient.

Autonomous AuthorizationFollowing a discussion of indications for the ther-

apy, disclosure of material risks, benefits, and alterna-tives, and having questions answered, the patient is ina position to make an informed decision. The patient’sauthorization to proceed with a proposed course oftreatment is an expression of his/her right of self-determination and is the basis for informed consent.

DocumentationIt is important to record the informed consent

process in the medical record. Many organizations areadopting a separate, written informed consent docu-ment for administration of anesthesia. Some statesrequire this, but there are other reasons to considerusing this approach: common risks of all techniquescan be clearly detailed; patient-specific risks can be

added in longhand; the patient and a witness sign theform; and it allows efficient documentation of theinformed consent process for the growing number ofpatients who require anesthesia for a non-surgicalprocedure. Other organizations rely on the surgicalconsent form to document consent to anesthesia. Thispractice is problematic as the consent document maybe completed in the surgeon’s office before the patienthas an opportunity to talk with an anesthesiologist ornurse anesthetist; reliance on the surgeon to conductan informed consent discussion for anesthesia pre-sumes that they are as competent as an anesthesiaprofessional to do this. Informed consent for anes-thesia should be provided by those who are compe-tent to do so. This important task pertains to a uniquescope of practice and should not be delegated to thoselacking this specialized knowledge and training.

Dr. O’Leary is an Associate Professor of Anesthesiol-ogy, Vice Chair for Clinical Affairs, and Director of Pre-operative Services at SUNY Upstate Medical University,Syracuse, New York. Ms. McGraw is Associate Counsel atSUNY Upstate Medical University, Syracuse, New York.

References

1. American Society of Anesthesiologists syllabus on ethics1999: introduction to informed consent. Park Ridge, IL:American Society of Anesthesiologists, 1999:A-1. Avail-able at: http://www.asahq.org/publicationsAndSer-vices/ EthicsSyllabus.pdf. Accessed April 4, 2008.

2. American Medical Association. Professional resources(legal issues) informed consent. Available at:http://www.ama-assn.org/ama/pub/category/4608.html Accessed on March 15, 2008.

by Jens Chapman, MD

Without doubt, the subjects of posterior ischemicoptic neuropathy (PION), specifically, and periopera-tive blindness, in general, remain particularly bitterand challenging aspects of surgical care for all partiesinvolved. Despite best efforts by many dedicatedresearchers there continues to be a lack of under-standing of the true incidence of this potentially dev-astating event, with many of its pathophysiologiccauses and potential for intraoperative monitoringunclear. Sadly, prevention efforts for PION and actualtreatment remain at least equally as elusive to date.As far as we now know, major reconstructive spinesurgery is one of the subspecialties more prevalentlyaffected by perioperative visual loss (POVL), withmagnitude and duration of surgery as well as posi-tioning identified as potential contributing factors.

In this context, preoperative counseling ofpatients achieves a higher relevance than might usu-ally be considered for adverse occurrences consideredexceedingly rare by many surgeons. Similar to other

well-recognized devastating perioperative events,such as death, paralysis, and stroke, blindness, due toits potential impact on patients’ lives, should receiveequal recognition in discussions with patients prior toengaging in elective procedures. Of course this dis-cussion is difficult in many ways, since the topic ofblindness especially strikes many patients entirelyunprepared as they contemplate a procedure such aselective spine surgery. With no firm footing as to dataon incidence and clear prevention strategies availableto clinicians, entering this area of discussion isundoubtedly uncomfortable for many of us surgeons.As we strive for excellence in all aspects of health caredelivery and are often challenged to present complexclinical information pertinent to specific conditions topatients in a meaningful condensed fashion, theadded discussion of such extraneous sounding eventsas POVL may sound like an unwanted distractionfrom our essential mission. However, having person-ally been involved in the care of patients who haveexperienced POVL for unknown reasons, there is littledoubt that a clear preoperative discussion of this

entity helps set the stage for a continued, productivephysician-patient interaction in the unlikely case ofits actual occurrence. As devastated as patients, theirfamilies, and all affected care providers are aboutunexpected significant POVL, the most meaningfulcare under such circumstances can be provided in anatmosphere of trust and open communicationbetween these affected parties. As spine surgeons,we are striving to increase awareness about POVLthrough several of our professional societies. I per-sonally view preoperative consenting with inclusionof perioperative blindness as a first step to raisingdisease awareness as well as diagnosis and treat-ment. Through more transparent documentation,we all can hope to make headway on the physiology,prevention, monitoring, and eventual treatment ofthese conditions.

Dr. Chapman is Professor and Director, Spine Service,and holder of the Hans Jöerg Wyss Endowed Chair at theUniversity of Washington, Seattle, WA.

Spine Surgeons Striving to Increase POVL Awareness


Failure to check anesthesia equipment prior touse can lead to patient injury or “near misses.”1

Checking equipment has also been associated with adecreased risk of severe postoperative morbidityand mortality.2 Indeed, a pre-use anesthesia appara-tus checkout recommendation (AACR) was devel-oped many years ago and widely accepted as animportant step in the process of preparing to deliveranesthesia care.3 Despite the accepted importance ofthe 1993 AACR, available evidence suggests that it isnot well understood and not reliably utilized byanesthesia providers.4,5 Furthermore, anesthesiadelivery systems have evolved to the point that onecheckout procedure is not broadly applicable to allanesthesia delivery systems currently on the market.For these reasons, a new approach to the pre-useAACR has been developed. The primary goals ofthis new approach are to have a procedure that isapplicable to all anesthesia delivery systems, andone that will be reliably performed.

The effort to revise the AACR was initiated by theCommittee on Equipment and Facilities at the 2003annual ASA meeting after recognizing that the 1993AACR did not apply to modern anesthesia deliverysystems. A task force was established consisting ofrepresentatives from major anesthesia deliverysystem manufacturers, the American Association ofNurse Anesthetists (AANA), The American Society ofAnesthesia Technicians and Technologists (ASATT),and the ASA. The task force met for the first time atthe 2004 ASA meeting while working continuouslyvia e-mail since 2003. The result of this process is adocument entitled “Recommendations for Pre-Anes-thesia Checkout Procedures (2008)” and a growinglibrary of checklists for checking individual anesthe-sia delivery systems. This information is available onthe ASA website in the Clinical Information section(http://www.asahq.org/clinical/fda.htm).

checklists will typically require <5 minutes at thebeginning of the day, and <2 minutes between cases,but will provide you with the confidence that themachine will be able to provide all essential life sup-port functions before you begin a case.

The 2008 AACR recommends that 15 separateitems be checked or verified at the beginning of eachday, or whenever a machine is moved, serviced, or thevaporizers changed (Table 1). Eight of these itemsshould be checked prior to each procedure (Table 2).Some of these steps may be part of an automatedcheckout process on many machines. Following these

New Guidelines Available forPre-Anesthesia Checkout

by Jeffrey M. Feldman, MD, MSE; Michael A. Olympio, MD; Donald Martin, MD; Adam Striker, MD

While chatting with a patient about to undergo a laparoscopic cholecystectomy, you administer an inductiondose of propofol and an intubating dose of vecuronium. The patient loses consciousness and spontaneous respira-tion ceases. You adjust the mask on the patient’s face to establish a secure fit and squeeze the reservoir bag, only tofind that you are unable to deliver a positive pressure breath. A quick visual inspection of the breathing circuit doesnot reveal the cause of the problem. Can you reliably ventilate this patient before he becomes hypoxic? Is an alterna-tive method of ventilation readily available and functioning? Is there a reliable source of oxygen? Furthermore, youare using a relatively new anesthesia machine that performs an automated checkout procedure. What functions ofthe anesthesia machine did the automated checkout actually evaluate? Did you perform a thorough check of themachine before use that could have detected the source of this problem?

TABLE 1

Recommended Essential Steps in a Pre-Anesthesia Checkout ProcedureTO BE COMPLETED DAILY, OR AFTER A MACHINE IS MOVED OR VAPORIZERS CHANGED

ITEM TO BE COMPLETED RESPONSIBLE PARTY

Item #1: Verify Auxiliary Oxygen Cylinder and Manual Ventilation Device (Ambu Bag) are Available & Functioning. Provider and Tech

Item #2: Verify patient suction is adequate to clear the airway. Provider and Tech

Item #3: Turn on anesthesia delivery system and confirm that ac power is available. Provider or Tech

Item #4: Verify availability of required monitors, including alarms. Provider or Tech

Item #5: Verify that pressure is adequate on the spare oxygen cylinder mounted on the anesthesia machine. Provider and Tech

Item #6: Verify that the piped gas pressures are ≥ 50 psig. Provider and Tech

Item #7: Verify that vaporizers are adequately filled and, if applicable, that the filler ports are tightly closed. Provider or Tech

Item #8: Verify that there are no leaks in the gas supply lines between the flowmeters and the common gas outlet. Provider or Tech

Item #9: Test scavenging system function. Provider or Tech

Item #10: Calibrate, or verify calibration of, the oxygen monitor and check the low oxygen alarm. Provider or Tech

Item #11: Verify carbon dioxide absorbent is fresh and not exhausted. Provider or Tech

Item #12: Perform breathing system pressure and leak testing. Provider and Tech

Item #13: Verify that gas flows properly through the breathing circuit during both inspiration and exhalation. Provider and Tech

Item #14: Document completion of checkout procedures. Provider and Tech

Item #15: Confirm ventilator settings and evaluate readiness to deliver anesthesia care. (ANESTHESIA TIME OUT) Provider

See “Guidelines,” Next Page


Early in the process of developing the new recom-mendations, the task force recognized that a singlecheckout recommendation could not be applicable toall modern anesthesia delivery systems. Not only doesequipment design differ, but the automated checkoutprocedures built into many modern systems do notcheck all of the items that require attention, and varyfrom machine to machine. As a result, the task forcehas developed a guideline which describes the itemsthat should be checked prior to use, rather than howeach item should be checked. Actual checklists foreveryday use will be based upon the guideline, but tai-lored to the equipment and resources available at aspecific anesthetizing location. As a complement to theguideline, reference checklists are being developed foruse by practitioners and departments interested inrevising their checkout procedures. As new anesthesiadelivery systems are adopted, revised checkout proce-dures will be required as the traditional AACR doesnot apply to modern equipment.

The task force also recognized that complexity isan obstacle to completing the checkout procedure.Therefore, the group worked hard to differentiate theitems that must be checked by a clinician, from thoseitems that could be checked by appropriately trainedanesthesia technicians or clinical engineers. Depart-ments that have skilled technician and engineeringsupport may be able to develop checkout proceduresthat utilize these individuals, thereby reducing thetime required from clinicians and increasing compli-ance with checkout procedures. The guidelines indi-cate which items could be checked by a technicianalone or in conjunction with the anesthesia provider.Notwithstanding the role of the technician, the guide-lines emphasize, however, that the ultimate responsi-bility for insuring that equipment functions properlylies with the anesthesia provider.

The Task Force further realized a need to empha-size requirements for safe delivery of anesthesia care,and listed these at the beginning of the recommenda-tions. These requirements are the underlying rationalefor the guideline, which specifies what should bechecked prior to administering anesthesia. Therequirements are

• Reliable delivery of oxygen at any appropriateconcentration up to 100%.

• Reliable means of positive pressure ventilation.

• Backup ventilation equipment available and func-tioning.

• Controlled release of positive pressure in thebreathing circuit.

• Anesthesia vapor delivery (if intended as part ofthe anesthetic plan).

• Adequate suction.

• Means to conform to standards for patient monitoring.

The new guidelines for Pre-Anesthesia Checkoutwere approved in the Spring of 2007 by the ASA lead-ership as a work product of the Committee on Equip-ment and Facilities. Since that time, the ASATT, theAANA, and The American Academy of AnesthesiaAssistants (AAAA) have endorsed the document. TheFDA had endorsed the 1993 recommendations thathave been removed from their website, but the FDAhas agreed to provide a link on their website to theASA website where the new information will reside.The FDA has also endorsed the new guidelines aseducational information.

Now that guidelines for checkout procedureshave been developed, it is essential that cliniciansbe trained to utilize these procedures effectively.This is especially true when a new anesthesia deliv-ery system design is put into service. New designshave significant differences from legacy systems.

The APSF has spearheaded the “Technology Train-ing Initiative,” described on their website athttp://www.apsf.org/initiatives/technology_train-ing.mspx, to promote critical training on new, sophis-ticated, or unfamiliar devices that can directly affectpatient safety. The results and recommendations oftheir October 2007 “Workshop on Formal Trainingand Assessment before Using Advanced MedicalDevices in the Operating Room” are published in theprevious issue of the APSF Newsletter.

It remains to be proven if the goals of this effortwill be realized. All anesthesia providers are encour-aged to review the new guidelines and develop check-out procedures for use in their own practices. Thelibrary of checklists on the ASA website is intended tofacilitate the process of developing local checkout pro-cedures. We will continue to add to the library ofsample checklists under the direction of Adam Strikerfrom the University of Missouri, Kansas City. The ASAis urging the FDA to consider the recommendations inthe guideline when evaluating automated self-tests aspart of the 510K approval process of new anesthesiadelivery systems. Our Task Force believes thatproviders who adopt this new approach will havetaken all possible steps to eliminate the risk of patientinjury due to anesthesia equipment malfunction.

References1. Cooper JB, Newbower RS, Kitz RJ. An analysis of major

errors and equipment failures in anesthesia management:considerations for prevention and detection. Anesthesiol-ogy 1984;60:34-42.

2. Arbous MS, Meursing AE, van Kleef JW, de Lange JJ,Spoormans HH, Touw P, Werner FM, Grobbee DE.Impact of anesthesia management characteristics onsevere morbidity and mortality. Anesthesiology2005;102:257-68.

3. Anesthesia Apparatus Checkout Recommendations, 1993.Available at: http://www.osha.gov/dts/osta/anesthetic-gases/index.html#Appendix2. Accessed March 13, 2008

4. March MG, Crowley JJ. An evaluation of anesthesiologists'present checkout methods and the validity of the FDAchecklist. Anesthesiology 1991;75:724-9.

5. Lampotang S, Moon S, Lizdas DE, Feldman JM, Zhang RV.Anesthesia machine pre-use check survey: preliminaryresults. (abstract) Anesthesiology 2005;103(Suppl):A1195.

Task Force Members: Russell C. Brockwell, MD; JerryDorsch, MD; Susan Dorsch, MD; James Eisenkraft, MD;Jeffrey Feldman, MD (Task Force Chair); Julian Goldman,MD; Carolyn G. Holland, CRNA, MSN (AANA); Tom C.Krejcie, MD; Samsun Lampotang, PhD; Donald Martin,MD (Chair, ASA Committee on Equipment and Facilities);Julie Mills (GE Healthcare); Michael A.Olympio, MD;Gerardo Trejo (ASATT).

Contributors: (Individuals who have contributed in somefashion in the process of developing the new checkout guide-lines): Abe Abramovitch (Datascope); Charles Biddle,CRNA, PhD; Robert Clark (Dräger Medical); Ann Culp,CRNA, MSN; Chad Driscoll, CRNA, MHS; Ann Graham,CRNA (FDA); Marc Jans (Dräger Medical); MichaelWilkening (Dräger Medical); William Norfleet, MD (FDA).

TABLE 2

Recommended Essential Steps in a Pre-Anesthesia Checkout ProcedureTO BE COMPLETED PRIOR TO EACH PROCEDURE

SUBSET OF ITEMS IN THE DAILY CHECKLIST TO BE COMPLETED BETWEEN CASES RESPONSIBLE PARTY

Item #2: Verify patient suction is adequate to clear the airway. Provider and Tech

Item #4: Verify availability of required monitors, including alarms. Provider or Tech

Item #7: Verify that vaporizers are adequately filled and if applicable that the filler ports are tightly closed. Provider

Item #11: Verify carbon dioxide absorbent is not exhausted. Provider or Tech

Item #12: Breathing system pressure and leak testing. Provider and Tech

Item #13: Verify that gas flows properly through the breathing circuit during bothinspiration and exhalation. Provider and Tech

Item #14: Document completion of checkout procedures. Provider and Tech

Item #15: Confirm ventilator settings and evaluate readiness to deliver anesthesia care. (ANESTHESIA TIME OUT) Provider

Taskforce Recognizes Complexity of Checkout“Guidelines,” From Preceding Page


by Aleeta Somers-DeHaney, MD, and Joan Christie, MD

AbstractPurpose: This case report and review describe a

patient who sustained a burn in the operating roomsecondary to an alcohol-based skin preparation. Thepurpose of the report is to inform anesthesia profes-sionals that such burns may occur at great distancefrom the airway and in the absence of supplementaloxygen as the oxidizer.

Clinical Features: An obese adult patient under-went a femoral distal bypass graft under generalendotracheal anesthesia. The skin was prepared andlater re-prepared with an alcohol-based solution thatmay have saturated skin folds over time producingvapors under the drapes. A sterno-like fire burned thepatients’ leg after the vapors were exposed to the elec-trocautery.

Conclusions: Alcohol prep solutions are fre-quently used in the operating room. Certain precau-tions must be observed to prevent fires. Room air,trapped alcohol vapors, plus electrocautery are suffi-cient to produce a fire. This case illustrates that suchevents may occur far from the airway or an exogenousoxygen source.

IntroductionThe true incidence of operating room fires is

unknown since there is no central reporting facilityto track such data, and cases are underreported dueto liability issues. The ECRI, an independent non-profit health services agency, estimates about 100such fires occur in the US annually.1 In June 2003 theJoint Commission on Accreditation of HealthcareOrganizations (JCAHO) published a Sentinel EventAlert on surgical fires.2 Before the sentinel event alertall data regarding surgical fires were anecdotal andcollected via multiple agencies with no single report-ing mechanism.3

Anesthesia professionals are well aware of thepossibility of operating room fires involving theairway, warming devices, and IV bags.4 The anesthe-siology primary literature, texts, and presentations atprofessional meetings contain numerous reports andreviews of the phenomenon of airway fire.4-6 The riskof operating room fire from alcohol-based solutionshas not been well-described in anesthesiology jour-nals. Barker et al. reported experimental data and acase of a patient on supplemental oxygen who wasburned from vaporized isopropyl alcohol prep in a“closed tent.”7 In Barker’s report the ignition sourcewas electrocautery and the oxidizer was mask oxygenat 6 liters per minute. Although the fuel source wasdisputed in a subsequent letter to the editor byBruley,8 there have been a few other reports of alco-

Our case clearly illustrates that alcohol-basedsolutions can cause OR fires even in the absence ofsupplemental oxygen, and we report this case toinform anesthesia professionals and to underscore theimportance of proper surgical prep in patient safety.

A combination of 3 factors involving alcohol oralcohol prep solutions can lead to fire or burns:

1. Solution may wick to the patient’s hair and linensor pool on skin thus retarding drying time.

2. Drapes may be applied before the solution is com-pletely dry and alcohol vapors may becometrapped under surgical drapes.

3. Repreparation of an area increases the chance thatthe solution may pool and not thoroughly dry.

If these conditions occur, an electrocautery orother heat source may ignite the alcohol vapors. Bothof these factors may have contributed to the fire in thiscase. The patient was obese, and solution may havepooled in skin folds or drape crease. Reprep of theskin may have exacerbated the pooling effect.

Previous cases of alcohol-based fire have alldescribed an oxidizer in close proximity to the fueland heat sources.10,11 The usual oxidizer describedwas supplemental oxygen administered via mask ornasal cannulae. Our patient was unusual in thatalthough his trachea was intubated the surgical sitewas as far away as it could be from the airway. Thusthe oxidizer was room air (21% oxygen).

This fire was not detected during the case, as theburning vapors did not result in visible ignition. Thesurgeon felt a transient flash of heat as the sole indica-tor of the vapor fire beneath the drapes. He inter-preted the sensation as indicative of a pinhole in hisglove allowing a slight cautery hand burn.

Manufacturer’s instructions for the correct appli-cation of alcohol-based prep solutions have longwarned about the flammability of the alcohol in solu-tion and the need for adequate drying time. In Octo-ber 1997, suppliers revised labeling to instruct users toprevent the solution from pooling, blot any excesssolution, remove soaked drapes, and so forth.13 Sup-pliers require sales representatives to provide annualoperating room in-service training to customers.

The ECRI has made the following recommenda-tions for the use of alcohol-based prep solutions in theoperating room:14

1. The manufacturer’s instructions should be read andfollowed. Only skin preps and kits with clear andexplicit instructions and prominent warningsshould be purchased.

hol-based fires in the operating room.9 All of thereports thus far have involved fires in close proximityto an oxygen source near the airway.

We report the case of a patient undergoing a periph-eral vascular procedure who sustained a 1% total bodysurface area burn after his skin was prepared with a74% alcohol/iodophor liquid prep solution.

Case Report: Intraoperative Burn

An obese, adult patient was scheduled as an out-patient for unilateral femoral distal bypass. The patientwas taken to the OR and anesthesia was induced withmidazolam, propofol, succinylcholine, and rocuro-nium. His trachea was orally intubated and anesthesiawas maintained with sevoflurane and 30% oxygen.After intubation, the patient’s leg was prepared withthe 74% alcohol-based prep solution. Midway throughthe case the skin was reprepared. The surgeon reporteda heat sensation briefly during the case. About two-thirds into the procedure, the surgical drapes ignitedunder the patient’s left knee. Flames were extinguishedimmediately. Two oval burn areas behind the left kneewere noted. The surgeon was present, completedsurgery, and applied silversulfadiazine cream anddressing. The patient's neuromuscular blockade wasreversed and his trachea was extubated. He was takento the PACU in stable condition.

Consultation with a burn specialist was obtainedpostoperatively. The wounds included a 2nd degreeburn to the left posterior thigh, 3 x 3 cm deep to fullthickness; and a 2nd degree burn to the left posteriorpopliteal fold, 4 × 1 cm. The consultation assessmentwas that the patient had a less than 1% total body sur-face flame burn to the left lower extremity. Conserva-tive management with silver sulfadiazine dressingchanges was recommended with burn clinic follow-up.

DiscussionOur search of the US Food and Drug Administra-

tion’s (FDA) Manufacturer and User Device Experi-ence (MAUDE) database, using the keywords alcoholand fire revealed that 25% of reports specifically asso-ciate alcohol-based solutions with surgical fires orpatient burns. A recent closed claims anesthesiologyreport contrasted causes of burns prior to 1995 andsubsequent to that date.4 The percentage of firescaused by cautery (excluding primary cautery burns)increased from about 12% to 19% over the studyperiod. Thus, multiple data sources suggest thatcautery fires and fires involving alcohol-based prepsolutions are becoming more prevalent as a percent-age of operating room fires. There are only a fewreports in the anesthesiology literature of alcohol-based OR fires,7 and all occurred near the airway. Therole of alcohol-based surgical prep solutions in oper-ating room fires has been disputed. See “Fire,” Next Page

OR Fire Occurs in Absence of OxygenEnriched Environment: A Case Report


2. Surgical, emergency department, and all appropri-ate personnel should be alerted and made aware ofthe problem.

3. Alcohol based prep solution solution should beapplied like paint; it should not be laid on in athick, drippy, runny coating that could lead toexcessive drying times.

4. The drapes should not be applied until after theprep has fully dried as shown by loss of shine ofthe film. This may take several minutes.

5. Liquid prep that has dripped away from the surgi-cal site should be blotted with gauze spongesbefore it can soak into any absorbent material.Pooled prep solution should be wicked with gauzesponges instead of blotted or wiped so that theantimicrobial film is maintained on the skin.

6. If prep solution wicks into a material, staff mustreplace the material or allow sufficient time (possi-bly longer than 10 minutes) for the solution to drybefore the drapes are applied.

7. If alcohol-based preps are used, ensure that solu-tion does not soak into hair or linens. Sterile towelsshould be placed to absorb drips and runs and theyshould be removed before draping. Daubing ofprep pooled on skin (e.g., umbilicus, cricoid notch)may be necessary.

8. Use incise drapes if possible. If the incise materialdoes not adhere to the patient, the prep is likely stillwet and the patient should be redraped once theprep is fully dry.

9. During surgery be aware of any sudden flash ofheat. Such a flash of heat may indicate an occultalcohol fire. Search for smoldering materials andremove them.

We concur with the ECRI recommendationsabove. Anesthesiologists, nurse anesthetists, andanesthesiologist assistants are already informed andvigilant about heat sources and anesthetic gas oxi-dizers, including oxygen, particularly around theairway. In this unusual case, the oxidizer was roomair, the fuel was alcohol vapor from the prep solu-tion, and the fire was far from the airway. We wish toheighten awareness of the potential risk to patientsfrom alcohol prep solutions and to stress the impor-tance of strict adherence to the ECRI recommenda-tions for the safe application of alcohol-based skinpreparations.

Dr. Christie is an associate professor of anesthesiologyat the University of South Florida College of Medicine inTampa, FL.

Dr. Somers-DeHaney is a senior resident in anesthe-siology at the University of Miami in Miami, FL.

References1. A clinician’s guide to surgical fires: How they occur, how

to prevent them, how to put them out. Health Devices2003;32:5-24. Erratum in: Health Devices 2003;32:176.

2. Joint Commission on Accreditation of healthcare orga-nizations: Sentinel Event Alert 29: preventing surgicalFires, June 24, 2003. http://www.jointcommission.org/SentinelEvents/SentinelEventAlert/sea_29.htm. AccessedMay 8, 2008.

“Fire,” From Preceding Page

ECRI Recommendations Decrease Risks3. Joint Commission International Center for Patient Safety:

Preventing surgical fires: who needs to be educated? JtComm J Qual Patient Saf 2005;31:522-527.

4. Kressin KA: Burn injury in the operating room: a closedclaims analysis. ASA Newsletter 2004;68(6):9-11.

5. Cheney FW, Posner KL, Caplan RA, Gild WM. Burnsfrom warming devices in anesthesia: a closed claimsanalysis. Anesthesiology 1994;80:806-810.

6. Ehrenwerth J, Seifert HA. Fire safety in the operatingroom. ASA Refresher Courses in Anesthesiology. Ameri-can Society of Anesthesiologists. 2003;31:25-33.

7. Barker SJ, Polson JS. Fire in the operating room: a casereport and laboratory study. Anesth Analg 2001;93:960-965

8. Bruley ME, de Richemond AL. Supplemental oxygenversus latent alcohol vapors as surgical fire precursors.Anesth Analg 2002;95:1464-5.

9. Meltzer HS, Granville R, Aryan HA, et al. Gel Based sur-gical preparation resulting in an operating room fireduring a neurosurgical procedure. J Neurosurg (Pediatrics3)2005;102:347-349.

10. Spigelman AD, Swan JR. Skin antiseptics and the risk ofoperating theatre fires. ANZ J Surg 2005;75:556-8.

11. Tooher R, Maddern GJ, Simpson J. Surgical fires and alco-hol-based skin preparations. ANZ J Surg 2004;74:382-5.

12. Hazard Report: Fire Hazard Created by the Misuse ofDuraPrep Solution. Health Devices 1998;27(11):400-402.

13. National guideline Clearinghouse: HYPERLINK"http://www.guideline.gov/"www.guideline.gov :ECRI. A Clinician's guide to surgical fires: how theyoccur, how to prevent them, how to put the out. HealthDevices 2003 Jan; 32(1) :5-24

14. Hazard report: improper use of alcohol-based skin prepscan cause surgical fires. Health Devices 2003;32(11): 441-443.

Letter to the Editor

Reader ExaminesAccident RelatedTraitsTo the Editor:

As I pilot I’m interested that anesthesia is tryingto apply aviation principles to accident prevention.The FAA has been collecting accident reports for 60years now, and the same accidents are still happen-ing no matter what has been tried.

A few years ago a study was done to look at whatpersonality traits contributed to accidents, and fromthis a series of tests were developed to look for thesetraits in student pilots.

I actually talked to David Gaba about trying todo the same thing for anesthesia, but the Gulag gottoo busy to work on it. Table 1 outlines the traits.

Table 1. The Five Antidotes

Hazardous Thought Antidote

Anti-Authority

“Don’t tell me.” “Follow the rules. They are usually right.”

Impulsivity

“Do something—quickly!” “Not so fast. Think first.”

Invulnerability

“It won’t happen to me.” “It could happen to me.”

Macho

“I can do it.” “Taking chances is foolish.”

Resignation

“What’s the use?” “I’m not helpless.”

There is a fine line between macho and anti-authority.About 80% of all accidents are anti-authority related.

It would be interesting to look at closed claimsand see if this holds true for anesthesia. Since every-one is competing for residents, I doubt there wouldbe support for psychological screening of residents.

I’m sure readers saw the recent article on theneurosurgery problems in Rhode Island. They seemto fall into the macho/anti-authority class.

Colin McKinleyWinston-Salem, NC


Dear SIRS

The information in this column is provided forsafety-related educational purposes only, and doesnot constitute medical or legal advice. Individual orgroup responses are only commentary, provided forpurposes of education or discussion, and are neitherstatements of advice nor the opinions of APSF. It isnot the intention of APSF to provide specific medicalor legal advice or to endorse any specific views or rec-ommendations in response to the inquiries posted. Inno event shall APSF be responsible or liable, directlyor indirectly, for any damage or loss caused or allegedto be caused by or in connection with the reliance onany such information.

Dear SIRS refers to the Safety Infor-mation Response System. The purposeof this column is to allow expeditiouscommunication of technology-relatedsafety concerns raised by our readers,with input and responses from manufac-turers and industry representatives. Thisprocess was developed by Drs. MichaelOlympio, Chair of the Committee onTechnology, and Robert Morell, Editor ofthis newsletter. Dr. Olympio is oversee-ing the column and coordinating thereaders’ inquiries and the responsesfrom industry. Dear SIRS made itsdebut in the Spring 2004 issue.

S AFETY

I NFORMATION

R ESPONSE

S YSTEM

Dear SIRS:

We have just installed new GE Aisys anesthesiamachines that use the 7900 SmartVent®. This ventila-tor uses 2 breathing circuit flow sensors, which havea pressure sensor tube on each side of a small mylarflap. I understand how a pressure drop over a fixedresistance can be used to calculate flow, but this is avariable resistor because the flap opens as flowincreases. So how does this thing work? In otherwords, how do they calculate flow given both a pres-sure variable and a variable resistance? ARRRGGH-HHHH!!!!

James F. Szocik, MDUniversity of Michigan

In Response:

Dear Dr. Szocik,

Flow sensors are a critical monitoring and feed-back-regulating component of modern anesthesiamachine ventilators, and this type is common to manyof the GE-Datex machines. Dräger Medical, Inc., andDatascope, Inc., on the other hand, utilize a differenttype of flow sensor (a hot-wire anemometer, e.g., inFabius®, Apollo®, and Anestar® machines.) This ques-tion about the GE variety originally appeared in the

Society for Technology in Anesthesia (STA) listserv,with numerous responses from their membership.With their permission to reproduce this question, andto expand the understanding of flow sensor technolo-gies, we asked the experts from GE Healthcare andDräger Medical to enlighten us. I have included someadditional questions for them to consider: How is theinformation used by the ventilator, with particularregard to the inspiratory versus expiratory sensor?Under what conditions has this technology failed, oris likely to fail?

Michael A. Olympio, MDChair, Committee on Technology

In Response:

Dear Dr. Szocik,

Various technologies are used to measure airwaygas flow and volume deliveries. These include pneu-motachometers, hot wire anemometers, rotating vanespirometers, and ultrasound flowmeters. Each ofthese technologies offers different benefits and draw-backs depending on their underlying property usedto detect flow.

See “Dear SIRS,” Next Page

How Do Flow Sensors Work?

Figure 1. GE Healthcare flow sensor. In response to increasing gas flow, the flapper of the variable orifice opens more widelyto decrease resistance to flow, thereby straightening the differential pressure vs. flow response.


A pneumotachometer uses a restrictor in the gasflow passage to create a pressure drop that can besensed by a differential pressure transducer. (Note: Itis the difference and not the pressure from each sideof the orifice that is being measured.) Each outputsignal from the pressure transducer consistently rep-resents a unique gas flow rate, and is calibrated toaccurately report the measurement in gas flow rate.An orifice is a simple and inexpensive construction fora flow restrictor. The disadvantage of a fixed orifice isits non-linear relationship between the differentialpressures and the gas flow rates. The size of the fixedorifice is a compromise between a tolerable flow resis-tance at high flow rates, and adequate obstruction tocreate detectable differential pressures at low flowrates. If the selection of orifice size favors the low flowsensitivity, the pressure transducer runs out of mea-surement range at high flows. If the orifice size favorshigh flow range, the pressure transducer would notreceive detectable signal for measurement sensitivityat the low flow rates. The necessary compromise inmeasurement range also affects computation ofpatient tidal and minute volumes, which are derivedby integrating gas flows in the airway. The demandfor large flow range measurement is needed to caterto size of patients. Fixed orifice sensors require sepa-rate flow sensors for adult and pediatric patients. Thevariable orifice flow sensor elegantly solves this prob-lem, allowing a single sensor for adults, pediatricpatients, high flows, and low flows.

The 7900 Smartvent® in the Aisys®, Avance®,Aespire®, and Aestiva® Anesthesia System uses asingle restrictor comprised of a variable orifice to mea-sure gas flows in both pediatric and adult patients.Variable orifice flow sensing technology dates back tothe 1930s, but its practical adoption as airway flow

meters began many decades later with a flap thatopens with increase gas flows (Figure 1). The 7900Smartvent® flow sensors are available in a Mylar orstainless steel material. The former can be used inMagnetic Resonance Imaging (MRI) suites in con-junction with the Aestiva® MRI anesthesia system.The stainless steel flow sensors are autoclavable, andare designed for long-term use.

At very low flows, the flap is in its natural state toform a small slit orifice. This small orifice allows aneasily measurable differential pressure signal to begenerated despite the low flow. As the gas flowincreases, the flap opens more, reducing resistance togas flow. At a given flow rate, the differential pressureacross the deflected (more open) flap is lower than atits natural position. As in a fixed orifice, there is a one-to-one correspondence between each flow rate andthe pressure drop that it creates. This allows the dif-ferential pressure measurement to be uniquely con-verted to the gas flow rate. Furthermore, the variableorifice straightens the pressure-flow characteristic toprovide linear and uniform measurement sensitivitythrough its measured range.

While each individual variable orifice is uniqueand consistent, they differ slightly from transducer totransducer. To keep the tight specified accuracy, eachtransducer is individually calibrated in each directionof gas flow, and the calibrated table is electronicallystored in the variable orifice connector. The 7900Smartvent® “reads” the calibration table and convertsthe measured differential pressures across the variableorifice to the flow rates. The flow sensor is also cor-rected for variations in gas composition, altitude, andcircuit pressures to provide accuracy in clinical use.

The 2 variable flow sensors provide many usefulfeatures to deliver and monitor patient ventilation.

Fresh gas flow to, and gas compression in, the Anes-thesia Breathing System change the gas volume deliv-ered by the ventilator flow valve to the patient. The7900 Smartvent® uses the inspiratory flow sensor tomeasure the inspired tidal volume and compensatebreath-to-breath the inspired tidal volume delivery tomatch the user setting. This flow sensor is also sensi-tive in detecting small flow rates, as low as200 ml/min, at the start of a breathing effort to triggera synchronized assisted or supported breath in spon-taneously breathing patients, including neonates. Inaddition, the ventilator computes tidal and minutevolumes from the flow measurement. They are usedto detect low minute ventilation and apnea. Its abilityto detect bidirectional flow is used to monitor unex-pected flow reversal, such as caused by a stuck openinspiratory or expiratory check valve, in the Anesthe-sia Breathing System.

Tidal volumes and minute ventilation obtainedfrom the expiratory flow sensor are used to detect andalarm on low minute ventilation and apnea. This flowsensor also acts as a safety check to constantly moni-tor the appropriate volume delivered by the ventila-tor, and alarms when the expired gas volume variessignificantly from the setting. Such variations may becaused by leaks or valve or flow sensor issues. Mois-ture is an inherent by-product of carbon dioxideabsorption in the circle breathing system, especially inlow flow anesthesia practice. Moisture may causesmall beads of water or a foggy appearance in theflow sensor, which does affect performance. Pooledwater in the flow sensor or water in the sensing linescould result in false readings. The Off-set Flow Sensor(Figure 2a) is designed to address this issue by addingtaper and grooves in the sensor housing to channelwater away from the affected areas, as shown inFigure 2b. The Off-set flow sensor allows the use of

Manufacturers Explain Flow Sensor Technology

Figure 2a. External view of the GE Healthcare Off-set flowsensor for use in moist airways gas passages.

“Dear SIRS,” From Preceding Page

See “Dear SIRS,” Next PageFigure 2b. Cut away view of Off-set flow sensor body showing the taper and grooves design.

Grooves

Taper


the flow sensors in high humidity, without resortingto system heating.

We hope that this brief answers your questionand highlights the practical and beneficial use of ourdual breathing circuit flow sensor in patient ventila-tion during anesthesia.

Robert Tham, PhDAdvanced Technology GroupGE Healthcare, Life Support Solutions

Michael OberleR&D Manager—Anesthesia SystemsGE Healthcare, Life Support Solutions

General References

1. Osborn JJ. A flowmeter for respiratory monitoring, CritCare Med, 1978; 6: 349-351.

2. Avance User’s Reference Manual (M1077716), 2007.Datex-Ohmeda, Inc, a General Electric Company.

3. EXPLORE! Aisys®, 2005. Datex-Ohmeda, Inc, a GeneralElectric Company.

In Response:Dear Dr. Szocik,

We thank the editor for the opportunity torespond to this general topic. As the technology forthe instrumentation of our anesthesia systems andmonitors has improved, our trust and reliance uponthe data that the sensors provide has risen in relation.Drs. Szocik and Olympio make a valuable observationthat we should understand the behaviors and limita-tions of the technology, otherwise we run the risk ofmisinterpreting the situation presented. The anesthe-sia machine, ventilator, or monitor relies upon theinformation that it receives from the sensor technolo-gies employed.

The measurement of respiratory gases in anesthe-sia has to take into account not only the gas mixture,which changes during the procedure, but also chang-ing airway pressures and humidity. Water vapor inthe respiratory gases is an inevitable reality in the OR.Indeed, it is desirable to humidify and warm the freshgas prior to it being delivered to the patient. In orderto minimize the impact of water vapor on the breath-ing system and the respiratory gas measurement,Dräger Medical many years ago decided the best

“Dear SIRS,” From Preceding Page approach was to maintain the water as vapor ratherthan allow it to condense out in the absorber system,which is typically the coldest part of the gas path.This removes the historical limitation for the use oflow and minimal fresh gas flow techniques.

The hot-wire anemometer used by Dräger in thecurrent range of anesthesia devices has the charac-teristic of being insensitive to water vapor and has avery low resistance and no moving parts. The sensorworks by measuring the cooling effect of the gaspassing over a thin, heated wire. The higher the cool-ing effect, the higher will be the flow of gas. In orderto be accurate, the sensor needs to know the densityof the gas, which is provided to the measurementsystem by the gas analysis data. This same technol-ogy is used internally in the GE Aisys® anesthesiamachine for the measurement of fresh gas flow aswell as in many other industries including aeronau-tics where the hot wire anemometer has become thestandard for air speed measurement in aircraft.

Robert Clark MEng, MBADirector of Marketing, Perioperative CareDräger Medical, Inc.Telford, PA, USA

Gas Measurements Affected By Water VaporDear SIRS

George A. Schapiro, ChairAPSF Executive Vice PresidentDan Brennan ..............................................Abbott LaboratoriesSean Lynch ..................................................Anesthesia Healthcare

PartnersCliff Rapp ....................................................Anesthesiologists Professional Insurance

CompanyNassib G. Chamoun ..................................Aspect Medical SystemRepresentative pending ............................Baxter HealthcareMichael S. Garrison....................................Becton DickinsonTimothy W. Vanderveen, PharmD..........Cardinal HealthcareRoger S. Mecca, MD ..................................CovidienThomas W. Barford....................................Datascope CorporationRobert Clark................................................Dräger MedicalKevin L. Zacharoff, MD ............................EKR TherapeuticsMike Gustafson ..........................................Ethicon Endo-SurgeryCarolyne Coyle ..........................................GE HealthcareTim Hagerty................................................HospiraSteven R. Block ..........................................LMA of North AmericaJoe Kiana......................................................Masimo

Nancy Stahulak ..........................................Medical ProtectiveBrian Eckley ................................................MGI Pharma, Inc.Representative pending ............................OrganonDominic Corsale ........................................OridionWalter Huehn ............................................Philips Medical SystemsEdward C. Mills ........................................Preferred Physicians Medical Risk

Retention GroupKeith Serzen ................................................ResMedMichael Stabile, MD ..................................Safer SleepAndrew Rose ..............................................Smiths MedicalDominic Spadafore ....................................SomaneticsJoseph Davin ..............................................SpacelabsPeter McGregor ..........................................Teleflex MedicalChristopher M. Jones ................................Tensys MedicalRepresentative pending ............................The Doctors CompanyTerry Wall ..................................................Vital SignsAbe AbramovichCasey D. Blitt, MDRobert K. Stoelting, MD

A N E S T H E S I A P A T I E N T S A F E T Y F O U N D A T I O N

CORPORATE ADVISORY COUNCIL


Anesthesia Patient Safety FoundationCorporate Donors Founding Patron ($500,000 and higher) American Society of Anesthesiologists (asahq.org)

CommunityDonors (includes Anesthesia Groups, Individuals,Specialty Organizations, and State Societies)Grand Sponsor ($5,000 and higher)Alabama State Society of AnesthesiologistsAmerican Academy of Anesthesiologists

Assistants American Association of Nurse AnesthetistsAsheville Anesthesia AssociatesFlorida Society of AnesthesiologistsDr. and Mrs. Thomas R. HillIndiana Society of AnesthesiologistsIowa Society of AnesthesiologistsFrank B. Moya, MD, Charitable FoundationNorth American Partners in AnesthesiaRobert K. Stoelting, MDValley Anesthesiology FoundationVance Wall FoundationWilmington Anesthesiologists, PLLC,

Wilmington, NC

Sustaining Sponsor ($2,000 to $4,999)Anaesthesia Associates of MassachusettsAnesthesia Consultants Medical GroupAnesthesia Resources ManagementArizona Society of AnesthesiologistsCritical Health Systems, Inc.Nassib G. ChamounGeorgia Society of AnesthesiologistsMadison Anesthesiology ConsultantsMassachusetts Society of AnesthesiologistsMichigan Society of AnesthesiologistsMinnesota Society of AnesthesiologistsOhio Society of AnesthesiologistsOld Pueblo Anesthesia GroupPennsylvania Society of AnesthesiologistsPhysician Specialists in AnesthesiaProvidence Anchorage Anesthesia

Medical GroupSociety of Cardiovascular AnesthesiologistsTennessee Society of AnesthesiologistsDrs. Mary Ellen and Mark Warner

Contributing Sponsor ($750 to $1,999)Affiliated Anesthesiologists of Oklahoma

City, OKAmerican Association of Oral and

Maxillofacial SurgeonsAmerican Society of Critical Care

AnesthesiologistsAmerican Society of PeriAnesthesia Nurses J. Jeffrey Andrews, MD

Anesthesia Associates of Northwest Dayton, Inc.

Anesthesia Services of BirminghamAssociated Anesthesiologists of St. Paul, MNAssociation of Anesthesia Program DirectorsSorin J. Brull, MDRobert A. Caplan, MDFrederick W. Cheney, MDCalifornia Society of AnesthesiologistsConnecticut State Society of AnesthesiologistsJeffrey B. Cooper, PhDDr. Robert and Mrs. Jeanne CordesSteven F. Croy, MDMark T. Destache, MD (Associated

Anesthesiologists)District of Columbia Society of

AnesthesiologistsDavid M. Gaba, MDJohn H. Eichhorn, MDWilliam L. Greer, MDIllinois Society of AnesthesiologistsRobert. H. Intress, MDKansas City Society of AnesthesiologistsKentucky Society of AnesthesiologistsJohn W. Kinsinger, MDKunkel-Shaker FamilyLorri A. Lee, MDRodney C. Lester, CRNAEdward R. Molina-Lamas, MDMaryland Society of AnesthesiologistsMichiana Anesthesia CareMissouri Society of AnesthesiologistsRobert C. Morell, MDNebraska Society of AnesthesiologistsJohn B. Neeld, MD, in honor of Eugene P.

Sinclair, MDNevada State Society of AnesthesiologistsNurse Anesthesia of MaineOhio Academy of Anesthesiologist AssistantsOklahoma Society of AnesthesiologistsOregon Society of AnesthesiologistsOregon Anesthesiology GroupPhysician Anesthesia ServicePittsburgh Anesthesia AssociatesSanta Fe Anesthesia Specialists Society of Academic Anesthesia ChairsSociety for Ambulatory Anesthesia Society of Neurosurgical Anesthesia and

Critical CareSociety for Pediatric AnesthesiaStockham-Hill FoundationTexas Association of Nurse AnesthetistsTexas Society of AnesthesiologistsDr. and Mrs. Donald C. TylerWashington State Society of AnesthesiologistsWisconsin Association of Nurse AnesthetistsWisconsin Society of Anesthesiologists

Sponsor ($100 to $749)Sean S. Adams, MDAlaska Association of Nurse Anesthetists

Ellen Allinger, AA-C and James Allinger, MDKristy Z. Baker, MDRobert L. Barth, MDRam J. Bhat, MDTerrence D. Bogard, MDPhilip F. Boyle, MDE. Jane Brock, DOJames W. Chapin, MDLillian K. Chen, MDSampath K. Chennamaneni, MDMarlene V. Chua, MDJohn L. Clark, MDMelvin A. Cohen, MDColorado Society of AnesthesiologistsKathleen A. Connor, MDStephen C. Cotton, MD David M. Clement, MDPaula A. Craigo, MDDennis D. Crane, DOMark L. D’Agostino, MDEric R. Davies, MDGlenn DeBoer, MDDavid R. DeMask, CRNAJohn DesMarteau, MDSteven R. Dryden, MDJames E. Duckett, MDWalter C. Dunwiddie, MDMarcel E. Durieux, MDRobert J. Egan, MDJan Ehrenwerth, MDJames Ellwood, MDBruce W. Evans, MDThomas R. Farrell, MDHerbert M. Floyd, MDAnthony M. Frasca, MDB. L. Friedberg, MDJane C. K. Fitch, MD/Carol E. Rose, MDAnuradha J. Ghogale, MDIan J. Gilmour, MDGregory E. Ginsburg, MDBarry M. Glazer, MDRichard Gnaedinger, MDJames D. Grant, MDJoel G. Greenspan, MDGriffin Anesthesia AssociatesJohn A. Hamel V, MDAlexander A. Hannenberg, MDTimothy N. Harwood, MDDaniel E. Headrick, MDWilliam D. Heady, CRNAPeter L. Hendricks, MDJames S. Hicks, MDAnna Barczewska-Hillel, MDDavid P. Holder, MD Dr. and Mrs. Glen E. HolleyVictor J. Hough, MDHoward E. Hudson, Jr., MDEric M HumphreysJay C. Horrow, MDRobert E. Johnstone, MD

Kaiser Permanente Nurse AnesthetistAssociation

Tamos Kallos, MDSteven M. Karon, MDScott D. Kelley, MDC. Herschel King, MDDaniel J. Klemmedson, DDS, MDKansas Society of AnesthesiologistsBettyLou Koffel, MDMichael G, Kral, MDForrest Krause, MDGopal Krishna, MDGeorge Lederhaas, MDAnn S. Lofsky, MDJason P. Lujan, MDAnne Marie Lynn, MDDavid P. Maguire, MDMaine Society of AnesthesiologistsAlan P. Marco, MDMaryland Association of Nurse AnesthetistsGregory B. McComas, MDE. Kay McDivitt, MDTom L. McKibban, CRNACora B. McKnight, CRNAMedical Anesthesiology Consultants

CorporationTricia A. Meyer, Pharm DMississippi Society of AnesthesiologistsRoger A. Moore, MDErvin Moss, MDJoseph T. Naples, MDDr. Eric A. NelsonCarlos E. Neumann, MDNew Hampshire Society of AnesthesiologistsNew Jersey State Society of AnesthesiologistsNew Mexico Society of AnesthesiologistsDan Nguyen, MDL. Charles Novak, MDDenise O’Brien, RNRobert H. Odell, Jr., MD, PhDMichael A. Olympio, MDFredrick K. Orkin, MDCarmelita S. Pablo, MDSrikanth S. Patankar, MDPennsylvania Association of Nurse

AnesthetistsMukesh K. Patel, MDGaylon K. Peterson, MDBeverly K. Philip, MDJames H. Philip, MDPhysician Specialists in AnesthesiaRichard C. Prielipp, MDDebra D. Pulley, MDRhode Island Society of AnesthesiologistsHenry C. Safford, CRNAEduardo A. Salcedo, MD (Salmon Medical

Innovations)Drs. Chris and David SantamoreJo Ann and George Schapiro

Philanthropic Fund

Larry M. Segers, MDGeorge P. Sessions, MDMuthia Shanmugham, MBLarry D. Shirley, MDHarinder P. Singh, MDAndrew O. Smith, MDLiberacion L. Soriano, MDSociety for Obstetric Anesthesia and

PerinatologySociety for Technology in AnesthesiaSouth County Anesthesia AssociationSouth Carolina Society of AnesthesiologistsGustav E. Staahl, MDShepard and Marlene StoneRohan Sundaralingam, MDGeraldine A. SyverudGary E. Takahashi, DOHaig G. Tozbikian, MDUniversity of Maryland Department

of AnesthesiologyVermont Society of AnesthesiologistsPrem K. C. Vindhya, MDVirginia Society of AnesthesiologistsMark M. Vogelhut, MDMartin D. Wagner, MDT. F. Walker, MDThomas L. Warren, MDMatthew B. Weinger, MDDr. and Mrs. Donald L. WeningerWest Virginia State Society of AnesthesiologistsAndrew S. Weisinger, MDDr. and Mrs. WetchlerWichita Anesthesiology, CharteredG. Edwin Wilson, MDWisconsin Academy of Anesthesiologist

AssistantsJohn M. Zerwas, MDPhilip J. Zitello, MD

In MemoriamIn memory of Dr. Marc Balin (anonymous)n memory of Louis S. Blancato, MD (Dr. and

Mrs. Bernard V. Wetcheler, MD)In memory of Maurice Chait, MD

(Texas Society of Anesthesiologists)In memory of Bertram Watts Coffer, MD

(American Society of Anesthesiologists)In memory of Margie Frola, CRNA

(Sharon Rose Johnson, MD)In memory of Stephen D. Graham, MD

(Texas Society of Anesthesiologists)In memory of Laurie A. Noll, MD

(The Coursin family)In memory of Bonnie J. Slarsky

(Jeffrey B. Cooper, PhD)In memory of Dr. Richard Strausbaugh

(Anesthesia Associates of York, PA)In memory of Rex E. Thomas, MD

(Texas Society of Anesthesiologists)In memory of Leroy D. Vandam, MD

(Dr. and Mrs. George Carter Bell)

Note: Donations are always welcome. Send to APSF; c/o 520 N. Northwest Highway, Park Ridge, IL 60068-2573 (Donor list current through May 9, 2008)

Organon (organon.com)Philips Medical Systems

(medical.philips.com)

Grand Patron ($150,000 to $199,999)Anesthesia Healthcare Partners, Inc.

(AHP) (ahphealthcare.com)

Sponsoring Patron ($75,000 to $149,999)

GE Healthcare (gemedical.com)

Benefactor Patron ($25,000 to $49,999)Abbott Laboratories

(abbott.com)

Aspect Medical Systems(aspectms.com)

Covidien (covidien.com)

Hospira (hospira.com)Masimo Corporation

(masimo.com)

Supporting Patron ($15,000 to $24,999)Baxter Anesthesia and Critical Care (baxter.com)Cardinal Health, Alaris Products (alarismed.com)Dräger Medical (draeger.com)Preferred Physicians Medical (ppmrrg.com)

Patron ($10,000 to $14,999)DocuSys (docusys.net)Ethicon Endo-Surgery (ethiconendo.com)iMDsoft (imd-soft.com) Oridion Capnography (oridion.com)Somanetics Corporation (somanetics.com)Spacelabs Medical (spacelabs.com)

Sustaining Donor ($5,000 to $9,999)Anesthesiologists Professional Assurance Company

(apacinsurance.com)Becton Dickinson (bd.com)Datascope Corporation (datascope.com)EKR Therapeutics (ekrtx.com)LMA of North America (lmana.com)Medical Protective (medpro.com)ProAssurance (proassurance.com)ResMed (resmed.com)Safer Sleep LLC (safersleep.com)Smiths Medical (smiths-medical.com)Teleflex Medical (teleflexmedical.com)Tensys Medical (tensysmedical.com)

The Doctors Company (thedoctors.com)Vital Signs (vital-signs.com)Sponsoring Donor ($1,000 to $4,999)Anesthesia Business Consultants (anesthesiallc.com)Allied Healthcare (alliedhpi.com)Armstrong Medical (armstrongmedical.net)B. Braun Medical, Inc. (bbraunusa.com)Cook Critical Care (cookgroup.com)Intersurgical, Inc. (intersurgical.com)King Systems (kingsystems.com)Medical Education Technologies, Inc. (meti.com)Micropore, Inc. (extendair.com)TRIFID Medical Group LLC (trifidmedical.com)

W.R. Grace (wrgrace.com)Corporate Level Donor ($500 to $999)Belmont Instrument Corporation (belmontinstru-

ment.com)ProMed Strategies, LLCSharn Anesthesia, Inc.Wolters KluwerParticipating AssociationsAmerican Association of Nurse Anesthetists

(aana.com)Subscribing SocietiesAmerican Society of Anesthesia Technologists and Tech-

nicians (asatt.org)

MGI Pharma, Inc.(mgipharma.com)

Cardinal Health Foundation(cardinal.com)


The information provided is for safety-related educational purposes only, and does not constitute medical or legal advice. Individual or group responses are onlycommentary, provided for purposes of education or discussion, and are neither statements of advice nor the opinions of APSF. It is not the intention of APSF to pro-vide specific medical or legal advice or to endorse any specific views or recommendations in response to the inquiries posted. In no event shall APSF be responsible orliable, directly or indirectly, for any damage or loss caused or alleged to be caused by or in connection with the reliance on any such information.

See “Q&A,” Next Page

Dear Q&A,

Last year, the Executive Committee of theAPSF considered whether or not it would besafe to re-use the syringe of medication withinthe syringe pump, if in fact the small-boreextension tubing was changed betweenpatients. We did not know whether it wouldbe possible for retrograde contamination tooccur, if in fact the syringe was pressurizedand the tubing was connected to a proximalintravenous port. Although there was varia-tion in individual response, our opinionmostly, if not unanimously, opposed suchpractice. We knew that previous studies haddemonstrated via Hemoccult® testing thatinvisible blood could migrate many inches ret-rograde up free-flowing IV tubing, at least.Does your committee have any opinion orfacts in this matter?

Dear Executive Committee,

Your question generated numerous emphaticresponses that are listed here:

I would never use IV sets or infusions frompatient to patient regardless of extensiontubing or type of pressurized pump.

I am strongly against the practice of using asyringe for more than one patient. There are theinfectious disease issues, which include boththe theoretical retrograde contamination withbacteria, viruses, and prions and also the issueof having the medication drawn out of a sterilevial and remaining in a syringe for longer peri-ods than if it were freshly drawn. Additionally,there is also the concern that a drug labelingerror (though less likely with propofol) couldnow affect more than one patient.

I would think that a "multiple use" practicewould be a legal problem as well.

As a former hospital administrator, I can’timagine such a practice being defensible.Therefore I would avoid it.

Reuse of a syringe with change of tubingbetween patients is totally unacceptable,

administration of all pharmaceuticalagents provided by each manufacturershall be read and followed. Drug admin-istration by injection offers many oppor-tunities for contamination. These includepreviously used needles, syringes, drugadministration sets, intravenous tubing,and fluid containers.

#11. Do not reprocess for multiple useany intravenous fluids, tubing, or otherintravascular infusions or connectors thatare single-use disposable items. Thisincludes transducers, tubing, and otheritems that make contact with the vascularsystem or other body compartments.

In our Clinical Engineering department weinspect syringe pumps for delivery accuracy.After multiple uses, we notice that the syringeintegrity begins to degrade. This is manifestedby the downstream occlusion pressure contin-uing to rise, secondary to increasing frictionbetween plunger and barrel. We experiencedsome syringes causing false occlusion alarmsduring these tests. Such testing is performedusing just water, and changing the fluidmedium would undoubtedly have an impact.Many operators would not think the syringe iswearing out when it “looks” perfectly fine.You cannot determine the self-integrity of amultiple-used syringe unless you attach apressure meter to it. Furthermore, fluid deliv-ery rate can influence the friction; slower rateshave more problems. These are just some tech-nical things to consider if using a syringe mul-tiple times.

Editor’s Note:

Subsequent to the consideration of thisquestion and the answers provided above,the highly publicized incident of actualcross-contamination in Nevada1 madenational headline news, and in February2008 the U.S. Department of Health andHuman Services Centers for Disease Controland Prevention released a Fact Sheet, “APatient Safety Threat–Syringe Reuse,” online

although one type of tubing contains a one-wayvalve with a forward cracking pressure ofapproximately 100 mmHg and a reverse crack-ing pressure that is much, much higher.Nonetheless, reuse of syringes with a change oftubing between patients is totally unacceptable.

In my opinion, currently UN-controlled sub-stances with potential for abuse might needinternal control or at least internal audit capa-bility. This is one more reason for not reusing apropofol syringe between patients, for example.

There is no possible justification for such prac-tice, no matter how small the risk of cross-con-tamination.

I am in full agreement . . . absolutely no justifi-cation for re-using the syringe. Interestingly, Iparticipate in providing anesthesia and medicalleadership for surgical mission work (e.g.,Guatemala) on a regular basis. We are alwaysburdened with very limited resources, butwould never support or condone such a practice.

I think providing opinion is helpful, but pro-viding evidence is better. A short search ofPubMed found several pertinent articles. Amore detailed search would probably findmore specific articles; however, the generalconsensus of these articles (from many coun-tries and over many years) is that a tubing setshould be used with only one patient. Byextension, the suggested practice is wrong andvery likely dangerous.

It seems that there is pretty uniform con-sensus against this. The professional soci-eties should also be a resource, and here,for example, are relevant quotes from theAANA's infection control manual (avail-able online at http://aana.com/resources.aspx?ucNavMenu_TSMenuTargetID=51&ucNavMenu_TSMenuTargetType=4&ucNav-Menu_TSMenuID=6&id=732):

Administration of Drugs and SolutionsThe potential for infection and transmis-sion of microorganisms exists during theadministration of drug therapy. Instruc-tions for preparation, storage, and

Numerous questions to the Committee on Technology are individually and quickly answered each quarter by knowledgeable committee members. Manyof those responses would be of value to the general readership, but are not suitable for the Dear SIRS column. Therefore, we have created this simple columnto address the needs of our readership.


at http://www.cdc.gov/ncidod/dhqp/ PS_Syrin-geReuseFS.html, to patients who may have beenexposed to multiple use vials/syringes/needles.That fact sheet, in addition to advising suchpatients, contains a link for health care providers:2http://www.cdc.gov/ncidod/dhqp/gl_isola-tion_standard.html, regarding standard precau-tions for preventing transmission of infectiousdiseases, specifically including “Safe injection prac-tices” under section IV.H. The precautions andpractices state

Do not administer medications from asyringe to multiple patients, even if theneedle or cannula on the syringe ischanged. Needles, cannulae and syringesare sterile, single-use items; they shouldnot be reused for another patient nor toaccess a medication or solution that mightbe used for a subsequent patient.

The following comment was opined after reve-lation of the Nevada event:

I think it is correct but insufficient to con-demn such a practice without acknowl-edgement of the factors that could lead tosyringe re-use. Addressing the symptomswithout trying to cure the underlying “dis-ease” would be but a short-term solution.Thus, we must investigate, understand,and eliminate the factors that predisposeone to the practice of unsafe medicine: asclinicians, we face severe production pres-sure and take “shortcuts” in the process ofsafe preparation of medication; we maygive in to the financial importance thatothers, or we ourselves, place on speed andefficiency; or we may sincerely believe thatwe are preventing waste, thereby reducingthe cost of medicine. An understanding ofthis complex environment may help toeliminate the root cause of such behaviors,which could then facilitate safer practices.

Dr. Olympio

1 Wells A, Harasiim P. Exposure Feared: 40,000 LV clinicpatients urged to be tested for viruses. Syringe reuse atEndoscopy Center of Southern Nevada “common prac-tice.” Las Vegas Review-Journal. Feb. 28, 2008.

2 Siegel JD, Rhinehart E, Jackson M, Chiarello L, and theHealthcare Infection Control Practices Advisory Com-mittee, 2007. Guideline for isolation precautions: pre-venting transmission of infectious agents in healthcaresettings, June 2007.

Nevada EventsPrompt Response

More

“Q&A,” From Preceding PageDear Q&A,

I am a private practice physician at a communityhospital where the administration purchasesand maintains our fleet of anesthesia machines.Several years ago they committed to replace allof our machines. Our understanding was that asingle model of machine would be placedthroughout the facility. Currently we have ablend of manufacturers and models, some ofwhich will not be supported after next year. Weare asking to expedite the purchase process atthis time and make the fleet consistent withinthis facility. I have been asked to provide infor-mation justifying this move. Specifically, I wasasked it there is an ASA standard (or equivalent)addressing the benefits of a single machinemodel within a facility. Or, asked another way,what are the drawbacks of having multipletypes of anesthesia machines within a singlegroup of users? Does such information exist orcan you point me to any resources?

Michael G. Royce, MDTulsa, OK

Dear Dr. Royce,

Thank you very much for your question to theQ&A column. We are unaware of any ASA stan-dards or other recommendations regarding yoursituation, and, a similar question pertaining to anacademic installation is also pertinent. Pleaseallow us to categorize our responses to you.

Confusion. The range of currently availableanesthesia delivery systems includes many dif-ferent models and manufacturers, includingmachines for office-based practice, MRI, andDay Surgery centers. Having multiple modelsand manufacturers in a single operating roomsuite relies on the fact that each provider hasbeen trained on, and maintains intimate famil-iarity with, a much larger spread of features,shortcomings, and quirks, than if a single anes-thesia delivery system were deployed. Attentionmay be misdirected to the operation of the anes-

thesia machine and could have negative conse-quences for the patient.

Education. This immediately brings to mind theDear SIRS article in the Winter 2004 Newsletter.Who will be the key individual or local “cham-pion” for this endeavor, and does he or she meetthe attributes outlined in the article? Will thisindividual have the time, desire, patience, anddiligence to provide training on each machinefor new anesthesiologists, nurse anesthetists,anesthesiologist assistants,anesthesia techni-cians and technologists, and biomedical equip-ment technicians? How will those responsiblefor training receive expensive manufacturertraining on so many machines? The learningcurve for competency on multiple machines willbe far greater than the learning curve for onemachine. Training alone sounds like a near full-time job for someone even with a modestturnover of anesthesia providers. For academicinstitutions, an in-depth approach to trainingresidents cannot be met if the goal is to exposeall residents to such a wide range of machines.How does one handle the first 6 months of anes-thesia training, when students are facing a dif-ferent machine each day while trying to learn somany aspects of anesthesia care?

Interchangeability. The multi-model/manufac-turer selection is even less compelling given thatevery manufacturer and model available offersa unique range of solutions for the clinical prob-lems that providers face. Objectively viewed,while there may be significant differences inoperation and use, there probably are not suffi-cient differences in performance or features tohave some of each available. Other issues, suchas complexity of managing service arrange-ments, interchangeability of vaporizers andother components, familiarity of technical per-sonnel with simple troubleshooting routines,etc., suggest that there are serious problemswith this approach.

Safety. The safety issue is serious, since the"new provider danger period" is significantly

The information provided is for safety-related educational purposes only, and does not constitute medical orlegal advice. Individual or group responses are only commentary, provided for purposes of education or discus-sion, and are neither statements of advice nor the opinions of APSF. It is not the intention of APSF to providespecific medical or legal advice or to endorse any specific views or recommendations in response to the inquiriesposted. In no event shall APSF be responsible or liable, directly or indirectly, for any damage or loss caused oralleged to be caused by or in connection with the reliance on any such information.

Pros and Cons of Multiple Machine Types

See “Q&A,” Next Page


extended, and affected not only by time-on-machine, but now by incidence of exposure toEACH machine. Providers who work intermit-tently (part-time or PRN), are going to be in theposition of working with equipment with whichthey are only marginally familiar. New systemswill incorporate more sophisticated modes ofventilation and monitoring, requiring the oper-ator to be proficient on multiple machines thatthey may work with infrequently. Proficiencymust include topics ranging from basic opera-tion and understanding to the design featuresand troubleshooting. Proliferating anesthesiamachines from multiple vendors, and perhapsmultiple models from the same vendor, couldpotentially become a breeding ground forhuman error, especially in stressful situations.And, if this is a teaching OR, the safety issue iseven more serious, since residents and studentsare trying to learn many diverse aspects of anes-thesia care and should not have their attentiondiverted from patient care to learn the setup,machine checkout, nuances of operation, andtroubleshooting of many different machines.

Technical Support. Issues related to the owner-ship and support of multiple anesthesiamachines from numerous vendors would pre-sent significant challenges to any hospital. Theissues include training of technologists and sup-port staff with documentation of competency,spare machines, spare parts, a variety of dispos-ables, as well as introducing interface complex-ities to patient monitors and record-keepingsystems, and monitoring and maintaining mul-tiple service contracts.

Economics. There are economic reasons to useonly one type of machine, such as volume pur-chase discount, smaller stock of disposables, andlower training costs. For example, oxygen fuelcells and CO2 absorbent cartridges may not beuniversally compatible and would need to be

stocked for each of the machine types. Record-keeping would also vary from machine tomachine and could cause patient record prob-lems. If a patient problem results, the cost todeal with the problem would most likely be atleast the cost differential of buying one brand ofmachine over another.

Compromise. If there are multiple machines ina large institution, perhaps the best approachwould be to populate different surgical siteswith different types of machines. For example,the main operating room suite could have asingle type of machine; the outpatient surgerycenter could have another type of machine, andthe pediatric hospital yet another type. For theproviders who live in each one of these singleenvironments, there would be no issue withusing a different machine each day. This mightfit best for academic training programs that typ-ically follow monthly rotations. The anesthesiaproviders at each site would only have to learna single machine, thereby increasing patientsafety and greatly reducing the learning curvefor attaining proficiency.

Summary. Multiple models and manufacturersof anesthesia machines represent a number ofpotential hazards with additional liability, andwill ultimately cost the hospital a great dealmore money to support. Is it appropriate tomake that milieu even more complex to newproviders by adding the difficulties of learninghow to operate and effectively use multiplepotentially very different anesthesia machines?

Additionally, new microprocessor-based anes-thesia machines come with the potential forundiscovered catastrophic failure modes.With multiple new machines the likelihood ofdiscovering some of these modes at an inoppor-tune moment in a given suite of operatingrooms will increase. Our consensus is that theconcept of placing multiple different anesthe-sia machines in a single suite of operatingrooms is seriously flawed.

Hazards of Machine Diversity

More

“Q&A,” From Preceding Page

The information provided is for safety-related educational purposes only, and does not constitute medical orlegal advice. Individual or group responses are only commentary, provided for purposes of education or discus-sion, and are neither statements of advice nor the opinions of APSF. It is not the intention of APSF to providespecific medical or legal advice or to endorse any specific views or recommendations in response to the inquiriesposted. In no event shall APSF be responsible or liable, directly or indirectly, for any damage or loss caused oralleged to be caused by or in connection with the reliance on any such information.

MachineObsolescence

Response to Q&A:

In response to the Q&A article on oldermachines (APSF Newsletter 2008;22(4):78), I wouldlike to report that we are replacing our 2 Narkomen2B machines in 2008 after 24 years of service. The“near” 100% non-failure rate involved only 2 in-flight failures. One was a sticky valve, replaced inflight, and the other an electronic display failureeasily remedied with a replacement board.

Our greatest safety issue over these 24 yearswas certainly not the machine hut the primitiveagent level gauge on the vaporizers. An exceptionto this statement is the Ohmeda Tec 6 plus vapor-izer, with its light and squawk alarm before thevaporizer is empty.

In evaluating the new machine choices avail-able, it is discouraging to still see vaporizers witha 10¢ glass tube for an agent level gauge.

My question is, in light of unwanted patientmovement or patient awareness from an emptyvaporizer, why do we continue to utilize such apoor agent level gauge? Is it a patent restrictionthat allows only the Ohmeda Tec 6 vaporizer tohave a safe agent level alarm? Or is it because weclinicians are requesting the machine engineers toprovide larger drawers, a writing shelf, or a bettercockpit light instead?

I welcome any response.

Robert R. Jirgl, CRNADowagiac, MI

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by Jonathan V. Roth, MD, and Matthias L. Riess, MD, PhD

After a needle is inserted through the stopper of amedication vial, a small piece of the stopper is some-times sheared off (known as coring) and may not benoticed. This small foreign body can then be aspiratedinto a syringe and injected into a patient. For manyyears, the contamination of parenteral fluids andmedications by particulate matter has been recog-nized as a potential health hazard and has been asso-ciated with adverse reactions ranging from clinicallyoccult pulmonary granulomas detected at autopsy tolocal tissue infarction, pulmonary infarction, anddeath.1,2 Riess and Strong recently reported a casewhere a cored piece of stopper blocked the intra-venous infusion of propofol during a total intra-venous anesthetic (TIVA), requiring the immediateinsertion of another intravenous catheter.3 Othershave reported coring when drawing up propofol.4-6

The first author has also experienced coring whendrawing up vecuronium. Although there are no data,it would seem likely that coring events may be bothunrecognized and underreported.

There are strategies that both we and the manu-facturers can employ to help reduce or eliminate therisk of coring. If the needle must pierce a stopper,there is a needle insertion technique that reduces therisk of coring during needle insertion through thestopper of a medication vial.6-7 The needle should beinserted at a 45-60° angle to the plane of the stopperwith the opening of the needle tip facing up (i.e., awayfrom the stopper). A small amount of pressure isapplied and the angle is gradually increased as theneedle enters the vial. The needle should be at a 90°angle just as the needle bevel passes through the stop-per. Second, if the stoppers were made of a materialthat always floated and were of a noticeable color,they would be easier to spot and would be less likelyto be injected in a vertically-oriented syringe. In Riessand Strong’s report, their coring sank to the bottom ofthe propofol vial, thus explaining why it was notnoticed until it blocked the intravenous catheter.3

Also, medications can be drawn up via a needle witha filter such as that found in various spinal anesthetickits. It is unclear whether the incidence of coringvaries with the use of a blunt fill needle versus a con-ventional sharp needle.3,8

Another strategy would be to eliminate the needto pierce a stopper with a needle altogether. This canbe accomplished in several ways. First, a vial can havea stopper held in place by a crimp ring that isdesigned to easily peel off (e.g., 2% lidocaine HCl,Abraxis Pharmaceutical Products, Schaumburg, IL).Alternatively, we can remove a crimped stopper witha pliers-like device (e.g., Kebby Decapper, Kebby

Industries, Inc., Rockford, IL). Additionally, the phar-maceutical manufacturers can provide us with singleuse medication vials where one just pulls off the entiretop (e.g., various local anesthetics from AstraZenecaLP, Wilmington, DE), or where syringes attachdirectly to the vials (e.g., various local anestheticsfrom AstraZeneca LP, Wilmington, DE). Lastly, med-ications can be supplied in prefilled syringes (e.g.,propofol from AstraZeneca LP, Wilmington, DE). Anadditional benefit of not having to pierce a stopper isthat it removes any concern of latex contamination inlatex allergic patients.

We hope this communication will bring to theattention of the readership a probably infrequent butpotentially serious problem that is not well known inthe anesthesia community. We hope this letterprompts the manufacturers to consider an engineer-ing solution, of which several suggestions were pre-sented above. In the meantime, we should utilize thetechnique described above when piercing a stopperwith a needle, which adds no financial cost and takesat most an additional 1 or 2 seconds.

Dr. Roth is an Associate Professor of Anesthesiology atThomas Jefferson School of Medicine, Philadelphia, PA.Dr. Riess is with the Department of Anesthesiology, Med-ical College of Wisconsin, Milwaukee, Wisconsin.

References

1. Lehr HA, Brunner J, Rangoonwala R, Kirkpatrick CJ. Par-ticulate matter contamination of intravenous antibioticsaggravates loss of functional capillary density in postis-chemic striated muscle. Am J Respir Crit Care Med2002;165:514-20.

2. Kirkpatrick JC, Lehr HA, Otto M, Bittinger F, Rangoon-wala R. Clinical implications of circulating particulate con-tamination of parenteral injections: a review. Critical Careand Shock 1999;4:166-73.

3. Riess ML, Strong T. Near-embolization of a rubber corefrom a propofol vial. Anesth Analg 2008;106:1020-1; authorreply 1021.

4. Adachi Y, Takigami J, Watanabe K, Satoh T. [A case ofcoring on using a 1% Diprivan vial] Masui 2001;50:635-6.

5. Shiroyama K. The incidence of "coring" during aspirationof propofol from a 50-ml vial. J Anesth 2001;15:120.

6. Roth JV. How to enter a medication vial without coring.Anesth Analg 2007;104:1615.

7. Turco SJ, King RE. Sterile dosage forms: their preparationand clinical application. Philadelphia: Lea & Febiger, 1974.

8. Riess ML, Strong T. Near-embolization of a rubber corefrom a propofol vial. (response) Anesth Analg2008;106:1021.

Manufacturers Can Also HelpReduce the Chance of Coring

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To the Editor:

We were glad to see positive mention of lipidemulsion therapy for local anesthetic toxicity in theletter by Dr. Baumgarten and again by Dr. Morell in arecent commentary in the APSF Newsletter. Dr. Baum-garten’s note detailed several suggestions for improv-ing safety of peripheral nerve and plexus blocks andreferred to a patient who survived severe, systemicbupivacaine toxicity by virtue of a heroic resuscita-tion—possible only because there happened to be aprimed bypass machine nearby.1 Unfortunately,despite precautions taken to prevent it, local anes-thetic toxicity continues to occur and all patients arenot as lucky, nor all outcomes as favorable. The com-mentary by Dr. Morell reminds readers that lipidemulsion infusion provides a simple, less invasivemethod of treating systemic local anesthetic toxicity.2

There are now several published case reports ofsuccessful resuscitation with lipid emulsion from car-diac arrest from local anesthetic toxicity3-6 and onerelated to bupropion overdose.7 Symptoms of toxicitywere rapidly reversed in all patients, often after fail-ure of standard resuscitative measures includingcountershocks and adrenergic therapy. Notably, allrecovered without cardiac or neurological deficits.Similar cases have also been posted on the educa-

tional website www.lipidrescue.org where cliniciansare encouraged to post their experiences and severalmore are in press (personal communication). Webelieve the scientific evidence and clinical experiencesupporting lipid therapy are now sufficient to justifystocking lipid emulsion at all sites where large dosesof local anesthetics are used.

Paradoxically, a recent survey by Corcoran et al.8found a general lack of coordinated preparation forthese potentially fatal occurrences in US academicanesthesiology departments. The need for a consen-sus in this area was recognized by the Association ofAnaesthetists of Great Britain and Ireland, whichrecently issued guidelines for treating severe localanesthetic toxicity, (http://www.aagbi.org/publica-tions/guidelines/docs/latoxicity07.pdf). This excel-lent document goes some distance to remedying thedeficiency, but only part way. A universally acceptedprotocol for treating systemic local anesthetic toxicitywould reduce treatment variance, improve physicianpreparedness and patient safety, and ultimately con-tribute to the APSF mission: “To ensure that nopatient is harmed by anesthesia.”

Guy Weinberg, MDDavid Mayer, MDChicago, IL

References1. Baumgarten R. Cardiac arrest after popliteal block: Are

there any safety lessons to be learned? APSF Newsletter2006;21:51.

2. Morell R. Intralipid might saves lives as a rescue frombupivacaine toxicity. APSF Newsletter 2007;22:30.

3. Foxall G, McCahon R, Lamb J, et al. Levobupivacaine-induced seizures and cardiovascular collapse treated withintralipid. Anaesthesia 2007;62:516-8.

4. Litz RJ, Popp M, Stehr SN, Koch T. Successful resuscitationof a patient with ropivacaine-induced asystole after axil-lary plexus block using lipid infusion. Anaesthesia2006;61:800-1.

5. Rosenblatt MA, Abel M, Fischer GW, et al. Successful useof a 20% lipid emulsion to resuscitate a patient after a pre-sumed bupivacaine-related cardiac arrest. Anesthesiology2006;105:217-8.

6. Zimmer C, Piepenbrink K, Riest G, Peters J. [Cardiotoxicand neurotoxic effects after accidental intravascular bupi-vacaine administration : Therapy with lidocaine propofoland lipid emulsion.] Anaesthesist 2007;56:449-53.

7. Sirianni AJ, Osterhoudt KC, Calello DP, et al. Use of lipidemulsion in the resuscitation of a patient with prolongedcardiovascular collapse after overdose of bupropion andlamotrigine. Ann Emerg Med 2007.

8. Corcoran W, Butterworth J, Weller RS, et al. Local anes-thetic-induced cardiac toxicity: a survey of contemporarypractice strategies among academic anesthesiologydepartments. Anesth Analg 2006;103:1322-6.

Letter to the Editor

Lipid Emulsion: The Time Has Come for a Consensuson Treating Systemic Local Anesthetic Toxicity

Check out the Virtual Anesthesia Machine Website

and theAPSF Anesthesia

Machine Workbookat

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To the Editor:

In Dr. Ann Lofsky's review of maternal arrestcases for The Doctors Company (Summer 2007 APSFNewsletter), she reported on 8 cases in which patientsin labor suffered respiratory arrest followingepidural anesthesia. For these cases, there was nomention as to whether a test dose was used before thefull anesthetic dose was administered. All the otherpoints noted had to do with the management of atotal spinal block due, apparently, to inadvertentinjection of the agent into the subarachnoid space.

The use of a test dose, to determine whether theneedle or catheter is in the epidural or the subarach-noid, has been standard practice for more than 40years. Whether that simple test was used andrecorded is essential to support the statement in thesummary: “the above cases are a testament to the factthat it still can and does occur—even when currentlyacceptable anesthesia practices are followed.”

This review treats respiratory arrest afterepidural anesthesia as if it were bad luck, or the act ofan evil spirit. That may be true from a lawyer’s pointof view, but it is only a catastrophe (worst case sce-nario) when the “anesthesia provider” is not trainedand equipped to deal with this complication by 1)being aware of its possibility, 2) having the necessaryequipment at hand, and 3) having the training andskill to keep the patient ventilated and the circulationmaintained. Dealing with an unexpectedly apneicpatient is the trained anesthetist’s basic skill, but atleast the basic equipment of an operating room needsto be at hand. (Note the one good outcome in whichthe anesthesiologist acted appropriately.) Epiduralanesthesia under any other circumstances should notbe attempted. It is rarely essential to the safe conductof a delivery.

Van S. Lawrence, MD Minneapolis, MN

Test Dose is Standard Practice


Letters to the Editor

There Is NoSubstitutefor Readingthe LabelTo the Editor:

Once again, I find the material in the APSFNewsletter to be informative and noteworthy. Onceagain, I note in the Winter 2007-08 issue (Vol. 22, No.4) two examples of similar color cues causing confu-sion between 2 very different drugs. Page 79 discussedwhy a “blue-blocker” eye shield changed the color offentanyl labels from the expected blue color to grey,the color of bupivacaine labels. Then, 2 pages later, pic-tures of similar blue and white packaging that causeda near mix-up of 2 rather dissimilar drugs.

I have always thought that these color and shapeclues lead to mistakes when 2 or more drugs aredressed in closely similar clothing. So, why not makeALL labels and ALL drug packaging look as muchalike as possible. Look alike—except for a singular dif-ference—the letters printed on the label; lettersspelling out the name of the drug, as free as possiblefrom color or shape clues. That way, the health careprofessional (no providers here, please) could andwould only learn the name of the drug by actuallyreading the label. There would be, to the extent possi-ble, no color or shape differences in the packaging.

Again, the APSF Foundation and Newsletter arewonderful tools for improving the safety of patientsreceiving the services of anesthesia professionals. I amvery appreciative of your mission and wish you well.Thank you.

Nicholas Workhoven, MD Coos Bay, OR

Labetalol AffectsHemodynamicsTo the Editor:

I read with great interest the Letter to the Editor"Labetalol May Decrease Cerebral Perfusion in BeachChair Position," and wish to thank Dr. Lofsky forpointing out important issues related to the clinicalpharmacology of labetalol. I would like to mentionsome additional supporting and relatively under-appreciated aspects of this drug and would like tostress the need for us to understand each patient'shemodynamic situation and how our actions affect it.

At our institution we frequently monitor cardiacoutput and its components with the esophagealDoppler. Monitoring esophageal Doppler hemody-namics confirms and underscores the fact thatlabetalol's stronger beta-1 blocking decreases heartrate and contractility preferentially. We have seenprofound effects on contractility with this drug,including frequent decreases in aortic peak velocitiesby 50% and greater. Cerebral, as well as overall perfu-sion, is not well supported with low perfusion pres-sure, low cardiac output, and low flow velocities.

Anesthesiologists need to be very certain that anymethod used for decreasing, or increasing, blood pres-sure is the desired mechanism for the given clinical sit-uation. The mechanism of labetalol-reduced bloodpressure is just one example of how little we knowabout each individual's hemodynamics when we lackobjective information regarding left ventricular fillingand emptying characteristics, when we lack real-timedata as to how our treatments affect these, and blindlygive convenient drugs to change the blood pressureone way or another. We need to assure that our thera-peutic actions are providing conditions for safe andfavorable outcomes, and to do so we need to under-stand the hemodynamic situation in real time.

Paul W. Corey, MDSan Diego, California

APSF gratefully acknowledges the support of Cardinal Health Foundation in the full funding of a 2008 APSF Research Grant that will be designated the

APSF/Cardinal Health Foundation Research Award

Supports APSF Research

Reader Calls Attentionto Change FromBaseline PressureTo the Editor:

Since I have spent a significant part of my acade-mic career investigating the fidelity and accuraterecording of invasive blood pressure measurements,I was quite intrigued by the discussion of adverseneurologic outcomes after shoulder arthroscopy inthe beach chair position, and how these adverse out-comes may relate to the measurement of blood pres-sure.1-4 In my opinion Dr. Munis hones in on therelevant issues.4 Transmural pressure at the level ofthe head is absolutely NOT the issue; perfusion pres-sure is! As such, memorizing correction factors forblood pressure at the level of the head (while thepatient is in the beach chair position), while takingreadings at the level of the heart is a waste of time andeffort. Not only is it a waste of time, it diverts one’sfocus from the real issue. As Dr. Munis points out, thereal issue for anesthesiologists is to what degree bloodpressure can be lowered from preoperative levels.What exactly is a safe blood pressure? The problemis—we don’t know. And it is probably true that decre-ments in blood pressures that are safe in somepatients may not be safe in others. Dr. Munis shouldbe commended for directing our attention to the realissue in these tragic cases; and pointing out why weshould not be distracted by the nonissues of trans-mural pressures, altering transducer height, and “cor-rection” formulas.

Bruce Kleinman MDMaywood, IL 60153

References

1. Cullen DJ, Kirby RR. Hazards of beach chair positionexplored (letter 1). APSF Newsletter 2008; 22(4): 81.

2. Budnyk S. Hazards of beach chair position explored (letter2). APSF Newsletter 2008; 22(4): 81.

3. Cucchiara RF. Hazards of beach chair position explored(letter 3). APSF Newsletter 2008; 22(4): 81.

4. Munis J. The problems of posture, pressure, and perfusion:cerebral perfusion pressure defined. APSF Newsletter 2008;22(4): 82-83.


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Also in this issue:

If My Spine Surgery Went Fine, Why Can’t I See?

Ischemic Optic Neuropathy (late examwith optic nerve pallor) (Photo courtesy ofDr. Sohan S. Hayreh, University of Iowa)

Postoperative Visual Loss and Informed Consent

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