American Osteopathic College of Occupational and Preventive Medicine OMED 2013, Mandalay Bay Convention Center, Las Vegas Tuesday, October 1, 2013, Aerospace Day A-1 National Disaster Medical System Preventive /Aerospace/Occupational Medicine Role Allen J. Parmet, MD, MPH, FACPM, FASMA, FACOEM, AIAASM MO1-DMAT [email protected]Disclosure Information Ame rican Osteopathic College of Occupational & Pre ventive Me dicine OMED-Las Vegas, NV-October 1, 2013 Allen J. Parmet, MD I have no financial relationships to disclose. I will not discuss off-label use and/or investigational use in my presentations National Disaster Medical System • United States Department of Health and Human Services (HHS) responsible for managing Federal government's medical response to major emergencies and disasters • NDMS was returned to DHHS (US Department of Health and Human Services) on January 1, 2007 by an Act of Congress). • Federal Partners: FEMA, DoD, DVA National Disaster Medical System (NDMS) Response Teams • Disaster Medical Assistance Team (DMAT) (55) • Disaster Mortuary Operational Response Teams (DMORT) (10) • International Medical Surgical Response Team (IMSURT) (4) • National Veterinary Response Team (NVRT) (10) National Disaster Medical System Disaster Medical Assistance Team (DMAT) Disaster Mortuary Operational Response Team (DMORT) International Medical Surgical Response Team (IMSuRT)
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American Osteopathic College of Occupational and Preventive MedicineOMED 2013, Mandalay Bay Convention Center, Las Vegas
Tuesday, October 1, 2013, Aerospace Day
A-1
National Disaster MedicalSystem
Preventive /Aerospace/OccupationalMedicine Role
Allen J. Parmet, MD, MPH, FACPM,FASMA, FACOEM, AIAASM
Disclosure InformationAmerican Osteopathic College of Occupational & Preventive
Medicine OMED-Las Vegas, NV-October 1, 2013
Allen J. Parmet, MD
I have no financial relationships to disclose.
I will not discuss off-label use and/or investigational usein my presentations
National DisasterMedical System
• United States Department of Health andHuman Services (HHS) responsible formanaging Federal government's medicalresponse to major emergencies and disasters
• NDMS was returned to DHHS (US Departmentof Health and Human Services) on January 1,2007 by an Act of Congress).
International Medical Surgical Response Team(IMSuRT)
American Osteopathic College of Occupational and Preventive MedicineOMED 2013, Mandalay Bay Convention Center, Las Vegas
Tuesday, October 1, 2013, Aerospace Day
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Disaster Medical Assistance Team(DMAT)
A DMAT is a group of professional and para-professional medicalpersonnel (supported by a cadre of logistical and administrativestaff) designed to provide medical care during a disaster or otherevent. NDMS recruits personnel for specific vacancies, plans fortraining opportunities, and coordinates the deployment of theteams.
DMATs are designed to be a rapid-response element to supplementlocal medical care until other Federal or contract resources can bemobilized, or the situation is resolved. DMATs deploy to disastersites with sufficient supplies and equipment to sustain themselvesfor a period of 72 hours while providing medical care at a fixed ortemporary medical care site. The personnel are activated for aperiod of two weeks.
State Disaster Medical AssistanceTeam (DMAT)
MO1-DMAT/MoDRS
The DMAT as a state organizationis a 501.3c taxexemptentitywhich can be activatedbythestate disaster response systemand respond to the governor’srequests to supportmedicalneeds in anyemergency.
Examples in tornados, floods, icestorms augmenting or replacinglocal medical resources,sheltering special needs andinstitutionalized persons.
Aerospace Medicine in DMAT
• Team Occupational Medicine
– Fitness For Duty
– Pre-deployment vaccinations, respirator fits
– Deployment injuries, illness and follow-up
• Deployed Public Health
• Aeromedical Evacuation
MODRS Information: Personnel should check their “go‐kits” Monitor your email closely for any MODRSrelated information Check your personaland family preparednessplans and change the batteries in yourAl l ‐Hazards Weather RadioTHIS DOCUMENT IS FOR OFFICIAL USE ANDINFORMATIONAL PURPOSESONLYAND IS NOT INTENDED TOBE AN OPERATIONSORDER OR MISSIONASSIGNMENT.ADDITIONAL UPDATESWILL BE SENT ASWARRANTED.###
DMATs around the USA Strike Team-Rapid Response Unit4 hours, 5 people, 4 Beds
American Osteopathic College of Occupational and Preventive MedicineOMED 2013, Mandalay Bay Convention Center, Las Vegas
Tuesday, October 1, 2013, Aerospace Day
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Full Team-Mobil Medical Unit24 hours, 50 people, 50 Beds
• 2006-Hurricane Charlie-Punta Gorda, FL
Tornado Response-Joplin, MOMay 22, 2011
Tornado Response-Joplin, MOMay 22, 2011
Casualties158 Dead1,150 Injured450 Patients in St. John’s Hospital$3 Billion damages
Tornado Response-Joplin, MOMay 22, 2011
Timeline:May 22 5:34-6:12 PM CDT-Tornado in Joplin
6:25-Governor declares disaster6:40-MO1-DMAT Activated8:30 First Strike TeamArrives
May 23 2:30 AM-Third Strike Team Arrives2:00 PM-Mobil Medical Unit sets up4:00 PM-Patients transferred from
St. JohnsMay 25 Strike Teams closeMay 29 Mobil Medical Unit turned over
to St. John’s staff and is designatedSt. John’s/Mercy Field Hospital
June 1 DMORT 7 completes casualty IDs
Disaster Mortuary OperationalResponse Teams (DMORTs)
• The National Response Framework (NRF) utilizes the NationalDisaster Medical System (NDMS), as part of the Department ofHealth & Human Services, Assistant Secretary for Preparedness andResponse (ASPR), Office of Preparedness and Operations (OPEO),under Emergency Support Function #8 (ESF #8), Health and MedicalCare, to provide victim identification and mortuary services. Theseresponsibilities include:
American Osteopathic College of Occupational and Preventive MedicineOMED 2013, Mandalay Bay Convention Center, Las Vegas
Tuesday, October 1, 2013, Aerospace Day
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DMORT Teams
• REGION I (ME, NH, VT, MA, CT, RI)• REGION II (NY, NJ, PR, VI)• REGION III (PA, MD, DC, DE, VA, WV)• REGION IV (AL, KY, TN, NC, SC, GA, MS, FL)• REGION V (MN, WI, IL, IN, MI, OH)• REGION VI (NM, TX, OK, AR, LA)• REGION VII (NE, IA, KS, MO)• REGION VIII (MT, ND, SD, WY, UT, CO)• REGION IX (AZ, NV, CA, HI)• REGION X (WA, AK, OR, ID)
International Medical SurgicalResponse Team (IMSURT)
• The International Medical Surgical Response Team(IMSURT) is a National Disaster Medical System (NDMS)team of medical specialists who provide surgical and criticalcare during a disaster or public health emergency.Originally conceived to address the needs of U.S. citizensinjured overseas, the IMSURT role has expanded over theyears to include both domestic deployments, including theWorld Trade Center Bombings and Hurricane Katrina, andinternational deployments, including the earthquakes inBam, Iran, and Port au Prince, Haiti.
• IMSURT personnel are Federal employees used on anintermittent basis to deploy to the site of a disaster orpublic health emergency and provide high quality, lifesaving surgical and critical care.
IMSURT
National Veterinary Response Team(NVRT)
• The National Veterinary Response Team (NVRT) is a cadre ofindividuals within the NDMS system who have professionalexpertise in areas of veterinary medicine, public health andresearch.
• Assessing the Veterinary Medical Needs of the Community• Medical Treatment and Stabilization of Animals• Animal Disease Surveillance
• Zoonotic Disease Surveillance and Public Health Assessments• Technical Assistance to Assure Food Safety and Water Quality
• Hazard Mitigation• Care and Support of Animals Certified as Official Responders
to a Disaster or Emergency
National Veterinary Response Team(NVRT)
Strategic National Stockpile(SNS)
CDC's Strategic National Stockpile (SNS) has largequantities of medicine and medical supplies to protectthe American public if there is a public healthemergency (terrorist attack, flu outbreak, earthquake)severe enough to cause local supplies to run out. OnceFederal and local authorities agree that the SNS isneeded, medicines will be delivered to any state in theU.S. in time for them to be effective. Each state hasplans to receive and distribute SNS medicine andmedical supplies to local communities as quickly aspossible.
American Osteopathic College of Occupational and Preventive MedicineOMED 2013, Mandalay Bay Convention Center, Las Vegas
Tuesday, October 1, 2013, Aerospace Day
A-5
Emergency System for Advance Registration
of Volunteer Health Professionals (ESAR-VHP)
• The Emergency System for Advance Registration ofVolunteer Health Professionals (ESAR-VHP) is a federalprogram created to support states and territories inestablishing standardized volunteer registrationprograms for disasters and public health and medicalemergencies.
• The program, administered on the state level, verifieshealth professionals' identification and credentials sothat they can respond more quickly when disasterstrikes. By registering through ESAR-VHP, volunteers'identities, licenses, credentials, accreditations, andhospital privileges are all verified in advance, savingvaluable time in emergency situations.
Series of CNS DCS Incidents Jan 02-Dec 09• Confirmed cases (16): documented in medical
records• Probable cases (4): reported but insufficient
documentation• Possible cases (0): retrospective reports (unofficial)
by pilots Research Limited to Existing Sources:
• Medical & physiological support records• Flight, maintenance, & safety records
Jersey SL, Hundemer GL, Stuart RP, West KN, Michaelson RS, Pilmanis AA. Neurological
decompression sickness among U-2 pilots: 2002-2009. Aviat Space Environ Med 2011; 82:1-10
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American Osteopathic College of Occupational and Preventive MedicineOMED 2013, Mandalay Bay Convention Center, Las Vegas
Tuesday, October 1, 2013, Aerospace Medicine Day
Distribution A: Approved for public release; distribution is unlimited. Case Number: AFMC-2013-0137, 3 Sep 2013
Patient Characteristics
20 Total Cases – 16 Confirmed, 4 ProbableIncidents• 12 pilots with one incident each• 4 pilots with two incidents each
Pilot Ages: 30 to 48 yo Gender: 15 men, 1 woman BMI: 21 to 32 Prior Medical History:
• All non-smokers• 2 pilots had prior history of rhino-septoplasty for sinus
disease o/w negative
No routine medical use prior to incidents• No medications taken prior to flight• 3 of 16 pilots used dexamphetamine during flight
7 Distribution A: Approved for public release; distribution is unlimited. Case Number: AFMC-2013-0137, 3 Sep 2013
Initial Treatment
Standard of Care
• Aircrew: descend & return ASAP after symptom onset
• Flight Docs: must TREAT if DCS is considered (diagnosis of exclusion)
• ABCs, O2, & transport to nearest hyperbaric chamber
• USN Treatment Table 6; keep treating until symptoms resolve/plateau
Most Cases Received Appropriate Treatment
• 19 of 20 cases received prompt hyperbaric oxygen (HBO) treatment
• Responses varied by case (see following slides)
• Treatment delayed in some cases
• Some patients required multiple HBO treatments
Treatment Delayed Inappropriately – 1 Case
• Combination of factors contributed to delay
• Symptoms resolved after HBO treatment 11 days later
8
Distribution A: Approved for public release; distribution is unlimited. Case Number: AFMC-2013-0137, 3 Sep 2013
Spectrum of ClinicalOutcomes
•In 5/20 (25%) cases, pilots reported DCS symptoms immediately
•Prompt HBO treatment administered
•Full resolution of symptoms with no recurrence or persistence
•In 5/20 (25%) cases, pilots reported DCS symptoms immediately
•Prompt HBO treatment administered
•Full resolution of symptoms with no recurrence or persistence
Expected ClinicalResponse
•4/20 (20%) cases: delayed symptom recognition, reporting, or treatment
•Treatment delayed by hours up to 11 days
•Symptoms resolved with no recurrence or persistence
•4/20 (20%) cases: delayed symptom recognition, reporting, or treatment
•Treatment delayed by hours up to 11 days
•Symptoms resolved with no recurrence or persistence
Good ClinicalOutcome DespiteTreatment Delay
•19/20 (95%) cases received appropriate HBO treatment in theater
•2/20 (10%) cases had recurrent symptoms during commercial flights
•Symptoms recurred in 2 more (10%) after elevation changes while driving
•19/20 (95%) cases received appropriate HBO treatment in theater
•2/20 (10%) cases had recurrent symptoms during commercial flights
•Symptoms recurred in 2 more (10%) after elevation changes while driving
Recurrent SymptomsAfter Treatment
•10/16 (62.5%) pilots reported persistent symptoms for 3 months to 9 years+
•Similar constellation of symptoms (headache, fatigue, irritability, etc.)
•Considered permanent in 2/16 (12.5%) pilots lasting > 6 & 9 years, respectively
•10/16 (62.5%) pilots reported persistent symptoms for 3 months to 9 years+
•Similar constellation of symptoms (headache, fatigue, irritability, etc.)
•Considered permanent in 2/16 (12.5%) pilots lasting > 6 & 9 years, respectively
Persistent orPermanent
Symptoms DespiteAdequate Treatment
**NO FATALITIES**9 Distribution A: Approved for public release; distribution is unlimited. Case Number: AFMC-2013-0137, 3 Sep 2013
Clinical CourseThe Good
9/20 cases with no adverse clinical outcomes• 5/20 (25%) reported promptly (in-flight)• 4/20 (20%) delayed, but no problems after HBO
Delays in treatment varied from a few hoursup to 11 days:• Situational: can’t teleport to a chamber• Pilots: hard to recognize vague symptoms in operational
environment• Docs: some didn’t recognize or know how to treat DCS• Both(?): some pilots still didn’t trust docs (fear of grounding)
Symptoms resolved completely with HBO treatment• No reported recurrent orpersistent symptoms
Returned to flying status after normal exam• 6/9 (67%) of these pilots voluntarily left U-2 program after
incidents Are historical outcomes as rosy as we think?
• Reported permanent symptoms extremely rare• No long-term follow-up in recorded DCS cases in literature
10
Distribution A: Approved for public release; distribution is unlimited. Case Number: AFMC-2013-0137, 3 Sep 2013
• Recurrence of symptoms during commercial flights (2 cases)
• Recurrence of symptoms after elevation changes while driving (2 cases)
• Reported cases responded to repeat treatment with hyperbaric oxygen
14
Distribution A: Approved for public release; distribution is unlimited. Case Number: AFMC-2013-0137, 3 Sep 2013
Clinical CourseThe Ugly
10/16 (62.5%) pilots with persistent symptoms• Ranged from 3 months up to 9+ years• Considered permanent in at least 2 cases
5 life-threatening cases* (4/5 cases at same location)• 3 cases of severe neurological/pulmonary symptoms• 2 cases of abrupt onset severe neurological symptoms in
flight• No fatalities – all 5 pilots recovered & treated with HBO
Good initial response to HBO treatment in all• Appropriate HBO treatment in all cases (life saving in 5)• Symptoms plateaued after repeat HBO treatments
Common constellation of physical symptoms in 7/9• Symptoms similar to those seen after mild TBI
*See published case reports for two life-threatening incidents:1. Pickard BJ. Altitude decompression sickness in a pilot wearing a pressure suit above 70,000 ft. Aviat Space Environ Med 2003;
74:357-9.
2. Jersey SL, Baril RT, McCarty RM, Millhouse CM. Severe neurological decompression sickness in a U-2 pilot. Aviat Space Environ
Med 2010; 81:64-8.
15 Distribution A: Approved for public release; distribution is unlimited. Case Number: AFMC-2013-0137, 3 Sep 2013
Persistent and/or PermanentSymptoms
Presenting Symptoms
Headache (10/20 cases)
Fatigue (7/20)
Confusion/memory lapses(7/20)
Impaired mentation (5/20) Paresthesias (5/20)
Vision problems (3/20)
Nausea (3/20) Dizziness (2/20)
Loss of consciousness (2/20)
Disorientation (2/20) Weakness (2/20)
Persistent Symptoms
Inappropriate fatigue (9/20)
Headaches (7/20)
Personality changes (5/20)
Memory problems (5/20)
Difficulty concentrating (2/20)
Difficulty sleeping (2/20)
• 10 of 16 pilots (62.5%)• Duration: 3 months to 9+ years• Considered permanent in at least 2 cases
?
Variable recognitionof symptom onset
(2.5 – 36 h)Return home on
commercial flight
(48-72 h later)
Further treatment& evaluation
Return toflying status
Landing HBO treatment
1-h restingpre-breathe
Foggythinking
16
Distribution A: Approved for public release; distribution is unlimited. Case Number: AFMC-2013-0137, 3 Sep 2013
Clinical CourseThe Ugly
Typical clinical course in each case:• Good initial response to HBO treatment• 2-4 days later: fatigue, headaches, etc.• 3 of 4 treated with repeat HBO (partial relief)
Medication for symptomatic relief problematic in one case• Including: steroids, NSAIDs, ergot, sleep, anti-depressants• Little relief with adverse clinical & occupational impacts• Attempted repeat HBO months after incident – no relief• Pilot eventually permanently disqualified from all flying
Minimized medication use in remaining pilots• NSAIDs used as needed for headache• Partial improvement with increased rest, duty restrictions• Limited success– only one pilot returned to unrestricted
U-2 duties• Heavy psychological sx (anxiety, depression, PTSD) in all• Permanent flying restrictions (7) and/or DQ (2)
17 Distribution A: Approved for public release; distribution is unlimited. Case Number: AFMC-2013-0137, 3 Sep 2013
Return to Flying Status
No Previous History of Long-Term Effects
•Few case reports of lasting effects after HBO treatment
•A ltitude DCS considered less severe than divingDCS
Operational Incentives to Return Pilots toFlying
•Eachnew U-2 pilot costs ~$2.5 million to train•Limited pool of pilots to man deployment s lots
•Limited housing& personnel s lots at deployed locations
Medical Consequences:
•P ilots flew home from deployment ASAP (< 72 h) after DCS
•P ilots attempted return to flyings tatus soon after DCS•Waiver guide: returnafter resolutionof symptoms, normalexam
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American Osteopathic College of Occupational and Preventive MedicineOMED 2013, Mandalay Bay Convention Center, Las Vegas
Tuesday, October 1, 2013, Aerospace Medicine Day
Distribution A: Approved for public release; distribution is unlimited. Case Number: AFMC-2013-0137, 3 Sep 2013
Persistent DCS Symptoms Aviation DCS is Rare, Particularly CNS
Manifestations• Overall incidence less than 1% (Butler et al. – USAF, Bason
et al. – USN)• Only 10-20% of these cases involved CNS symptoms• Recurrent symptoms after treatment extremely rare (38
USAF, 6 USN cases)• No reported incidents of CNS DCS in U-2 operations before
1991 Persistent CNS Symptoms Extremely Rare in
Modern Aviation DCS• Butler et al.: 95-98% treatment success with 1153 USAF
cases (1941-99)• Wirjosemito: 97.7% treatment success in 133 CNS DCS
eventually cleared)• No series we reviewed had any significant follow-up
19 Distribution A: Approved for public release; distribution is unlimited. Case Number: AFMC-2013-0137, 3 Sep 2013
Persistent DCS Symptoms
Permanent Neurological Sequelae Common withDiving-Related DCS
7/16 (44%) Pilots had Similar Constellation ofLong-Term Symptoms• Headaches, central fatigue, sleep disturbance,
irritability, memory deficits• Similar symptoms reported after TBI, concussions• Is there a common final pathway for brain injury?• Have we overlooked significant long-term effects from
altitude DCS?
20
Distribution A: Approved for public release; distribution is unlimited. Case Number: AFMC-2013-0137, 3 Sep 2013
Lessons Learned
Changes made as a result of these cases:• Reinforced preexisting procedures (maintain hydration, descend, etc.)
• Encouraged pilots to report suspected symptoms
• Operational decision – trial of exercise-enhanced pre-breathe
• Increased recovery time between flights
• Increased number of pilots in training (reduce operational burden)
• CNS DCS cases treated with USN TT6 with 2 extensions at baseline
Results:• Cultural resistance to some changes initially, eased with time
• Subjectively greater willingness to report symptoms
• Impact of pre-breathe changes positive
?
Variable recognitionof symptom onset
(2.5 – 36 h)Return home on
commercial flight
(48-72 h later)
Further treatment& evaluation
Return toflying statusLanding HBO treatment
1-h restingpre-breathe
21 Distribution A: Approved for public release; distribution is unlimited. Case Number: AFMC-2013-0137, 3 Sep 2013
Lessons Learned
4/20 (20%) cases had recurrent symptoms after indicatedHBO treatment
Possible explanations for recurrent symptoms:• Mild hypoxia known to occur during commercial flights
• Damaged neurons susceptible to further injury during flight
Changes made as a result of these cases:• Pilots must wait at least 7 days before flying home after HBO treatment;
pilots flying home must use supplemental oxygen
• Pilots at Travis AFB admitted or remain on base 72 hours after HBO
No new cases of recurrent symptoms since changesimplemented (Aug 09)
?
Variable recognitionof symptom onset
(2.5 – 36 h)Return home on
commercial flight
(48-72 h later)
Further treatment& evaluation
Return toflying statusLanding HBO treatment
1-hr restingpre-breathe
22
Distribution A: Approved for public release; distribution is unlimited. Case Number: AFMC-2013-0137, 3 Sep 2013
Lessons Learned
10/16 (62.5%) pilots had persistent/permanent symptoms
One pilot with medical course complicated by medication use
At least 4/16 (25%) pilots reported clinically significant mentalhealth problems
Only 3/16 (19%) case pilots returned to unrestricted U-2 duty
Lessons learned:• Minimize use of medication (esp. narcotic/sedating meds)
• Provide proactive, persistent mental health support to pilots/family
• Flight surgeon & flying squadron manage work schedules
• “Cooling off” period of 6 months of no flying activities
?
Variable recognitionof symptom onset
(2.5 – 36 h)Return home on
commercial flight
(48-72 h later)
Further treatment& evaluation
Return toflying statusLanding HBO treatment
1-h restingpre-breathe
23 Distribution A: Approved for public release; distribution is unlimited. Case Number: AFMC-2013-0137, 3 Sep 2013
ACS Evaluation
Six “incident” U-2 pilots underwent a directed
evaluation 10/2010 – 1/2011
Comprehensive medical and neurological exam
Cardiac exam to include ECHO (PFO in 1 of 6)
Neurophysiological exam (EEG, VEP – normal)
Neurocognitive exam (no deficits)
Comprehensive brain imaging
• MRI, MRS, DTI, PET
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American Osteopathic College of Occupational and Preventive MedicineOMED 2013, Mandalay Bay Convention Center, Las Vegas
Tuesday, October 1, 2013, Aerospace Medicine Day
Distribution A: Approved for public release; distribution is unlimited. Case Number: AFMC-2013-0137, 3 Sep 2013
MRI (pilot “A”) 49 lesions (39 WMH/10 ependymal)
0.425 cm3 volume loss
158 “clean” controls age 30-40
• Population-based, Hispanic
• Avg 6.18 lesions
• 0.094 cm3 volume loss
25 Distribution A: Approved for public release; distribution is unlimited. Case Number: AFMC-2013-0137, 3 Sep 2013
MRI (pilot “B”) Necrotic appearing
lesion at gray-whitejunction
1 WMH
26
Distribution A: Approved for public release; distribution is unlimited. Case Number: AFMC-2013-0137, 3 Sep 2013
MRI Transformation Process Nonbrain removed from FLAIR image
FLAIR registered to T1-weighted image
Registered to Talairach-atlas-based stereotactic frame
Lesions analyzed using Talairach-based boundaries
27 Distribution A: Approved for public release; distribution is unlimited. Case Number: AFMC-2013-0137, 3 Sep 2013
Transformed MRI (pilot “A”)
Transformed FLAIR
images
• Lesions better defined
• Normalized brain size
Permits cross-subject comparison
28
Distribution A: Approved for public release; distribution is unlimited. Case Number: AFMC-2013-0137, 3 Sep 2013
SubjectID
TotalSubcortical
Lesions
TotalEpendymal
Lesions
TotalLesions
TotalFLAIR
Volume(cm3)
TotalSubcortical
Volume(cm3)
TotalEpendymal
Volume(cm3)
C5 39 10 49 1.068 0.425 0.643
C6 18 6 24 0.928 0.417 0.5103
C1* 1 6 7 1.395 0.023 1.3732
C2* 2 4 6 3.271 0.060 3.211
C3 1 8 9 1.615 0.011 1.6052
C4 3 6 9 2.446 0.115 2.332
Mean 10.67 6.67 17.33 1.787 0.175 1.612
Controls 6.18 0.094
* Does not include necrotic lesions
Total Lesion Number/Volume
29 Distribution A: Approved for public release; distribution is unlimited. Case Number: AFMC-2013-0137, 3 Sep 2013
ACS Assessment
Subcortical injury occurring
• Unusual in pattern of distribution
Single subject with an apparent embolic lesion
U-2 population concerned
Unknowns:
• Prevalence of injury in entire U-2 population
• Proximate precipitating factors for NDCS
Possibly ops tempo related
• Neurocognitive impairment (now & long term)
• Mission impact
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American Osteopathic College of Occupational and Preventive MedicineOMED 2013, Mandalay Bay Convention Center, Las Vegas
Tuesday, October 1, 2013, Aerospace Medicine Day
Distribution A: Approved for public release; distribution is unlimited. Case Number: AFMC-2013-0137, 3 Sep 2013
Research Options 9/2011 – Decision brief to AF/SG2 re: primate
model
• Limited (nonsignificant p-value) data on 24 subjects
• Extremely high uncertainty re: primate protocol success
• Questions on validity of “normative” data and on “new”technology
Research re-scoped to obtain true normative
data
• Similar age range
• FC-II neurological standards
• Similar neurocognitive performance skills
31 Distribution A: Approved for public release; distribution is unlimited. Case Number: AFMC-2013-0137, 3 Sep 2013
Normative Study
Age 26 – 45 active duty
FC-II neurological standards
• Exclusionary criteria:
Significant head trauma/surgery
Significant headache/migraine history
Significant psychiatric history
Family history of degenerative neurological disease
History of seizure after age 6
History of DCS
32
Distribution A: Approved for public release; distribution is unlimited. Case Number: AFMC-2013-0137, 3 Sep 2013
Normative Study
Doctorate limb (n=212)
Flight Surgeon limb (n=82) – ≥ 1 operational
tour
Altitude Exposure limb (n=82) – > 50 exposures> 20,000 ft
Calibration limb (n=20)
Image at WHASC
33 Distribution A: Approved for public release; distribution is unlimited. Case Number: AFMC-2013-0137, 3 Sep 2013
Cortical Thickness(n= 99 DCS; 75 DOC+FSG)
Blue shaded regions represent areas of relative
thinning of cortex compared to normative controls
34
Distribution A: Approved for public release; distribution is unlimited. Case Number: AFMC-2013-0137, 3 Sep 2013
WMH Comparison – U-2 Pilots11/9/2012
Significant difference between control (DOC + FSG)
and all U-2 (scaled and unscaled) irrespective ofclinical NDCS symptoms
• Among only U-2 pilots significant difference betweenclinical NDCS vs. no clinical NDCS (p=0.026)
McGuire et al. Neurol 2013 (submitted)35 Distribution A: Approved for public release; distribution is unlimited. Case Number: AFMC-2013-0137, 3 Sep 2013
Hypothesis
If pilots exposed tohighaltitudes demonstratechanges onMRI…
what about these folks?
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American Osteopathic College of Occupational and Preventive MedicineOMED 2013, Mandalay Bay Convention Center, Las Vegas
Tuesday, October 1, 2013, Aerospace Medicine Day
Distribution A: Approved for public release; distribution is unlimited. Case Number: AFMC-2013-0137, 3 Sep 2013
Typical Altitude ChamberExposure
25K ft
18K ft
5K ft-ear/sinuscheck
30 min
denitrogenation
37 Distribution A: Approved for public release; distribution is unlimited. Case Number: AFMC-2013-0137, 3 Sep 2013
MRI Abnormalities in AltitudeChamber Technicians
38
Distribution A: Approved for public release; distribution is unlimited. Case Number: AFMC-2013-0137, 3 Sep 2013
MRI Abnormalities in AltitudeChamber Technicians
39 Distribution A: Approved for public release; distribution is unlimited. Case Number: AFMC-2013-0137, 3 Sep 2013
WMH Comparison – Chamber12/31/2012
Significant difference between control(DOC+FSG) and PHY (hypobaric physiologypersonnel)• WMH distribution similar in pattern to DCS (U-2 pilots)• Unrelated to clinical episodes of NDCS• Correlation with exposure hours not yet performed
Difference noted for cortical thickness as well
PHY (n=57) DOC+FSG(n=102)
p-value(2-tailed Mann-Whitney)
Subcortical WMHvol
0.157±0.481 cm3 0.042±0.076 cm3 p=0.029
Subcortical WMHcount
7.4±12.8 3.3±5.6 p=0.022
40
Distribution A: Approved for public release; distribution is unlimited. Case Number: AFMC-2013-0137, 3 Sep 2013
Cortical Thickness(n= 52 PHY; 75 DOC+FSG)
Blue-shaded regionsrepresent areas of relativethinning of cortexcompared to normativecontrols
41 Distribution A: Approved for public release; distribution is unlimited. Case Number: AFMC-2013-0137, 3 Sep 2013
WMH in Other Populations WMH nonspecific – seen in a variety of
neurological conditions as well as a consequenceof aging
WMH reported in high-altitude mountainclimbers, even in the absence of clinicalsymptoms of mountain sickness – attributed to acombination of hypoxia and hypobaria
WMH change present in 23% (26/113) of Turkishmilitary divers with no history of DCS comparedwith 11% (7/65) of controls
WMH change was found in 43.7% of Frenchmilitary divers with no history of DCS comparedwith 21.8% of controls
Fayed et al. A mJ Med 2006; 119(2):168.e1-6Erdem et al. Aviat Space EnvironMed 2009;80:2-4Gempp et al. AviatSpace EnvironMed 2010; 81:1008-12
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American Osteopathic College of Occupational and Preventive MedicineOMED 2013, Mandalay Bay Convention Center, Las Vegas
Tuesday, October 1, 2013, Aerospace Medicine Day
Distribution A: Approved for public release; distribution is unlimited. Case Number: AFMC-2013-0137, 3 Sep 2013
Pathophysiology of NDCS(Classic View)
Believed to be secondary to nitrogen gas bubble formation
• Subsequent application of direct pressure on nerves and othertissues, blockage of small arteriolar vessels, and interactionwith proteins in the blood
Venous bubble formation occurs in 47%-66%of subjects exposedto chamber altitudes of 8992 m (29,500 ft)
• In lab clinical symptoms of DCS occur in 40%-42%
• CNS involvement (NDCS) is infrequent 49/1108 (4%) of labDCS events 1983-2003
Standard DCS therapy is U.S. Navy Treatment Table 6 (100%FIO2; 2.8 atmospheres absolute)
• Based on empirical experience – not laboratory studies
Pilmanis et al. Aviat Space Environ Med 1999;70:22-9.
Webb et al. Aviat Space Environ Med 2002;73:1161-6.
Balldin et al. Aviat Space Environ Med 2004;75:969-72
Bennett et al. Cochrane Database of Systematic Reviews 2007 (2) DOI: 10.1002/14651858.CD005277.pub2
43 Distribution A: Approved for public release; distribution is unlimited. Case Number: AFMC-2013-0137, 3 Sep 2013
Pathophysiology(Alternative Mechanism)
Lesion distribution pattern suggests simple compression ofwhite matter by arteriolar gas bubble not completeexplanation
Microbubble (<30 μm) shower
Accelerated coagulation of human whole blood and cell-freeplasma with in vitro bubbles
In rabbits, platelet thrombi found in pulm art
In SCUBA platelet count decreased with venous bubbles
In SCUBA microparticle production & neutrophil activation
In cerebrovascular disease, early platelet adhesion andactivation orchestrates a “thrombo-inflammatory” cascadenot dependent upon platelet aggregation and thrombusformation
Pontier et al. J Appl Physiol 2011;110:724-729.
Hallenbeck et al. Aerospace Med 1973;44:712-714.
Tanoue et al. J Appl Physiolo 1987;62(5):1772-1779.
Pontier et al. Aviat Space Environ Med 2008;79(12):1096-9.
Nieswandt et al. J Thromb Haemost 2011;9(suppl. 1):92-104.Thom et al. J Appl Physiol 2012;112:1268-1278
44
Distribution A: Approved for public release; distribution is unlimited. Case Number: AFMC-2013-0137, 3 Sep 2013
Implications?
WMH associated with impairment of executive
processing in other neurological diseases
• Statistical but not clinical deficits noted in U-2pilots
• Is there a threshold effect?
Presumably a “static” process
Standard treatment for NDCS is hyperbaria
• Should this be augmented by anti-thrombotic
or anti-inflammatory treatment?
Is there a dose:effect relationship to exposure?
45 Distribution A: Approved for public release; distribution is unlimited. Case Number: AFMC-2013-0137, 3 Sep 2013
Questions?
46
B-8
American Osteopathic College of Occupational and Preventive MedicineOMED 2013, Mandalay Bay Convention Center, Las Vegas
American Osteopathic College of Occupational and Preventive MedicineOMED 2013, Mandalay Bay Convention Center, Las Vegas
Tuesday, October 1, 2013, Medicine Aerospace Day
Hyperbaric Oxygen forIdiopathic Sudden
Sensorineural HearingLoss
Leonardo Profenna, MD, MPH
Medical Director of Wound Care and Hyperbaric Medicine
Connally Memorial Medical Center
Introduction - ISSHL
US Incidence
5-20 cases/100,000/year
~4000 cases annually
Many cases unreported
Heavy social and economic burden
Difficult to obtain, keep jobs
Stigmatization and isolation
Special educational needs
Most common cause of disability globally
15th leading cause of burden of disease
Introduction - ISSHL
Definition
Per ceptivehearing loss
Hear ing loss occurred w ithin 72 hours
Sever ity of the hear ing loss averages at least 30 dB HL for three subsequent oneoctave steps in fr equency as shown in the standard pure-tone audiogram
Hear ing loss is nonfluctuating
Etiology r emains unknown after clinical, labor atory and imaging studies
Blank otological histor y in an otherwise healthy individual
Unilater al in >97% of cases
Common presentation – Sudden unilater al hearing loss
Tinnitus (70%-90%)
Sensation of aur al fullness (blocked or full ear )
Dizziness
Ver tigo (20-60%)
Diagnosis
Symptom complex
On phone – ask pt to hum – if sound lateralizes to side of hearing loss – suspectconductive (non-urgent)
If doesn’t later alize or lateralizes to opposite ear, ur gent eval
History: trauma, pain, drainage, fever, FNS, HA, diplopia,eye pain, pr ior historyof hearing loss
American Osteopathic College of Occupational and Preventive MedicineOMED 2013, Mandalay Bay Convention Center, Las Vegas
Tuesday, October 1, 2013, Medicine Aerospace Day
Ear anatomy
Blood supply to Ear Etiology of ISSHL
Unclear!
Vascular occlusion
Viral infections
Labyrinthine membrane breaks
Immune associated disease
Abnormal cochlear stress response
Abnormal tissue growth
Toxins
Cochlear membrane damage
Natural History of ISSHL
Often quoted recovery rate of 65%
Lamm et al. – 25 - 68% spontaneous full remissions and47 – 89% partial remissions
Difficult to judge efficacy of therapy given highremission rate and low incidence
Costs
Hearing aids $1,500 – 3,000 per pair
Replace 3-5 years
Cost of ten HBO2 treatments $2,000 – 5,000
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American Osteopathic College of Occupational and Preventive MedicineOMED 2013, Mandalay Bay Convention Center, Las Vegas
Tuesday, October 1, 2013, Medicine Aerospace Day
Corticosteroids and ISSHL
Rationale
Decrease inflammation and edema
Scant data – Cochrane review – two randomized, controlled trials
Results conflicting – one no difference, one statisticallybetter outcome with steroids
1980 – 67 pts with SSHL within 10 days (poor study)
Glucocorticoid (varying dose) vs. Placebo – overall 61% vs.32% recovery, RR 1.3, 95% CI 0.91-1.86
Pts with mild loss recovered regardless
Profound hearing loss no benefit
Moderate loss – GC 78% vs. placebo 38%, RR 1.74, CI 1.19-2.55
Corticosteroids, cont.
2001 randomized trial, 41 patients
4 treatment groups – glucocorticoids, carbogen inhalation,placebo, combined
No difference
Multiple retrospective studies equivocal
AmericanAcademy of Otolaryngology - Head and Neck Surgery
Recommend treatment with oral glucocorticoids
Most likely to help if early in course
1mg/kg/day (max 60 mg) x 10-14 days
Can give intratympanic glucocorticoids – recommended if noimprovement with oral or oral contraindicated
Antivirals and ISSHL
Not recommended by AAO-HNS due to lack of evidenceof efficacy and risk of side effects
Rationale for HBO2 use
High metabolism and scant vascularity to cochlea
Cochlea and inner structures require a high O2 supply
Oxygen to supply to inner cochlea is via oxygen diffusionthrough perilymph
Studies of perilymph pO2 showed trend toward low O2 inISSHL
Normobaric O2 (3.4 X) and HBO2 (9.4 X) raise perilymphO2 compared to room air
HBO2 also is anti-inflammatory, reduces edema andblunts ischemia-reperfusion injury
Cochrane reviews
2005, 2007, 2009, 2010, 2012 reviewed corticosteroids,vasodilators and HBO2
Only HBO2 received conservatively favorable review
2007 and 2010 – “For people with acute ISSHL, theapplication of HBO2 significantly improved hearing, butthe clinical significance remains unclear.”
Average hearing gains of 19.3 dB for moderate loss and37.7 dB for severe
Cochrane Review 2012
7 studies, 392 participants form 1985 to 2004
207 received HBOT and 185 control
Dosages from 1.5 ATA for 45 minutes daily X 15 days to 2.5 ATAfor 90 minutes daily X 25 days
Exclusions and comparator regimens were different – some to notreatment, some to pharmacologic treatment, some to sham.
F/U periods varied 10 days to 3 months
Entry criteria also different (time, dB loss, pharmacologicfailure, etc)
Overall blinding and randomization procedures were poor
D-4
American Osteopathic College of Occupational and Preventive MedicineOMED 2013, Mandalay Bay Convention Center, Las Vegas
Tuesday, October 1, 2013, Medicine Aerospace Day
Cochrane Review 2012 Results
Proportion of participants with > 50% return of hearing
2 trials, 114 patients
RR of improvement with HBOT 1.53, p=0.16, 95% CI 0.85 to2.78.
Proportion of participants with > 25% return of hearing
2 trials, 114 patients
RR of improvement with HBOT 1.39, p=0.02, 95% CI 1.05 to1.84, NNT 5 for improvement in 1
Mean improvement in pure tone average as percentage ofbaseline
1 trial, 50 participants, with HBOT 61%, without 24%, so 37%better with HBOT, statistically significant
Cochrane Review 2012 Results
Mean improvement in hearing over all frequencies
4 trials (169 participants), 2 dropped due to lack ofstandard deviations (both were positive), so 91 participants
HBOT 15.6 dB improvement over controls, p=0.03, CI 1.5 to29.8
Severe and moderate did better than mild
Cochrane 2012 Review Conclusions
Limited evidence from poor studies
HBOT improves hearing in pts with ISSHL
Within 2 weeks
Might improve tinnitis
No evidence that improvement is functionally significant
Routine use cannot be justified
Impairment ranges
Slight
26 – 40 dB – hear and repeat spoken words at 1 meter
Moderate
41 – 60 dB – hearing aids
Severe
>61 dB – hearing aids, lip-reading, sign language training
Additional data
12 retrospective and prospective case-controlled studies
>1650 patients
All but 2 studies positive, none negative
Six of the studies combined HBOT with oral steroids
Of randomized controlled studies, none negative
UHMS conclusion
Given the large amount of positive data - recommendtreatment as an adjunct with corticosteroid treatment
Patient selection
Moderate to profound hearing loss
Early in course of disease (< 14 days)
Use as adjunct to corticosteroids
< 60 years old
Dosage
100% O2 at 2 to 2.5 ATA for 90 minutes daily X 10-20treatments
D-5
American Osteopathic College of Occupational and Preventive MedicineOMED 2013, Mandalay Bay Convention Center, Las Vegas
Tuesday, October 1, 2013, Medicine Aerospace Day
AAO-HNS Clinical Practice Guideline
Although hyperbaric oxygen therapy (HBOT) is notwidely available in the United States and is notrecognized by many US clinicians as an intervention forISSNHL, the panel felt that the level of evidence forhearing improvement, albeit modest and imprecise, wassufficient to promote greater awareness of HBOT as anintervention for ISSNHL.
Questions?
E-1
American Osteopathic College of Occupational and Preventive MedicineOMED 2013, Mandalay Bay Convention Center, Las Vegas
Tuesday, October 1, 2013, Aerospace Medicine Day
Hypoxia
• COL Brian W. Smalley DO, MSPH, CPE
Office
Or this… Or even this…
Hypoxia
• State of oxygendeficiency in theblood cells andtissues sufficient tocause impairmentof function
• 4 Types– Hypoxic
– Hypemic
– Stagnant
– Histotoxic
E-2
American Osteopathic College of Occupational and Preventive MedicineOMED 2013, Mandalay Bay Convention Center, Las Vegas
Tuesday, October 1, 2013, Aerospace Medicine Day
TYPES OF HYPOXIA
HISTOTOXIC(POISONING)
STAGNANT(POOLING)
HYPEMIC(BLOOD)O2
O2
O2O2
HYPOXIC(ALTITUDE)
Reduced pO2
in the lungs(high altitude)
Body tissue
Redblood cells
Hypoxic Hypoxia
ALVEOLAR PO2AIR
Po2 = 152 mm HgPco2 = 0.3 mm Hg
ALVEOLIPo2 =
103 mmHg
Pco2 =
40 mm Hg
Po2 = 40 mm Hg Po2 = 100 mm Hg
Pco2 = 46 mm Hg Pco2 = 40 mm Hg
LUNGCAPILLARIES
RIGHTHEART
LEFTHEART
VEINSARTERIES
PH2O = 47 mmHg
increased temp,Pco2,ordecreasedpHshift curveto the right
OxyhemoglobinDissociation Curve
ALVEOLAR AIR AT SEA LEVEL
GAS mmHg
N2 563
O2 103
CO2 40
H2O 47
TOTAL 760
O2Hb SAT = 98%
ALVEOLAR AIR AT 10,000 FT
GAS mmHg
N2 376
O2 61
CO2 35
H2O 47
TOTAL 522
O2Hb SAT = 87%
E-3
American Osteopathic College of Occupational and Preventive MedicineOMED 2013, Mandalay Bay Convention Center, Las Vegas
Tuesday, October 1, 2013, Aerospace Medicine Day
ALVEOLAR AIR AT 25,000 FT
GAS mmHg
N2 179
O2 30
CO2 27
H2O 47
TOTAL 283
O2Hb SAT = 55%
ALVEOLAR AIR AT 34,000 FT
GAS mmHg
N2 90
O2 26
CO2 24
H2O 47
TOTAL 187
O2Hb SAT = 42%
ALVEOLAR AIR AT 34,000 FTON 100% OXYGEN
GAS mmHg
N2 0
O2 100
CO2 40
H2O 47
TOTAL 187
O2Hb SAT = 98%
OTHER CAUSES:
• Hypoventilation
• Airway obstruction
• Reduction in gas exchange area
• Impairment of gas exchange
Hypemic Hypoxia
+
+
+
+
++
+
++
+
+
+
+ ++
Inability of theblood to accept
oxygen inadequate amounts
+
CAUSES
• Reduced RBC count
– blood donation
– hemorrhage
• Carbon Monoxide (CO)
– incomplete combustion
– forms carboxyhemoglobin
• Sulfa drugs/Ferricyanide– forms methemoglobin
E-4
American Osteopathic College of Occupational and Preventive MedicineOMED 2013, Mandalay Bay Convention Center, Las Vegas
When hemoglobin saturation fallsbelow 65% seriouscellular dysfunction occurs; and if prolonged, can causedeath!
WARNING!
TUC
(time of useful consciousness)
• The time from an interruption of anadequate oxygen supply to the time usefulfunction is lost.
TUC
Altitude TUC
FL 430 & up 9-12 sec
FL 400 15-20 sec
FL 350 30-60 sec
FL 300 1-2 min
FL 280 2-3 min
FL 250 3-5 min
FL 180 20-30 min
Signs of Hypoxia (what you might see)
• Hyperventilation
• Cyanosis
• Mental confusion
• Poor judgment
• Lack of muscle coordination
Mental Disturbance
E-8
American Osteopathic College of Occupational and Preventive MedicineOMED 2013, Mandalay Bay Convention Center, Las Vegas
Tuesday, October 1, 2013, Aerospace Medicine Day
Performance Disturbance
CAUTION! Failure to recognize your signs and symptoms by thedisturbance stage may result in an aircraft mishap
Back on oxygen
Time off Oxygen
1 minute
2 minutes
3 minutes
4 minutes
5 minutes
6 minutes
Handwriting at 25K
Factors InfluencingHypoxia and TUC
• Altitude (cabin)
• Rate of Ascent
• Duration of Exposure
• Fitness Level
• Activity at Altitude
• Temperature
• Self-imposed stress
Hypoxia
• Prevention– Limit time at
altitude
– Know yoursymptoms
– Pressurized
cabin
– Minimize selfimposed
stressors
– 100% O2
• Treatment
– Descend to a safe altitude
– 100% O2
RECOVERY FROM HYPOXIARECOVERY FROM HYPOXIA
• RAPID AND COMPLETE
• O2 PARADOX– DECREASE IN PCO2
– INTRODUCTION OF HIGH FIO2
• RAPID AND COMPLETE
• O2 PARADOX– DECREASE IN PCO2
– INTRODUCTION OF HIGH FIO2
QUESTIONS?
F-1
American Osteopathic College of Occupational and Preventive MedicineOMED 2013, Mandalay Bay Convention Center, Las Vegas
Tuesday, October 1, 2013, Aerospace Medicine Day
Lectures References Link
www.baromedical.com/clarkefiles.asp
Hyperbaric Medicine 2013
Best Evidence and Practice Standards
American Osteopathic College ofOccupational and Preventive Medicine
Las Vegas, Nevada
‘Approved’ Indications for Hyperbaric Oxygen Therapy
FDA…’on label’ standard
UHMS…leading scientific resource
Published evidence…EBM hierarchy
CMS/Medicare…leading health care purchaser
Commercial insurers…largely guided by CMS
Cerebral Arterial Gas Embolism
Pathophysiology
I/R injury clarifies earlier relapse issues
Essential elimination of USN TT 6A
Hyperbaric dosing: USNTT 6; Comex Cx 30
Differential diagnosis ‘CAGE vs. DCS’ unnecessary
Iatrogenic prevalence
The monoplace chamber
Cerebral Arterial Gas Embolism
Pathophysiology
I/R injury clarifies earlier relapse issues
Essential elimination of USN TT 6A
Hyperbaric dosing: USNTT 6; Comex Cx 30
Differential diagnosis ‘CAGE vs. DCS’ unnecessary
Iatrogenic prevalence
The monoplace chamber
F-2
American Osteopathic College of Occupational and Preventive MedicineOMED 2013, Mandalay Bay Convention Center, Las Vegas
Tuesday, October 1, 2013, Aerospace Medicine Day
National Board of Diving & Hyperbaric Medical Technology
Position Statement (2009-04)
Intermittent Air BreathingIt is the position of the National Board of Diving & Hyperbaric Medical Technologythat every recompression treatment facility and every clinical hyperbaric oxygenchamber, regardless of type or class, be equipped to provide intermittent airbreathing. Intermittent airbreathing, commonly referred to as an ‘air break’,serves to prophylax against and lower the incidence of central nervous systemoxygen toxicity. Intermittent air breathing also serves to treat premonitory signsand symptoms of oxygen toxicity, thereby reducing the potential for symptomprogression to overt seizure.
The application and sequencing of intermittent air breathing will be at thediscretion of the hyperbaric physician. However, intermittent air breathing shouldbe immediately instituted (by either multiplace chamber tender or monoplacechamber operator) whenever an acute change in patient status occurs and isconsistent with, or suggestive of, CNS oxygen toxicity.
www.nbdhmt.org
Decompression Sickness
Cochrane: recompression universally accepted standard
US Navy Diving Manual Rev. 6; 2005 TT6 (Comex Cx 30)
Serial dosing protocol
Basic science advances
Effects of treatment delay; current controversy
Monoplace aspects
Clinical Outcome as a Function of Treatment Delay
Delay(h) N CR IR Effectiveness
1 – 6 2,559 2,401 (94%) 135 (5%) 2,536 (99%)
6 – 12 1,802 1,579 (88%) 216 (12%) 1,795 (97%)
12 – 24 555 473 (85%) 80 (14%) 553 (100%)
24 – 36 234 189 (81%) 43 (18%) 232 (99%)
> 36 119 90 (76%) 29 (24%) 119 (99%)
~ 5,278 consecutive cases
Xu W, et al. PLoS One 2012;7(11):e 50079
Decompression Sickness
Cochrane: recompression universally accepted standard
US Navy Diving Manual Rev. 6; 2005 TT6 (Comex Cx 30)
Serial dosing protocol
Basic science advances
Effects of treatment delay; current controversy
Monoplace aspects
F-3
American Osteopathic College of Occupational and Preventive MedicineOMED 2013, Mandalay Bay Convention Center, Las Vegas
Tuesday, October 1, 2013, Aerospace Medicine Day
Carbon Monoxide Poisoning
Oxygen is the antidote…
Cochrane: ‘Existing RCT’s do not establish whether HBO reduces
incidence of adverse neurologic outcomes’
RCT trial design & interpretation issues: O2 dosing; serious vs.
mild cases; blinding/shams; f/u periods and screening tools
Raphael, et al. 1989 Ducasse, et al. 1995 Thom, et al. 1995
Scheinkestel, et al. 1999 Weaver, et al. 2002
Annane, et al. 2011 Garrabou, et al. 2011
Carbon Monoxide Poisoning
1. Lab studies uniformly (less 1) support HBOdemonstrate HBO mechanisms; superiority of HBO
at 3 ATA oxygen
2. Pregnant pts. not studiedlab, retrospective and prospective (Elkharrat, et al. 1991)
data produce an essential ‘hyperbaric’ consensus; nocontrarian views
trans-placental physiology ‘fetus as a sponge’
Annane group treat pregnant pts.
3. Pediatric pts. not studiedsofter consensus; no published debates pro and con
4. Severe* cases, preponderance of evidence supports HBO