Hospital anaesthesia and generalpractice - The BMJ: … ·  · 2008-12-24anaesthetic whichmaycause problemsandwhichare ... and pre-existing chronic obstructive air- ... Disorder

Hospital anaesthesia and general practice

Ian H Shaw, John M Evans

IntroductionIt is usual for the full preoperative assessment ofpatients presenting for anaesthesia to take place afteradmission to hospital. This assessment may discloserisk factors previously not recorded in the hospitalnotes but possibly known to the patients or theirgeneral practitioners. It would be beneficial if generalpractitioners were familiar with the issues that concernanaesthetists when patients are referred for admissionto hospital-in particular, whether they can be treatedas day cases. After being discharged from hospitalpatients may present with unusual signs or symptomsthat are related to the anaesthesia.We review some of the more common issues of

managing patients before and after they receive ananaesthetic which may cause problems and which arerelevant to anaesthetists and general practitioners (seebox).

Past medical historyWhen admitted to hospital patients often forget or

fail to volunteer important information which under-standably they may regard as irrelevant to the manage-ment of their illness. Similarly, in referring patientsgeneral practitioners may not fully appreciate theimportance of some aspects of a patient's history ortreatment to the proposed anaesthetic procedure.

CARDIOVASCULAR DISEASE

Cardiovascular disease is one of the commonestproblems presented to the anaesthetist. Patients withuntreated hypertension tend to have labile cardio-vascular responses during anaesthesia and respondpoorly to some anaesthetic agents, blood loss, andpositioning.' Procedures associated with pronouncedsympathetic activity, such as laryngoscopy and in-tubation,2 can cause such patients stress and inducehypertensive and acute myocardial ischaemia. Duringintubation a patient's blood pressure can rise from160/100 mm Hg to 250/140 mm Hg or higher.Consequently, hypertension should be controlled be-fore the operation. Failure to identify hypertensionbefore a patient is referred for surgery under generalanaesthesia is one of the most common causes ofavoidable cancellation. In the absence of symptomsand electrocardiographic changes a diastolic pressureof less than 110 mm Hg does not seem to be associatedwith an appreciable increase in morbidity.3 Ideally,however, blood pressure should be within the normalrange for the patient's age. Patients with ischaemicheart disease often have limited cardiovascular reservesand any associated hypertension should be rigorouslycontrolled.A patient who has anaesthesia within six months of a

myocardial infarction carries a considerable risk ofreinfarction. Goldman has identified several cardio-vascular abnormalities which increase the morbidityand mortality of anaesthesia and surgery (see box).4These, risks are further enhanced when the patient iselderly or the operation is an emergency.

RESPIRATORY DISEASE

Respiratory disease presents the anaesthetist withseveral problems. Anaesthesia is associated with a fallin compliance, functional residual capacity, and airtrapping in the dependent airways leading to an

imbalance between ventilation and perfusion. Endo-tracheal intubation can induce profound bronchospasmin susceptible patients. Postoperative atelectasis is notuncommon, especially in association with thoracicand upper abdominal surgery, obesity, postoperativeimmobility, and pre-existing chronic obstructive air-ways disease.5 Acute upper respiratory tract infectionscan be exacerbated by anaesthesia, and all but thebriefest procedures should be postponed for sevendays; this is especially important for patients withasthma.

Anaesthesia should be avoided in patients withexacerbated chronic obstructive airways disease. Co-existent infections and reversible bronchospasm shouldbe treated in good time with medication and physio-therapy. Time spent before the operation optimisingthe patient's respiratory function is worth while andmay avoid the need for intensive therapy after theoperation. Vital capacity and peak flow measurementsare a useful and simple means of assessing preoperativetreatment. In patients with chronic obstructive airwaysdisease elective surgery should be avoided during thewinter months.

ASPIRATION OF STOMACH CONTENTS

Patients with hiatus hernia may aspirate stomachcontents. Gastro-oesophageal reflux is a potentiallyfatal condition for a patient under anaesthesia; re-gurgitation and aspiration of gastric contents is asso-ciated with appreciable morbidity and a mortality of25%. Not surprisingly, many patients with known butasymptomatic hiatus hernias fail to volunteer thisinformation. Any history of reflux is relevant sincetreatment with antacids with H2 antagonists before theoperation can offer substantial protection by raisingthe gastric pH.6 Symptomatic improvement may alsobe obtained if a patient loses weight and reducesalcohol and tobacco use.

Patients who are referred to hospital with acuteconditions for which anaesthesia may be requiredshould not eat or drink until instructed to do so bythe hospital staff. Patients with oesophageal reflux orfull stomachs require anaesthetic techniques that aredesigned to miimmise the possibility of pulmonaryaspiration.

OBESITY

Obesity can be a major complication, and thehazards of anaesthesia and surgery are greatly in-creased (fig 1). Obesity is associated with an increasedincidence of cardiovascular disease, respiratory in-adequacy during and after anaesthesia, difficultieswith intubation, gastro-oesophageal reflux, and post-operative complications.7 Obese patients should beencouraged to lose weight when elective surgery isbeing considered.

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Topics of particularinterest to theanaesthetistPast medical historyPrevious anaesthetic

historyDrug treatmentAllergiesFamily historySocial history

Nuffield Department ofAnaesthetics, RadcliffeInfirmary, OxfordOX2 6HEIan H Shaw, FFARCS, registrarJohn M Evans, FFARCS,consultant

Correspondence to: Dr IanShaw, Department ofCardiothoracic Anaesthesia,Freeman Hospital,Newcastle upon TyneNE7 7DN.

Preoperative cardiovascular factors associated withenhanced morbidity and mortality after anaesthesiaand surgery4Raised jugular venous pressureGallop rhythmMore than five ventricular ectopic beats per minuteRhythm other than sinus rhythmAppreciable aortic stenosisMyocardial infarction in preceding six months

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FIG 1-In an obese patient with a receding chin it may be difficult tovisualise the larynx. (Photograph courtesy ofDrS Cook)

MUSCULOSKELETAL DISORDERS AND ARTHRITIS

In patients with arthritis or musculoskeletal dis-orders it may be difficult to maintain the airway orperform endotracheal intubation ifthe cervical spine orthe temporomandibular joints are affected.8 Arthritisof the cervical spine or cervical spondylosis can beexacerbated by attempts at intubation. Calcification ofthe lumbar spine may make it impossible to give aspinal or epidural anaesthetic. Patients with scoliosisoften develop impaired respiratory and cardiovascularfunction and are often hypoxaemic, have a diminishedvital capacity, and show an imbalance of ventilationand perfusion. Pulmonary hypertension leading toright ventricular failure may also arise. Scoliosis isoften associated with various muscle diseases.

TEETH

If teeth are loose or diseased they may be damaged ordislodged during anaesthesia (fig 2). Aspiration ofdental fragments can cause bronchospasm, airwaysobstruction, and infection necessitating removal of thefragments with a bronchoscope. Patients should beencouraged to have loose teeth attended to beforesurgery. Expensive and complex prosthetic dentitionrenders endotracheal intubation more demanding, anddamage to teeth and prostheses is a common cause oflitigation.9

PREGNANCY

Anaesthesia is best avoided during the first trimesterofpregnancy, and any essential elective surgery shouldbe postponed until the second trimester. Pregnancyshould be excluded before an anaesthetic is given.Pregnant patients requiring anaesthesia present severalproblems for the anaesthetist, the most importantbeing gastro-oesophageal regurgitation and supinehypotension due to aortocaval compression in thesupine position.'0"

Previous anaesthetic historyAny information that the general practitioner has

about a patient that may be related to previousanaesthetics should be noted in hospital referral letters.To this end anaesthetists should be encouraged to

inform general practitioners of notable problems withanaesthesia, particularly if these are likely to recur.Adverse reactions to drugs or perioperative incidentssuch as difficulties with intubation or awareness duringanaesthesia are especially important. Repeat admini-stration of halothane within three months is contra-indicated in adults; a potentially fatal halothanehepatitis can be induced.'2 Altered liver function testresults, jaundice, or fever occurring after anaesthesiaare important and need a detailed review. Patients whohave had a complication with anaesthesia may fear arecurrence, but precautions can be taken to minimisethat possibility and to reassure the patient.

Drug treatmentIt is important to know a patient's current and recent

drug treatment since drug interactions with anaestheticagents are common. With a few notable exceptionsall drug treatment should be maintained until theanaesthetic is given. This is especially important withtreatment for cardiovascular disease where withdrawalmay be associated with cardiovascular instability andthe risk of perioperative myocardial ischaemia. 13Table I lists commonly used drugs of concern tothe anaesthetist. Several important interactionsnecessitating drug withdrawal preoperatively are dis-cussed below.

Oral contraceptive pill-The association of theoral contraceptive pill, surgery, and anaesthesia withthromboembolic disease is well known.'4 Hypotensiveanaesthesia carries a risk of cerebral thromboembolismand would be contraindicated in patients taking thepill. Current guidelines on the management of patientsmay be found in the British National Fornulary. Forpatients having minor elective procedures with fullrecovery and mobilisation the same day the low doseoestrogen pill need not be stopped. An exception tothis would be surgery on the legs or feet such asfor varicose veins. A previous or family history of

TABLE I-Drugs ofspecial importance when an anaesthetic is given

Drug Effect

Cardiovascular drugs:,B blockers Cardiovascular instability if

stopped prematurely'8Calcium channel blockers Enhanced negative inotropic and

chronotropic effects inassociation with some volatileanaesthetics"

Diuretics Hypokalaemia provokingarrhythmias and prolongedneuromuscular blockade

Digoxin Enhanced arrhythmias especially ifassociated with hypokalaemia

Antibiotics Many antibiotics of theaminoglycoside group canpotentiate neuromuscularblockade and induce microsomalenzymes

Psychopharmacological drugs:Monoamine oxidase inhibitors See textTricyclic antidepressants Enhanced arrhythmias with some

volatile anaestheticsLithium Potentiation of neuromuscular

blockadeNeuroleptics Exaggerated hypotensive effects in

association with anaesthesiaAntiepileptic agents Microsomal enzyme induction and

high protein binding-someanaesthetic agents are mildlyepileptogenic

Antiplatelet drugs:Aspirin May enhance haematomaDipyridamole formation with regional

anaesthetic techniquesSteroids Supplementation necessary to

avoid cardiovascular instabilityperioperatively-supplement-ation necessary up to threemonths after treatment isstopped

Phospholine iodide See textTimnolol maleate See textOral contraception See text

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thromboembolic disease, smoking, diabetes, obesity,or hypertension would necessitate caution. Oestrogenbased pills should be stopped four weeks beforeelective surgery that will require postoperative im-mobility. The pill should be restarted at the firstmenses occurring at least two weeks after the pro-cedure, assuming the patient is fully mobilised. Altern-ative methods of contraception should be used in theinterim. Progesterone only pills need not be stopped.Where anaesthesia and surgery are unavoidable in apatient on the pill then low dose heparin or intravenousdextran in the postoperative period may be indicated.

Phospholine iodide (ecothiopate iodide) eye drops-These have anticholinesterase activity and attenuatethe metabolism of suxamethonium chloride, a shortacting neuromusclar blocking drug, leading to pro-longed apnoea.I Ecothiopate is extensively proteinbound and treatment needs to be discontinued threeweeks before anaesthesia is given. Patients can generallybe easily managed, however, if they remain on phos-pholine provided the anaesthetist knows of the treat-ment.

Timolol maleate eye drops-Systemic absorption ofthe , antagonist timolol from ophthalmic dropscan cause respiratory and cardiovascular side effects.Bronchospasm and bradycardia are most commonly.seen. A profound bradycardia may occur duringophthalmic surgery if an ocular-cardiac reflex is in-duced by traction on extraocular muscles.Monoamine oxidase inhibitors-Giving anaesthesia to

a patient who has taken a monoamine oxidase inhibitorwithin 14 days can be potentially fatal due to druginteractions-in particular with pethidine. Complexand poorly understood interactions with narcoticanalgesics and sympathomimetic amines necessitates acareful choice ofanaesthetic technique in such patients.Monoamine oxidase inhibitors should ideally bestopped at least two weeks before an anaesthetic isgiven and in consultation with a psychiatrist. Themonoamine oxidase B inhibitors (selegiline), used insevere parkinsonism, seem not to interact and need notbe stopped; no reports of interactions with this drughave appeared in publications on anaesthesia.

AllergiesAny history of atopy is relevant. Anaphylactic and

anaphylactoid reactions, as well as halothane hepatitis,

FIG 2-Chronic periodontal disease. If teeth are loose or diseased they may be damaged or dislodged duringanaesthesia. (Courtesy of the Department of Oral Pathology, Dental School, University of Newcastleupon Tyne)

occur more commonly in people who are atopic. Manydrugs used in anaesthesia have the potential to releasehistamine and provoke severe anaphylactoid reactions.That these severe reactions are seldom fatal canprobably be attributed to the immediate availability ofskilful care and facilities.

Family historyFortunately, inherited conditions of concern to the

anaesthetist are rare. Table II lists the most importantdisorders.

TABLE iI-Inherited orfamilial disorders ofrelevance to anaesthesia

Disorder Implications

Pseudocholinesterase Atypical cholinesterase resulting inprolonged paralysis aftersuxamethonium chloride isgiven; family members should betested to identify those at risk20

Porphyria Acute porphyria can beprecipitated by severalanaesthetic agents and carefulselection of anaesthetictechnique is required

Malignant hyperpyrexia syndrome Very rare but lethal subclinicalmyopathy provoked almostexclusively by some anaestheticagents; family members need tobe investigated to identify thoseat risk2

Haemoglobin S Sickle cell trait is less obvious thanthe disease; sickle tests should beperformed on patients of Indian,West Indian, and African origin

Hyperlipidaemia Increased probability of seriouscardiovascular disease

Sudden infant death syndrome Potential association withmalignant hyperpyrexiasyndrome

Social historySmoking- Smoking is associated with an increase in

postanaesthetic complications, in particular respiratorydisorders.'6 High carboxyhaemoglobin concentra-tions impair oxygen transport, and cardiovascular andrespiratory disorders are common. All patients shouldbe encouraged to reduce or stop smoking several weeksbefore receiving anaesthesia.Alcohol-Excessive alcohol consumption can lead to

tolerance of anaesthetic agents, increased gastric acidproduction, and oesophageal reflux; enzyme inductionand tissue tolerance to anaesthetic agents often devel-op. A withdrawal syndrome may develop postopera-tively. In addition, alcoholics often have diminishedadrenocortical responses, electrolyte and fluid im-balance, bone marrow depression, and cardiomy-opathy.'7Drug abuse-Abuse of "street drugs" presents

problems. Access to veins may be limited, and the riskto staff and patients of infection with hepatitis B andthe human immunodeficiency virus is ofgreat concern.It is important for hospital staff to be aware ofbehaviour that might suggest a risk of contracting theseinfections so that precautions may be taken.

Postoperative considerationsGeneral practitioners may be consulted by patients

who have recently had anaesthesia (particularly as daysurgery has increased) with a variety of symptomsrelated to anaesthesia.Suxamethonium chloride myalgia ("scoline" pains)-

Myalgia may follow the use ofsuxamethonium chloridefor endotracheal intubation. Muscle pains can besevere, particularly when they occur the day afteranaesthesia. The incidence in ambulant patients isabout 60%. The pains are often diffuse but usually

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affect the large muscle masses such as the pectoral andneck muscles. The discomfort is self limiting and bestmanaged by bed rest and simple analgesics.

Sore throat-A sore throat is a common occurrenceafter anaesthesia with or without endotracheal in-tubation. Symptomatic treatment is usually sufficient.Intubation can cause persistent hoarseness, in whichcase an opinion should be sought from an ear, nose,and throat surgeon as granulomatous lesions of thevocal chords may occur.

Thrombophlebitis-Phlebitis may occur at the siteof intravenous cannulation and drug administration.Many anaesthetic agents are irritant when injectedextravascularly, and the discomfort persists for severaldays.

Loss of radial pulse-An absent radial pulse mayfollow the insertion of an intra-arterial cannula forintraoperative measurement of blood pressure duringmajor or hypotensive anaesthesia. The pulse usuallyreturns in a few weeks.

Shoulder tip pain-Pain over the shoulder, oftenpersisting for several days, may follow laparoscopy inwhich carbon dioxide is insufflated into the abdominalcavity. The discomfort passes off as the gas is re-absorbed or when the patient is lying down.

Epidural anaesthesia-Epidural anaesthesia may beassociated with some transient local tenderness at theinjection site. About 1% of patients will experience a"dural tap"-that is, inadvertent puncture of the duraby a large 16 gauge or 19 gauge epidural needle. Thiscan lead to symptoms of neck stiffness, headache,photophobia, nausea, and vomiting 24 to 48 hourslater. The headache is classically postural, symptomaticrelief being obtained when the patient lies flat, and24 hours of supine bed rest usually resolves thediscomfort. In severe, persistent cases a small quantityof the patient's own blood can be injected into theepidural space at the level of the puncture to occludethe dural puncture-a so called epidural "bloodpatch." Patients who have persistent headache afterspinal or epidural anaesthesia should be referred tohospital for review and management where necessary.

Spinal anaesthesia- Spinal anaesthesia is ideallyperformed with fine needles (eg, 26 gauge) and rarelycauses postanaesthetic headaches. The patient may beunaware of having had a spinal as it is not uncommon tocombine a spinal with a general anaesthetic or heavysedation. Persistent headache due to dural puncturecan be treated with a "blood patch."

Nerve palsies-Peripheral nerve palsies may rarelyfollow peripheral nerve block for local anaesthesia.The radial, ulnar, and sciatic nerves can be subject totraumatic compression during anaesthesia or during

recovery. Similar injuries can be produced by surgicaltourniquets.

Corneal abrasion-While unconscious patients can-not protect themselves from injury. The eyes areparticularly at risk of injury during head and necksurgery and appropriate protection of the eyes isroutine. Corneal injury may occur, however, wheneverthe patient is unconscious.

Awareness dunrng anaesthesia-Awareness is acommon fear of many patients who are about toundergo anaesthesia. The incidence of awareness isestimated to be about 1%. Awareness usually amountsto a limited auditory recall of events, but on occasionsthe patient may have a full and detailed recall of eventsand experience pain. Postoperative neurosis as a con-sequence has been described.22 Any suggestion ofawareness should be followed up. A full and frankexplanation of the events is desirable.

I Prys-Roberts C, Meloche R, Foex P. Studies of anaesthesia in relation tohypertension. I. Cardiovascular responses of treated and untreated patients.BrjAnaesth 1971;43:112-37.

2 Low JM, Harvey JT, Prys-Roberts C, et al. Studies of anaesthesia in relation tohypertension. VII. Adrenergic responses to laryngoscopy. Br J Anaesth1986;58:471-7.

3 Goldman L, Caldera RN. Risks of general anaesthesia and elective operation inthe hypotensive patient. Anesthesiology 1979;50:285-92.

4 Goldman L, Caldera DL, Nussbaum SR, et al. Multifactorial index of cardiacrisk in noncardiac surgical procedures. N lEnglj Med 1977;297:845-50.

5 Milledge JS, Nunn J. Anaesthesia and the patient with respiratory disease. In:Gray TC, Nunn JF, Uttig JE, eds. General anaesthesia. 4th ed. London:Butterworths, 1980:511-30.

6 MacDonald AG. The gastric acid problem. In: Atkinson RS, Adams AP, eds.Recent adzvances in anaesthesia and analgesia. Edinburgh: Churchill Living-stone, 1985:107-31.

7 Fisher A, Waterhouse TD, Adams AP. Obesity: its relation to anaesthesia.Anaesthesia 1975;30:633-47.

8 Edelist G. Principles of anaesthetic management of rheumatoid arthritis.Anesth Analg 1964;43:227.

9 Medical Defence Union. Anaesthesia and dental damage. Medical DefenceUnion Annual Report 1987. London: MDU, 1987:18-9.

10 Kerr MG, Scott DB, Samuel E. Studies of the inferior vena cava in latepregnancy. BrMedj 1964;i:532-3.

11 Moir D. Obstetrtc anaesthesia and analgesia. 3rd ed. London: Bailliere Tindall,1986.

12 Neuberger J, Williams R. Halothane anaesthesia and liver damage. Br MedJ1984;289:1136-9.

13 Prvs-Roberts C, Green LT, Meloche R, et al. Studies of anaesthesia in relationto hypertension. II. Haemodynamic consequences of induction and endo-tracheal intubation. Brj Anaesth 1971;43:531-46.

14 Guillebaud J. Surgery and the pill. BrMedJ1985;291:498-9.15 Pantuck EJ. Ecothiopate iodide eye drops and prolonged response to

suxamethonium. Brj Anaesth 1966;38:406-7.16 Jones RM, Rosen M, Seymour L. Smoking and anaesthesia. Anaesthesia

1987;42:1-2.17 Edwards R. Anaesthesia and alcohol. BrMedJ1985;291:423-4.18 Prys-Roberts C, Foex P, Biro GP, et al. Studies of anaesthesia in relation to

hypertension. V. Adrenergic beta-receptor blockade.BrJ Anaesth 1973;45:67 1-80.

19 Jones RM. Calcium antagonists. In: Atkinson RS, Adams AP, eds. Recentadvances tn anaesthesta and analgesia. Edinburgh: Churchill Livingstone,1985:89-106.

20 Bauld HW, Gibson PJ, Jebson PJ, et al. Aetiology of prolonged apnoea aftersuxamethonium. BrMedj 1974;46:273-81.

21 Grronert GA. Malignant hyperthermia. Anesthesiology 1980;53:395-423.22 Blacher RS. Awareness during anesthesia. Anesthesiology 1984;61:1-2.

(Accepted 7 September 1988)

ANY QUESTIONSIs there any evidence to suggest that nasal polypectomy precipitates or worsensasthma?

An association between nasal polyps and asthma has been recognised forover a century. Several recent studies have shown the frequency of thisassociation. The frequency of nasal polyps in people with proved nasalallergy seems to be about 4%; in those with nasal allergy and asthma thefrequency is 6-7%.1 Roughly 20% of patients with polyps have asthma andabout 30% of patients with asthma have polyps.2Asthma undoubtedly occurs in some patients shortly after nasal

polypectomy but is rare. Only 2% of polypectomies are followed byasthma, and in only 0 5% does this occur within a few months.2 In a veryfew patients asthma occurs within days of the procedure, and it is thefrequent occurrence of asthma within 24-48 hours that might be expectedif polypectomy was truly a precipitating factor and not just a chanceoccurrence in two diseases that so frequently coexist. It also seems true thatthose people with asthma who have coexistent nasal polyps have severenasal polyps that require more frequent surgical removal. It is much more

likely, therefore, that in these patients an asthma attack follows nasalpolypectomy as a chance occurrence.

Other evidence against a precipitating relation is that the onset of asthmaoccurs more frequently before the onset of nasal polyposis (ratio 2 5:1) andthat the highest rate of the onset of asthma occurs on either side of the timeof first polypectomy, with an even distribution about this point.2 A wealthof anecdotal evidence testifies to the improvement of lower respiratorytract symptoms after polypectomy. Though this is unproved it is at leastlogical, as the copious quantities of often infected nasal secretion and theconstant mouth breathing accompanying nasal polyposis are hardly likelyto improve any lower respiratory tract symptoms.

Episodes of asthma immediately after polypectomy do occur but arerare. All evidence so far points to this occurrence being one of chance, forthe two diseases often coexist and have common aetiological factors. Thelong term effect of nasal polypectomy on asthma is probably beneficial. -W V CARLIN, ear, nose, and throat surgeon, Stoke on Trent

1 Settipan GA, Chafee FH. Nasal polyps in asthma and rhinitis. J Allergy Clin Immunol1977;59: 17-21.

2 M\aloney JR. Nasal polyps, nasal polypectomy, asthma, and aspirin sensitivity. J Laryngol Otol1977;91:837-46.

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