Adverse reaction to neuromuscular blockers: frequency, investigation, and epidemiology

Perioperative anaphylaxis and investigations: a local study in Hong Kong

INTRODUCTION

Data on local intraoperative anaphylaxis in Hong Kong is scarce, with few reviews available. We aimed to study the characteristics, presentations and workup results of cases referred to a local allergy clinic.

METHODS

A retrospective review was performed of patient referrals and workup results for suspected intraoperative anaphylaxis at Queen Mary Hospital drug allergy clinic in 2012-2016.

RESULTS

Tryptase was checked in only 81.7% (49/60) of the cases, most of which showed elevation (71.4%, 35/49). Among the 59 patients who received a workup, 47 (79.7%) showed positive findings, with a particularly high yield in the tryptase-positive subgroup (88.6%, 31/35). Among the 54 patients who consented to skin tests (the most sensitive investigation), 43 (79.6%) cases were positive. Overall, neuromuscular blockers were the commonest cause (25.0%, 15/60) of intraoperative anaphylaxis, while antibiotics ranked second (23.3%, 14/60). The timing of reactions was an important indication of potential allergens. For example, the majority of the neuromuscular blocker allergies occurred during the induction phase, while all gelofusine allergic events were in the maintenance phase of anaesthesia. 13 (21.7%) out of 60 cases received subsequent general anaesthesia procedures, with no recurrence of allergic reactions.

CONCLUSION

Proper workup after an intraoperative anaphylactic event has a fairly good chance of identifying the causative allergen. These results are useful for patient management and the planning of subsequent anaesthetic procedures.

Clinical Practice Guidelines for Sustained Neuromuscular Blockade in the Adult Critically Ill Patient

OBJECTIVE

To update the 2002 version of "Clinical practice guidelines for sustained neuromuscular blockade in the adult critically ill patient."

DESIGN

A Task Force comprising 17 members of the Society of Critical Medicine with particular expertise in the use of neuromuscular-blocking agents; a Grading of Recommendations Assessment, Development, and Evaluation expert; and a medical writer met via teleconference and three face-to-face meetings and communicated via e-mail to examine the evidence and develop these practice guidelines. Annually, all members completed conflict of interest statements; no conflicts were identified. This activity was funded by the Society for Critical Care Medicine, and no industry support was provided.

METHODS

Using the Grading of Recommendations Assessment, Development, and Evaluation system, the Grading of Recommendations Assessment, Development, and Evaluation expert on the Task Force created profiles for the evidence related to six of the 21 questions and assigned quality-of-evidence scores to these and the additional 15 questions for which insufficient evidence was available to create a profile. Task Force members reviewed this material and all available evidence and provided recommendations, suggestions, or good practice statements for these 21 questions.

RESULTS

The Task Force developed a single strong recommendation: we recommend scheduled eye care that includes lubricating drops or gel and eyelid closure for patients receiving continuous infusions of neuromuscular-blocking agents. The Task Force developed 10 weak recommendations. 1) We suggest that a neuromuscular-blocking agent be administered by continuous intravenous infusion early in the course of acute respiratory distress syndrome for patients with a PaO2/FIO2 less than 150. 2) We suggest against the routine administration of an neuromuscular-blocking agents to mechanically ventilated patients with status asthmaticus. 3) We suggest a trial of a neuromuscular-blocking agents in life-threatening situations associated with profound hypoxemia, respiratory acidosis, or hemodynamic compromise. 4) We suggest that neuromuscular-blocking agents may be used to manage overt shivering in therapeutic hypothermia. 5) We suggest that peripheral nerve stimulation with train-of-four monitoring may be a useful tool for monitoring the depth of neuromuscular blockade but only if it is incorporated into a more inclusive assessment of the patient that includes clinical assessment. 6) We suggest against the use of peripheral nerve stimulation with train of four alone for monitoring the depth of neuromuscular blockade in patients receiving continuous infusion of neuromuscular-blocking agents. 7) We suggest that patients receiving a continuous infusion of neuromuscular-blocking agent receive a structured physiotherapy regimen. 8) We suggest that clinicians target a blood glucose level of less than 180 mg/dL in patients receiving neuromuscular-blocking agents. 9) We suggest that clinicians not use actual body weight and instead use a consistent weight (ideal body weight or adjusted body weight) when calculating neuromuscular-blocking agents doses for obese patients. 10) We suggest that neuromuscular-blocking agents be discontinued at the end of life or when life support is withdrawn. In situations in which evidence was lacking or insufficient and the study results were equivocal or optimal clinical practice varies, the Task Force made no recommendations for nine of the topics. 1) We make no recommendation as to whether neuromuscular blockade is beneficial or harmful when used in patients with acute brain injury and raised intracranial pressure. 2) We make no recommendation on the routine use of neuromuscular-blocking agents for patients undergoing therapeutic hypothermia following cardiac arrest. 3) We make no recommendation on the use of peripheral nerve stimulation to monitor degree of block in patients undergoing therapeutic hypothermia. 4) We make no recommendation on the use of neuromuscular blockade to improve the accuracy of intravascular-volume assessment in mechanically ventilated patients. 5) We make no recommendation concerning the use of electroencephalogram-derived parameters as a measure of sedation during continuous administration of neuromuscular-blocking agents. 6) We make no recommendation regarding nutritional requirements specific to patients receiving infusions of neuromuscular-blocking agents. 7) We make no recommendation concerning the use of one measure of consistent weight over another when calculating neuromuscular-blocking agent doses in obese patients. 8) We make no recommendation on the use of neuromuscular-blocking agents in pregnant patients. 9) We make no recommendation on which muscle group should be monitored in patients with myasthenia gravis receiving neuromuscular-blocking agents. Finally, in situations in which evidence was lacking or insufficient but expert consensus was unanimous, the Task Force developed six good practice statements. 1) If peripheral nerve stimulation is used, optimal clinical practice suggests that it should be done in conjunction with assessment of other clinical findings (e.g., triggering of the ventilator and degree of shivering) to assess the degree of neuromuscular blockade in patients undergoing therapeutic hypothermia. 2) Optimal clinical practice suggests that a protocol should include guidance on neuromuscular-blocking agent administration in patients undergoing therapeutic hypothermia. 3) Optimal clinical practice suggests that analgesic and sedative drugs should be used prior to and during neuromuscular blockade, with the goal of achieving deep sedation. 4) Optimal clinical practice suggests that clinicians at the bedside implement measure to attenuate the risk of unintended extubation in patients receiving neuromuscular-blocking agents. 5) Optimal clinical practice suggests that a reduced dose of an neuromuscular-blocking agent be used for patients with myasthenia gravis and that the dose should be based on peripheral nerve stimulation with train-of-four monitoring. 6) Optimal clinical practice suggests that neuromuscular-blocking agents be discontinued prior to the clinical determination of brain death.

Successful resuscitation in a case of sudden cardiac arrest in an epileptic patient posted for spinal surgery

A 17-year-old girl was posted for spinal surgery for traumatic spinal injury. The patient was a well-controlled epileptic with history of seizure since 8 years of her age. She was induced with thiopentone sodium and muscle relaxant atracurium was administered. Minutes after that, she had an episode of ventricular tachycardia, this converted to ventricular fibrillation despite of institution of cardiopulmonary resuscitation (CPR). CPR was continued for a prolonged period of 45 minutes and after 45 minutes, QRS complexes appeared and later sinus rhythm restored. Next 24 hours, she was kept on mechanical ventilation. Within 24 hours, Glasgow Coma Scale (GCS) improved and patient was conscious and extubated. We suggest that the neuromuscular blocking drug contributed to an anaphylactic reaction which might be the cause of cardiac arrest and highlight the importance of prolonged resuscitation and successful outcome in this scenario.

Rocuronium bromide induced anaphylaxis in a child -A case report-

Anaphylaxis or anaphylactoid reaction in pediatric patient during anesthesia is rare. We report a rocuronium induced anaphylactic reaction in a 33-month-old female. The patient was scheduled to undergo escharectomy due to injuries suffered from a major burn. Shortly after administration of rocuronium, the patient developed severe hypotension, tachycardia, and hypoxia. A similar reaction occurred after administration of rocuronium on subsequent anesthesia. She underwent uneventful anesthesia with volatile induction and maintenance of anesthesia with sevoflurane on her next 7 operations without using of muscle relaxant.

Adverse effects of neuromuscular blocking agents based on yellow card reporting in the U.K.: are there differences between males and females?

BACKGROUND

Adverse drug reactions (ADRs) are known to occur during anaesthesia; in the U.K. such ADRs may be reported through the Yellow Card Scheme (YCS). Our aim was to determine the demographics of ADRs to neuromuscular blocking drugs without formal causality assessment.

METHODS

A retrospective analysis of ADRs to seven neuromuscular blocking drugs reported via the YCS during a greater than 30-year period was performed. Sex and age were analysed in order to identify at risk groups.

RESULTS

Of 998 reports, 969 included gender. Non-allergic suspected reactions occurred with almost the same frequency as those with an allergic component. The majority occurred in females 676 (70%), and significant sex differences were measured between drugs. Males were more likely to have suffered an ADR to atracurium (p = 0.01) whilst females experienced more ADRs to suxamethonium (p = 0.01). ADRs proved fatal in 81 (9%) of the 950 reports for single drugs. Mortality following suxamethonium was significantly higher in males at 22% compared with 9% females (p < 0.001). More women than men were reported to have allergic reactions, 73% (362/499) compared with 27% (137/499) respectively. The female:male ratio for ADRs was reversed for subjects < 10 years compared with peak ADR reports during the decade from 31-40 years.

CONCLUSIONS

Sex differences in mortality exist in this analysis. The unexpected high frequency of non-allergic ADRs suggests that morbidity and mortality from reactions to established drugs is twice that expected from allergic reactions alone. Standards and guidance for the reporting of ADRs warrant urgent development.

[Anaphylactic and anaphylactoid reactions occurring during anaesthesia in France. Seventh epidemiologic survey (January 2001-December 2002)]

OBJECTIVES

Hypersensitivity reactions IgE-mediated (anaphylaxis) or non-IgE-mediated (anaphylactoid) reactions occurring during anaesthesia remain a major cause of concern for anaesthesiologists, since these reactions remain usually unpredictable, may be potentially life-threatening even when appropriately treated. The authors report the results of the last 2-year survey (2001, 2002) of such reactions conducted in France by the GERAP (groupe d'etude des reactions anaphylactoides peranesthesiques), and compare these results with their previous published surveys.

METHODS

Between January 1, 2001 to December 31, 2002, 712 patients who experienced immune-mediated (anaphylaxis) or non-immune-mediated (anaphylactoid) reactions were referred to one of the 40 allergo-anaesthesia centres members of the GERAP. Anaphylaxis was diagnosed on the basis of clinical history, tryptase measurements during the adverse reaction, and skin tests and/or specific IgE assay.

RESULTS

Anaphylactic and anaphylactoid reactions were diagnosed in 491 cases (69%) and 221 cases (31%), respectively. The most common causes of anaphylaxis were neuromuscular blocking agents (NMBA) (n=271, 55%), latex (n=112, 22.3%), and antibiotics (n=74, 14.7%). Succinylcholine (n=102, 37.6%) and rocuronium (n=71, 26.2%) were the most frequently incriminated NMBAs. Cross-reactivity between NMBAs was observed in 63.4 % of cases of anaphylaxis to a NMBA. No difference was observed between anaphylactoid and anaphylactic reactions when the incidences of atopy, food, or drug intolerance were compared. However atopy, asthma and food allergy were significantly more frequent in case of latex allergy, when compared with NMBA allergy. Clinical manifestations were more severe in anaphylaxis. The positive predictive value of tryptase measurement for the diagnosis of anaphylaxis was 95.3%, the negative predictive value 49%. The diagnostic value of specific neuromuscular blocking agent IgE assays was confirmed.

CONCLUSION

Our results further corroborate the need for systematic screening in case of immediate hypersensitivity reaction during anaesthesia and for the constitution of allergo-anaesthesia centres to provide expert advice to anaesthesiologists and allergologists.

Allergic reactions occurring during anaesthesia: diagnostic approach

Anaphylactic and anaphylactoid reactions to anaesthetic and associated agents used during the perioperative period have been increasingly reported during the last 3 decades. The frequency of life-threatening hypersensitivity reactions occurring during anaesthesia has been estimated to vary between 1/1.000 and 1/25.0000 procedures, with muscle relaxants being involved in almost three quarters of the cases. The mortality from these reactions is in the range of 3-6%. Nowadays, natural rubber latex also accounts for a significant number of perioperative anaphylaxis, particularly in children. Clinical manifestations do not allow to differentiate between IgE-mediated anaphylaxis and anaphylactoid reactions resulting from non-specific mediator release. Successful management of these patients requires multidisciplinary approach and includes prompt recognition and stabilisation of the acute event by the attending anaesthetist, determination of the responsible agent(s) with avoidance of subsequent administration of incriminated compound(s). The latter is based upon correct identification of the responsible drug and potentially cross-reactive compounds by the allergist and requires a detailed review of the anaesthetic report as well as appropriate in vitro and in vivo allergy tests. At present, the overall performance of skin tests makes them the "gold standard" for diagnosis of muscle relaxant-induced perioperative hypersensitivity reactions. In addition, given their good negative predictive value, skin tests have been proven to be a useful tool to tailor the appropriate therapeutic alternative. For other compounds diagnosis is more difficult but newer techniques such as analysis of in vitro activated basophils can be helpful.

Rocuronium and cisatracurium-positive skin tests in non-allergic volunteers: determination of drug concentration thresholds using a dilution titration technique

BACKGROUND

Muscle relaxants are believed to be responsible for 2/3 of the cases of anaphylactic reactions during anesthesia. This assumption is based mainly on positive skin tests obtained in individuals that have experienced anesthesia-related anaphylaxis. A positive skin test is supposed to be associated with mast cell degranulation of vasoactive amines. In the present study we tested the frequency of positive skin tests with two commonly used muscle relaxants, rocuronium and cisatracurium, in a selected group of volunteers with low potential for allergic reactions.

METHODS

Thirty healthy volunteers without known allergy or previous exposure to muscle relaxants were studied. Low potential for allergic reactions was determined prior to inclusion in the study, using various allergy tests. Each individual was tested with intradermal and skin prick tests, and molar drug concentration thresholds for positive skin reactions were determined using a dilution titration technique. The presence or absence of mast cell degranulation was tested by electron microscopic investigation of skin biopsies obtained from positive and negative skin reactions.

RESULTS

None of the volunteers had a positive skin prick test. More than 90% of the volunteers had a positive intradermal test with both rocuronium and cisatracurium. The highest molar drug concentration that was not associated with a positive intradermal test was 10(-6) M (rocuronium) and 10(-7) M (cisatracurium), equivalent to vial dilution 1 : 1000 for both drugs. In none of the volunteers was mast cell degranulation detected.

CONCLUSION

Non-mast-cell-mediated positive intradermal skin reactions are frequently occurring with rocuronium and cisatracurium, even at vial dilution 1 : 1000. A clinically applicable test technique is needed that is able to separate positive skin tests associated with mast cell degranulation from non-mast-cell-mediated reactions.

Anaphylactic reactions during surgical and medical procedures

The most common agents that are responsible for intraoperative anaphylaxis are muscle relaxants. However, latex accounts for a significant number of these reactions, and the incidence of intraoperative anaphylaxis caused by latex is increasing. It is now probably the second most important cause of intraoperative anaphylaxis. Following muscle relaxants and latex are probably antibiotics and anesthesia induction agents. Other agents that are responsible include colloids, opioids, and radiocontrast material. However, they account for less than 10% of all reactions. The clinical manifestations of intraoperative reactions differ from those of anaphylactic reactions outside of anesthesia. Cutaneous manifestations are far less common; cardiovascular collapse may be more common. The diagnosis can be made more difficult because patients cannot express symptoms. There is a paucity of cutaneous findings; the patient is draped, and concomitantly administered drugs may alter the manifestations. These additional drugs can also complicate therapy. There are populations who are at-risk for anaphylaxis to latex during surgical procedures: individuals with a genetic predisposition (atopic individuals), individuals with increased previous exposure to latex (eg, anyone who requires chronic bladder care with repeated insertion of latex catheters or chronic indwelling catheters), health care workers who are exposed to latex mainly by inhalation, and possibly patients who have undergone multiple surgical procedures and therefore have been exposed to latex intravascularly and by catheterization on a number of occasions. It has been shown that pretreatment with antihistamines and corticosteroids that are used successfully for the prevention of reactions to radiocontrast material are not as effective in the prevention of anaphylactic reactions to latex. Therefore, the major emphasis has been on prevention. The key elements of prevention include an adequate history, testing for latex allergy in high-risk patients, preadmission measures, and the establishment of a "latex-free environment" while the individual is hospitalized. This is particularly important in the operating and recovery rooms.

Rapacuronium and the risk of bronchospasm in pediatric patients

We conducted this study to determine the risk factors for the development of bronchospasm after the administration of rapacuronium and to determine if children with bronchospasm on induction of anesthesia were more likely to have received rapacuronium compared with other muscle relaxants. In a retrospective cohort study, all anesthetic records in which rapacuronium was administered were reviewed to determine which patients developed bronchospasm during induction of anesthesia. Two-hundred-eighty-seven patients were identified, of whom 12 (4.2%; 95% confidence interval [CI], 2.2%--7.2%) developed bronchospasm during induction of anesthesia. Significant risk factors for the development of bronchospasm with administration of rapacuronium included rapid sequence induction (relative risk [RR], 17.9; 95% CI, 2.9--infinity) and prior history of reactive airways disease (RR, 4.6; 95% CI, 1.5--14.3). In a case-control study, all cases of bronchospasm during induction of anesthesia in the 5-mo time period that rapacuronium was available for clinical use were identified. Aside from the 12 cases of bronchospasm with rapacuronium, 11 additional cases of bronchospasm were associated with the use of other muscle relaxants. Four controls were randomly selected for each of the 23 cases of bronchospasm. Children with bronchospasm during induction of anesthesia were several times more likely (odds ratio, 10.1; 95% CI, 3.5--28.8) for having received rapacuronium compared with other muscle relaxants.

IMPLICATIONS

In a retrospective cohort study, significant risk factors for the development of bronchospasm with the administration of rapacuronium on induction of anesthesia included rapid sequence induction and prior history of reactive airways disease. In a case-control study, children with bronchospasm during induction of anesthesia were several times more likely to have received rapacuronium compared with other muscle relaxants.

Rocuronium and anaphylaxis--a statistical challenge

Drug induced anaphylaxis is frequently attributed to the use of muscle relaxants during anaesthesia. Recently The Norwegian Medicines Agency recommended that rocuronium bromide (Esmeron) be withdrawn from routine practice due to frequent reports of anaphylaxis. Over a period of two and a half years approximately 150,000 patients received rocuronium as part of their anaesthesia. In this period the Norwegian drug authorities received 29 reports of anaphylaxis or anaphylactoid reactions in patients treated with rocuronium. This is in stark contrast to the situation in other Nordic countries where a total of only seven cases of anaphylaxis in approximately 800,000 patients treated with rocuronium had been recorded by December 2000. This situation highlights the many potential problems of the surveillance of adverse drug reactions: reporting bias may lead to an over-estimate of the risk of one drug compared to another, and the possibility of under-reporting of adverse events (due to a weak reporting culture) further limit the validity of such comparisons. The surveillance of adverse drug reactions also represents a statistical challenge. While adverse event reports may help us to estimate the anaphylaxis rate we need to appreciate the uncertainty of such estimates. Adverse reactions are rare, random, and mostly independent events, resulting from the successive exposure of patients to a low risk intervention. The frequency distribution of adverse events will therefore conform to that of a Poisson process. The resulting Poisson distribution may inform us about the variability of adverse event data. An understanding of these methodological problems and statistical challenges will allow anaesthesiologists to make informed decisions concerning the use of muscle relaxants and other drugs associated with severe adverse reactions.

Cost identification analysis for succinylcholine

The cost of a dose of succinylcholine from society's perspective equals the acquisition cost of the drug plus the cost of its adverse outcomes. We hypothesized that although the acquisition cost of succinylcholine is minimal, the true cost would be much larger. We reviewed the medical literature to identify the total cost of a dose of succinylcholine when administered for nonemergency purposes according to manufacturers' guidelines (i.e., to adults only). We found that 88% of the cost per dose of succinylcholine was for the chance of dying or sustaining permanent brain injury from anaphylactic or anaphylactoid reactions to succinylcholine. Consequently, the estimated cost per dose of succinylcholine was sensitive to the incidence of anaphylactic or anaphylactoid reactions to succinylcholine, the risk of severe injury from anaphylactic or anaphylactoid reactions, and the financial value of unforeseen instant death or permanent brain injury. The range for the cost per dose of succinylcholine was thus large, $9 to $93. Our best estimate of the cost per dose was $37. We conclude that the true cost per dose of succinylcholine from society's perspective is more than 20 times the acquisition cost. However, a precise costing requires better knowledge of the incidence and consequences of anaphylactic or anaphylactoid reactions to succinylcholine.

IMPLICATIONS

The true cost of succinylcholine is more than 20 times the acquisition cost of the drug. The estimated cost is very sensitive to the risk and cost of patients dying or sustaining brain injury from anaphylactic or anaphylactoid reactions to succinylcholine.

Management of anaphylactic shock evaluated using a full-scale anaesthesia simulator

BACKGROUND

The diagnosis of an anaphylactic reaction during anaesthesia is not the first consideration for the anaesthetist and might be missed. The aim of this study was to describe anaesthetists' management of an anaphylactic reaction concerning diagnosing, treatment and application of anaesthesia crisis resource management (ACRM) in a full-scale anaesthesia simulator.

METHODS

Forty-two anaesthetists in teams of two attended training sessions with a critical incident of anaphylactic shock in a full-scale simulator. Trained observers from the study group evaluated the medical treatment according to a treatment sequence developed from the literature and graded the ACRM performance on a five-point scale where 1 is bad and 5 is best.

RESULTS

None of the teams made the correct diagnosis within 10 min and treatment according to the treatment sequence was not initiated. Only 6/21 teams considered the right diagnosis but first after hints from the instructor 15 min after the start of the incident. Evaluation of the use of the total ACRM concept (that is the use of all of the ACRM expressions seen in a total connection: called general impression) gave a median value of 2.0 with a range of (1-3).

CONCLUSION

Anaphylactic shock was difficult to diagnose and no structured plans were used for the treatment in the simulated incident in this study.

Persistent anaphylactic reaction after induction with thiopentone and cisatracurium

A 6-year-old boy presented for surgery for phimosis. The anaesthetic technique included intravenous induction with thiopentone and neuromuscular blockade with cisatracurium. Severe persistent bronchospasm and central cyanosis followed the administration of these drugs. A continuous i.v. infusion of epinephrine at 0.2 microg. kg(-1) x min(-1) was necessary to break the severe refractory bronchial hyperresponsiveness. There was no previous exposure to anaesthetic drugs and no definite family history of allergy. Through increased serum eosinophil cationic protein, tryptase and histamine levels and IgE levels specific to cisatracurium, we demonstrated an IgE-mediated anaphylactic reaction to cisatracurium in the child's first exposure to this new neuromuscular blocking agent. Anaphylactic reactions to new anaesthetic drugs may be challenging to recognize and treat during general anaesthesia in children. The pathogenesis, diagnosis and management of life threatening persistent allergic reactions to intravenous anaesthetics are discussed.

Anaphylactic reactions during induction of anaesthesia using rocuronium for muscle relaxation: a report including 3 cases

Anaphylaxis during induction of anaesthesia is a dreaded complication with a mortality rate of 3-6%, most frequently associated with the use of muscle relaxants. Current knowledge on this matter is reviewed in relation to the presentation of 3 cases of anaphylaxis and bronchospasm associated with the use of the recently released nondepolarizing muscle relaxant rocuronium. Bronchospasm may be the sole sign of a serious drug reaction, triggered by precipitation of insoluble thiopental crystals when mixed with a muscle relaxant in the intravenous (iv) line. It is recommended that these drugs are administered via different injection ports. The hypotension requires immediate treatment with oxygen, epinephrine and large amounts of iv fluids. Epinephrine infusion may be needed for hours. It is recommended that serum tryptase is measured approximately 2 h after debut of the serious drug reaction. Allergy testing should be performed for all the drugs the patient was exposed to, 4-8 weeks after the incident, and due to cross-reactivity, including all available muscle relaxants. Doctors are urged to inform their patients, and systematically register adverse drug reactions.

[Substances responsible for peranesthetic anaphylactic shock. A third French multicenter study (1992-94)]

Since 1989, the epidemiological survey of anaphylactoid reactions occurring during anaesthesia is obtained in France with repeated inquiries by the Perioperative Anaphylactic Reactions Study Group. The members of this group collect during the study period the cases of patients having suffered from an anaphylactoid reaction and tested in their allergo-anaesthetic outpatient clinic, their characteristics (age, gender), the results of the allergological tests (mechanism, agents responsible for the reactions). The two previous surveys published in the Annales françaises d'anesthesie et de réanimation in 1990 and 1993 included 1,240 and 1,585 patients respectively. The current survey concerned 1,750 patients tested in 27 diagnostic centres, from January 1992 to June 1994. The reactions occurred at all ages, predominantly between 10 and 50 years, the sex-ratio (F/M) was 2.4. Allergological tests carried out to diagnose an immune mechanism for the shock were cutaneous tests in all centres (prick-tests in 21 centres, intradermal tests in 27 centres) using the same dilutions for the tested agents and the same threshold for positivity. Specific IgE antibodies against muscle relaxants, thiopentone and propofol, were measured by radio immunoassays in 20 centres. The leucocyte histamine release test was used in 10 centres. The immune origin of the shock--IgE dependent anaphylaxis--was diagnosed in 1,000 patients (57.8%) and due to 1,030 agents muscle relaxants (59.2%), latex (19%), hypnotics (5.9%), benzodiazepines (2.1%), opioids (3.5%), plasma substitutes (5%), antibiotics (3.1%) and other drugs given during anaesthesia such as aprotinine and protamine (2.2%). Suxamethonium was responsible for 39.3% of muscle relaxant anaphylaxis, vecuronium for 36%, atracurium for 14.5%, pancuronium for 4.8%, gallamine for 3.1% and alcuronium for 2.3%. The latter has been withdrawn from the French market in 1993. These differences in the incidence of reactions are correlated with the clinical use of muscle relaxants in France for vecuronium and atracurium, however not for suxamethonium, responsible for 39% of the reactions but representing only 5% of the muscle relaxants sold in France. The comparison with the two previous surveys confirms that the mechanism of more than half of the anaphylactoid reactions occurring during anaesthesia is of immune origin, due to specific IgE antibodies. It is therefore essential to systematically carry out an allergologic assessment several weeks after the reaction, in order to discard for the subsequent anaesthetics the agent(s) responsible for anaphylaxis. If the muscle relaxants remain the first drugs involved in shock occurring at induction, there is a significant increase in latex shock, as demonstrated by the three epidemiological surveys (0.5%, 12.5% and now 19%). The incidence of other anaesthetic agents, antibiotics and plasma substitutes remains unchanged.