Allergy of anaesthetizing agents in Spain

Self-reported drug allergies and the diagnostic work-up in the surgical population

OBJECTIVE

The diagnostic work-up of a drug hypersensitivity reaction is indeed difficult. In general, medical documentation of allergic reactions in medical reports is usually highly deficient or non-existent. The aim of this study was to analyse the prevalence of self-reported drug allergies in the surgical population as well as the criteria used in the diagnosis of drug hypersensitivity reactions.

METHODS

A prospective study with the consecutive participation of 1439 patients, following surgical intervention, attended the Post-Operative Care Unit. Previously, as a routine process during the pre-anesthesia consultation, all patients were questioned about whether they had any drug allergies to report and diagnostic work-up.

RESULTS

The prevalence of self-reported drug allergies was 8.3% (119/1439): 3.6% considered themselves allergic to β-lactams and 2.4% to non-steroidal anti-inflammatory drugs. Approximately one-third of the subjects (40 out of the 119) had not been subjected to any allergy diagnostic procedure and with 79 (66.4%), the only diagnostic test used by the Allergy Unit had been the skin prick-test. None of those participating in the study had tryptase, methylhistamine, specific IgE or intradermal tests carried out to characterize the diagnosis of the allergic reaction.

CONCLUSIONS

These results show that self-reported drug allergies are highly prevalent and as yet little explored. It is an important prevalence which should bring about modifications to the prescription of certain medicaments. The medical personnel must be made aware of the need to make an accurate diagnosis of allergies to medicaments.

General anesthetic allergy testing

Anaphylaxis in the setting of general anesthesia is a rare but potentially lethal event. The investigation of severe reactions is important for confirming the clinical diagnosis and identifying likely causative agents and safe agents that may be used in the future. Many comprehensive reports have described the testing protocol of individual specialized units, whereas there has been no standardization of testing techniques or formal assessment of these tests' diagnostic accuracy. We review the literature with reference to the recently published standards for reporting of diagnostic accuracy (STARD) and make recommendations for future studies of diagnostic accuracy in the field.

Prick-test evaluation to anaesthetics in patients attending a general allergy clinic

BACKGROUND AND OBJECTIVES

To analyse the prevalence of positive prick-tests to all medicaments normally checked in allergy units when a patient is suspected of being allergic to anaesthetics. To establish the degree of agreement between the antecedents of a previous history of an allergic reaction to a medicament and the positive result, or not, to the specific prick-test for the said medicament.

METHODS

This was a prospective study, during 2003 and 2004, which analysed 473 patients referred by their doctors to allergy units to make retrospective diagnoses of an allergy to a drug. The prick-test was done using the undiluted drug. All patients were tested for 41 drugs. These include antibiotics, trimethoprim-sulphamethoxazole, non-steroidal anti-inflammatory drugs (NSAIDs) and perioperative drugs (PD): neuromuscular blocking drugs, latex, iodine, local anaesthetics, hypnotics, opioids and coadjuvants. Cohen's Kappa Index was used to determine the degree of agreement.

RESULTS

71.5% of patients studied presented a positive prick-test. The largest number of positive cases was found in antibiotics (56.4%), followed by PD (15.6%), NSAIDs (14.4%) and trimethoprim-sulphamethoxazole (12.7%). Among PD, the highest prevalence of positive prick-tests was found for neuromuscular blocking drugs (5.3%). Agreement between the substance suspected of causing the allergic reaction and the positive prick-test was excellent for penicillin (Kappa = 0.74) and other antibiotics (Kappa = 0.721) and good for NSAIDs (Kappa = 0.47) and iodine (Kappa = 0.54).

CONCLUSIONS

The prevalence of patients with positive prick-tests to PD occurred in 15.6% in this prospective cohort. Neuromuscular blocking drugs were found to have the highest prevalence of positive prick-tests. There is positive agreement when the substance responsible for the allergic reaction is suspected, otherwise agreement is low.

Prevalence of positive prick test to anaesthetic drugs in the surgical population

Prevalence of patients with positive prick tests to anaesthetics occurred in 4.7% of the surgical population.

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.