Perioperative Anaphylaxis in Patients Attending University Hospitals (Egypt - UK).

Perioperative anaphylaxis is associated with significant morbidity and mortality. Most textbooks describe it as a rare event of the order of 1 in 10 to 1 in 20,000 general anaesthetic cases. However, a recent study in the United Kingdom suggested that 1 in 350 cases have features suspicious of perioperative anaphylaxis. This study suggests that perioperative anaphylaxis may be under recognised and under reported.

When perioperative anaphylaxis is recognised, it would be ideal to carry out investigations firstly to confirm the diagnosis of anaphylaxis and secondly to identify the causative agent. The latter can be difficult in the context of anaesthesia where the patient is exposed to several drugs and other reagents in a short space of time.

One of the interesting aspects of perioperative anaphylaxis is that there is variability in its epidemiology between different countries, for example between the United Kingdom, France, Scandinavia and Australia and New Zealand. There are currently no data from Egypt to include in such comparisons and to inform clinical practice.

As well as being at risk if a drug allergen is not identified, patients can also be at risk from an incorrect allergy label. The most common example of this is penicillin allergy where fewer than 10% of patients with a history of penicillin allergy are found to be allergic. Incorrect penicillin allergy labels are potentially harmful for patients attending for surgery because the label independently increases the risk of developing infection to resistant organisms, longer hospital stays and mortality.

Aim of the work:

This project proposes the following studies:

• The incidence of suspected perioperative anaphylaxis in an Egyptian population.
• Sensitivity and specificity of tryptase changes under surgery and anaesthesia.

Patient and Methods:

• In order to define the incidence of possible anaphylaxis, data will be collected on 1000 consecutive general anaesthetic procedures in Assiut University Hospitals. After each elective operating list the anaesthetist will be asked to complete a form in which they will document the number of patients receiving general anaesthesia on the list and the number of those patients who developed any of the following features: unexpected, unexplained hypotension; unexpected bronchospasm resistant to treatment; angioedema; urticaria; severe itching; widespread erythema.
• Tryptase is a relatively stable protein released from mast cells alongside histamine during allergic anaphylaxis. Mast cell tryptase is recognised as a useful biomarker for perioperative anaphylaxis but there is debate concerning what degree of change in mast cell tryptase produces the greatest combination of sensitivity and specificity for perioperative anaphylaxis. Variable results from different countries suggest that population specific normal responses may need to be defined.

This study will be conducted in Assiut University Hospitals. A blood cell sample for mast cell tryptase will be taken immediately prior to surgery and 1 hour following induction of anaesthesia in the following groups of patients (n = 30 in each case):

• Children undergoing elective surgery between the ages of 3 and 10 years
• Adults between the ages of 16 and 30 years undergoing orthopaedic trauma surgery
• Adults more than 60 years of age undergoing orthopaedic surgery
• Women of any age undergoing gynaecological surgery
• Adults of any age undergoing emergency general surgery
• Adults undergoing cardiac surgery involving cardiopulmonary bypass (samples will be taken immediately preoperatively, prior to cardiopulmonary bypass and 1 hour after cardiopulmonary bypass)
• Women undergoing caesarean section under general or regional anaesthesia

Inclusion criteria

• In order to define the incidence of possible anaphylaxis, data will be collected on 1000 consecutive general anaesthetic procedures in Assiut University Hospitals.
• A blood cell sample for mast cell tryptase will be taken immediately prior to surgery and 1 hour following induction of anaesthesia in the following groups of patients (n = 30 in each case):

(a) Children undergoing elective surgery between the ages of 3 and 10 years (b) Adults between the ages of 16 and 30 years undergoing orthopaedic trauma surgery (c) Adults more than 60 years of age undergoing orthopaedic surgery (d) Women of any age undergoing gynaecological surgery (e) Adults of any age undergoing emergency general surgery (g) Women undergoing caesarean section under general or regional anaesthesia

Exclusion criteria

patient refusal, history of previous allergic reaction.