INTRODUCTION
Although the prevalence of analgesic intolerance (AI) has been reported to be about 1 % in general population, its incidence rises in some special conditions like bronchial asthma. AI affects 10 % of the adult asthmatics and about one fourth of the patients with nasal polyposis and chronic urticaria1. The triad of asthma, nasal polyposis and analgesic intolerance has been called as aspirin-induced asthma (AIA) or Samter's syndrome1-9. It has been accepted that hereditary tendency play a role in both AI and AIA. Severe and protracted symptoms are superimposed on a background of aggressive inflammation of the airways in AIA. Pansinusitis and nasal polyposis may also easily exacerbate on the inflamed upper airways1-9. Recent advances in AIA have demonstrated an altered arachidonic acid metabolism with cysteinil leukotriene overproduction1-3,5,6,10.
Although several other allergic conditions may accompany AI, the reports in the literature are usually about asthma1,3,5,11,12. The most bothersome issue about these patients concerning the physicians is the possible cross-sensitivity of the AIA/AI patients to general anaesthetic agents. It is well known that there are quite frequent cross-reactions between some analgesics and antibiotics, but it is not clear if there is a relation between analgesic intolerance and general anaesthesia. This uncertainty sometimes leads to the postponement of an important operation and sometimes the performance of unnecessary, time-consuming and expensive serologic allergy tests with low sensitivity and specificity.
A marked cross sensitivity with NSAIDs, which may also precipitate severe bronchospasm and adverse reactions, is the main problem for the anaesthetists regarding post-operative pain management. Unfortunately, all the NSAIDs favoured currently by anaesthetists (including diclofenac, ibuprofen, indomethacin, ketoprofen, ketorolac and piroxicam, metamizole) are extremely potent cyclooxygenase inhibitors and are implicated in this problem1-3,5-7,9,12.
Paradoxically, some NSAIDs, including sodium salicylate, choline, magnesium trisilicate and salicylamide are well tolerated by aspirin-sensitive asthmatic patients probably because they do not inhibit the cyclo-oxygenase enzyme. Although paracetamol is safe for most of the aspirin sensitive patients some cases of intolerance have been reported1,2,5.
Patients with aspirin sensitivity confront anaesthesia for nasal polypectomy or several other reasons. Anaesthetists must be aware of their pulmonary dysfunction, because anaesthetic management of asthma needs specific approach.
The aim of this article was to mention the peroperative and postoperative general anaesthesia related allergic problems in patients with AIA and/or AI who have been evaluated by an allergist preoperatively and received a special general anaesthesia protocol used for the asthmatic patients.
ANAESTHETIC MANAGEMENT OF THE AIA PATIENTS
Asthma is a common obstructive lung disease with a hallmark of airway inflammation, and hyperreactivity in response to a variety of stimuli. The characteristic of the disease is resistance to airflow. Elevated airway resistance and air trapping increases the work of breathing; respiratory gas exchange is impaired because of ventilation/perfusion imbalance. The predominance of expiratory airflow resistance results in air trapping; increase in residual volume and total lung capacity. Wheezing is a common physical finding that represents turbulent airflow13.
The clinical history is important during the preoperative assessment. No or minimal dyspnoea, wheezing or cough must be achieved, and complete resolution of exacerbation should be confirmed by chest auscultation. Pulmonary function testing; particularly expiratory airflow measurements and peak expiratory flow rate and chest radiogram should be used to confirm clinical impressions.
Asthmatic patients with active bronchospasm presenting for emergency surgery should undergo a period of intensive treatment. Supplemental oxygen aerosolised β2 agonists or intravenous glucocorticoid; due to their bronchodilatator, anti-inflammatory and membrane stabilizing effects respectively, can dramatically improve lung function in a few hours.
Bronchodilators should be continued up to the time of surgery. Patients who have been receiving long-term glucocorticoid therapy should be given supplemental doses to compensate for adrenal suppression13.
Preoperative sedation is important, especially for the patients whose disease has an emotional component. Benzodiazepines are the drugs of choice for this purpose13.
The most critical time for an asthmatic patient undergoing general anaesthesia is during instrumentation of the airway. Pain, emotional stress or stimulation during light general anaesthesia may precipitate bronchospasm. The cornerstone of general anaesthesia is a smooth induction avoiding drugs with histamine releasing property such as thiopental, meperidine, morphine, atracurium, mivacurium and succinylcholine. Propofol and etomidate are suitable agents for induction. Ketamine is the only agent that has bronchodilating property, especially suitable for the patients who are hemodinamically unstable. Vecuronium bromide is the muscle relaxant of choice. Volatile anaesthetics with their bronchodilating properties can be safely used for the maintenance of anaesthesia. It must be remembered that halothane may sensitise the heart to aminophilline and β -adrenergic agonists administered during anaesthesia. Ventilation should be controlled with warmed, humidified gasses if possible under capnographic monitorisation. Intraoperative bronchospasm is usually manifested as wheezing, increased peak inflation pressures, decreased exhaled tidal volumes. The first approach must be deeping the anaesthesia. If wheezing does not resolve, obstruction of the endotracheal tube, pulmonary oedema or embolism, bronchospasm must be excluded. Bronchospasm should be treated with β -adrenergic agonist, and steroids13.
At the end of the surgery, reversal of nondepolarizing neuromuscular blocking agents with anticholinesterase does not precipitate bronchoconstriction if preceded by appropriate dose of an anticholinergic. Extubation must be performed under deep general anaesthesia to avoid bronchospasm13.
It must be remembered that high spinal and epidural anaesthesia may aggravate bronchospasm by blocking sympathetic tone to the lower airway. Vagal afferents in the bronchi are sensitive to histamine and several noxious stimuli. Reflex vagal activation results in bronchoconstriction, which is mediated by an increase in intracellular cyclic guanosine monophosphate13,14.
One of the problems for the anaesthesiologists in AIA is the marked cross sensitivity with NSAIDs, which are used in pain management. Analgesics causing histamine release such as morphine, mepheridine may also precipitate severe bronchospasm and other adverse reactions in susceptible individuals5. Fentanyl, a potent narcotic analgesic is used for early postoperative pain management whereas safe alternative analgesics referred by allergy clinics were used for the late ones.
We had experienced 47 patients who had been diagnosed as AIA between 1991 and 2003 in the department of chest diseases and adult allergy unit then who had been operated under general anaesthesia. The mean age of the 47 patients was 43.7 ± 14.01 and 30 (63.8 %) were females similar to the literature1,3. Fifty-three surgical procedures were performed under general anaesthesia for 47 AIA patients. The types of surgery were as fallows; Ear, nose and throat 35 (66 %), orthopaedic 5 (9.4 %), general surgery 10 (18.8 %), thoracic 2 (3.7 %), urologic 1 (1.8 %) procedures15. No complications have appeared in relation to anaesthesia and pain management except in a 44-year-old woman with AIA who had a reaction in the postoperative period after receiving an inappropriate analgesic. Although contraindication for metamizol application was noted in her file, it was administered to a patient for postoperative pain relief two hours after leaving post anaesthetic care unit depending on the information the patient had given. This 44-year-old woman having AIA was admitted to the intensive care unit because of acute urticaria and arrhythmia and followed up over a night. We must bare in mind that the data about the safe drugs must be taken from the notes of allergists in the file instead of the patient himself/herself, because general anaesthesia may cause a loss in cognitive functions for several hours or even days9-16.
CONCLUSION
It may be concluded that, preoperative evaluation and preparation of AIA patients in collaboration with allergy and anaesthesiology clinics and the suitable anaesthetic approach in all types of surgical procedures is important for the prevention of preoperative, peroperative and postoperative complications.
According to our standard anaesthesia protocol for AIA patients; atropine and diazepam in the premedication, propofol and fentanyl during induction, muscle relaxation facilitation by vecuronium and sevoflurane or isoflurane for maintenance, fentanyl, a potent narcotic analgesic, and safe alternative analgesics referred by allergy clinics for early postoperative analgesia, seem to be the safe anaesthetic approach for AIA patients.
