A 17 year old male with a history of bronchial asthma was admitted to the intensive care unit in severe respiratory distress. During a two week period of intensive respiratory care he received large doses of aminophylline and corticosteroids. In addition, pancuronium was given to facilitate ventilation and to reduce airway pressure. Large doses of pancuronium, as much as 5 mg/hr, were required to stop spontaneous respiratory efforts and restlessness. The total pancuronium dose given during the two week period was 800 rag. One hour after pancuronium was discontinued the patient could open his eyes and move his lips. Peripheral nerve stimulation indicated partial paralysis which improved promptly following a test dose of edrophonium.The authors speculate that aminophylline, which is a known inhibitor of the enzyme phosphodiesterase, raised the level of c-AMP and, in turn, the level of acetylcholine at the neuromuscular junction and thus antagonized the blocking effect of pancuronium. In addition, the large doses of eorticosteroids that the patient had received may have enhanced the release of acetylcholine and further facilitated neuromuscular transmission.KEY WORDS: DRUG INTERACTION, pancuronium, aminophylline, steroids. AMINOPHYLLINE 1 and hydrocortisone 2 have been shown to reverse the neuromuscular blocking effect of pancuronium. The following is a case report of resistance to pancuronium in an asthmatic patient receiving large doses of aminophylline and steroids.
CASE REPORTThe patient, a 17 years old male weighing 55 kg, had a history of bronchial asthma and multiple hospitalizations due to repeated episodes of severe wheezing and respiratory distress from the age of three years. He had been taking aminophylline and terbutaline orally and inhaling nebulized metaproteranol and belcomethasone intermittently, On arrival in the emergency room on this admission the patient was in severe respiratory distress, unresponsive, and deeply cyanotic. Respiratory rate was 38/min, blood pressure 21.3/10.6 kPa (160/80 torr), and pulse 156/rain and regular. The trachea was immedi- Can. Anaesth. Soc. J., vol. 29, no. 3, May 1982 ately intubated and the lungs ventilated mechanically, 10 ml'kg -1 at a rate of 10 breaths/min, and the following medications were given: terbutaline 0.5 mg subcutaneously, isoetharine 2.5 ml by a nebulizer, hydrocortisone 250mg and aminophylline 500 mg both intravenously. Diazepam 40 mg and morphine 20 mg, in intermittent doses, were also given for sedation.At first the patient's condition improved and his arterial blood gases on F~o2 0.5 were: Po2 9.57 kPa (72 torr), PCO2 5.32 kPa (40 torr), [H +] a 46.77 nmol/1 (pH 7.33). But shortly thereafter his condition deteriorated: wheezing and airway pressure increased and arterial blood gases declined (Po2 5.85 kPa (44 tort), Pco2 7.98kPa (60 torr), [H § ] a 125.89 nmol/l (pH 6.9)) and the patient became combative. A variety of bronchodilators, steroids, sedatives, and pancuronium in large doses were given during the following two weeks (see Tab...
