[Unusual cardiocirculatory response to naloxone administration. Clinical case]

A patient in good general condition and a negative clinical history was anaesthetised for right lower extremity varices. Preanaesthesia with 10 mg diazepam and 0.3 mg atropine 45 min prior to surgery was followed by uneventful induction with thiopental sodium and succinylcholine orotracheally, and maintenance with N2O, O2 and Ethrane in standard percentages. Muscle relaxation was obtained with pancuronium bromide. Automatic ventilation was used to maintain a VT of 12 ml per kg body weight and a respiration rate of 10 breaths per minute. At the end of the operation, 2.5 mg neostigmine and 1.5 mg atropine were given. Since the patient failed to breather spontaneously, automatic ventilation was resumed and 0.4 mg naloxone were administered i.v. After about 2 min, the patient exhibited the classic signs of left ventricular insufficiency, with BP 260/150 mmHg, clinical evidence of acute pulmonary oedema, and an ECG showing atrial tachycardia and variable A-V block. Treatment with PEEP and i.v. furosemide led to spontaneous resolution of the clinical picture, and early normalisation of the ECG. The part played by naxolone in this picture is discusses with reference to similar cases in the literature. It is felt that massive release of catecholamines in response to pain after administration of naloxone is capable of triggering the typical clinical picture of left ventricular insufficiency. The possible role of naloxone vis-à-vis opium and endorphin receptors is also discussed.