Sodium nitroprusside and lidocaine in the anaesthetic management of pheochromocytoma

Abstract

Recent advances in pharmacology, physiology, and biochemistry have revealed the pathophysiologic derangements encountered in pheochromocytoma, and the rational foundations for its management; this is illustrated in reports of two cases. For pre-operative preparation we use phenoxybenzamine to block the alpha adrenergic receptors, as it allows improvement in the cardiovascular status, expansion of the blood volume, decrease in the basal metabolic rate and plasma free fatty acids and protection against adrenergic crisis. We use propranolol pre-operatively subsequent to effective alpha adrenergic receptor blockade only to control serious dysrhythmia, angina or myocardial ischaemia. The alpha and beta blocking agents are withheld 12 hours prior to operation. Preanaesthesic medication includes morphine, diazepam and scopolamine and induction and subsequent maintenance of anaesthesia are achieved with diazepam, fentanyl, pancuronium, nitrous oxide and oxygen. Lidocaine (50-100 mg) is administered prophylactically before induction of anaesthesia, tracheal intubation and concomitant with exaggerated pressor responses to surgical manipulations. These latter reactions are managed by phentolamine ( 1-5 mg ) until the first manifestation of tachyphylaxis; at this juncture we resort to a drip of sodium nitroprusside ( 50-100 ζ/minute). Successful management of pheochromocytoma demands anticipation of potential problems, prior preparation of necessary medication, adequate monitoring and close post-operative observation. © 1977 Canadian Anesthesiologists.