SIMPLIFIED ANESTHETIC MANAGEMENT OF THE PATIENT UNDERGOING RESECTION OF A PHEOCHROMOCYTOMA

The only curative treatment of phaeochromocytoma consists in surgical removal. This carries a high risk due to the acute release of catecholamines. General anaesthesia cannot by itself prevent haemodynamic disturbances during surgical manipulation of the tumour. Careful preparation, based on intravascular volume repletion as well as alpha-, and, if required, beta-adrenergic blockade, has been shown to reduce morbidity and mortality. However, this protocol is often cumbersome, and does not prevent totally the haemodynamic instability as a decrease in blood pressure at the start of treatment, or after removal of the tumour. Since voltage-dependent calcium channels are involved in both secretion and action of catecholamines, calcium-channel antagonists might be an interesting therapeutic alternative. In fact, short-term treatment by dihydropyridines may attenuate blood pressure variability during the preoperative period. During surgery, a dose-dependent reduction in systemic vascular resistances has been shown with intravenous nicardipine. However, dihydropyridines do not control cardiac adrenergic stimulation, which causes tachycardia or persistently increased blood pressure in spite of low or normal systemic vascular resistances. Such an acute cardiac hyperactivity, which can only be assessed by continuous haemodynamic monitoring, is electively sensitive to a beta-adrenergic blocker rather than a calcium channel antagonist with high cardiac affinity (diltiazem, verapamil). Esmolol is available for intravenous administration. It is an ultra-short acting agent, ensuring a selective dose-related cardiac beta-1-blockade. Combining esmolol with nicardipine gives control over almost all episodes of haemodynamic worsening during phaeochromocytoma resection. Preoperative medical treatment no longer aims to suppress adrenergic stimulation completely, but to prevent acute haemodynamic changes. During surgery, step-by-step management of haemodynamic alterations will be based on invasive monitoring and such manoeuvers as volume loading and the use of short-acting drugs (sodium nitroprusside, nicardipine, esmolol).