HEMODYNAMIC HETEROGENEITY AND TREATMENT WITH THE CALCIUM-CHANNEL BLOCKER NICARDIPINE DURING PHEOCHROMOCYTOMA SURGERY

Background: Favourable outcome of phaeochromocytoma surgery requires t hat paroxysmal hypertension and arrhythmia be controlled, and that hyp otension be prevented. Is nicardipine, a calcium channel blocking drug , always adequate ? Methods: Nineteen consecutive patients underwent s urgery for phaeochromocytoma. Management was standardised with regards to anaesthesia and antihypertensive treatment. Nicardipine was used a s a vasodilator and was given in order to maintain systemic vascular r esistance lower than 1600 dyn.s.cm(-5). Results: Hypertension did not occur at any time during surgery in 6/19 patients. Blood pressure rose acutely in 3/19 patients at the time of tracheal intubation or surgic al approach to the tumour, and was controlled by increased depth of an aesthesia. Hypertensive episodes occurred in 11/19 patients during tum our manipulation. Nicardipine always succeeded in maintaining low syst emic vascular resistance but its dosage varied widely between patients (0.5 to 70 mg), a fact that may be accounted for by the striking inte rsubject variability of haemodynamic behaviour during surgery. In 7/11 patients, despite nicardipine treatment, sustained increase in blood pressure persisted with increased cardiac index, but low systemic vasc ular resistance. Following tumour removal, transient serious hypotensi on (MAP <60 mmHg) occurred in 4 patients, and was corrected by fluid v olume expansion. Perioperative incidence of hypertension or hypotensio n was not related to preoperative clinical status. Conclusion: Adequat e management of patients operated upon for phaeochromocytoma requires invasive monitoring, since the mechanisms underlying hypertensive cris es are heterogeneous with regards to systemic vascular resistance and not predictable from preoperative data. Nicardipine provides a good co ntrol of vasoconstriction during phaeochromocytoma surgery with limite d risk of serious hypotension after tumour removal.