Haemodynamic heterogeneity and treatment with the calcium channel blocker nicardipine during phaeochromocytoma surgery

Background: Favourable outcome of phaeochromocytoma surgery requires that paroxysmal hypertension and arrhythmia be controlled, and that hypotension be prevented. Is nicardipine, a calcium channel blocking drug, always adequate ? Methods: Nineteen consecutive patients underwent surgery for phaeochromocytoma. Management was standardised with regards to anaesthesia and antihypertensive treatment. Nicardipine was used as a vasodilator and was given in order to maintain systemic vascular resistance 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 surgical approach to the tumour, and was controlled by increased depth of anaesthesia. Hypertensive episodes occurred in 11/19 patients during tumour manipulation. Nicardipine always succeeded in maintaining low systemic vascular resistance but its dosage varied widely between patients (0.5 to 70 mg), a fact that may be accounted for by the striking intersubject 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 vascular resistance. Following tumour removal, transient serious hypotension (MAP <60 mmHg) occurred in 4 patients, and was corrected by fluid volume expansion. Perioperative incidence of hypertension or hypotension was not related to preoperative clinical status. Conclusion: Adequate management of patients operated upon for phaeochromocytoma requires invasive monitoring, since the mechanisms underlying hypertensive crises are heterogeneous with regards to systemic vascular resistance and not predictable from preoperative data. Nicardipine provides a good control of vasoconstriction during phaeochromocytoma surgery with limited risk of serious hypotension after tumour removal.