Purpose: To report a case of pheochromocytoma exhibiting an increase in systemic vascular resistance index (SVRI) and decreased cardiac index (CI) after use of labetalol.
Clinical features: A 36-yr-old male underwent adrenectomy for pheochromocytoma. Midazolam 5 mg, fentanyl 100 microg and labetalol 20 mg were administrated intravenously for premedication upon arrival in the operating theatre. After induction of anesthesia with fentanyl, thiopental and atracurium, 30 mg iv labetalol was administered. The blood pressure gradually rose to 178/101 mmHg with mildly increased SVRI (1958 dn-sec(-1).m(2).cm(5)) and stable CI (3.8 L.min(-1).m(2) ). The blood pressure reached 247/150 mmHg after intubation with an increase in SVRI (3458 dn-sec(-1).m(2).cm(5)) and a decrease in CI (3.6 L.min(-1).m(2)). The SVRI increased further to 4986 dn-sec(-1).m(2).cm(5) and CI declined to 2.4 L.min(-1).m(2) after the administration of additional labetalol 20 mg. Sodium nitroprusside was administered and the blood pressure declined immediately to 108/72 mmHg, with a decreased SVRI (2526 dn-sec(-1).m(2).cm(5)) and stable CI (2.3 L.min(-1).m(2)).
Conclusions: The elevated SVRI with low CI was considered to result from increased alpha-adrenergic activity secondary to ss-adrenergic blockade with labetalol. Clinicians should be aware of the possibility of a hypertensive crisis after iv labetalol. We suggest that labetalol should be replaced promptly with alpha-adrenergic blockers or other vasodilators when such a condition arises.