[Influence of nicardipine on the renin-angiotensin system ina hypertensive crisis during operation in elderly patients]

Abstract

We studied the influence of nicardipine on renin-angiotensin (RA) system in twelve elderly patients, because the suppression of RA system, the decrease in reactivity of its feedback mechanism, and a high probability of arteriosclerosis and hypertension are well recognized in elderly patients. In hypertensive crisis during operation, intravenous bolus injection of nicardipine was done promptly by anesthesiologists in charge. Plasma renin activity (PRA), angiotensin I (A I), and angiotensin II (A II) were measured with RIA methods before administration of nicardipine and after hemodynamics were stabilized. Changes of systemic arterial pressure and heart rate were simultaneously recorded. Concentrations of PRA, A I, and A II were not significantly elevated, whereas systemic and diastolic blood pressures decreased significantly at 5 min, 15 min, 30 min and 60 min after administration of nicardipine. Heart rate was unchanged. But in a few cases there was an increase in PRA and A I. Average total dose of nicardipine was 26.8 micrograms.kg-1 and average fall of blood pressure was 23.9%. In conclusion, we can use intravenous nicardipine safely and stabilize hemodynamics easily without activation of RA system and rebounding of its feedback mechanism.