BACKGROUND: Nicardipine or nitroglycerin has been used to induce controlled hypotension in healthy patients undergoing orthopedic surgery. Despite the fact that controlled hypotension reduces the amount of blood loss during surgery, the changes in the regional blood flow (RBF) are unclear. This study compared the effects of nicardipine and nitroglycerin on the RBF using a laser Doppler flowmeter.

METHODS: Twenty adult patients, ASA physical status I or II, who were scheduled for hip or spine surgery under general anesthesia, were randomly divided into two groups. After inducing general anesthesia, Group N (n = 10) was infused with nitroglycerin to induce hypotension, and group P (n = 10) was infused with nicardipine. The RBF was measured at the upper arm (1 cm lateral from the acromion of the scapula and deltoid region) and the second fingernail of the same side during the prehypotensive and hypotensive states.

RESULTS: There was no significant difference in the estimated level of blood loss and urine output between the groups. The reduction in the mean arterial pressure was faster in group P than in group N. There was no difference in the time for the mean arterial pressure to return to the baseline after the stopping drug infusion. Although the change in the RBF during the hypotensive period was significantly higher in group N than in group P, there was a similar estimated level of blood loss.

CONCLUSIONS: Nicardipine is better than nitroglycerin in maintaining the regional blood flow in the peripheral tissue during controlled hypotension and induces controlled hypotension more rapidly.