Target-controlled Infusion of Remifentanil during Propofol Induction in Hypertensive Patients: Effects of Three Different Remifentanil Concentrations on Hemodynamic Changes

Abstract

Background: This study compared the hemodynamic effects of target-controlled infusion (TCI) of remifentanil (4, 5, or 6 ng/ml) during propofol induction in normotensive and hypertensive patients. It was also examined whether increasing the remifentanil concentrations might reduce propofol consumption at the loss of consciousness (LOC). Methods: Seventy five ASA 1 or 2 normotensive (N) and 75 ASA 2 hypertensive (H) patients were randomly allocated according to the remifentanil target effect-site concentration of 4, 5, 6 ng/ml (groups N4, N5, N6, H4, H5, H6 respectively). After the start of remifentanil TCI, when the target effect-site concentration of remifentanil had been reached, the TCI of propofol (4μg/ml) was started. The effect-site concentration of propofol at LOC was recorded. When the target effect-site concentration of propofol was reached, 0.6 mg/kg of rocuronium was administered. Tracheal intubation was carried out after 2 minutes. The noninvasive blood pressure, heart rate (HR), bispectral index (BIS) and infused dose of remifentanil and propofol were recorded. Results: Groups H5, H6 and N6 resulted in significant decrease in blood pressure after intubation. In groups N4 and H4, clinically significant increases in HR (above 25% of the baseline) were observed at 1 minute after intubation. The effect-site concentration of propofol at LOC was significantly lower in groups N6 and H6 compared to groups N4 and H4. Conclusions: In hypertensive patients, a dosing requirement of lower effect-site concentration of 4 ng/ml remifentanil might be adequate during propofol induction. Increasing the remifentanil concentrations from 4 to 6 ng/ml may reduce the propofol requirements for hypnosis. (Korean J Anesthesiol 2007; 53: S 12∼8)