Dose - Responses of Intravenous Propofol for Induction of Anesthesia

Kil, Hae Keum; Kim, Won Oak; Shin, Yang Sik; Kim, Jong Rae

Abstract

Propofol(2, 6-diisopropylphenol) represents a new class of intravenous anesthetic agent, being chemically unrelated to barbiturate, steroid or eugenol agents. It has been reported as a suitable induction agent for short procedures and day case surgery due to its property of rapid induction and recovery from anesthesia. Induction of anesthesia with propofol 2.0~2.5mg/kg frequently causes decreasing blood pressure and causes apnea that may last 60s or more. And it is well recognized that propofol may causes pain on injection when administered intravelnously. In the present study, we evaluated the hemodynamic and SpO2 changes after propofol injection and the dos-responses to the loss of verbal command response, eyelid reflex and trapezius reflex in premedicated patients. Also we assessed the degree of pain on injection .Patients were divided into five groups with the doses the degree of pain on injection. Patients were divided into five groups with the doses of 1.0, 1.2, 1.5, 2.0 and 2.5mg/kg(group1,2,3,4 and 5, respectively). The systolic, diastolic blood pressure, heart rate and SpO2 were measured after 60 seconds propofol injection in all the patients. And response, to verbal command, eyelid and trapezius reflex and pain complaint were checked. The systolic and diastolic blood pressure were mostly decreased(17.34 and 21.92%) in group5(propofol 2.5mg/kg)(p<0.05). Heart rate increased 10% in group 4 and 5(p<0.05). There was a dose-dependent decreasing tendency of blood pressure and increasing tendency of heart rates. SpO2 was also more reduced in group 4 and 5 (p<0.05). The overall incidence of pain on injection was 47% of the injection sites, the incidence of pain was highest on the dorsum of hand(23%). Also, the degree of pain on injection was wevere on the dorsum of hand. The value of ED50 and ED95 for loss of verbal command response, eyelid reflex and trapezius reflex were 0.81, 1.35, 2.02, 1.91 and 3.60mg/kg. We concluded that the ED95 for loss of eyelid reflex is 2.02mg/kg and it is a sufficient dosage to induction of anesthesia in premedicated patients with little significant hemodynamic changes.