Pharmacokinetics of Propofol in Elderly Coronary Artery Bypass Graft Patients under Total Intravenous Anesthesia.

Abstract

Intravenous infusion of propofol induces a rapid and smooth onset and clearing of anesthesia, and has minimal accumulation in the body over long-term administration. 1)Propofol anesthesia enables the smooth maintenance of unconsciousness devoid of excitatory problems.2-4) Propofol is increasingly used for cardiac anesthesia and postoperative sedation. Since pharmacokinetic parameters vary among distinct patient populations, rational drug dosing for cardiac surgery patients is dependent on the characterization of the drug's pharmacokinetic parameters in coronary artery bypass graft. The pharmacokinetic profile of propofol, with its short elimination half-life and high total body clearance makes it ideally suited for administration as an infusion. However, many factors (age, weight, drug interaction, and pre-existing disease) alter propofol's pharmacokinetic properties. Of these, age is one of the most important factors. There have been reports of the pharmacokinetics of propofol infusion in Japanese patients. 5) However, there have been few reports of the pharmacokinetics of propofol in elderly patients with coronary diseases under surgery. In this study, we investigated the pharmacokinetics of propofol in two elderly patients with angina pectoris undergoing coronary artery bypass graft.Case Reports A 78-year-old Japanese man (164 cm, 64 kg, patient A) with unstable angina pectoris was operated on in an off pump coronary artery bypass graft under total intravenous anesthesia with propofol after written informed consent was obtained. The liver function was normal (GOT: 22.0, GPT: 22.7) before the operation. Propofol (Diprivan ® injection) was purchased from Astra Zeneca Co., Ltd. (Osaka, Japan). For the induction of anesthesia, 1.5 mg/kg propofol (96 mg) was administered as a single bolus infusion. From 20 min after the end of the bolus infusion, anesthesia was maintained using the step-down infusion regimens of propofol with an infusion pump, at 10 mg/kg/h for 10 min, 8 mg/kg/h for 10 min, 6 mg/kg/h for 5 min, 4 mg/kg/h for 30 min, 8 mg/kg/h for 10 min, 6 mg/kg/h for 50 min, 4 mg/kg/h for 190 min, and 3 mg/kg/h for 40 min until the end of the surgical procedure (total 1792 mg of propofol). Blood samples were collected at 5 min from the end of the bolus infusion, and at 60, 120, 195, 240, 300, 365, 395, 425 and 725 min.A 76-year-old Japanese man (162 cm, 64.1 kg, patient B) with unstable angina pectoris was operated on in a minimally invasive direct coronary artery bypass graft under total intravenous anesthesia with propofol after written informed consent was obtained. The liver function was normal (GOT : 23.5, GPT : 20.1) before the operation. For the induction of anesthesia, 1.5 mg/kg propofol (100 mg) was administered as a single bolus infusion. Anesthesia was maintained using the step-down infusion regimens of propofol using the infusion pump, at 10 mg/kg/h for 20 min, 8 mg/kg/h for 10 min, 6 mg/kg/h for 10 min, 4 mg/kg/h for 30 min, 6 mg/kg/h for 20 min, 4 mg/kg/h for 165 min, and 3 mg/kg/h for 20 min until...