Prevention of injection pain by prior continuous infusion of low-dose propofol

We investigated whether prior low-dose continuous infusion of propofol would prevent the injection pain during induction of anesthesia. Thirty-one patients, 13 - 68 yr, scheduled to undergo epidural anesthesia for surgical procedures were randomly assigned to one of three groups; 14 patients (P-2 group), and 9 patients (P-4 group) received propofol intravenously at a rate of 2 and 4 mg/kg/hr during epidural catheterization, respectively, while 8 patients (control group) received no propofol infusion before induction dose. Degree of sedation, and respiratory and hemodynamic measurements were recorded. Then, anesthesia was induced with 2 mg/kg of propofol IV over 30 sec. Pain during propofol injection was assessed before the patient lost consciousness. Fewer patients in the P-2 and P-4 groups (28.6% and 22.2%, respectively) complained of injection pain, compared with the control group (75.0%) (p < 0.05). Fifteen min after the start of continuous infusion of propofol, sedative effect was greater in the P-4 group than the P-2 group (p < 0.05). Continuous infusion of propofol at a rate of 2 mg/kg/hr before induction dosage was effective for the prevention of injection pain, and provides appropriate sedation during epidural blockade.