BACKGROUND: Propofol has a high incidence of pain when administered by intravenous injection. Among the many different methods available, lidocaine is used most frequently to minimize this pain. Propofol also has a depressant action on hemodynamics, especially in the elderly. The present study was aimed to examine whether lidocaine affects hemodynamic changes associated with propofol injection and endotracheal intubation, and whether it attenuates propofol-induced pain.

METHODS: Eighty patients, over 60 years old, ASA physical status I and II, were randomly divided into four groups of 20 each according to lidocaine dosage mixed with 2 mg/kg of propofol given over 30 seconds during the induction of anesthesia; 0 mg (control group), 20 mg, 40 mg and 80 mg. Mean arterial blood pressure (MAP), heart rate (HR), and bispectral index scale (BIS) were measured before anesthetic induction (baseline value), 1 minute after the start of induction, immediately before endotracheal intubation, and then every minute for 5 minutes. Injection pain was scored as none, mild, moderate, or severe.

RESULTS: MAP decreased significantly following the propofol injection and then increased after endotracheal intubation in all four groups, the magnitude of this decrease did not differ among the groups. HR increased after the propofol injection and then decreased. It increased again after intubation in all four groups. BIS was decreased by the induction of anesthesia, but was not affected by endotracheal intubation in any group. The three lidocaine groups had a lower incidence and severity of propofol-induced pain than the control group, and the effect were comparable among the lidocaine-treated groups.

CONCLUSIONS: Our results indicate that lidocaine 20, 40 or 80 mg mixed with propofol does not affect the hemodynamic changes associated with propofol and endotracheal intubation, but that they similarly attenuate the injection pain associated with propofol.