Induction pain perception after premedication with propofol vs lidocaine: a pilot study

Propofol, an intravenous (i.v.) sedative-hypnotic agent, is commonly used for the induction of general anesthesia. It has, however, a substantial potential for causing burning pain at the i.v. site. Several preinduction pharmacologic agents are used routinely to blunt or diminish this burning sensation. Little is published on the effect of a preinduction dose of propofol for pain reduction. Lidocaine, the most studied agent, is recommended by the manufacturer of propofol as a preinduction agent to minimize this burning sensation. If lidocaine could be eliminated, time and cost savings from decreased use of drug, syringes, needles, and alcohol swabs would be realized. The purpose of this study was to determine the clinical effectiveness of administering preinduction doses of lidocaine vs propofol for decreasing pain experienced during anesthetic induction with propofol. Thirty unmedicated patients, ASA physical status I or II, scheduled to undergo general anesthesia for a surgical procedure were included. Patients were randomly assigned, using a random number chart, to receive 20 mg propofol or 40 mg lidocaine intravenously before entering the operating room suite. A minimum of 30 seconds, but not more than 45 seconds, following the administration of randomized drug with open-flow i.v. fluid, the induction dose of propofol (2.5 mg/kg) was begun through the same i.v. site. When one half of the dose had been administered and cleared the tubing by visualization, the patient was asked whether any discomfort was felt in the hand. If the response was yes, the patient was asked to rate the pain as mild, moderate, or severe. Then, the anesthetic process continued normally. No statistically significant difference occurred in pain prevention between treatment groups. In the lidocaine group, 53% (8/15) of patients were pain-free; in the propofol group, 47% (7/15) were painfree. However, when pain occurred, it was more likely to be classified as severe by the propofol group, 50% (4/8), compared with the lidocaine group, 14% (1/7). No difference existed in the ability of propofol or lidocaine to decrease the incidence of pain during an induction dose of propofol. The incidence of severe pain, however, was more frequent in the propofol group. The small number of patients experiencing severe pain precluded statistical analysis. Blunting pain associated with propofol warrants further study.