Effect of Lignocaine Versus Sodium Bicarbonate on Reducing Pain Due to Intravenous Injection of Propofol : a Prospective Randomised Double-blinded, Controlled Study

Propofol is the most commonly used intravenous (IV) anesthetic drug for induction of anesthesia and for sedation. It is almost an ideal IV anesthetic agent, but pain which occur during its injection still remains a problem. This pain may not be a serious complication, but most patients remember it as an unpleasant encounter with anesthetists. In one survey, pain on propofol injection (POPI) stands 7th most important problem in the current practice of anesthesia . About 70 to 90% of patients who were given propofol for anesthesia induction experience pain during injection and this pain can be quite severe. All phenols irritate skin and mucous membranes. Thus, propofol being an alkyl-phenol is expected to induce pain despite the fact that it is almost isotonic. POPI has also been described as angialgia which means that the pain is due to vascular involvement . POPI is immediate as well as delayed after 10-20 seconds . The immediate pain is due to irritation of vein endothelium while as delayed pain is due to the release of mediators such a kininogen from kinin cascade . The most frequently used drug to alleviate POPI is intravenous lignocaine. The use of lignocaine to decrease POPI is due to its local anesthetic effect on the veins. However, it does not alleviate pain effectively in about 40% of the patients treated in this way (2). Administration of sodium bicarbonate was proved to reduce POPI. The proposed mechanism is through increasing sodium ions concentration as well as increasing serum pH through its buffering effect.