Low-dose propofol reduces the incidence of moderate to severe local pain induced by the main dose

Background Local pain on injection of propofol remains a considerable problem in clinical anaesthesiology. As slow infusion of a low dose of propofol induces little or no pain at the site of injection, and as propofol-induced pain fades during prolonged exposure, this randomized, double-blind, clinical cross-over study was designed to test whether pain on injection of propofol is attenuated by initial slow injection of a low dose of propofol by the same intravenous line. Methods Seventy-seven adult surgical patients were cannulated in a dorsal vein on each hand. In each cannula, a 0.5-ml priming dose of either propofol 10 mg/ml dissolved in an emulsion of medium- and long-chain triglycerides or aqueous sodium chloride 9.0 mg/ml was injected over 30 s, and followed 120 s later by a main dose of 2.0 ml of the same propofol formula over 6 s. After each injection, the patients were asked by a blind investigator to score the maximal pain intensity on a visual analogue scale (VAS). Results Although the decrease in maximal pain intensity did not reach statistical significance (P = 0.070), significantly fewer patients reported moderate or severe pain intensity (corresponding to 3.0 VAS units or more) after the main dose of propofol was preceded by a priming dose of propofol than by sodium chloride (P = 0.041). Conclusions The incidence of moderate to severe local pain induced by intravenous propofol can be decreased by a readily applicable technique in which a low dose of propofol emulsion is slowly administered by the same intravenous route 2 min in advance