Discomfort on injection: a comparison between two formulations of propofol

A randomized double-blind controlled trial was performed to determine if there was a difference in discomfort on injection between two preparations of propofol. A long-chain triglyceride preparation (LCT-propofol (Fresenius)) was compared against a medium- and long-chain triglyceride preparation (MCT/LCT-propofol (BBraun)).

One hundred and twenty ASA I-II patients listed for elective procedures were consented and randomized to receive either induction agent. A standard rate of infusion was used for induction of anaesthesia and subjects were questioned about discomfort until contact was lost. Discomfort was recorded as none, mild, moderate or severe. Incidence of postoperative nausea and vomiting and anti-emetic requirements were recorded in the postanaesthetic care unit.

There was seen to be a 54% reduction in moderate/severe discomfort with MCT/LCT-propofol compared with LCT-propofol (P < 0.006). There was a 70% reduction in severe discomfort with MCT/LCT-propofol compared with LCT-propofol (P < 0.04). The term discomfort was used during the study because there is a wide array of unpleasant sensations felt by patients during propofol induction which are not always reported as pain. There was no significant difference in the incidence of postoperative nausea and vomiting or anti-emetic use between the two groups.

There is a significant decrease in the incidence of discomfort with MCT/LCT-propofol compared with LCT-propofol. This difference is more marked in subjects reporting severe discomfort.