Opioid use after propofol or sevoflurane anesthesia: a randomized trial

The intravenous anesthetic propofol is a gamma-aminobutyric acid A receptor agonist. Propofol promotes analgesia by depressing nociceptive transmission in peripheral neurons, antagonizing N-methyl-D-aspartate receptors, and activating gamma-aminobutyric acid A receptors in dorsal root ganglion receptor cells. Nevertheless, it remains unclear whether intraoperative propofol causes clinically meaningful postoperative analgesia. We therefore tested the hypothesis that patients anesthetized with sevoflurane require a greater quantity of postoperative opioids (from the end of surgery until the next postoperative morning) than those anesthetized with propofol.

With Institutional Review Board and EudraCT Number approval (2009-011038-82) and patients' informed consent, ninety patients scheduled for open vein stripping were randomized to either sevoflurane or propofol anesthesia at the Medical University of Vienna General Hospital and the Danube Hospital, the largest regional hospital in Vienna. Pain was treated with bolus piritramide and patient-controlled morphine hydrochloride. The primary outcome was total opioid use from the end of surgery until the first postoperative morning. For the initial four postoperative hours and on the first postoperative morning, a blinded investigator recorded pain scores on an 11-point Likert verbal response scale.

The median [interquartile range] morphine sulfate equivalents were 9.8 [4-19] mg in the sevoflurane group and 10 [6-20] mg in the propofol group. Sevoflurane was not superior to propofol on postoperative opioid consumption, giving a ratio of means of 0.91 (95% interim-adjusted confidence interval [CI], 0.33 to 2.45; P = 0.74). Additionally, no difference in pain scores was found over time between the two groups, with a mean difference on an 11-point scale of 0.20 (95% interim-adjusted CI, -0.36 to 0.73; P = 0.31).

Intraoperative sevoflurane did not reduce postoperative analgesia. This finding is consistent with the results in most previous reports. This trial was registered at ClinicalTrials.gov: NCT00712517.