Continuous intravenous analgesia with fentanyl or morphine after gynecological surgery: a cohort study.

PURPOSE: This retrospective study aims to compare postoperative pain relief offered by continuous intravenous infusion of either fentanyl or morphine.

METHODS: Sixty American Society of Anesthesiologists Physical Status I and II women who had undergone open gynecological surgery were enrolled. All patients received total intravenous postoperative analgesia for 24 h with continuous infusion of either fentanyl or morphine at comparable doses (38 patients received 0.3 µg/kg/h fentanyl and 22 received 0.02 mg/kg/h morphine). The primary endpoint was the need for analgesic rescue therapy during the postoperative period as assessed by an experienced nurse blinded to the design of the study, while the time to gastrointestinal bowel recovery was the main safety outcome measure. Visual analog scale was used to evaluate postoperative pain. Ramsay sedation score, multiparametric monitoring, bowel function and adverse effects were also recorded at 1, 6, 12, 18 and 24 h after the end of surgery.

RESULTS: Data analysis showed that four patients (10 %) in the fentanyl group versus eight patients (36 %) in the morphine group needed to be treated with analgesic rescue drugs [unadjusted OR for fentanyl 0.2 (0.05-0.80); p = 0.02]. Patients treated with fentanyl showed a faster gastrointestinal recovery [1 (1-2) vs 3 (2.7-4) days; p < 0.001] and a shorter hospital length of stay [4 (3-5) vs 5.5 (5-7.2) days; p < 0.001].

CONCLUSION: In low-risk patients undergoing open gynecological surgery, continuous intravenous infusion of both fentanyl and morphine for postoperative pain relief is effective. In our cohort of patients, continuous intravenous infusion of fentanyl was associated with lower need for analgesic rescue drug, faster bowel recovery and shorter hospital length of stay.