Intrathecal morphine in planned gynecologic surgery: Recovery and postoperative pain control

Background: To compare post-operative pain control and side effects of intrathecal morphine (ITM) given in two different doses in patients undergoing gynecological surgery. Methods: This was a retrospective data base cohort study conducted between 2015 and 2017 at the Shaare Zedek Medical Center. Surgeries were divided into subgroups: vaginal, abdominal and oncological. A comparison was made between 2 distinct doses of ITM (standard – 150 mcg and high - 200 mcg) in terms of post-operative pain as reflected by visual analog scale (VAS) scores and side effects. Additional subgroup of the three surgical groups was made regardless of the ITM dose used. Multivariate analysis was carried out using appropriate tests. Results: The study included 156 patients. Forty five patients received a standard dose ITM and 111 received the high dose. Sixty three patients had vaginal surgery, 80 had benign abdominal surgery and 13 had a gynecologic oncology surgery. No difference was noted in VAS scores during the first 24 h of hospitalization. However, average and maximal VAS scores were higher among those who received high dose ITM. This difference did not remain significant in the multivariate analysis controlling for patient age and surgery type. Patients treated with high dose ITM had a higher incidence of pruritus. No difference was noted in respiratory depression as reflected by medically indicated oxygen consumption between those treated with high vs. standard dose ITM. Conclusions: ITM dose higher than 150 mcg is associated with a higher rate of pruritus without any additional benefit on the analgesic effect as reflected by post-operative VAS scores.