PCA ketamine-morphine versus PCA morphine as post-operative analgesia in colorectal surgery

Ketamine has undergone a recent resurgence of interest as an opioid-sparing agent in pain management. The purpose of this study is to evaluate the effectiveness of patient-controlled analgesia (PCA) ketamine-morphine in comparison to conventional PCA morphine alone as post-operative analgesia in colorectal surgery patients.

Double-blind, randomized, controlled study.

This study was conducted at a single, tertiary hospital.

Sixty patients who underwent elective colorectal surgery were randomly assigned into two groups.

Group A received PCA ketamine-morphine 0.5:0.5 mg mL^-1, while Group B received PCA morphine 1 mg mL^-1 as post-operative analgesia.

Patients' pain scores, total PCA demands, cumulative morphine consumption, side effects, and their overall satisfaction score were recorded and analyzed.

Overall, there was no significant difference in pain score in both groups, except at 24-hour intervals where Group A had significantly lower mean pain score at rest (1.10 ± 1.37 vs 2.10 ± 1.65, p = 0.017). Total PCA demands were comparable between both groups. Cumulative morphine consumptions however were significantly lower in Group A at all intervals with 24.7 ± 15.2 vs 48.9 ± 30.4 mg (p < 0.001) at 24-hour interval and 38.3 ± 22.4 vs 77.8 ± 46.3 mg (p = 0.001) at 48-hour interval. There was no significant difference in the incidence of side effects and overall satisfaction score in both groups.

PCA ketamine-morphine was as effective as PCA morphine as post-operative analgesia in colorectal surgery, with comparable pain scores, PCA demands, side effects, and significant reduction in morphine consumption.