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

Objective: 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.

Design: Double-blind, randomized, controlled study.

Setting: This study was conducted at a single, tertiary hospital.

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

Interventions: 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.

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

Results: 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.

Conclusions: 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.