A randomized double-blind controlled study comparing epidural morphine and epidural morphine with ketamine for post-op pain relief in abdominal surgeries.

Introduction. This is a prospective, randomized, double-blinded clinical study comparing epidural morphine with ketamine to epidural morphine alone for efficacy of pain relief 24 hours after major abdominal surgeries. This study was done to evaluate the effectiveness of epidural ketamine as an adjunct to morphine in alleviating post-operative pain in terms of morphine consumption, duration and quality of analgesia and incidence of side effects.

Methods. ASA I or II subjects, aged 18 to 65 years, with body mass index of 18.5 to 24.9, who underwent major abdominal procedures were enrolled in the study. They were randomly assigned into one of the two treatment arms and blinded: Group A received 2 mg epidural morphine while Group B received epidural morphine 2mg + ketamine 20mg for post-operative analgesia. Parameters noted were number of supplemental and meperidine doses, time to request for analgesia (TFA), Visual Analogue Scale (VAS) score on TFA and side effects like sedation and nausea/ vomiting. Statistical analyses used were t-test and Pearson Chi-square test.

Results. Thirty-one patients were included in the study. The total number of meperidine and supplemental doses of morphine +/- ketamine in the first 24 hours post-operatively was significantly less (p = 0.001) in Group B than Group A. TFA was significantly longer (p=0.003) in Group B than Group A. The patients' VAS scores on TFA significantly differed (p = 0.008), group B had lower VAS scores as compared to Group A. Side effects were comparable in both groups.

Conclusion. This study showed that the addition of epidural ketamine 20mg to morphine 2mg effectively decreased morphine consumption, improved and increased the duration of analgesia twenty-four hours after major abdominal surgery without increasing side effects. (Author)