The addition of ketamine to patient controlled morphine analgesia does not improve quality of analgesia after total abdominal hysterectomy

We undertook a prospective, randomised, double-blind clinical trial of 50 ASA I and II patients undergoing total abdominal hysterectomy to compare the effect of intraoperative ketamine (0.3 mg kg −1 i.v.) and ketamine 1 mg ml −1 plus morphine 1 mg ml −1 patient controlled analgesia (PCA) (group MK) — with morphine 1 mg ml −1 PCA (group M) for postoperative analgesia. There was no significant difference in pain scores at rest or after compulsory cough at 24 hours. The mean total dose of morphine used at 24 hours was 33 mg in the control group vs 34.5 mg in the ketamine group (ns). Patient reporting of adverse effects was similar in both groups, although the ketamine group reported significantly less sleepiness. No patients reported hallucinations, confirming that low-dose ketamine is well tolerated. Overall satisfaction with the quality of analgesia was significantly better in the control group. Our results have not confirmed that the addition of low-dose ketamine to a standard anaesthetic/postoperative regimen in total abdominal hysterectomy patients provides any improvement in analgesia, morphine sparing effect or a reduction in adverse effects (except sedation).