Effect of the addition of ketamine to morphine in patient-controlled analgesia

This randomised double-blind, prospective study compared morphine (1 mg.m(-1)) with the combination of morphine (1 mg.m(-1)) and ketamine (0.75 mg.m(-1)) via a patient-controlled analgesia system (PCAS) for postoperative pain control. A total of 42 female patients, ASA grade I and II, undergoing elective total abdominal hysterectomy was studied. During a standardised anaesthetic, a loading dose from the PCA syringe of 10 ml.m(-2) of body surface area was given. A PCAS with a background infusion was commenced postoperatively. Pain and side-effects were assessed using numerical scoring systems and cardiovascular and respiratory parameters were recorded. There was no statistically significant difference between the groups in total morphine consumption or pain scoring. Side-effect profiles and time to mobilisation were similar. This study concludes that the addition of ketamine to morphine, in this dosage regimen, administered via PCAS for postoperative pain control, does not confer benefit following total abdominal hysterectomy.