Adding ketamine to morphine for patient-controlled analgesia after major abdominal surgery: A double-blinded, randomized controlled trial

D. E. Lindholm, P. S. Myles, H. Fletcher, J. O. Hunt

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In this double-blinded, randomized controlled trial we tested if the addition of ketamine to morphine for patient-controlled analgesia (PCA) resulted in improved analgesic efficacy and lower pain scores compared with morphine PCA alone after major abdominal surgery. Seventy-one patients were randomly allocated to receive either morphine 1 mg/mL (Group M) or morphine 1 mg/mL plus ketamine 1 mg/mL (Group MK) delivered via PCA after surgery. No other analgesics or regional blocks were permitted during the 48-h study period. Postoperatively there were no differences between the groups for subjective assessment of analgesic efficacy, pain scores at rest, and on movement, opioid consumption, or adverse events. Group MK patients performed worse in cognitive testing (P = 0.037). There was an increased risk of vivid dreaming in patients who received ketamine (relative risk = 1.8, 95% confidence interval 0.78-4.3). We conclude that small-dose ketamine combined with PCA morphine provides no benefit to patients undergoing major abdominal surgery.

Original languageEnglish
Pages (from-to)116-120
Number of pages5
JournalAnesthesia and Analgesia
Issue number1
Publication statusPublished - 2001
Externally publishedYes

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