A randomized, controlled trial of a clinical pharmacist intervention in microdiscectomy surgery - Low dose intravenous ketamine as an adjunct to standard therapy

Abstract

Aim: The hypothesis that postoperative pain would be reduced by using 1 μg/kg/min of ketamine, both intra- and post-operatively, for lumbar microdiscectomy surgery was assessed by measuring morphine consumption. Patient side effects were reported.

Methods: Forty-five patients undergoing microdiscectomy surgery were randomized under double-blind conditions into three groups: Group1 (G1) received normal saline, Group 2 (G2) ketamine (1 μg/kg/min) intra-operatively and Group 3 (G3) ketamine (1 μg/kg/min) both intra- and post-operatively. Morphine consumption, pain scores, nausea and vomiting, CNS disorders were recorded for 24 h post surgery. This study was conducted by applying the concept of a clinical pharmacist intervention.

Results: The time for the first analgesia demand dose was significantly shorter (P < 0.05) in G117 ± 1.7 min than for G2 and G3. In G3 morphine consumption 6, 12, and 24 h after surgery was 3 ± 2.26, 9.2 ± 2.11 and 26.9 ± 2.71 mg. Total morphine consumption was significantly lower for G3 than for G1 or G2 (P < 0.05). The visual analog scale score (VAS) values were significantly lower in G3 (P < 0.05) than for the other groups during the first 24 h. The rate of nausea and vomiting was significantly higher in G1 vs G3 (P < 0.05). No difference in drug induced CNS disturbances was observed among the groups.

Conclusions: Using 1 μg/kg/min of ketamine hydrochloride intra- and post-operatively for microdiscectomy surgery could be an adjunct therapy to reduce postoperative morphine consumption minimizing its side effects. Collaborative clinical pharmacy practice on the basis of pharmacology had an effective role in improving the general outcome of microdiscectomy surgery.

Keywords: Intra-operative; Ketamine; Microdiscectomy surgery; Morphine consumption; Nausea and vomiting; Post-operative.