Background and objective: It has been hypothesized that combinations of analgesics with different mechanisms of action may reduce or even prevent postoperative pain. We, therefore, investigated the analgesic effect of gabapentin, dexamethasone and low-dose ketamine in combination with paracetamol and ketorolac as compared with paracetamol and ketorolac alone after hip arthroplasty.
Methods: In this double-blind study, 42 patients were randomly assigned to either a combination group [gabapentin 1200 mg+dexamethasone 8 mg+ketamine (0.15 mg kg(-1))+paracetamol 1 g+ketorolac 15 mg] or a control group (placebo+paracetamol 1 g+ketorolac 15 mg). The medication was given preoperatively except for ketorolac, which was given at the end of surgery. Postoperative pain treatment was paracetamol 1 gx3; ketorolac 15 mgx3; and patient-controlled intravenous morphine. Morphine consumption, pain intensity at rest and during mobilization, nausea and vomiting, sedation, dizziness, hallucination and consumption of ondansetron were recorded 2, 4 and 24 h after operation. A P value of less than 0.05 was considered statistically significant.
Results: Morphine consumption was not significantly different between groups (P=0.085). Overall pain scores were improved in the combination group as compared with the control group both at rest (P=0.042) and during mobilization (P=0.027). In the combination group, individual pain score above 30 mm on a 100 mm visual analogue scale was almost eliminated. The incidence of side effects did not differ between the groups.
Conclusion: Preoperative gabapentin, dexamethasone and ketamine combined with paracetamol and ketorolac reduced overall pain scores in patients after hip arthroplasty as compared with paracetamol and ketorolac alone. Morphine consumption was not reduced.