The effect of gabapentin on postoperative pain and opioid-related side effects in patients undergoing combined spinal-epidural anesthesia (a preliminary study)

Abstract

Purpose: Combined spinal-epidural anesthesia (CSEA) is a technique, which is frequently preferred in lower extremity surgery. It has been reported that preoperative administration of gabapentin, approved for neuropathic and chronic pains, also reduces postoperative pain. In this study, the effect of preoperative administration of gabapentin on postoperative pain in patients who had CSEA during lower extremity surgery is investigated. Material and Methods: After obtaining the approval of the Ethics Committee and the written consent, 60 patients (ages between 18-65 years) who were lower extremity surgery candidates and classified as ASA I-III, were included in the study. The patients were classified randomly into two groups. Group P (n=30) was given 0.5% levobupivacaine (10-15 mg) and fentanyl (25 μg) by spinal route. In the postoperative period, morphine (3 mg) was administered via epidural catheter after the spinal block has resolved. Group G (n=30) was administered 600 mg of gabapentin 1-2 hours prior to surgery, in addition to the medication of Group P. In the postoperative period, hemodynamic data (SAP, DAP, HR), pain scores (VAS), sedation scores, pruritus scores, other side effects (nausea, hypotension, respiratory depression, bradycardia), and the need for antihistaminic and additional analgesics were assessed. Results: The demographic characteristics, hemodynamic parameters, duration of surgery, and sedation scores of the groups were similar. It was found that the postoperative pain scores (VAS) were lower in group G at the 30 th and 60 th minutes and at 18 th and 24 th hours (p<0.05). In the postoperative period, 10 patients in Group P experienced pruritus at the 18 th hour, as did eight patients at the 24 th hour, whereas none of the patients in Group G reported pruritus at either the 18 th or 24 th hours (p<0.001, p<0.005). The differences between the nausea scores and other side effects of the two groups were not statistically significant. Conclusion: It was concluded that preoperative gabapentin statistically decreased postoperative pain levels as well as pruritus caused by opioids, but did not improve nausea in patients undergoing lower extremity surgery.