The Effect Of Preoperative Oral Gabapentin On Perioperative Hemodynamic Variables And Postoperative Pain In Patients Undergoing Open Abdominal Hysterectomy

Background:Gabapentin is an antiepileptic drug that is effective in treatment of neuropathic and acute pain. In this study, we investigated the effect of single oral preoperative dose of gabapentin on postoperative pain and intraoperative hemodynamic variables.Methods’.32ASA I-II patients undergoing open abdominal hysterectomy under general anesthesia were randomly assigned to one of the following two groups that received either gabapentin or placebo2h before anesthesia and an intraoperative remifentanil infusion. Group gabapentin received1200mg gabapentin and0.3μg/kg/min remifentanil, group placebo received placebo capsules and0.3μg/kg/min remifentanil. Clinically relevant pain was assessed both directly and indirectly. Direct assessment included pain threshold for mechanical punctate stimuli on non-dominant upper arm preoperatively and24h after surgery and the area of hyperalgesia around the site of incision at24h postoperatively using Von Frey filaments. Indirect assessment included postoperative pain intensity using VAS scores at1,6,12and24h, time to1st postoperative analgesic requirement and24h cumulative PCA volume consumption. The perioperative hemodynamic variables such as heart rate, systolic, diastolic and mean arterial pressure at various predefined time points were also assessed. The incidence of side-effects between the two groups was also evaluated.Results:The time to1st postoperative analgesic requirement was significantly shorter in the placebo group. The24h cumulative PCA volume consumption was significantly greater in the placebo group. The normalized area of hyperalgesia around the site of incision at24h was significantly shorter in the gabapentin group. The pain threshold at24h on non-dominant upper arm was significantly decreased when compared to preoperative threshold in the placebo group. The heart rate, systolic, diastolic, mean arterial pressure at laryngeal manipulation and endotracheal intubation was significantly less in the gabapentin group. The incidence of dizziness was significantly more in the gabapentin group. Patients in the gabapentin group required significantly more intraoperative rescue sympathomimetic to treat hypotensive episodes.Conclusions:1200mg oral gabapentin administered2h before anesthesia decreases postoperative pain and postoperative opioid consumption. It also blunts the hemodynamic response to laryngeal manipulation and endotracheal intubation.