Gabapentin improves pain relief following caesarean delivery, according to a study presented here at the 2014 Annual Meeting of the Canadian Anesthesiologists’ Society (CAS).
“We think that gabapentin can become, if not a routine addition to the analgesia we offer these women, then certainly a valuable alternative should elements of the standard package be contraindicated or unavailable,” said Joe Carvalho, MD, Mount Sinai Hospital, University of Toronto, Toronto, Ontario.
This latest trial was prompted by 2 prior, smaller randomised controlled trials that provided equivocal findings concerning the pain relief benefit of gabapentin 600 mg offered along with a spinal anaesthesia regimen that included intrathecal morphine. The hypothesis driving the latest trial was that the perioperative use of gabapentin would reduce pain after caesarean delivery.
Participants were 187 healthy women aged 18 to 55 years, ASA I or II, with a singleton term pregnancy. Exclusion criteria included epilepsy or chronic pain, use of anticonvulsants or neuropathic analgesics, abuse of opioids or intravenous drug use, use of antacids, and allergy/contraindication to gabapentin.
All patients were scheduled for elective caesarean delivery performed under a standard spinal anaesthesia protocol involving 0.75% hyperbaric bupivacaine 1.6 to 1.8 mL, fentanyl 10 µg, and morphine 100 µg. The patients were randomised to receive a perioperative course of gabapentin (n = 96) or placebo (n = 91). The gabapentin dosing comprised a preoperative dose of 600 mg followed by a 48-hour postoperative course of 200 mg 3 times daily. Both groups received a standardised regimen of regular oral acetaminophen and diclofenac. Parenteral morphine was administered as required.
Postoperative pain, both at rest and with movement, and patient satisfaction with pain relief were measured on a visual analogue scale (VAS, 0-100 mm) 24 and 48 hours after incision, as was opioid consumption and side effects. Maternal anxiety and catastrophising was measured using the AnxNRS and the Pain Catastrophizing Scale, respectively, with severe anxiety defined as a score of greater than 7. Neonatal outcomes were APGAR scores, need for resuscitative support, umbilical blood gases, and breastfeeding difficulties. Telephone interviews were conducted at 2 and 6 weeks to assess persistent pain.
The primary outcome was pain on movement at 48 hours after surgery. The study was 80% powered to detect a 10-mm difference in the primary outcome.
Patients in both study arms were well matched at baseline for age, body mass index, gestational age, and parity. There was no difference in VAS pain scores on movement at 48 hours between those receiving gabapentin and those receiving placebo (mean 33.6 ± 21.2 vs 35.6 ± 24.5; P = .54). However, VAS pain scores at rest were significantly reduced in those receiving gabapentin (12.2 ± 16.3 vs 18.3 ± 17.6; P = .015), as were movement (39.0 ± 21.6 vs 46.9 ± 23.1; P = .016) and greater satisfaction scores (mean 87.9 ± 15.8 vs 77.5 ± 22.2; P = .003) at 24 hours.
The percentage of patients who required additional parenteral opioids in the first 24 hours after surgery was significantly lower in those who received gabapentin (17.0% ± 17.7% vs 29.0% ± 31.9%; P = .025). The gabapentin group displayed a significant increase in the incidence of sedation during the first 24 hours (55.2% vs 39.6%; P = .032).
Neonatal outcomes and pain scores at 2 weeks postpartum did not differ between the groups. Notably, in patients who were classified as severely anxious (AnxNRS greater than 7; 28 in the gabapentin group and 29 in the placebo group), those receiving gabapentin displayed a marked attenuation of pain at rest and during movement at both 24 and 48 hours compared with those receiving placebo.
“This study shows that a perioperative course of gabapentin improves pain relief and satisfaction after elective caesarean delivery at the expense of some extra sedation in the first 24 hours,” said Dr. Carvalho.
“Even the small improvement that was seen was impressive, given the effectiveness of our standard regimen, inclusive of spinal anaesthesia, intrathecal morphine, acetaminophen, and nonsteroidal anti-inflammatory drugs,” he concluded.
[A Perioperative Course of Gabapentin Improves Pain Relief After Cesarean Delivery: A Randomized Controlled Trial. Abstract 39292]