Study of the Effect of the Drug Gabapentin on Postoperative Pain and Incidence of Postoperative Nausea and Vomiting

• Effect of preoperative and postoperative administration of gabapentin on postoperative opioid requirement. [ Time Frame: 48 hours ] [ Designated as safety issue: No ]
  
• Effect of preoperative and postoperative administration of gabapentin on incidence of postoperative nausea and vomiting. [ Time Frame: 48 hours ] [ Designated as safety issue: No ]
  

• Effective of preoperative and postoperative Gabapentin on the incidence of respiratory depression as evidenced by pulse oximetry data [ Time Frame: 48 hours ] [ Designated as safety issue: Yes ]
  

The occurrence of morbid obesity is at epidemic proportions in the United States. Laparoscopic gastric bypass is an effective means of safely facilitating patient weight loss and thereby drastically reducing the prevalence and severity of many future health complications [1]. However, managing morbidly obese surgical patients poses certain obstacles for anesthesiologists, including a high incidence of obstructive sleep apnea [2].

Laparoscopic gastric bypass, like all surgical interventions, has associated postoperative challenges including pain management and prevention/control of postoperative nausea and vomiting. To assure the highest patient satisfaction, all areas of patient comfort must be addressed. However, with pain management in morbidly obese patients, caution must be used when administering opioids, as they can have an increasing effect of respiratory depression in patients already at risk due to obstructive sleep apnea [3]. Gastric bypass is also associated with a significant incidence of protracted postoperative nausea and vomiting [4]. Therefore, regimens that address both patient safety and patient comfort are desired.

Gabapentin (Neurontin) is an alkylated analog of the inhibitory neurotransmitter gamma-aminobutyric acid (GABA) that has been FDA approved for the treatment of seizures, headaches fibromyalgia and chronic neuropathic pain due to various etiologies [5]. Many randomized controlled trials have been performed with perioperative gabapentin [6-10]. The effect of perioperative administration of gabapentin on postoperative pain and opioid consumption has been extensively studied and several meta-analyses have been published in the last several years examining to overall findings of these studies. The general consensus is that gabapentin has anti-hyperalgesic and opioid-sparing properties and may also reduce the incidence of postoperative nausea and vomiting [5, 11-15]. Most research has shown that gabapentin is beneficial in the treatment of postoperative pain, but some show neither positive nor negative effects. There has been no evidence that gabapentin is detrimental or poses any risks to the postoperative patient. However, gabapentin has not been specifically studied in bariatric surgery. Therefore, the purpose of this study is to explore the hypothesis that perioperative gabapentin has anti-hyperalgesic and opioid-sparing properties, thus increase patient comfort and satisfaction by decreasing pain scores and reducing the adverse effects of opioids, such as postoperative nausea and vomiting.

This is a randomized, double-blind and placebo controlled study, which will be performed in adult laparoscopic gastric bypass patients coming to surgery for morbid obesity. The major end-points of analyses are intraoperative and postoperative opioid requirements and the incidence of nausea and vomiting in the postoperative period.