Dexamethasone Alone Versus in Combination With Transcutaneous Electrical Acupoint Stimulation or Tropisetron for Prevention of Postoperative Nausea and Vomiting in Gynaecological Patients Undergoing Laparoscopic Surgery

wherein nausea and vomiting were the secondary end points, triggering criticism about insufficient power and increased heterogeneity. The current study was tailored to address these limitations by assessing the pooled effects of preoperative gabapentin among studies designed to explore PONV as a primary end point. This approach showed that preoperative gabapentin reduced postoperative nausea, vomiting, and rescue antiemetic requirements. Additional analysis of all included trials that cited PONV end points (primary or secondary) also resulted in the conclusion that preoperative gabapentin was associated with a reduced incidence of PONV, nausea, vomiting, and rescue antiemetic requirement. These findings, as a result of pooled data from the largest cohort of trials to date, suggest a role for preoperative gabapentin in the prevention of PONV. The mechanism by which gabapentin attenuates PONV is debatable. Some studies have postulated a reduction in calcium signaling in the area postrema, as well as reduced tachykinin neurotransmission. Others have suggested a decrease in postoperative inflammation, thereby mitigating ileus and subsequent PONV. Still, others point to the reduction in perioperative opioid requirements associated with gabapentin as the operative mechanism. One might conjecture that some combination of these mechanisms may be responsible. Nonetheless, the central nervous system effects of gabapentin must be acknowledged. Potential excessive sedation and dizziness in the postoperative period have been reported, although the current study did not identify an association between gabapentin and dizziness/lightheadedness, headache, and drug mouth. The current investigation, however, did detect notable incidences of excessive postoperative sedation and somnolence. Another unanswered question is whether preoperative gabapentin has any effect on postdischarge PONV. Certainly, the current meta-analysis should stimulate further research in many germane areas.