Association between nitrous oxide and the incidence of postoperative nausea and vomiting in adults: a systematic review and meta‐analysis

Abstract

SummarySome, but not all studies have suggested intra-operative use of nitrous oxide is correlated with postoperative nausea and vomiting. We performed a meta-analysis of randomised controlled trials to compare the incidence of nausea and vomiting in adults following general anaesthesia with or without nitrous oxide. We retrieved 30 studies (incorporating 33 separate trials) that investigated a 'nitrous oxide group' (total 2297 patients) vs a 'no-nitrous oxide group' (2301 patients). Omitting nitrous oxide significantly reduced postoperative nausea and vomiting (pooled relative risk 0.80, 95% CI 0.71-0.90, p = 0.0003). However, the absolute incidence of nausea and vomiting was high in both the nitrous oxide and no-nitrous oxide groups (33% vs 27%, respectively). In subgroup analysis, the maximal risk reduction was obtained in female patients (pooled relative risk 0.76, 95% CI 0.60-0.96). When nitrous oxide was used in combination with propofol, the antiemetic effect of the latter appeared to compensate the emetogenic effect of nitrous oxide (pooled relative risk 0.94, 95% CI 0.77-1.15). We conclude that avoiding nitrous oxide does reduce the risk of postoperative nausea and vomiting, especially in women, but the overall impact is modest. Postoperative nausea and vomiting (PONV) is probably the most common cause of morbidity following anaesthesia [1], occurring in 20-30% of patients (but in up to 70% of those with certain risk factors [2]). Sometimes considered a minor, unavoidable complication, many patients perceive PONV as highly unpleasant, and some even describe it as worse than postoperative pain [3]. PONV increases the cost of procedure because anti-emetic medication becomes necessary, or because discharge from hospital is delayed.Marked advances have been made in our knowledge of risk factors associated with PONV, and predictive scoring systems have been developed [4]. However, the pathophysiology of PONV is still not well established. Many studies are essentially epidemiological [5], and genetic or molecular mechanisms have not been extensively examined [6].It has been suggested that nitrous oxide (N 2 O) contributes significantly to PONV [7][8][9], perhaps influencing the vestibular system by its diffusion into the closed cavity of the middle ear, or by expanding the intestinal wall or releasing endogenous opioid peptides and activating the area postrema of the brain [10]. While many studies have demonstrated a positive correlation between N 2 O and PONV [11][12][13], others have found no association [14][15][16].When trials reach differing conclusions, a systematic quantitative review of the original randomised clinical trials is a useful method of assessing the evidence. Our main purpose, therefore, was to compare the incidence of PONV in adults following general anaesthesia with or

The Incidence of Postoperative Nausea and Vomiting after Thyroidectomy using Three Anaesthetic Techniques

“…6,22 Furthermore, nitrous oxide may increase the incidence of PONV. In a recent meta-analysis by Fernández-Guisasola et al 23 PONV following anaesthesia increased from 27% without nitrous oxide to 33% with nitrous oxide. In previous studies, the incidence of PONV was reported to be as high as 71% when isoflurane and nitrous oxide were used for women who underwent YJ Won, JY Yoo, YJ Chae et al Anaesthetic technique and PONV thyroidectomy.…”

Anaesthetic considerations for pectus repair surgery

“…Nitrous oxide should be avoided because the risk of pneumothoraces during the procedure (48) and also because of its effect on post-operative nausea and vomiting (49) which could be particularly harmful due to the presence of the prosthesis and reconstruction. The anaesthesia could be supplemented with a continuous intraoperative epidural infusion or an intravenous target controlled remifentanil infusion (0.1-0.5 mcg/kg/min).…”

Patients with Obstructive Sleep Apnea for Ambulatory Surgery: Challenges and Management

“…This allows for rapid emergence from anesthesia [23] and avoidance of opioidinduced respiratory complications. Although many avoid N 2 O due to concerns of increased incidence of postoperative nausea and vomiting (PONV) and pressure effects through expansion of closed spaces, the clinical significance of these side effects in modern anesthetic practice has been questioned [24]. Importantly, even a minor degree of residual neuromuscular blockade (usually not appreciated clinically) can increase postoperative morbidity including inadequate ventilation, hypoxia, and the need for reintubation [25,26].…”