April 1997

Nitrous oxide does not increase vomiting after dental restorations in children.

Splinter WM, Komocar L;

Anesthesia and Analgesia 1997; 84: 506-508.

[ see abstract below ]

Splinter et al, examine the effect of nitrous oxide on the incidence of postoperative vomiting in children. 330 pediatric patients, 2 - 12 years of age scheduled for dental procedures were entered into the study. Some children were premedicated with oral midazolam (0.5 mg/kg up to 15 mg). Some children then underwent a gaseous induction of anesthesia with halothane while others were induced with intravenous propofol. There was no difference between groups in age, weight, incidence of premedication, incidence of propofol induction, duration of anesthesia, or the use of spontaneous vs. controlled ventilation. None of the children received opioids. Patients were observed for in-hospital vomiting events as well as for post 24 hour discharge vomiting events.

There was a slight but statistically significant increase in vomiting while in the hospital (24 vs. 15% - p < 0.03) but there was no difference in the overall incidence of vomiting (35 vs. 30%). The authors conclude that "nitrous oxide does not alter postoperative vomiting after halothane anesthesia for dental restorations in children."

This is an interesting paper because despite the use of a premedication which has anti-vomiting qualities (midazolam), an induction agent with similar properties (propofol), a procedure which does not involve intraabdominal contents, and the complete absence of the use of opioids, roughly one third of pediatric patients still experienced postoperative vomiting.

This paper once and for all lays to rest the myth that nitrous oxide contributes to the incidence of vomiting. We should feel free to continue to take advantage of the potent analgesic properties of nitrous oxide without fear of increasing postoperative discomfort due to vomiting. More importantly however, this study emphasizes how often postoperative vomiting occurs and that the majority of vomiting occurs after hospital discharge. (Out of site - out of mind). Unfortunately, even ondansetron is not effective in all patients after approximately 8 hours.

This means if we are to improve patient satisfaction in the long run, we need longer acting drugs. I guess we all still hope for the magic bullet which is both low cost and 100% effective. I am not advocating that every patient receive an antiemetic, but it would be wonderful if we could predict with greater certainty which patients would benefit from such treatment bedsides the tonsillectomy and strabismus patients, patients with a prior history of post-anesthesia nausea and vomiting, and possibly cochlea implant patients.

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ABSTRACT