Clinical study of diffusion hypoxia after nitrous oxide analgesia.

In order to estimate the incidence of diffusion hypoxia, arterial oxygen saturation was measured in 104 healthy adult dental patients who were administered nitrous oxide-oxygen analgesia and who did not receive postcessation oxygen. Pretreatment saturation levels as determined by pulse oximetry ranged from 93% to 100%. When the nitrous oxide-oxygen administration ceased, the saturation levels were from 95% to 100%. The mean saturation dropped about 2% over the next 4 min and then stabilized. No patient had a posttreatment oxygen saturation of less than 92%.