Nitrous Oxide Elimination and Diffusion Hypoxia During Normo- And Hypoventilation

Should nitrous oxide be discontinued before desflurane after anaesthesia with desflurane/N2O?

“…This was expected as the solubility of NzO in most tissues other than blood is lower than that of desflurane. The washout curve of nitrous oxide was similar to that during induced hypoventilation previously published by our group (2). In that study, the effect of hypoventilation, as compared with normoventilation, on NzO elimination was most pronounced during the first few minutes.…”

“…Group 2: Desfuranel N 2 0 anaesthesia with desflurane (E' 4.6%) for 10 rnin prior to emergence. For comparison, previous results by Jones et al (11) and Einarsson et al (2) have been added. percentiles given at 0, 5, 10 and 15 min.…”

A model to describe the rate of oxyhaemoglobin desaturation during apnoea

“…Lampe and colleagues British Journal of Anaesthesia [14] found that when nitrous oxide was added to isoflurane it failed to increase the incidence of early or late postoperative hypoxaemia compared with only oxygen and isoflurane. However, Einarsson and his co-workers [15] found reduced oxyhaemoglobin saturation after nitrous oxide anaesthesia in hypoventilating patients even when 2 O I F was 0.3. As none of their desaturations was :90 %, diffusion hypoxia is probably an unimportant cause of postoperative hypoxaemia.…”

Nitrous oxide: time to stop laughing?

“…It increases the size of pneumothoraces and air emboli, it increases middle ear pressure and causes bowel distention, both of which may be associated with postoperative nausea and vomiting. It has been known that its presence can cause postoperative hypoxaemia since Fink described the phenomenon of diffusion anoxia in 1955 [6], but whether or not this is important clinically has been contested in the literature [7, 8]. Since the incidence of hypoxaemia in the immediate postoperative period can be significantly reduced by the administration of supplemental oxygen this point remains largely of academic interest.…”