Oxygen saturation and diffusion hypoxia in children following nitrous oxide sedation

Oxygen saturation of arterial blood (SaO2) was assessed in children after discontinuing N2O/O2 sedation for dental procedures. Two post-treatment methods were used: breathing 100% O2 for 5 min after the procedure, and breathing room air for 5 min. Participants were 24 healthy children ages 41 to 113 months. Each child was treated twice and a crossover design was used. The mean length of procedures that were followed by O2 was 28.8 (+/- 10.9 SD) min; for those followed by room air, 28.3 (+/- 12.4 SD) min. SaO2 was monitored continuously by pulse oximetry and recorded at predetermined intervals before, during, and after N2O/O2 administration. When participants received post-treatment O2, the mean SaO2 at 1 min after N2O cessation (99.91 +/- 0.63 SD) and 5 min after cessation (99.94 +/- 0.17 SD) was statistically significantly higher than the pretreatment value of 99.28 (+/- 0.63 SD). When participants received post-treatment room air, the mean SaO2 1 min after N2O cessation (99.44 +/- 0.8) was also statistically significantly higher than the pretreatment mean (99.08 +/- 0.96). After 2 min, however, the mean SaO2 decreased and was statistically indistinguishable from the pretreatment level after 5 min (99.13 +/- 0.9 SD). Fluctuations in SaO2, though statistically significant, were less than 1%. Allowing children to breathe room air immediately after cessation of N2O/O2 inhalation did not reduce SaO2 below clinically acceptable levels. This study further documents the safety of N2O/O2 sedation, and gives the clinician additional information concerning the safe and effective administration of inhalation sedation. (Pediatr Dent 15:88-92, 1993).