We performed preoxygenation on 25 patients, aged 1-12 yr. End-tidal ox
ygen sampling was used to find the duration of preoxygenation required
to reach an end-tidal oxygen fraction of 0.9. All children reached th
is end-point within 80 s, which was markedly more rapid than that obse
rved in adult subjects. The clinical applications of this form of moni
toring in children are discussed.