PREOXYGENATION BEFORE LARYNGOSCOPY IN CHILDREN - HOW LONG IS ENOUGH

The ideal preoxygenation period prior to laryngoscopy in children is u nclear. This study was performed to determine an appropriate duration of preoxygenation for infants and children prior to laryngoscopy using endtidal oxygen (FE'O-2) criteria. Healthy paediatric patients for el ective day surgery procedures were studied. An inflatable mask connect ed to an oxygen-primed paediatric anaesthesia semiclosed circuit was p laced on the face while patients breathed spontaneously during 6.min(- 1) oxygen flow. An FE'O-2 of 0.9 was considered the endpoint, and if n ot achieved in two min the protocol was ended. Fifty-eight children we re studied. Six patients never achieved an FE'O-2 of 0.9 and were not considered in the analysis. The times (in seconds with mean+/-SD and r ange) to achieve a minimum endtidal (FE'O-2) of 0.9 for under six mont hs were 36 +/- 11.4(20-50), 7-12 months were 35.5 +/- 13.3(20-60), 13- 36 months were 42.6 +/- 18.7(20-90), 37-60 months were 50.8 +/- 18.5(3 0-90), >60 months were 68.4 +/- 24.1(30-100). Logistic regression curv es were determined for each age group describing the probability of ac hieving an FE'O-2 Of 0.9 against time of preoxygenation. All children with satisfactory mask fit were able to preoxygenate to an FE'O-2 of 0 .9 within 100 s.