Background: Preoxygenation is recommended in pediatric anesthesia but it has been poorly assessed. Fractional expired oxygen concentration (F(ET)O(2)) is a preoxygenation monitor. The aim of this prospective study in children was to compare three techniques of preoxygenation by the measurement of F(ET)O(2).
Methods: Twenty children (6-15 years) were included. F(ET)O(2) was measured with the child in a supine position, holding the face mask. The F(ET)O(2) value was measured after 3 min of calm breathing of room air (baseline) and during the three preoxygenation techniques performed in random order: 3 min of tidal volume breathing using an O(2) flow of 9 l x min(-1) (TV x 3 min)--four deep breaths within 30 s using an O(2) flow of 15 l x min(-1) (4 DB)--eight deep breaths within 1 min using an O(2) flow of 15 l x min(-1) (8 DB). Between each technique, at least 5 min breathing room air was allowed to return to baseline F(ET)O(2). Fisher's exact test was used and P < 0.05 was considered significant.
Results: Twenty children were studied (age: 11.5 +/- 3 years, weight: 42 +/- 21 kg). The F(ET)O(2) > or = 90% was found to be 79% in 74 +/- 40 s with TV x 3 min, 11% with 4 DB, and 68% with 8 DB.
Conclusions: In children, Vt x 3 min is the most efficient preoxygenation technique to reach F(ET)O(2) > or = 90%.