Study of the optimal duration of preoxygenation in children.

[STUDY OBJECTIVE] To determine the optimal length of preoxygenation in children.

[DESIGN] Random design and comparison among groups.

[SETTING] Operating room of a plastic surgery hospital of the Chinese Academy of Medical Sciences and the Peking Union Medical College.

[PATIENTS] Forty healthy, ASA status 1 children (age 2 to 7 yrs), undergoing elective plastic surgery.

[INTERVENTIONS] Children in Group 1 breathed 100% oxygen (O2) for 1 minute. Group 2 children breathed 100% O2 for 2 minutes. Group 3 and Group 4 children breathed 100% O2 for 3 minutes. Anesthesia was induced with midazolam 0.3 mg/kg, fentanyl 5 micrograms/kg. Muscle relaxation was achieved with vecuronium 0.1 mg/kg (Groups 1, 2, and 3) or succinylcholine 1.5 mg/kg (Group 4).

[MEASUREMENTS AND MAIN RESULTS] Oxygen saturation (SpO2) was measured by pulse oximeter. The oximeter probe was applied to the right big toe. After preoxygenation, the times for SpO2 to decrease to 98% (T98), 95% (T95), and 90% (T90), respectively, were recorded during the apneic period. T98, T95, and T90 were significantly shorter in Group 1 than in Group 2 or Group 3. There was no statistically significant difference among Groups 2, 3, or 4 regarding T98, T95, and T90. The times for SpO2 to decrease from 95% to 90% were similar among the four groups.

[CONCLUSIONS] 2 minutes of preoxygenation in children can provide the maximum benefit of denitrogenation and achieve 2 minutes of safe apea. 95% and 99% confidence intervals were 69 to 100 and 59 to 100, respectively. Succinylcholine had only a slight effect on the safe apneic period.