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: Fort y healthy, ASA status I children (age 2 to 7 yrs), undergoing elective plastic surgery. Interventions: Children in Group 1 breathed 100% oxy gen (O-2) for 1 minute. Group 2 children breathed 100% O-2 for 2 minut es. Group 3 and Group 4 children breathed 100% O-2 for 3 minutes. Anes thesia was induced with midazolam 0.3 mg/kg, fentanyl 5 mu g/kg. Muscl e 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 Resul ts: Oxygen saturation (SpO(2)) was measured by pulse oximeter. The oxi meter probe was applied to the right big toe. After preoxygenation, th e times for SpO(2) to decrease to 98% (T-98), 95% (T-95), and 90% (T-9 0), respectively, were recorded during the apneic period. T-98, T-95, and T-90 were significantly shorter in Group 1 than in Group 2 or Grou p 3. There was no statistically significant difference among Groups 2, 3, or 4 regarding T-98, T-95, and T-90. The times for SpO(2) to decre ase from 35% 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 apnea. 95% and 99% c onfidence intervals were 69 to 100 and 59 to 100, respectively. Succin ylcholine had only a slight effect on the safe apneic period.