DURATION OF APNEA IN ANESTHETIZED INFANTS AND CHILDREN REQUIRED FOR DESATURATION OF HEMOGLOBIN TO 95-PERCENT - THE INFLUENCE OF UPPER RESPIRATORY-INFECTION

Sixty-one patients ASA physical status 1-2 aged 1 month to 12 years undergoing elective surgery were included in the study. Anesthesia was induced via a mask with sevoflurane up to 5% and 66% nitrous oxide in oxygen. After paralysis with vecuronium (0.12 mg/kg iv), the trachea was intubated and the lungs were ventilated manually with 3% sevoflurane in oxygen until the end-tidal nitrous oxide decreased to less than 5%. Apnea was started by disconnecting the breathing circuit from the endotracheal tube. The time from the start of apnea to Sp(O2) of 95% was measured. Manual ventilation was reinstituted when Sp(O2) decreased to 95% and another set of vital signs was recorded. Twenty of 61 patients had symptoms of upper respiratory infection. The time to Sp(O2) of 95% correlated well with height, age, and body weight both by linear and non-linear regression analyses. The patients with symptomatic upper respiratory infection required less time for Sp(O2) to decrease to 95% compared to the asymptomatic children. We conclude that younger children require less time for Sp(O2) to decrease to 95%. The presence of upper respiratory infection is an additional factor increasing the susceptibility of small children to hypoxemia.