CHANGES IN BLOOD-GAS TENSIONS DURING APNEIC OXYGENATION IN PEDIATRIC-PATIENTS

We report changes in arterial blood-gas tensions for up to 5 min of ap noeic oxygenation in 26 anaesthetized paediatric patients (21 children , five infants). Changes in oxygen and carbon dioxide tension were gre atest in the first minute of apnoeic oxygenation. In subsequent minute s, rates of change in gas tension were approximately constant. The rat e of decline in oxygen tension (31 (95% confidence interval (CI) 20.1- 42.2) mm Hg min(-1)) was more than three times that reported in studie s in adults. The rate of increase in carbon dioxide tension (4.2 (95% CI 3.7-4.7) mm Hg min(-1)) was similar to that reported in adults. Aft er successful preoxygenation; oxygen tension remained greater than 290 mm Hg in all children (age >1 yr) throughout the study. This was not the case in infants. We found no correlation between changes in blood- gas tensions and age or weight of patients. The small number of infant s studied showed rapid decreases in oxygen tension which if sustained would be expected to limit the safe duration of apnoeic oxygenation, u nlike adults where apnoeic oxygenation is limited by hypercapnia. Extr apolation of our results suggests that when preoxygenation has been su ccessful, apnoeic oxygenation could continue safely in children for at least 10 min. Infants may become hypoxic after only 2 min.