Data on arterial oxygen saturation (SaO2), transcutaneous PO2, pCO2 (tcpO2, tcpCO2) and breathing patterns in sleeping healthy term infants were obtained during the first 9 mo after birth. Forty-four healthy infants, mean GA at birth 40 +/- 1.0 wk, mean BW 3520 +/- 562 g were examined between 2 wk and 9 mo postnatally in a cross-sectional study. SaO2, tcpO2, tcpCO2, heart rate (HR), rib cage and abdominal respiratory movements were recorded during natural nocturnal sleep, stratified for sleep states (active sleep (AS), indeterminate sleep (IS), quiet sleep (QS)). The data on AS and IS were pooled as in previous studies. The variables were analysed with respect to age. SaO2 in AS + IS and QS was 96.1 +/- 1.3%, 96.6 +/- 1.4%, respectively. TcpO2 in AS + IS was 10.6 +/- 1.1 kPa and 10.7 +/- 1.3 kPa in QS, while tcpCO2 in AS + IS was 5.4 +/- 0.3 kPa and 5.4 +/- 0.4 kPa in QS. Neither SaO2 nor tcpO2 was influenced by age. TcpCO2 decreased significantly postnatally. Five infants (11.3%) experienced episodes of hypoxaemia with a mean decrease in SaO2 to 86 +/- 1.5%. In four infants these hypoxaemic episodes were linked to upper airway obstructions. Episodes of SaO2 < 90% in conjunction with a decrease in HR to < 100 bpm were detected in one infant only. Periodic breathing (PB) was observed in 38.6% of infants.
Conclusion: Oxygenation and carbon dioxide levels in sleeping healthy term infants were comparable to those reported in older children. Hypoxaemic episodes, if present, are associated with upper airway obstruction. PB, often assumed to be a pathological feature, is a normal breathing pattern in this age group.