EFFECT OF BREATHING PATTERN ON OXYGENATION DURING SLEEP IN PREMATURES

Abstract

Periodic breathing (PB) occurs commonly in ostensibly healthy preterm infants, yet its significance is unknown. To elucidate the effect of PB on oxygenation, we studied 13 AGA 32 wk infants with a mean BW of 1744 gms at a postnatal age of 7 days. Infants in good condition were selected and morbid conditions such as asphyxia at birth were specifically excluded. Impedance pneumography, R-R interval, PtcO2 and PtcCO2 were continuously recorded for up to 8 hrs. The O2 and CO2 electrodes were calibrated at a temperature of 43.5 and 44°C, respectively. Sleep state was determined using the behavioral criteria of Prechtl. Periods of regular breathing (RB) and PB were identified for both active (AS) and quiet sleep (QS). PB was defined as repetitive pauses of 3-5 sec. duration separated by 10-15 sec. of RB. After stabilization in each sleep state, the first 2 min. of RB and PB were selected for determination of PtcO2 and PtcCO2 levels. For analysis, samples were taken every 10 sec. and averaged over the 2 min. period. No difference in mean PtcCO2 levels occurred in either breathing pattern or sleep state. PtcCO2 was lower during PB than RB in both sleep states. Marked variability of levels occurred during AS with only occasional fluctuations during QS, but there were no differences in the mean levels between AS and QS. Since respiratory rate was reduced in PB, the relative hypoxia during PB under normal conditions is determined by respiratory rate and not by sleep state.