Objective: To evaluate whether cardiac responses to a level of hypoxic hypercapnia that may be observed in rebreathing studies are altered with infant sleep position.
Methodology: Eighteen healthy term infants (< 5-days-old) were studied. Heart rate (HR) and HR variability were monitored during air breathing and during 3 min exposure to a mixture of 15% O2/3% CO2 in both the prone and supine positions. Power spectral analysis of HR was performed.
Results: Heart rate was the only measured variable to be significantly changed in response to 15% O2/3% CO2. Hypoxic hypercapnia elicited no significant responses in power spectral HR variables. There was no effect of sleeping position on any of the measured variables.
Conclusions: There are no significant differences in cardiac responses to mild hypoxic hypercapnia between sleep positions and power spectral indices of the autonomic control of HR are not altered by sleep position in newborn babies.