Cardioventilatory coupling in preterm and term infants: effect of position and sleep state.

This study documented the effect of position on cardioventilatory coupling (CVC), the triggering of inspiratory onset by a preceding heartbeat, in infants. Cardiorespiratory signals and corresponding oxygen saturation (SpO(2)) were downloaded from Quiet Sleep (QS) and Active Sleep (AS) in prone and supine from preterm (PT) and term (T) infants. Inspiratory onsets (I) and timing of the corresponding ECG R wave were determined and R-R and R-I intervals calculated. The RI(-1) interval (time between inspiration and the preceding R wave) dispersion was measured using proportional Shannon Entropy of the RI(-1) interval (SH(α)), to provide a quantitative measure of CVC. CVC was more frequently seen in QS in PT (p=0.002) and T (p=0.02) infants but not influenced by position (p=0.71, p=0.46). CVC correlated with SpO(2) in PT (r=-0.230, p=0.03) but not T infants (r=0.085, p=0.34). These data imply an augmentation of cardiac influence on ventilatory rhythm in infants in QS. In preterm infants CVC may have a role in supporting oxygenation.