Physiological parameters evaluation following apnea in healthy premature infants

To assess responses to central and obstructive apnea, we performed 10-hour polygraphic recordings in healthy 33-34 wGA infants. Each apnea period was paired with a control period. The presence of body movements (BM) and augme nted breaths (AB), the EEG, heart rate (HR), respiratory rate, phase relati onships between thoracic and abdominal respiratory movements, and changes i n SaO(2) were evaluated. No apnea caused awakening. Apnea were not usually followed by motor events (no significant differences with control periods), with the exception of most obstructive apnea longer than 10 s. The mean pe rcentage of changes following apnea, normalized to baseline values, was sig nificant for the EEG (frequency slightly increased, mainly after obstructiv e apnea), HR (deceleration), and respiratory rate (increased). However, the mean values masked heterogeneity across apnea in the direction of the chan ge in each parameter. The only significant correlation was between changes in HR and SaO(2). The increases in EEG frequency and respiratory rate seen in our study can be considered markers of CNS activation, but were small an d inconsistent. The heart rate decelerations and SaO2 changes are not activ ation markers. Thus, mechanisms underlying restarting of breathing efforts following apnea remain unclear in premature babies. Our investigation estab lishes the importance of using control data to distinguish between spontane ous and apnea-related events. Copyright (C) 2000 S. Karger AG, Basel.