HEART-RATE-VARIABILITY DURING SLEEP IN INFANTS WITH BRONCHOPULMONARY DYSPLASIA - EFFECTS OF MILD DECREASE IN OXYGEN-SATURATION

We sought to determine whether abnormal heart rate modulation by the a utonomic nervous system occurs in patients with severe bronchopulmonar y dysplasia (BPD) in relation to sleep stages and mild changes in arte rial oxygen saturation SaO(2). On 10 oxygen-dependent 7- to es-month-o ld infants with BPD, polygraphic recordings, including heart and respi ratory rate and body movement detection, were performed. Heart rate va riability was evaluated in high (HF), mid, and low (LF) frequency band s. Parameters were analyzed in two ranges of SaO(2): normal range, (Sa O(2) greater than 95%), and mild decrease in (SaO(2), values of 90 to 94%). In contrast to what is normally observed, LF at normal SaO(2) wa s less marked in rapid eye movement, (REM) sleep than in non-rapid eye movement (NREM) sleep stage 2. A mild decrease in SaO(2), as compared with a normal SaO(2) value, was associated with: (1) a heart and resp iratory rate acceleration, (2) a decrease in HF in REM sleep (p<0.02); (3) an increase in LF in NREM sleep stage 2 (p<0.02), intensifying th e change observed in a normal SaO(2) level. These data show that a mil d decrease in SaO(2) increases modifications of autonomic control obse rved in infants with severe BPD.