Heart rate chaos in obstructive sleep apnea in children

Obstructive sleep apnea syndrome (OSAS) in children is associated with a bradytachyarrhythmia during an obstructive event. Polysomnographic recordings were obtained from 15 children; 9 had OSAS (apnea/hypopnea index = 13.6 /spl plusmn/ 8.2/hr, mean /spl plusmn/ SD) and 6 normal controls. Heart rate variability was analyzed for the presence of chaotic dynamics. Using a 5-minute sliding window, chaos was detected using numerical titration technique. In both groups, REM had a higher chaotic intensity than NREM sleep (p < 0.05). Furthermore, chaos was significantly increased during periods with apneic events compared to stable breathing. These data indicate that sleep state and disordered breathing are important determinants of the autonomic control of heart rate chaos in children.