158 Is Sighing a Resetting Mechanism of the Autonomic Nervous System?

Sighs are important components of normal breathing. They occur isolated or associated with respiratory pauses. Functional residual capacity and lung compliance increase after sighs. Sighs have been shown to be part of an arousal reaction in infants and to induce heart rate modifications. We investigated the influence of sighs on the autonomic balance in infants. METHODS: 107 sighs (a single breath of at least twice the amplitude of the preceding breaths, not followed by an apnea) from 23 term infants were selected. The selection was made in conditions known not to interfere with spontaneous HR variability (quiet sleep,absence of movements, apnea or false detections of QRS during the 2 preceding and following minutes. Spectral analysis of RR variability was performed on the 2 minutes preceding and the 2 minutes following the sigh. To study the role of the ANS in the development of a sigh, spectral analysis of the period just before the sigh and of the 2 preceding minutes were compared. RESULTS: The 2 minutes following the sigh were characterized by an increased RR interval (p 0.001), an increased total power (p