Phase Relationships Between Thoracic and Abdominal Respiratory Movement During Sleep in 31 - 38 Weeks CA Normal Infants. Comparison with Full-Term (39-41 Weeks) Newborns¹

Abstract

This study was carried out in 30 premature and full-term newborns and in 6 prematurely borns, arriving at the age of normal term infants. Phase relationships between the upper thoracic and the abdominal respiratory movements were coded using independently 2 methods: according to the maximum phase shift observed during every 20 sec. epoch, and according to the minimum phase shift observed during the same 20 sec. epoch:1. Both methods showed a predominance of the in-phase respirations in quiet sleep and the predominance of the 180° phase shift respiration in active sleep (p<0.001). The results were similar, without significant differences in all age groups.2. The in phase thoracic and abdominal respiratory movements were accompanied by simultaneous inspiratory EMG activity at the upper intercostal (2nd or 3rd space) and the diaphragmatic levels. During the 180° out-of-phase respiration, the upper intercostal inspiratory EMG was selectively inhibited. During the approximately 90° out-of-phase respiration, it was usually present.