Analysis of components of fetal breathing cycles.
The duration of the inspiratory phase (Ti) and the expiratory phase (Te) together with the relative amplitude (Amp) of successive breathing movements of the chest wall or abdominal wall were measured by real-time ultrasound in 12 fetuses of normal gestation. The observations were performed at 33-39 gestational weeks. The distributions of Ti, Te, the duration of the breathing cycle (Ttot), Amp and the ratios Amp/Ti and Ti/Te were all considerably skewed. Correlations between these variables differed markedly in different fetuses. Running correlations, however, showed the presence of alternations with time in the correlations between Ti and Te, and between Amp and Ttot. These findings suggest the possibility of central nervous system mechanisms controlling these events, operating over time spans considerably longer than the individual breathing cycle.
Gennser
G M
GM
Department of Obstetrics and Gynaecology, University Hospital, Malmö, Sweden.
Hathorn
M K
MK
D005260:Female; D005323:Fetal Monitoring; D005333:Fetus / Q000502:physiology*; D005865:Gestational Age; D006801:Humans; D008297:Male; D012119:Respiration; D014463:Ultrasonography