Simultaneous non-invasive measurement of breathing and ductal flow at birth

The transition to extra uterine life at birth represents one of the greatest
physiologic challenges that most humans encounter and begins with lung aeration
and the onset of air-breathing. Liquid that fills the airways before birth must
be cleared immediately after birth to allow the entry of air, the recruitment
of a functional residual capacity (FRC), and the onset of pulmonary gas
exchange. These processes initiate respiratory and cardiovascular responses in
the newborn that underpin the successful transition from fetal to postnatal
life. The processes include a large increase in pulmonary blood flow, closure
of vascular shunts to separate the systemic and pulmonary circulations, the
onset of sustained regular breathing, and increased blood oxygenation.

Much of our knowledge of the hemodynamic and respiratory transition at birth is
based on animal studies. Data in human newborns are sparse because of the
invasive techniques that would be necessary to obtain them. Recently we have
shown that it is feasible to perform echocardiographic measurements immediately
after birth. One of our findings was that a large inspiratory effort causes an
immediate and significant increase in left to right shunt through the ductus
arteriosus. The increase in left to right shunt may play an important role in
compensating the up to 50% reduced systemic venous return to the right
ventricle which takes place after clamping the umbilical cord. Furthermore, the
shunt will lead to an increased blood flow to the pulmonary vasculature at
birth, thereby increasing preload to the left ventricle. Thus, the change in
ductus arteriosus blood flow will have direct influence on both the respiratory
and hemodynamic transition shortly after birth.
A better understanding of this physiological adaptation is essential when
attempting to understand problems associated with circulation in the immediate
newborn period and to develop strategies to support transition.

To investigate the effect of breathing on ductus arteriosus flow by gathering
simultaneous hemodynamic and respiratory data in healthy term infants

Prospective observational study

none