Control of Inspiratory Timing in Newborn Infants

ABSTRACT

In order to determine if inspiratory time in preterm infants was influenced by lung volume, two studies were carried out. In the first investigation, carbon dioxide was used to stimulate tidal volume to a level three to six times normal. The anticipated decrease in inspiratory time at increased tidal volumes was not found. These preterm infants behaved in a similar fashion to vagotomized animals studied in the same way by Clark and von Euler. In the second investigation, Hering-Breuer activity was measured in relation to lung volume changes occurring with growth, measured in a body plethysmograph. Although thoracic gas volume correlated well with age and weight, inspiratory slowing with airway occlusion was found to be independent of both age and lung volume. These investigations suggest that neurologic factors have a significant influence on the inspiratory time in newborn human infants.