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.
