The effect of a low continuous positive airway pressure on the reflex control of respiration in the preterm infant.

The airway occlusion technique was used to measure the strength of the Hering-Breuer inflation reflex before and during the administration of low pressure CPAP. In five of 12 preterm infants studied in the first two weeks of life, CPAP did not alter the inflation reflex. In the other seven premature infants, shortened rather than lengthened inspiratory efforts were observed on occlusion 32 times of CPAP but only twice on CPAP. In seven term infants at 1 to 2.5 hours of age this shortening was noted only twice in 58 occlusions. In the preterm infants exhibiting short responses, the peak inspiratory pressure generated in response to occlusion rose on CPAP from 3.4 to 7.1 cm H2O (p less than 0.005), while respiratory rate fell from 61 to 49 breaths/minute (p less than 0.025). This data suggests that CPAP enhances these infants' ability to adjust to increased respiratory loads, possibly by the elimination of a Hering-Breuer deflation reflex.