A low continuous positive airway pressure induces regular breathing and increased inspiratory activity in newborn lambs.

To determine the lowest continuous positive airway pressure (CPAP) at which breathing becomes regular and to determine whether the phrenic nerve activity changes simultaneously, breathing pattern and phrenic nerve activity were studied in spontaneously breathing newborn lambs at various levels of CPAP. A CPAP of 0.25 kPa decreased the variability of phrenic burst interval, i.e. made the breathing regular. This CPAP also increased the mean impulse frequency within the phrenic nerve bursts, indicating greater inspiratory activity. A high CPAP did not offer any further advantages to the breathing pattern or to the inspiratory activity.