One of the qualities characterizing a CPAP system is pressure stability. Pressure swings caused by the infants breathing causes a drop in pressure during inhalation and an increase in pressure during exhalation. These swings come at an effort for the infant (increased work of breathing) and increase the risk for failure on CPAP.
The experiments below illustrate the pressure stability for the rPAP and two kinds of T-piece resuscitators. All systems are set at a CPAP of 5 cm of water and the rubber bellow simulates an infant breathing through the system.