Functional Evaluation of Bubble CPAP for Neonates Using a Leak Model

Abstract

Objective:We evaluated the influence of bias flow magnitude and leak flow on the provided CPAP level in the presence or absence of a reservoir bag. Methods:The 500 mL soft plastic reservoir bag was connected to the bubble CPAP system.The leak pathway and a valve were prepared to simulate the function of the mouth. The pressure and flow in the regions corresponding to the lower airway (Pdistal)and the leak flow were recorded simultaneously using a flow analyzer. Results:At a bias flow of 3 L/min,use of a reservoir bag resulted in a significant decline of the pressure swing magnitude at 60 and 90 breaths/min.A reservoir bag attenuated the rapid aspiration-induced decreases of the mean airway pressure.When bubbling disappeared due to complete opening of the leak valve,the mean airway pressure was maintained at approximately 2 cmH O.Additionally,the mean airway pressure increased with increasing bias flow even under 100% leak condition. Conclusions:Even when a large leak occurs,a low but significant airway pressure is loaded under moderate bias flow.Inclusion of a reservoir bag in the bubble CPAP may offer an effective and inexpensive option for providing respiratory support to preterm infants.Shinshu Med J 61: 65―73, 2013 (Received for publication December 18,2012;accepted in revised form January 8,2013)