Seven Ventilators Challenged With Leaks During Neonatal Nasal CPAP: An Experimental Pilot Study

BACKGROUND: Nasal CPAP is the most common respiratory support for neonates. Several factors are considered important for effective treatment, including leaks at the patient interface and the delivery of pressure-stable CPAP. Investigations of pressure stability during leaks should include both the change in the mean delivered CPAP and the pressure variation during each breath. The aim of this study was to examine the response of ventilators delivering nasal CPAP when challenged with leaks at the patient interface. METHODS: Seven ventilators providing nasal CPAP at 4 cmH(2)O were challenged with leaks during simulated neonatal breathing. Leak was applied for 15 consecutive breaths at a constant level (1-4 L/min). RESULTS: The 2 aspects of pressure stability were evaluated by measuring the mean delivered CPAP and the amplitude of pressure swings before, during, and after leaks. The ability to maintain the delivered CPAP and the amplitude of pressure swings varied greatly among the 7 ventilators before, during, and after leaks. Four of the ventilators tested have built-in leak compensation. CONCLUSIONS: There was no simple relationship between maintaining delivered CPAP during leaks and providing CPAP with low pressure swing amplitude. Maintaining the delivered CPAP and providing this without pressure swings are 2 separate aspects of pressure stability, and investigations concerning the clinical importance of pressure stability should address both aspects. This study also shows that compensation for leaks does not necessarily provide pressure-stable CPAP.