A physiological approach to applying CPAP in the preterm infant.

Nasal continuous positive airway pressure (CPAP) is increasingly used for respiratory support in preterm infants with respiratory distress syndrome at birth and after extubation from mechanical ventilation. Controversies with CPAP use still exists due to non-uniformity of devices and interfaces used, equivalence of testing conditions for different CPAP systems, differences in study designs, and short study periods that may be insufficient to detect important and relevant clinical outcomes. Compared with ventilator-derived constant-pressure flow-opposition CPAP, variable fluidic flow-opposition CPAP systems may be advantageous and offer some clinical benefits. The distinction between constant-flow fluid-sealed bubble CPAP and variable-flow fluidic flow-opposition systems is less clear. Appropriately designed randomized clinical trials that separately address the controversies with CPAP use in various clinical settings, are necessary to determine which CPAP system results in best outcomes.