Physiological basis of non-invasive ventilation in the newborn.

Non-invasive ventilation (NIV) is a form of respiratory support provided primarily to preterm born infants in an effort to avoid any endotracheal intubation or as a weaning step following invasive ventilation. In the context of the respiratory distress syndrome of the newborn, NIV could target and partially reverse specific pathophysiological phenomena, by improving alveolar recruitment and establishing adequate functional residual capacity. It can also assist in minimizing lung injury by avoiding excessive pressure delivery, which can be harmful for the developing lung. Non-invasive ventilation can unload the respiratory muscles and decrease the work of breathing as reported by studies that compare the measured work of breathing at increasing levels of non-invasive support. NIV can also be beneficial in moderating the frequency and intensity of apnea of prematurity. Unintended physiological effects of NIV include gaseous distension of the gastrointestinal tract and increased incidence of air-leak complications. During NIV there is also a lack of direct access to the trachea for suctioning and pulmonary toiletry. Insufficient non-invasive respiratory support could be associated with inadequate oxygenation and ventilation, insufficient gas exchange and atelectotrauma. Excessive provision of non-invasive support could be inefficient or harmful, as overdistention can be associated with decreased compliance of the respiratory system, impaired gas exchange and abnormal diaphragmatic function. An individualized physiological approach could, thus, aim to optimize the beneficial effects of non-invasive ventilation while avoiding inadequate or excessive levels of support.