Core Concepts: Neonatal Tidal Volume: Physiologic, Technologic, and Clinical Considerations

Abstract

Neonatal tidal volume breathing is fundamental to gas exchange and ventilatory support after birth. In uniquely vulnerable preterm infants, excessive tidal volume, volutrauma, is a significant contributor to ventilator-induced lung injury (VILI). This biotrauma triggers a cascade of proinflammatory responses associated with an increased occurrence of bronchopulmonary dysplasia (BPD). Understanding of physiologic determinants of tidal volume allow for optimal tidal volume delivery by using minimal pressures to achieve desired carbon dioxide exchange without air-trapping. Tidal volumes (Vt) can be measured continuously by monitoring airflow signals of assisted ventilation. Currently, pneumotachography is the most commonly utilized bedside technology. Ideal techniques to measure continuous, bi-directional airflow proximal to the endotracheal tube require accuracy over a range of airflow, negligible contribution to dead space and resistive load, reliability, minimal need for operator intervention or calibration, adaptability to a warmed and humidified environment, and validated performance for long-term use. For all infants receiving assisted ventilation, clinicians require accurate technologies to continuously measure Vt until respiratory stability is reached to minimize the risk of VILI.