Mean Airway Pressure-An Informative but Overlooked Indicator of Mechanical Power.

Mean airway pressure, a monitored variable continuously available on the modern ventilator, is the pressure measured at the airway opening averaged over the time needed to complete the entire respiratory cycle. Mean airway pressure is well recognized to connect three key physiologic processes in mechanical ventilation: physical stretch, cardiovascular dynamics, and pulmonary gas exchange. Although other parameters currently employed in adults to determine "safe" ventilation are undoubtedly valuable for daily practice, all have limitations for continuous monitoring of ventilation hazard. The purpose of this communication is to explore the often-underappreciated link between mean airway pressure and the mechanical power (cumulative inflation energy/min) that helps determine the adverse consequences of invasive ventilation (ventilator-induced lung injury).