The deflation limb of the pressure-volume relationship in infants during high-frequency ventilation.

Rationale: The importance of applying high-frequency oscillatory ventilation with a high lung volume strategy in infants is well established. Currently, a lack of reliable methods for assessing lung volume limits clinicians' ability to achieve the optimum volume range.Objectives: To map the pressure–volume relationship of the lung during high-frequency oscillatory ventilation in infants, to determine at what point ventilation is being applied clinically, and to describe the relationship between airway pressure, lung volume, and oxygenation.Methods: In 12 infants, a partial inflation limb and the deflation limb of the pressure–volume relationship were mapped using a quasi-static lung volume optimization maneuver. This involved stepwise airway pressure increments to total lung capacity, followed by decrements until the closing pressure of the lung was identified.Measurements and Main Results: Lung volume and oxygen saturation were recorded at each airway pressure. Lung volume was measured using respiratory ...