Anesthesiology
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Although it is recognized that pulmonary hysteresis can influence the effects of positive end-expiratory pressure (PEEP), the extent to which expansion of previously opened (vs. newly opening) peripheral airspaces contribute to increased lung volume is unknown. ⋯ The authors' study results suggest that in healthy lungs, larger lung volumes due to hysteresis are associated with smaller individual airspaces. This may be explained by opening of previously nonaerated peripheral airspaces rather than expansion of those already aerated. Setting PEEP on a descending ramp may minimize distension of individual airspaces.