Whole lung lavage: a unique model for ultrasound assessment of lung aeration changes

Whole lung lavage (WLL) pathophysiologically represents a human model of controlled lung de-aeration, resembling various pathological conditions encountered in the critically ill. Through one-lung ventilation and progressive alveolar flooding, it mimics, respectively, re-absorption atelectasis formation and lung consolidation. With re-ventilation of the treated lung, PEEP application and diuretics administration, it then creates a model of pulmonary edema and its progressive resolution. No studies have so far described lung aeration changes during WLL with ultrasound: objectives of the study were to describe ultrasound findings during WLL with validated semiotics in the critically ill and to investigate their relation with the lung's state of relative aeration. In seven patients, 12 lung areas/patient were prospectively studied with ultrasound during six procedural steps of WLL. A three-tiered pattern classification was assigned (1, normal/nearly normal; 2, alveolar-interstitial syndrome; 3, alveolar consolidation) consistently with their previously described meaning in terms of relative air content. The distribution was compared throughout different WLL maneuvers as it was for arterial oxygen measurement distribution. During one-lung ventilation and saline flooding, ultrasound findings shifted from artifact patterns (normal/nearly normal and alveolar-interstitial syndrome) to alveolar consolidation. Saline removal, re-ventilation and negative water balance were associated with a gradual return to alveolar-interstitial syndrome, then to a normal/nearly normal pattern. Arterial oxygen tension variations were not always consistent with these changes. In a controlled human model of lung air content variation, the different states of aeration determined by WLL procedure were reliably described with lung ultrasound.