Rapid alveolar epithelial fluid clearance following lung lavage in pulmonary alveolar proteinosis

Study objective: To measure the in vivo rate of alveolar epithelial fluid clearance of the human lung in patients with pulmonary alveolar phospholipoproteinosis (PAP). Design: Prospective clinical study. Setting: The medical-surgical ICUs of a university teaching hospital. Patients: Four patients with idiopathic PAP requiring therapeutic lung lavage. Interventions: Large-volume lung lavage with isotonic saline solution using fiberoptic bronchoscopy followed by serial sampling of alveolar fluid using a wedged bronchial catheter. Measurements and results: The rate of alveolar epithelial fluid clearance was calculated by measuring the concentration of protein in sequential samples. Alveolar epithelial fluid clearance over the first hour after lung lavage was 53 ± 14% (mean ± SD). Sequential samples in two patients indicated a sustained high rate of clearance over several hours. Plasma and alveolar fluid epinephrine levels were in the normal range in two patients. Conclusions and significance: Alveolar fluid clearance is rapid after lung lavage in patients with PAP and appears to be driven by catecholamine-independent mechanisms. The rapid rate of alveolar epithelial fluid transport explains why patients with PAP tolerate large-volume lung lavage.