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
Patients: Four patients with idiopathic PAP
requiring therapeutic lung lavage.
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
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.