Neutrophil margination in the lung in adult respiratory distress syndrome

Abstract

In patients who develop adult respiratory distress syndrome (ARDS), leukopenia may precede the clinical expression of lung injury. In order to determine if this finding is associated with neutrophil margination in the lung, we calculated neutrophil flux across the lung in eight patients who developed ARDS, 18 patients who were at risk but did not develop ARDS, and in eight control patients who had respiratory failure due to congestive heart failure or atelectasis. Neutrophil flux was calculated by multiplying cardiac output by the difference in neutrophil concentration between mixed venous and arterial blood. A positive value indicated margination and a negative value indicated demargination of neutrophils in the lung. Measurements were averaged during the 24-hour period of lowest PaO 2/FiO 2 in each patient. Margination of neutrophils was more frequent in patients who developed ARDS, whereas demargination of neutrophils was more frequent in patients who did not develop ARDS. In the patients who developed ARDS and who had margination of neutrophils, this phenomenon occurred 14.4 ± 9.1 (x ± SD) hours before the diagnosis of ARDS. The sensitivity and specificity of margination of neutrophils in the lung as a test for ARDS were 87% and 78%, respectively. Margination of neutrophils in the lung is one cause of leukopenia in ARDS and may be a useful discriminator of ARDS in patients at risk.