Pulmonary glutamine production:: effects of sepsis and pulmonary infiltrates

Objective. To define the role of the lung in the production of glutamine in the critically ill and to determine the effects of the presence of pulmonary infiltrates and the presence and severity of sepsis. Design and setting. Prospective clinical study in a single center; interdisciplinary intensive care unit at a university hospital. Patients. Eleven critically ill patients were compared to ten patients prior to cardiac bypass surgery. Measurements and results. Fluxes of glutamine and other amino acids were measured. Chest radiography was performed, and APACHE II and multiple-organ failure scores were calculated. Septic patients showed significantly higher glutamine efflux from the lungs than controls. At least one-half of this glutamine is estimated to result from protein breakdown. Severity of illness had no impact on glutamine fluxes. In the presence of pulmonary infiltrates on chest radiographs glutamine efflux did not differ from zero. Conclusions. The lungs produce significant amounts of glutamine in septic patients. Pulmonary infiltrates decrease the glutamine efflux from the lung in septic patients. We suggest that this is caused by uptake of glutamine by white cells in the lung exerting immunological functions.