| Summary: | <p>Abstract</p> <p>Background</p> <p>While the functional consequences of acute pulmonary infections are widely documented, few studies focused on chronic pneumonia. We evaluated the consequences of chronic <it>Pseudomonas </it>lung infection on alveolar function.</p> <p>Methods</p> <p><it>P. aeruginosa</it>, included in agar beads, was instilled intratracheally in Sprague Dawley rats. Analysis was performed from day 2 to 21, a control group received only sterile agar beads. Alveolar-capillary barrier permeability, lung liquid clearance (LLC) and distal alveolar fluid clearance (DAFC) were measured using a vascular (<sup>131</sup>I-Albumin) and an alveolar tracer (<sup>125</sup>I-Albumin).</p> <p>Results</p> <p>The increase in permeability and LLC peaked on the second day, to return to baseline on the fifth. DAFC increased independently of TNF-α or endogenous catecholamine production. Despite the persistence of the pathogen within the alveoli, DAFC returned to baseline on the 5<sup>th </sup>day. Stimulation with terbutaline failed to increase DAFC. Eradication of the pathogen with ceftazidime did not restore DAFC response.</p> <p>Conclusions</p> <p>From these results, we observe an adequate initial alveolar response to increased permeability with an increase of DAFC. However, DAFC increase does not persist after the 5<sup>th </sup>day and remains unresponsive to stimulation. This impairment of DAFC may partly explain the higher susceptibility of chronically infected patients to subsequent lung injury.</p>
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