Bacteremia

Abstract

Pulmonary effects, lung clearance and tissue retention of blood-borne Pseudomonas aeruginosa were compared in dogs (n = 5) and pigs (n = 5) during continuous 6 h i.v. infusion of 1.2(109) bacteria/min per 20 kg. Control pigs received an equal volume of sterile saline. In contrast to controls, experimental pigs developed pulmonary artery (PA) hypertension (mean, 30 .+-. SE 3; baseline 17 mm Hg) and pulmonary failure manifested by hypoxemia (mean PaO2, 49 .+-. 4; baseline, 78 .+-. 2 mm Hg; P < 0.001), increased intrapulmonary shunting (40-50%), noncardiogenic pulmonary edema and congestive atelectasis, a pattern of pulmonary failure very similar to sepsis-induced ARDS [adult respiratory distress syndrome] in humans. In dogs, PA pressures were unchanged from baseline, no edema was detected, and comparable hyperventilation was associated with an increase in PaO2 from 77 .+-. 4 (baseline) to 87 .+-. 2 mm Hg (P < 0.001). Tissue retention of viable blood-borne organisms in pigs was greatest in the lungs. In dogs, lung retention was minimal and greatest tissue retention occurred in the liver and spleen. Lung clearance of blood-borne organisms and bacteremia-induced pulmonary failure are host dependent.