Pulmonary edema after Escherichia coli peritonitis correlates with thiobarbituric-acid-reactive materials in bronchoalveolar lavage fluid

We developed a new model of acute lung injury caused by live Escherichia coli peritonitis in guinea pigs. Arterial blood gas determinations, arterial blood pressure, and white blood cell counts were monitored serially for 12 h after the injection of either 2 x 10⁹ E. coli J96 or saline. Lung water, albumin concentration in bronchoalveolar lavage fluid (BALF) and in lung tissue, WBC counts in BALF, and thiobarbituric-acid-reactive materials (TBARM) in plasma, lung tissue, and BALF were examined. Increased TBARM might be associated with pulmonary injury and are produced either by the generation of lipoperoxides secondary to oxygen-free radicals or as metabolic byproducts of prostanoid metabolism. Lung tissue sections were studied by light microscopy. E. coli peritonitis, as compared with control animals, caused significant peripheral neutropenia, histopathologic evidence of lung inflammation, acidosis, and hypotension. The wet-to-dry lung ratio was increased in the peritonitis group when compared with that in the control group (p < 0.01). Pulmonary edema in the peritonitis group was associated with significantly increased albumin concentration in BALF and lung tissue. We report the new finding of increased TBARM concentrations in BALF after E. coli peritonitis (p < 0.01 and p < 0.05, respectively). In contrast, plasma TBARM concentrations was unchanged. The levels of TBARM in the BALF correlated significantly with both lung water (p < 0.01) and lung tissue albumin concentration (p < 0.01). The measurement of elevated TBARM in BALF may allow acute lung injury to be detected. We conclude that this model may be useful for further studies of acute lung injury caused by E. coli peritonitis.