Pulmonary and extrapulmonary effects of increased colloid osmotic pressureduring endotoxemia in rats

Objectives: We tested the hypothesis that an increase in the blood colloid osmotic pressure (COP) that is maintained during early-stage endotoxemia ma y decrease fluid flux across capillaries and may reduce pulmonary and multi ple-organ edema. Design: Prospective study. Settings: Research laboratory in a hospital. Subjects: Male albino Sprague-Dawley rats. Interventions: Rats were anesthetized with pentobarbital, underwent tracheo tomies, were cannulated in the femoral vein and artery, and were randomly a ssigned to the following four groups comprising 11 rats each: group I, cont rols (saline solution treatment); group Il, albumin treatment (three doses of 1 g/kg 25% human albumin every 2 h); group III, endotoxin treatment with a single IV dose of 4 mg/kg endotoxin; and group IV, endotoxin and albumin -treatment (4 mg/kg endotoxin plus albumin treatment). Experiments lasted f or 6 h while fluid intake was equally maintained in all groups. Measurements and results: COP and other variables were measured every 2 h. To determine the water content of an organ, after the rat was killed, the l ung, heart, kidney, intestine, and liver were removed. Albumin treatment al one (group II) generated significant increases in COP (maximum, 58% from th e baseline measurement) but did not change the water content of the organ, compared with saline solution-treated controls. Endotoxin-treated rats (gro up III) developed significant reductions in COP, with significant increases in pulmonary, renal, and heart water content compared with controls. Album in treatment in endotoxemic rats (group IV) significantly increased the COP without improving the endotoxemia-induced organ edema. Pulmonary edema, ho wever, was increased further, compared with endotoxemia alone. Conclusions: COP elevation by albumin administration during the early stage of endotoxemia does not ameliorate pulmonary or multiple-organ edema and m ay aggravate pulmonary edema.