Systemic thermal injury in anesthetized rabbits causes early pulmonary vascular injury that is not ablated by lazaroids

Abstract

Purpose: To study the effects of a systemic thermal injury on the pulmonary vasculature with and without inhibitors of lipid peroxidation (U74389G). Methods: In a prospective, placebo control, randomized, and blinded multi-group study, burn shock was induced by scalding thermal injury (65C) to 35% body surface area in rabbits (n=28). Hemodynamics and gas exchange were followed for 240 min post bum in four groups; No Burn, Burn- Control, Burn-U74 (10 mg · Kg-1 U74389G), No Burn-U74 (10 mg · Kg-1 U74389G). Results: Scald resulted in early pulmonary injury as measured by increased pulmonary vascular resistance in the pooled Burn group compared with the No Burn groups (942 ± 358 vs 605 ± 255 dynes · sec-1 · cm-s respectively, P < 0.05). These pulmonary changes were associated with alveolar sequestration of leukocytes (4.8 ± 2.9 vs 17.7 ± 6.0 cells X 109 · L-1, P < 0.05) in the No Burn and Burn groups respectively. Histological evidence of decreased neutrophil sequestration after scald injury was present in U74 treated animals (3+ vs 2+, P < 0.05 in the Burn and No Burn groups respectively and 2+ vs 2+, P > 0.05 in the Burn-U74 and No Burn-U74 groups respectively) although bronchial alveolar lavage still demonstrated neutrophil sequestration (5.3 ± 2.5 vs 12.2 ± 3.3 cell 109L-1, P < 0.05 in No Burn-U74 and Burn-U74 groups respectively). Similarly, circulating white blood cells were increased in the Burn group but not Burn-U74 group four hours post burn. The increase in pulmonary vascular resistance after bum was not altered by administration of U74. Conclusions: Systemic burn results in early pulmonary vascular changes associated with leukocyte sequestration. After scald injury administration of lazaroids (U744389G) did not lessen pulmonary vascular resistance changes but did reduce neutrophil sequestration.