The Relationship Between Pulmonary Surfactant And Early-phase Pulmonary Injury In Combined Blast-anoxic Injury In Rat

Background and Aims The main character of Acute Lung Injury (ALI) is pneumonedema and alveolar collapse, there are many erythrocytic and plasmic-fibrous exudation in alveolar. Pneumonedema, alveolar and dysfunction of gas exchange is closely related to the decrease of pulmonary surfactant (PS). Pulmonary hemorrhage and pneumonedema are the significant pathological traits of pulmonary injury in blast injury. Alveolar epithelial type â…¡ cells (AT-â…¡) is deformed and the lamellar body (LB) is decreased. Anoxia can induce the dysfunction of AT-â…¡, which hampers the synthesis and secretion of PS. There are still no experimental evidences concerning the changes in functions of AT-â…¡ and in the level of PS with blast-anoxic complicated injury. Various pulmonary injuries leads to heightened permeability of alveolar-capillary barrier, the surfactant-associated protein A (SP-A) which is normally presented in lung leaks into bloodstream. And then the level of SP-A in serum increases in proportional to the degree of pulmonary injury. So the level of SP-A in serum can be marker of the degree of pulmonary injury. But there are no reports on the usefulness of the level of SP-A in serum in assessing the severity of pulmonary injury in blast-anoxic complicated injury. This study researches early pathomorphologic characteristics of blast-anoxic complicated injury, lung-body index, pulmonary water containing rate, as well as the changes of SP-A in serum and bronchioalveolar lavage fluid (BALF) in combined blast-anoxic injury in rats. The aim of the study is to explore the roles of SP-A in the pathogenesis of combined blast-anoxic injury, and to provide theoretical guide for assessing and treatment of combined blast-anoxic injury.Methods 120 Wister rats were divided into four groups randomly: normal comparative group (NC), blast injury group (BI), combined blast-anoxic injury group â…  (BAâ… ) , and combined blast-anoxic injury group â…¡ (BAâ…¡). The rats were inflicted of blast injury by BST-â…¡ bio-shock tube. Rats of BAâ… , BAâ…¡ were put into the anoxic-cabin immediately after they were inflicted of blast injury, the anoxic-cabin was then aerated the mixed gas of 12.5% O2 and 10% O2 respectively. The SP-A ontent in BALF and serum was determined with Western Blot method. SP-A in lung tissue was showed by immunohistochemistry. The pathologic change of the lung tissue, the lung-body index and the pulmonary water containing rate were also observed.Results 1.characteristics of the injury: the combined blast-anoxic injury was more severity than the blast injury, the main characteristics of the injured rats were dysphoria, tachypnea. Cyanosis was observed in BAâ…¡. The rats were unresponsive, shortness of breath after six hours. The lung-body index and the pulmonary water containing rate of the injured group were higher than NC, but there were no significant differences between the injured groups nor between the phases. The main pathomorphologic characteristics were pulmonary hemorrhage and pneumonedema. The constituent ratio of pneumonedema and severe haemorrhagia in BAâ…¡ group was higher than BAâ…  and BI. The blood capillary in pulmonary interstitial were congestive, the cavity of arteriole was constrictive. The edema and haemorrhagia could be observed in the pulmonary alveoli and interstitial. The alveolar were filled of erythrocytic and plasmic-fibrous exudation. The alveolar wall was disruption. The lamellar body in AT-II was decrease and bubble alterative. Many rats were dead in 1hr and none died after 6hr. The mortality rate of BI, BAâ… and BAâ…¡ was 2.13%, 8% and 37.5% respectively. The longer anoxic time was and the lower oxygen concentration was, the more serious pulmonary injury was, the higher mortality was in early phase.2. the SP-A level in BALF was significantly decreasing after injury (P<0.01). On the same phase, the SP-A level of BAâ…¡ was lower than BAâ…  and BI (P<0.05), the SP-A level of BAâ…  was lower than BI (P<0.05). After injury the SP-A concentration was gradually decrease, the concentration was lowest on 6hr.