Comparison of roles of inflammatory response in acute lung injury induced by blunt chest trauma versus by blunt chest trauma-hemorrhagic shock and resuscitation in rats

Objective To compare the roles of inflammatory response in acute lung injury (ALI) induced by blunt chest trauma verus by blunt chest trauma-hemorrhagic shock and resuscitation (double hits) in rats.Methods Thirty male Sprague-Dawley rats,aged 8 weeks,weighing 240-280 g,were randomly assigned into 3 equal groups (n =10 each) using a random number table:sham operation group (S group),blunt chest trauma group (T group),and blunt chest trauma and hemorrhagic shock and resuscitation group (THSR group).Lung contusion was induced in anesthetized rats by dropping a 300 g weight onto a precordial protective shield to direct the impact force away from the heart and toward the lungs.Blood was withdrawn via the left femoral artery 5 min later until MAP was decreased to 35-45 mmHg within 15 min and maintained at this level for 60 min,followed by resuscitation.At 6 h after the model was established,the arterial blood samples were collected for blood gas analysis and detection of serum concentrations of tumor necrosis factor-α (TNF-α),interleukin-6 (IL-6),IL-1β and IL-10 (by ELISA).The rats were then sacrificed and pulmonary specimens were obtained for determination of contents of TNF-α,IL-6,IL-1β and IL-10 in lung tissues and for microscopic examination.Results Compared with group S,PaO2 was significantly decreased,and the levels of TNF-α,IL-6,IL-1β and IL-10 in serum and lung tissues were increased in T and THSR groups.Compared with group T,PaO2 was significantly decreased,and the levels of TNF-α,IL-6,IL-1β and IL-10 in serum and lung tissues were increased in group THSR.The histopathological damage to lung tissues was aggravated in THSR group as compared with T group.Conclusion The role of inflammatory response in ALI induced by blunt chest trauma-hemorrhagic shock and resuscitation (double hits) is significantly stronger than that in ALI induced by blunt chest trauma alone in rats. Key words: Inflammation ;  Thoracic injury ;  Shock, Hemorrhagic ;  Respiratory distress syndrome, adult