Effects of prone ventilation on extra pulmonary acute lung injury / 中国中西医结合急救杂志

ABSTRACT

Objective To investigate the effects and mechanism of prone ventilation in rats with lipopolysaccharide(LPS)-induced extra pulmonary acute lung injury(ALI). Methods Thirty-two male Sprague-Dawley(SD)rats were randomly divided into four groupscontrol group,ALI group,supine position group(ALIS group)and prone position group(ALIP group). The ALI animal model was reproduced by intra-peritoneal injection of LPS 6 mg/kg,and 2 mL/kg sterile saline was intra-peritoneally injected in control group. After 24 hours,the ALIS group and ALIP group were mechanically ventilated for 4 hours in supine and prone positions respectively. Arterial partial pressure of oxygen(PaO2),carbon dioxide partial pressure(PaCO2),wet to dry weight ratio of lung(W/D) were observed,and the levels of tumor necrosis factor-α(TNF-α),interleukins(IL-6,IL-10)in bronchoalveolar lavage fluid(BALF)were measured. The degrees of histopathological changes of lung were investigated and assessed under light microscope. Results Compared with control group,PaO2 was significantly lower in ALI,ALIS and ALIP groups〔mmHg(1 mmHg=0.133 kPa)68±7,82±8,93±7 vs. 116±7〕,and the PaCO2 in ALI and ALIS groups was obviously higher(mmHg53±6,51±5 vs. 43±7,both P<0.05);lung W/D ratio as well as levels of TNF-α, IL-6 and IL-10 in BALF were significantly higher in ALI,ALIS and ALIP groups〔lung W/D ratio5.11±0.32, 4.71±0.38,4.53±0.45 vs. 4.48±0.15,TNF-α(ng/L)548±82,431±64,347±53 vs. 162±16,IL-6(ng/L)772±119,587±178,490±139 vs. 127±16,IL-10(ng/L)211±43,295±36,352±59 vs. 104±31,all P<0.05〕. Compared with ALI group,PaO2 in ALIS and ALIP groups was significantly higher,and in ALIP group,PaCO2 was lower,lung W/D ratio,TNF-α and IL-6 in BALF were obviously lower,while IL-10 in BALF was obviously higher(all P<0.05). Compared with ALIS group,the changes in ALIP group were more significant(all P<0.05). Compared with ALIS group,under light microscope,it was shown that the hyper-inflated areas were less,normal and collapsed areas were greater on the ventral side,and the collapsed area was less and the normal ventilation area was greater on the dorsal side in ALIP group(all P<0.05). Conclusion In rats with LPS-induced extra pulmonary ALI,the prone ventilation can improve gas exchange,promote uniform distribution of ventilation,decrease pulmonary edema and in the mean time attenuate inflammatory response.