机械通气对急性肺损伤兔肺水肿影响的实验研究

目的研究不同潮气量联合不同水平呼气末正压(PEEP)机械通气对急性肺损伤(ALI)兔肺水肿的影响。方法用数字表法将36只新西兰兔随机分为正常对照(NC)组、ALI组、常规潮气量(15mL/kg)低PEEP(5cmH2O)(CVLP)组、常规潮气量高PEEP(10cmH2O)(CVHP)组、小潮气量(8mL/kg)低PEEP(LVLP)组和小潮气量高PEEP组(LVHP组)。以内毒素静脉注射建立ALI动物模型,经机械通气的4组动物分别给予不同潮气量联合不同水平PEEP机械通气4h。实验结束后取肺组织测定湿质量/干质量比值评价肺水肿严重程度。结果NC组、ALI组、CVLP组、CVHP组、LVLP组和LVHP组的肺湿质量/干质量比值分别为4.81±0.19、5.84±0.20、5.47±0.28、5.25±0.12、5.24±0.12和5.12±0.10,NC组低于其他各组,差异有统计学意义(P<0.05);ALI组高于各机械通气组,差异有统计学意义(P<0.05);LVHP组低于CVLP组,差异亦有统计学意义(P<0.05)。结论机械通气能够减轻ALI肺水肿,小潮气量联合高PEEP机械通气减轻ALI肺水肿的作用更加显著。

Effect of Mechanical Ventilation on Lung Edema in Rabbits with Endotoxin-induced Acute Lung Injury

Objective To investigate the effects of mechanical ventilation with different tidal volumes(VT) and positive end-expiratory pressure(PEEPs) on the lung edema in acute lung injury rabbit(ALI) models.Methods Thirty-six New Zealand rabbits were randomized into 6 groups(6 in each group). ①normal control group(NC), ② ALI group(Lipopolysaccharides 50 μg/kg intravenously), ③CVLP group(ALI + ventilation with V_T 15 mL/kg and 5 cmH₂O PEEP), ④ CVHP group(ALI + ventilation with VT 15 mL/kg and 10 cmH₂O PEEP), ⑤ LVLP group(ALI + ventilation with V_T 8 mL/kg and 5 cmH₂O PEEP), ⑥ LVHP group(ALI + ventilation with V_T 8 mL/kg and 10 cmH₂O PEEP). The ALI models receiving ventilation with different tidal volumes and PEEPs were ventilated for 4 h. Lung wet-to-dry weight(W/D) ratio was used to assay the lung edema.Results The W/D ratios in CVLP group(5.47±0.28), CVHP group(5.25±0.12), LVLP group(5.24±0.12) and LVHP group(5.12±0.10) decreased significantly(P<0.05) as compared with that of the ALI group(5.84±0.20), but increased(P<0.05) as compared with the NC group(4.81±0.19). The W/D in LVHP group was lower than that in CVLP group(P<0.05).Conclusion Ventilation attenuates lung edema in ALI models. Ventilation with both low V_T and high PEEP is more beneficial for lung edema in ALI.