Comparison between conventional protective mechanical ventilation and high-frequency oscillatory ventilation associated with the prone position

ABSTRACT Objective: To compare the effects of high-frequency oscillatory ventilation and conventional protective mechanical ventilation associated with the prone position on oxygenation, histology and pulmonary oxidative damage in an experimental model of acute lung injury. Methods: Forty-five rabbits with tracheostomy and vascular access were underwent mechanical ventilation. Acute lung injury was induced by tracheal infusion of warm saline. Three experimental groups were formed: healthy animals + conventional protective mechanical ventilation, supine position (Control Group; n = 15); animals with acute lung injury + conventional protective mechanical ventilation, prone position (CMVG; n = 15); and animals with acute lung injury + high-frequency oscillatory ventilation, prone position (HFOG; n = 15). Ten minutes after the beginning of the specific ventilation of each group, arterial gasometry was collected, with this timepoint being called time zero, after which the animal was placed in prone position and remained in this position for 4 hours. Oxidative stress was evaluated by the total antioxidant performance assay. Pulmonary tissue injury was determined by histopathological score. The level of significance was 5%. Results: Both groups with acute lung injury showed worsening of oxygenation after induction of injury compared with the Control Group. After 4 hours, there was a significant improvement in oxygenation in the HFOG group compared with CMVG. Analysis of total antioxidant performance in plasma showed greater protection in HFOG. HFOG had a lower histopathological lesion score in lung tissue than CMVG. Conclusion: High-frequency oscillatory ventilation, associated with prone position, improves oxygenation and attenuates oxidative damage and histopathological lung injury compared with conventional protective mechanical ventilation.

摘要：
目的：在急性肺损伤（acute lung injury）实验模型中，对比高频振荡通气（high-frequency oscillatory ventilation）联合俯卧位与常规保护性机械通气（conventional protective mechanical ventilation）联合俯卧位对氧合、组织学及肺氧化损伤的影响。
方法：选取45只已实施气管切开术（tracheostomy）并建立血管通路（vascular access）的家兔，予以机械通气。通过气管内输注温生理盐水构建急性肺损伤模型。将实验动物分为3组：健康家兔+常规保护性机械通气+仰卧位（对照组（Control Group），n=15）；急性肺损伤家兔+常规保护性机械通气+俯卧位（CMVG组，n=15）；急性肺损伤家兔+高频振荡通气+俯卧位（HFOG组，n=15）。于各组专属通气方案启动后10分钟采集动脉血气分析（arterial gasometry）样本，将该时间点记为零点；采样完成后将动物置于俯卧位，并维持该体位4小时。采用总抗氧化能力检测试验（total antioxidant performance assay）评估氧化应激水平，通过组织病理学评分（histopathological score）判定肺组织损伤程度。本研究检验水准设为5%。
结果：与对照组相比，两个急性肺损伤模型组在造模完成后氧合功能均出现显著恶化。通气4小时后，HFOG组的氧合功能较CMVG组得到显著改善。血浆总抗氧化能力分析显示，HFOG组的抗氧化保护作用更强。HFOG组的肺组织病理学损伤评分低于CMVG组。
结论：相较于常规保护性机械通气，高频振荡通气联合俯卧位可有效改善氧合功能，减轻氧化损伤及肺组织病理学损伤。