■介绍潮气量的可变性,通气频率,在急性呼吸窘迫综合征(ARDS)的机械通气期间或两者均有益。我们调查了在ARDS模型中应用呼气末正压(PEEP)的逐周期变异性是否对肺功能产生有益影响。
■患有肺损伤的兔子被随机分配接受机械通气6小时,方法是应用压力控制模式,恒定PEEP为7cmH2O(PC组:n=6)或可变PEEP(VEEP),变异系数为21.4%,范围为4-10cmH2O(PC-VEEP组;n=6)。通气6h(H6)后肺氧合指数(Pao2/FiO2)是主要结果,肺容积,肺内分流术,和肺部炎症标志物是次要结局。
■肺损伤后,两组均出现中重度ARDS(Pao2/FiO2<27kPa).在H6时,PC-VEEP组的Pao2/FiO2显着高于PC组(12.3[sd3.5]vs19.2[7.2]kPa,P=0.013)和1-3h时CO2的动脉分压较低(P<0.02)。PC-VEEP可防止通气引起的气道阻力和组织弹性增加。没有证据表明分钟音量有差异,驱动压力,呼气末二氧化碳,肺容量,肺内分流分数,和通气模式之间的细胞因子。
■使用逐周期VEEP延长机械通气可防止ARDS模型中气体交换和呼吸力学的恶化,提示这种新型通气策略在不增加驱动压力和肺部过度扩张的情况下优化气体交换的益处。
UNASSIGNED: Introducing variability in tidal volume, ventilatory frequency, or both is beneficial during mechanical ventilation in acute respiratory distress syndrome (ARDS). We investigated whether applying cycle-by-cycle variability in the positive end-expiratory pressure (PEEP) exerts beneficial effect on lung function in a model of ARDS.
UNASSIGNED: Rabbits with lung injury were randomly allocated to receive mechanical ventilation for 6 h by applying a pressure-controlled mode with constant PEEP of 7 cm H2O (PC group: n=6) or variable PEEP (VEEP) with a coefficient of variation of 21.4%, range 4-10 cm H2O (PC-VEEP group; n=6). Lung oxygenation index (Pao2/FiO2) after 6 h of ventilation (H6) was the primary outcome and respiratory mechanics, lung volume, intrapulmonary shunt, and lung inflammatory markers were secondary outcomes.
UNASSIGNED: After lung injury, both groups presented moderate-to-severe ARDS (Pao2/FiO2 <27 kPa). The Pao2/FiO2 was significantly higher in the PC-VEEP group than in the PC group at H6 (12.3 [sd 3.5] vs 19.2 [7.2] kPa, P=0.013) and a lower arterial partial pressure of CO2 at 1-3 h (P<0.02). The ventilation-induced increases in airway resistance and tissue elastance were prevented by PC-VEEP. There was no evidence for a difference in minute volume, driving pressure, end-tidal CO2, lung volumes, intrapulmonary shunt fraction, and cytokines between the ventilation modes.
UNASSIGNED: Prolonged mechanical ventilation with cycle-by-cycle VEEP prevents deterioration in gas exchange and respiratory mechanics in a model of ARDS, suggesting the benefit of this novel ventilation strategy to optimise gas exchange without increasing driving pressure and lung overdistension.