急性心源性肺水肿机械通气患者呼气末正压设定的临床研究

目的探讨急性心源性肺水肿(ACPE)时不同呼气末正压(PEEP)水平对血流动力学与肺参数的影响。方法39例呼吸衰竭机械通气患者根据心排血指数(CI)分为两组。观察心功能正常组(n=18,CI≥2.0L·min-1·m-2)与心功能低下组(n=21,CI<2.0L·min-1·m-2)在双水平气道正压通气(BIPAP)模式下不同PEEP水平对血流动力学〔心排血量(CO)、CI、肺毛细血管血流(PCBF)、中心静脉压(CVP)、外周血管阻力(SVR)〕、肺参数〔内源性呼气末正压(PEEPi)、气道峰压(Ppeak)、平均气道压(Pmean)、每分通气量(MV)、肺泡通气量(Vtalv)〕及经皮血氧饱和度(SpO2)、血压(BP)、心率(HR)等的变化。结果心功能正常组PEEP在0～13cmH2O(1cmH2O=0.098kPa)对血流动力学无明显影响,肺参数中Ppeak、PEEPi随着PEEP增高而相应增高,气道阻力(R)下降;心功能低下组随着PEEP变化SVR、CO、CI呈曲线性变化,以PEEP0～7cmH2O时CO、CI值较高而SVR较低,10～13cmH2OCO、CI值较低而SVR较高,对肺参数影响以PEEP5～7cmH2O时PEEPi较小。结论ACPE患者机械通气调节应结合血流动力学变化并兼顾肺机械参数变化,PEEP使用具有明显个体化倾向,以PEEP5～7cmH2O(一般<10cmH2O)为宜。

Clinical study of the setting of positive end expiratory pressure in patients with acute cardiogenic pulmonary edema during mechanical ventilation

OBJECTIVE: To compare the effects on hemodynamics and lung mechanics when different positive end expiratory pressure (PEEP) levels were used in acute cardiac pulmonary edema. METHODS: Thirty-nine patients with respiratory failure and treated with mechanical ventilation were divided into two groups according to cardiac index (CI). The changes of hemodynamics [including cardiac output (CO), CI, pulmonary capillary blood flow (PCBF), central venous pressure (CVP), surround vascular resistance (SVR)], lung mechanical variables [intrinsic positive end expiratory pressure (PEEPi), peak inspiratory pressure (Ppeak), mean of airway pressure (Pmean), minute volume (MV), alveolar tidal volume (Vtalv)], percutaneous saturation of oxygen (SpO(2)) and blood pressure (BP) were determined with when selected different PEEP levels under the bi-level positive airway pressure (BIPAP) mode in normal cardiac function group (n=18, CI> or =2.0 L.min(-1).m(-2)) and poor cardiac function group (n=20, CI<2.0 L.min(-1)xm(-2)). RESULTS: In normal cardiac function group, PEEP has no effect on hemodynamics when varied from 0-13 cm H(2)O (1 cm H(2)O=0.098 kPa), and Ppeak and PEEPi increased with the elevation of PEEP. Resistance of airway (R) fell when PEEP was increased. However, in poor cardiac function group SVR, CO, CI showed curvilinear changes with an increase in PEEP, and CO, CI were high when PEEP changed from 0 to 7 cm H(2)O, but dropped markedly when PEEP was increased in 13 cm H(2)O, while the changes of SVR was the reverse of CO and CI. The effects on lung mechanics varied relatively smaller range when PEEP was set between 5-7 cm H(2)O, and the burden of breathing was slight. CONCLUSION: The mode of artificial ventilation should be adjusted according to the changes in hemodynamics and lung mechanics. PEEP should be individualized, and 5-7 cm H(2)O (normally below 10 cm H(2)O) is suitable.