Li Min, Qin Ying-zhi, Ma Li-jun
Intensive Care Unit, Tianjin Third Central Hospital, Tianjin 300170, China.
Zhongguo Wei Zhong Bing Ji Jiu Yi Xue. 2007 Feb;19(2):86-9.
To study the effects on the hemodynamics and the heart function when different positive end-expiratory pressure (PEEP) levels were used on patients treated with mechanical ventilation.
Thirty-nine critical patients with respiratory failure and treated with mechanical ventilation, and hemodynamics was monitored, were divided into two groups according to the cardiac index (CI). Hemodynamics was measured with non-invasive cardiac output (NICO) continuously. The changes in hemodynamic parameters [including cardiac output (CO), CI, pulmonary capillary blood flow (PCBF), central venous pressure (CVP), systemic vascular resistance (SVR)], lung mechanical parameters [intrinsic positive end expiratory pressure (PEEPi), peak inspiratory pressure (PIP), mean of airway pressure (Pmean)], pulse saturation of oxygen (SpO(2)), blood pressure (BP) and heart rate (HR)] were determined with different selected PEEP levels of 0, 5, 7, 10 and 13 cm H(2)O (1 cm H(2)O=0.133 kPa) under the bi-phasic positive airway pressure (BIPAP) mode in normal cardiac function group (CI > or =2.0 L x min(-1) x m(-2), n=18) and poor cardiac function group (CI<2.0 L x min(-1) x m(-2), n=18).
In the normal cardiac function group, the increase in PEEP led to an increase of CVP, but it had no significant effects on CO, CI, PCBF and SVR; in the poor cardiac function group, the increase of PEEP led to an increase of CVP and SVR, a decrease of PCBF, CO, CI, and the latter two variables showed a curvilinear change. In both groups, PIP, Pmean, PEEPi increased and the resistance of airway (R) fell with the increase of PEEP.
Under the condition of mechanical ventilation, when the lung volume was relatively constant, change in PEEP levels (0-13 cm H(2)O) had no obvious effects on the normal cardiac function group, but can significantly decrease right ventricular preload, PCBF and left ventricular preload. Optimal PEEP may improve the cardiac function. The change in the airway pressure is not consistent with the changes in cardiac function.
研究在机械通气治疗的患者中使用不同水平呼气末正压（PEEP）时对血流动力学和心脏功能的影响。
选取39例接受机械通气治疗的呼吸衰竭重症患者，根据心脏指数（CI）分为两组，采用无创心输出量（NICO）连续监测血流动力学。在双相气道正压（BIPAP）模式下，于正常心功能组（CI≥2.0L·min⁻¹·m⁻²，n = 18）和心功能较差组（CI＜2.0L·min⁻¹·m⁻²，n = 18）中分别选取0、5、7、10和13cmH₂O（1cmH₂O = 0.133kPa）不同水平的PEEP，测定血流动力学参数[包括心输出量（CO）、CI、肺毛细血管血流量（PCBF）、中心静脉压（CVP）、体循环血管阻力（SVR）]、肺力学参数[内源性呼气末正压（PEEPi）、吸气峰压（PIP）、气道平均压（Pmean）]、脉搏血氧饱和度（SpO₂）、血压（BP）和心率（HR）的变化。
在正常心功能组中，PEEP升高导致CVP升高，但对CO、CI、PCBF和SVR无显著影响；在心功能较差组中，PEEP升高导致CVP和SVR升高，PCBF、CO、CI降低，且后两者呈曲线变化。两组中，随着PEEP升高PIP、Pmean、PEEPi升高，气道阻力（R）降低。
在机械通气条件下，当肺容积相对恒定时，PEEP水平（0～13cmH₂O）的变化对正常心功能组无明显影响，但可显著降低右心室前负荷、PCBF和左心室前负荷。最佳PEEP可能改善心脏功能。气道压力变化与心脏功能变化不一致。
