呼吸机呼气末气道正压及其临床应用

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                    <section><section powered-by="gulangu"><section><section><p><img src="image/20201019/e5e7e34f8d69e7d33c5e008e02e20732_1.gif" /></p></section></section></section><section powered-by="gulangu"><section><section><p><br  /></p></section></section></section><section powered-by="gulangu"><section><section><section><section powered-by="gulangu"><section><section><p>呼气末气道正压</p></section></section></section></section></section></section></section><section powered-by="gulangu"><section><section><p>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp;任何气道本身病变或机械通气时，呼气末气道压力高于大气压均称为PEEP（positive end expiratory pressure,PEEP）。</p><p><br  /></p><p>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp;气道本身病变使呼气末气道压力高于大气压时称内源性呼气末气道正压（PEEPi）。经人工气道或面罩加压机械通气时增加呼气阻力，造成气道压力在呼气末也高于大气压时，称为机械通气呼气末气道正压（此处均称为PEEP），通常仅用于机械通气时。带有连续气道正压的自主呼吸被称为连续气道正压（CPAP）。在控制通气时可加用PEEP，此外还可在IMV、SIMV、ASB、A/C、MMV等模式时加用PEEP。</p><p><br  /></p><p>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp;<span>PEEP可增加肺泡内压力、气道平均压和功能残气量。适用于伴顺应性减退、功能残气量减少和肺毛细血管膜通透性增加的疾患，如肺水肿以及SARS引起的ARDS。根据以往的研究，PEEP可通过以下机制改善氧分压：（1）增加功能残气量（FRC），进而增加气体交换区域。(2)重新扩张萎陷的肺区域；（3）减少右→左分流；（4）避免呼气末肺泡萎陷；（5）改善通气/血流比值。简言之，PEEP启用萎陷肺泡并保持其扩张，因此减少生理分流和改善动脉血氧合。</span></p><p><span><br  /></span></p><p><span>&nbsp; &nbsp; &nbsp; &nbsp; </span><span>可预先在呼吸机中设定PEEP水平，实践中通常使用5～15 cmH2O PEEP。&nbsp;&nbsp; 但压力超过15 cmH2O左右时，PEEP的有益作用即被耗尽了，肺泡直径将不再随着PEEP的升高而增加，而且有产生过度膨胀和肺泡破裂的危险。此外，PEEP还有以下副作用：（1）由于减少静脉回流及增加胸内压减少心输出量&nbsp;&nbsp; ；（2）减少肾、肝、和内脏血液循环；（3）增加颅内压（减少颈静脉的静脉回流）。在逐步减少PEEP至3～5cmH2O时，可考虑给患者拔管。因为此时患者可通过声门关闭保持生理性PEEP在这一范围内。</span></p></section></section></section><section powered-by="gulangu"><section><section><p><br  /></p></section></section></section><section powered-by="gulangu"><section><section><section powered-by="gulangu"><section><section><p>欢</p></section></section></section></section><section><section powered-by="gulangu"><section><section><p>迎</p></section></section></section></section><section><section powered-by="gulangu"><section><section><p>关</p></section></section></section></section><section><section powered-by="gulangu"><section><section><p>注</p></section></section></section></section></section></section><section powered-by="gulangu"><section><section><p><br  /></p></section></section></section><section powered-by="gulangu"><section><section><section powered-by="gulangu"><section><section><p><img src="image/20201019/49692c66e805e7714887253296dfca5f_2.jpg" /></p></section></section></section></section><section><section powered-by="gulangu"><section><section></section></section></section></section><section><section powered-by="gulangu"><section><section><p>关注我们</p><p>一起涨姿势！</p></section></section></section></section></section></section></section>