Zakynthinos S G, Vassilakopoulos T, Zakynthinos E, Mavrommatis A, Roussos C
Department of Critical Care and Pulmonary Services, Athens University Medical School, Evangelismos Hospital, Athens, Greece.
Am J Respir Crit Care Med. 2000 Nov;162(5):1633-40. doi: 10.1164/ajrccm.162.5.9903084.
In spontaneously breathing (SB) patients expiratory muscle contraction leads to an overestimation of dynamic intrinsic PEEP (PEEP(i),dyn). To quantify this overestimation, PEEP(i),dyn measured with the esophageal balloon technique was corrected for the increase in Pga over the course of expiration (Pga,exp rise), for the whole decay of Pga during inspiration (Pga,total decay) or for the part of Pga decay restricted between the onset of inspiratory effort and the point of zero flow (Pga,zf decay). Corrections were compared with the reference PEEP(i),dyn (PEEP(i),dyn ref ), calculated by using the Campbell diagram. In 15 ventilator-dependent, SB, and actively expiring patients, we found that the difference PEEP(i),dyn - Pga, total decay (mean +/- SD, 5.7 +/- 1.9 cm H(2)O) was quite similar to PEEP(i),dyn ref (5.3 +/- 1.9 cm H(2)O). Their mean difference was 0. 37 cm H(2)O with limits of agreement -0.09 to 0.83 cm H(2)O, indicating strong agreement between these methods. PEEP(i),dyn - Pga, exp rise (6.0 +/- 2.1 cm H(2)O) was also similar to PEEP(i),dyn ref. Their mean difference was 0.72 cm H(2)O with limits of agreement -1. 69 to 3.13 cm H(2)O, indicating good agreement. In contrast, mean difference of PEEP(i),dyn - Pga,zf decay and PEEP(i),dyn ref was 3. 14 cm H(2)O with limits of agreement -0.46 to 6.74 cm H(2)O, indicating lack of agreement. The error in measurement due to the subtraction of Pga,zf decay from PEEP(i),dyn (i.e., [PEEP(i),dyn - Pga,zf decay] - PEEP(i),dyn ref ) was proportional to the intensity of expiratory muscle contraction, as expressed by the Pga,exp rise (r = 0.903, p < 0.001). We conclude that in actively expiring patients an adequate correction of PEEP(i),dyn for the overestimation caused by expiratory muscle contraction can be made by subtracting either Pga,total decay or Pga,exp rise from PEEP(i), dyn, the former achieving the best performance.
在自主呼吸（SB）患者中，呼气肌收缩会导致动态内在呼气末正压（PEEP(i),dyn）被高估。为了量化这种高估，用食管气囊技术测量的PEEP(i),dyn针对呼气过程中气道压力（Pga）的升高（Pga,exp rise）、吸气过程中Pga的整体下降（Pga,total decay）或吸气努力开始至零流速点之间受限的Pga下降部分（Pga,zf decay）进行了校正。将这些校正值与通过坎贝尔图计算得到的参考PEEP(i),dyn（PEEP(i),dyn ref）进行比较。在15例依赖呼吸机、自主呼吸且积极呼气的患者中，我们发现PEEP(i),dyn - Pga,total decay（均值±标准差，5.7±1.9 cm H₂O）与PEEP(i),dyn ref（5.3±1.9 cm H₂O）非常相似。它们的平均差值为0.37 cm H₂O，一致性界限为 -0.09至0.83 cm H₂O，表明这些方法之间具有高度一致性。PEEP(i),dyn - Pga,exp rise（6.0±2.1 cm H₂O）也与PEEP(i),dyn ref相似。它们的平均差值为0.72 cm H₂O，一致性界限为 -1.69至3.13 cm H₂O，表明具有良好的一致性。相比之下，PEEP(i),dyn - Pga,zf decay与PEEP(i),dyn ref的平均差值为3.14 cm H₂O，一致性界限为 -0.46至6.74 cm H₂O，表明缺乏一致性。由于从PEEP(i),dyn中减去Pga,zf decay导致的测量误差（即[PEEP(i),dyn - Pga,zf decay] - PEEP(i),dyn ref）与呼气肌收缩强度成正比，如Pga,exp rise所示（r = 0.903，p < 0.001）。我们得出结论，在积极呼气的患者中，通过从PEEP(i),dyn中减去Pga,total decay或Pga,exp rise，可以对因呼气肌收缩导致的PEEP(i),dyn高估进行适当校正，前者的性能最佳。
