外源性呼气末正压对慢性阻塞性肺疾病患者呼吸功的影响(英文)

Effects of extrinsic positive end-expiratory pressure on work of breathing in patients with chronic obstructive pulmonary disease

目的 探讨外源性呼气末正压 (PEEPe)对慢性阻塞性肺疾病 (COPD)患者呼吸功的影响及其机制。方法 选择接受气管插管和机械通气的COPD患者 10例 ,使用BicoreCP 10 0呼吸力学监测仪进行呼吸力学监测。首先测定PEEPe为零时的动态内源性呼气末正压 (表示为PEEPi,dynz) ,再以PEEPi,dynz的 0 %、4 0 %、60 %、80 %和 10 0 %随机设置PEEPe ;在每次改变PEEPe水平 30分钟后 ,测定呼吸力学及其它指标 (心率、血压及动脉血气 )。结果 患者呼吸功 (WOBp)、压力时间乘积、食道压差和动态内源性呼气末正压 (PEEPi,dyn)在加用PEEPe后即明显降低 ,而且随着PEEPe的增加继续下降。当PEEPe加至PEEPi,dynz的 80 %和 10 0 %时 ,呼吸机做功显著增加。WOBp的变化和PEEPi,dyn的变化之间有非常显著的直线正相关关系。结论 PEEPe可降低WOBp ,并且是通过降低呼气末肺泡与中心气道之间的压力差来降低WOBp的。

Objective To investigate the effects of extrinsic positive end-expiratory pressure (PEEPe) on work of breathing in patients with chronic obstructive pulmonary disease (COPD) and their corresponding mechanism.Methods Ten ventilated patients with COPD were included in the study. A Bicore CP-100 pulmonary monitor (Bicore Monitoring System, USA) was used for monitoring respiratory mechanics. First, dynamic intrinsic positive end-expiratory pressure (PEEPi,dyn) was measured when PEEPe was zero, which was called PEEPi,dynz. Then the PEEPe was set randomly at 0%, 40%, 60%, 80% and 100% of PEEPi,dynz respectively. Pulmonary mechanics and other parameters (heart rate, blood pressure and blood gas analysis) were measured 30 minutes after the level of PEEPe was changed.Results Work of breathing patient (WOBp), pressure time product, difference of esophageal pressure and PEEPi,dyn decreased significantly when PEEPe was applied, and continued decreasing as PEEPe was increased. Work of breathing ventilator increased significantly when PEEPe was increased to 80% and 100% of PEEPi,dynz. Significantly positive linear correlation was found between the changes in WOBp and in PEEPi,dyn.Conclusions WOBp decreases gradually as PEEPe is increased. WOBp decreases by narrowing the difference between the alveolus pressure and the central airway pressure at the end of expiration when PEEPe is applied.