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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 effect and mechanism of exogenous positive end expiratory pressure (PEEPe) on respiratory work in patients with chronic obstructive pulmonary disease (COPD). Methods Ten COPD patients who received endotracheal intubation and mechanical ventilation were enrolled in this study. Respiratory mechanics monitoring was performed using the BicoreCP 10 0 Respiratory Mechanics Monitor. PEEPe was first set at 0%, 40%, 60%, 80% and 100% of PEEPi and dynz, respectively. Respiratory mechanics and other parameters (heart rate, blood pressure and arterial blood gas) were measured after changing the PEEPe level for 30 minutes each time. Results WOBp, pressure time product, esophageal pressure difference and dynamic endogenous positive end expiratory pressure (PEEPi, dyn) decreased significantly after PEEPe addition, and continued to decline with the increase of PEEPe. When PEEPe was added to 80% and 100% of PEEPi, dynz, ventilator work was significantly increased. There was a significant linear positive correlation between changes of WOBp and changes of PEEPi and dyn. Conclusions PEEPe decreases WOBp and decreases WOBp by decreasing the pressure difference between the end-expiration alveolus and the central airway.