Xu Yong-Qing, Wu Da-Wei, Xie Jian, Li Tao
Intensive Care Unit, Qianfoshan Hospital, Medical School of Shandong University, Jinan 250014, China.
Zhongguo Yi Xue Ke Xue Yuan Xue Bao. 2006 Aug;28(4):507-11.
To study the effects of expiratory triggering sensitivity (ETS) on patient-ventilator expiratory synchrony and work of breathing in chronic obstructive pulmonary disease (COPD) patients during pressure support ventilation (PSV).
A total of 31 COPD patients were ventilated in PSV mode, and measured by a pulmonary monitor. Meanwhile, the electromyogram of the diaphragm (EMG(diaph)) was obtained with electromyography. Five levels of ETS, 1%, 15%, 25%, 35%, and 50% of peak inspiratory flow (PIF), were studied in random order. Each ETS level lasted 30 minutes and all the data were recorded simultaneously for 3 minutes at the end of each period. The effects of ETS on patient-ventilator expiratory synchrony were analyzed by measuring the phase angle of expiration between the EMG(diaph) and the flow wave curve, and the effects of ETS on work of breathing by calculating total work of breathing (Wtot), work of inspiration by patients (Wi, P) and expiratory work of breathing (Wex).
Ten patients were excluded from the study. At the 25% PIF level of ETS, patient-ventilator expiratory synchrony was the best, theta = (8 +/- 3) degrees, 16 patients - 15 degrees < or = theta < or = 15 degrees, and the amount of Wtot, Wi, p, Wex was the smallest among all the 5 levels of ETS, which was (1.86 +/- 0.53) J/L, (0.54 +/- 0.13) J/L, and (0.16 +/- 0.08) J/L respectively. When the level of ETS decreased, the occurrence of delayed termination of inspiration and the amount of Wex increased. At the level of 1% PIF, 18 patients theta > 15 degrees, and Wex was (0.48 +/- 0.10) J/L; at this level of ETS, Wi, p also increased significantly to (0.65 +/- 0.16 ) J/L. But when the level of ETS increased, the occurrence of premature termination of inspiration and the amount of Wi, p increased: at 50% PIF level of ETS, theta < - 15 degrees and Wi, p was (1.33 +/- 0.14) J/L in 19 patients.
The proper adjustment of ETS during PSV improves patient-ventilator synchrony and decreases work of breathing in COPD patients.
研究压力支持通气（PSV）期间呼气触发灵敏度（ETS）对慢性阻塞性肺疾病（COPD）患者的人机呼气同步性及呼吸功的影响。
31例COPD患者采用PSV模式通气，并用肺功能监测仪进行测量。同时，通过肌电图获取膈肌肌电图（EMG(diaph)）。随机研究5个ETS水平，即吸气峰流速（PIF）的1%、15%、25%、35%和50%。每个ETS水平持续30分钟，在每个时间段结束时同时记录所有数据3分钟。通过测量EMG(diaph)与流速波形曲线之间的呼气相位角分析ETS对人机呼气同步性的影响，通过计算总呼吸功（Wtot）、患者吸气功（Wi,P）和呼气功（Wex）分析ETS对呼吸功的影响。
10例患者被排除在研究之外。在ETS为25%PIF水平时，人机呼气同步性最佳，θ =（8±3）度，16例患者-15度≤θ≤15度，且在所有5个ETS水平中Wtot、Wi,P、Wex量最小，分别为（1.86±0.53）J/L、（0.54±0.13）J/L和（0.16±0.08）J/L。当ETS水平降低时，吸气延迟终止的发生率和Wex量增加。在1%PIF水平时，18例患者θ>15度，Wex为（0.48±0.10）J/L；在此ETS水平时，Wi,P也显著增加至（0.65±0.16）J/L。但当ETS水平升高时，吸气提前终止的发生率及Wi,P量增加：在ETS为50%PIF水平时，19例患者θ<-15度，Wi,P为（1.33±0.14）J/L。
在PSV期间适当调整ETS可改善COPD患者的人机同步性并降低呼吸功。
