Sun Xiumei, Chen Guangqiang, Yang Yanlin, Zhou Jianxin
Department of Critical Care Medicine, Beijing Tiantan Hospital, Capital Medical University, Beijing 100070, China. Corresponding author: Zhou Jianxin, Email:
Zhonghua Wei Zhong Bing Ji Jiu Yi Xue. 2020 Jul;32(7):808-813. doi: 10.3760/cma.j.cn121430-20200413-00282.
To evaluate the feasibility of esophageal pressure (Pes) calibration by the esophageal balloon pressure-volume (P-V) curve during assisted mechanical ventilation.
A prospective study was conducted. The postoperative patients admitted to intensive care unit of Beijing Tiantan Hospital Affiliated to Capital Medical University from June 2017 to January 2019 who needed pressure support ventilation by tracheal intubation and Pes monitoring with stable breath were enrolled. The Pes monitoring was performed by the esophageal balloon with a small geometric volume (2.8 mL). (1) Balloon volume tests of esophageal balloon were performed by inflating intermittently 0.5 mL increments up to 2.5 mL, the end-expiratory and end-inspiratory Pes were recorded to obtain end-expiratory and end-inspiratory P-V curves. The intermediate section in end-expiatory P-V curve that showed linear correlation was identified (as intermediate linear section), whose volume range was balloon working volume (V) and slope was esophageal wall elastance (Ees), the balloon volume with the largest difference between end-expiratory and end-inspiratory Pes was the best balloon volume (V), and the product of Ees and V was esophageal wall recoil pressure reacting to balloon filling. To minimize the effect of esophageal wall on Pes, the calibrated Pes was the difference of Pes and esophageal wall recoil pressure. The consistency of calibrated Pes obtained by balloon volume at V and other V were analyzed. (2) For the convenience of clinical application, a simplified method was introduced to calibrate Pes. Based on all V of patients located in 0.5-1.5 mL, the difference of end-expiratory Pes between balloon volume at 0.5 mL and 1.5 mL divided by 1.0 mL was used to estimate Ees, and the Pes among 0.5-1.5 mL was calibrated by Ees obtained by the simple method. The consistency of calibrated Pes obtained by the simple method and standard method were observed.
Totally 30 patients were enrolled, all end-expiratory and end-inspiratory P-V curves existed the intermediate linear section, the calibrated Pes at V did not increase with the balloon being inflated and had a good consistency with the calibrated Pes at V, mean difference and 95% confidence interval (95%CI) was -0.02 (-1.50-1.50) cmHO (1 cmHO = 0.098 kPa). The Ees and calibrated Pes estimated by the simple method had a good agreement with the standard method, mean difference and 95%CI was -0.2 (-1.0-0.6) cmHO/mL and 0.2 (-1.1-1.4) cmHO, respectively.
During assisted mechanical ventilation, the use of a small geometric volume esophageal balloon to monitor Pes and balloon P-V curve to calibrate Pes is feasible. The simple method can be used for simplifying clinical application, that's only by monitoring Pes at balloon volume at 0.5, 1.0 and 1.5 mL to evaluate the Ees and calibrate Pes.
评估在机械通气辅助期间通过食管球囊压力-容积（P-V）曲线校准食管压力（Pes）的可行性。
进行一项前瞻性研究。纳入2017年6月至2019年1月在北京天坛医院重症监护病房住院的术后患者，这些患者需要气管插管进行压力支持通气且呼吸稳定时需监测Pes。采用几何容积较小（2.8 mL）的食管球囊进行Pes监测。（1）对食管球囊进行球囊容积测试，以0.5 mL的增量间歇性充气至2.5 mL，记录呼气末和吸气末的Pes，以获得呼气末和吸气末P-V曲线。确定呼气末P-V曲线中显示线性相关的中间段（即中间线性段），其容积范围为球囊工作容积（V），斜率为食管壁弹性（Ees），呼气末和吸气末Pes差异最大时的球囊容积为最佳球囊容积（V），Ees与V的乘积为食管壁对球囊充盈的回缩压力。为尽量减少食管壁对Pes的影响，校准后的Pes为Pes与食管壁回缩压力之差。分析在V时通过球囊容积获得的校准后Pes与其他V时校准后Pes的一致性。（2）为方便临床应用，引入一种简化方法校准Pes。基于患者所有位于0.5 - 1.5 mL的V，用0.5 mL和1.5 mL球囊容积时呼气末Pes的差值除以1.0 mL来估算Ees，并通过该简化方法获得的Ees校准0.5 - 1.5 mL之间的Pes。观察通过简化方法和标准方法获得的校准后Pes的一致性。
共纳入30例患者，所有呼气末和吸气末P-V曲线均存在中间线性段，V时校准后的Pes不随球囊充气增加，与V时校准后的Pes具有良好的一致性，平均差值和95%置信区间（95%CI）为 -0.02（-1.50 - 1.50）cmH₂O（1 cmH₂O = 0.098 kPa）。简化方法估算的Ees和校准后的Pes与标准方法具有良好的一致性，平均差值和95%CI分别为 -0.2（-1.0 - 0.6）cmH₂O/mL和0.2（-1.1 - 1.4）cmH₂O。
在机械通气辅助期间，使用几何容积较小的食管球囊监测Pes并通过球囊P-V曲线校准Pes是可行的。简化方法可用于简化临床应用，即仅通过监测0.5、1.0和1.5 mL球囊容积时的Pes来评估Ees并校准Pes。
