基于气管内导管套囊压力估计气管压力的临床评估

Clinical evaluation of tracheal pressure estimation from the endotracheal tube cuff pressure.

作者信息

Wilder N A, Orr J, Westenskow D

机构信息

Department of Anesthesiology and Bioengineering, University of Utah, Salt Lake City 84132, USA.

出版信息

J Clin Monit Comput. 1998 Jan;14(1):29-34. doi: 10.1023/a:1007408204734.

DOI:10.1023/a:1007408204734

PMID:9641853

Abstract

OBJECTIVE

Air flow through an endotracheal tube causes a pressure drop across the tube. This pressure drop creates a difference between air pressure measured in the trachea and the pressure measured in the breathing circuit, which can lead to errors when calculating pulmonary mechanics and when setting ventilators. We have developed a method of estimating tracheal pressure from the pressure in the endotracheal tube cuff and tested this system in clinical trials.

METHODS

Pressure measurement ports were placed between the Y piece of the ventilator circuit and the ETT connector, in the trachea at the carinal end of the ETT, and in the ETT cuff inflation line. Tracheal pressures and cuff pressures were found at end-inspiration and end-expiration (no flow states) and used to define a linear relationship between cuff pressure and tracheal pressure. Using the estimated tracheal pressure (Ptrach) and the measured pressure at the Y piece of the breathing circuit (PY), the pressure drop across the ETT was found as a function of flow through the tube. Tracheal pressure was then calculated from the flow-dependent pressure drop and PY. Tests of this system were performed in six patients in the operating room and six patients in the intensive care unit.

RESULTS

The flow-based tracheal pressure estimates were within 0.7 +/- 0.4 cm H2O of actual tracheal pressure (mean +/- SD). At peak inspiratory pressure the difference averaged 0.5 +/- 0.3 cm H2O. The difference between our estimate of tracheal pressure and actual tracheal pressure was always less than 1 cm H2O.

CONCLUSION

The flow-based tracheal pressure estimates were accurate during intermittent spontaneous breathing, but not during spontaneous breathing or with a poorly inflated cuff. The estimates were more immune to noise than the cuff-based estimates of tracheal pressure. The estimates of tracheal pressure measured from the ETT cuff should be accurate enough for clinical use in the operating room.

摘要

目的

气流通过气管内导管会导致导管两端出现压力降。这种压力降会使气管内测得的气压与呼吸回路中测得的气压产生差异，进而在计算肺力学参数和设置呼吸机时导致误差。我们开发了一种根据气管内导管套囊压力估算气管压力的方法，并在临床试验中对该系统进行了测试。

方法

在呼吸机回路的Y形接头与气管内导管接头之间、气管内导管隆突端的气管处以及气管内导管套囊充气管路中设置压力测量端口。在吸气末和呼气末（无气流状态）测量气管压力和套囊压力，并用于确定套囊压力与气管压力之间的线性关系。利用估算的气管压力（Ptrach）和呼吸回路Y形接头处测得的压力（PY），得出气管内导管两端的压力降与通过导管的气流的函数关系。然后根据与气流相关的压力降和PY计算气管压力。该系统在手术室的6例患者和重症监护病房的6例患者中进行了测试。