BACKGROUND Airway pressure is usually measured by sensors placed in the ventilator or on the ventilator side of the endotracheal tube (ETT), at the Y-piece. These remote measurements serve as a surrogate for the tracheal or alveolar pressure. Tracheal pressure can only be predicted correctly by using a model that incorporates the pressure at the remote location, the flow through the ETT, and the resistance of the ETT if the latter is a predictable function of Y-piece flow. However, this is not consistently appropriate, and accuracy of prediction is hampered. METHODS This in vitro study systematically examined the ventilator pressure in dependence of compliance of the respiratory system (CRS), inspiratory time, and expiratory time during pressure-controlled ventilation by using a small intratracheal pressure sensor and a mechanical lung simulator. Pressures were measured simultaneously at the ventilator outlet, at the Y-piece, and in the trachea during pressure-controlled ventilation with a peak inspiratory pressure of 20 cm H2O and a PEEP of 5 cm H2O while changing CRS (10, 30, 60, 90, and 100 mL/cm H2O) and varying inspiratory time and expiratory time. RESULTS Tracheal pressures were always lower (maximum 8 cm H2O during inspiration) or higher (maximum 4 cm H2O during expiration) than the pressures measured proximal to the ETT if zero-flow conditions were not achieved at the end of the breathing cycles. CONCLUSIONS Dependent on CRS and the breathing cycle, tracheal pressures deviated from those measured proximal to the ETT under non-zero-flow conditions. Intratracheal pressure and pressure curve dynamics can differ greatly from the ventilator pressure, depending on the ventilator setting and the CRS. The small pressure sensor may be used as a measurement method of tracheal pressure via integration onto an ETT.

中文翻译：

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压力控制通气期间近端和气管气道压力的比较。

背景技术气道压力通常由放置在呼吸机中或位于气管插管(ETT)的呼吸机侧的Y形件处的传感器来测量。这些远程测量可以替代气管或肺泡压力。气管压力只能通过使用包含远程位置压力、通过 ETT 的流量以及 ETT 阻力（如果后者是 Y 形件流量的可预测函数）的模型来正确预测。然而，这并不总是合适的，并且预测的准确性受到影响。方法 这项体外研究通过使用小型气管内压力传感器和机械肺模拟器，系统地检查了压力控制通气期间呼吸机压力与呼吸系统顺应性 (CRS)、吸气时间和呼气时间的关系。在压力控制通气期间，同时测量呼吸机出口、Y 形件和气管内的压力，吸气峰值压力为 20 cm H2O，PEEP 为 5 cm H2O，同时更改 CRS（10、30、60、 90 和 100 mL/cm H2O）以及不同的吸气时间和呼气时间。结果 如果在呼吸周期结束时未达到零流量条件，则气管压力始终低于 ETT 附近测得的压力（吸气期间最大 8 cm H2O）或更高（呼气期间最大 4 cm H2O）。结论 根据 CRS 和呼吸周期，气管压力与非零流量条件下 ETT 附近测量的压力存在偏差。气管内压力和压力曲线动态可能与呼吸机压力有很大差异，具体取决于呼吸机设置和 CRS。通过集成到 ETT 上，小型压力传感器可用作气管压力的测量方法。