BACKGROUND Automode is a feature on Servo ventilators that automatically switches between mandatory and spontaneous breaths. Spontaneous breaths suppress mandatory breaths until apnea. The period from the last spontaneous breath to the first mandatory breath is automatically adjusted by a calculated apnea time limit based on a maximum apnea time setting, the mandatory breathing frequency setting, and the spontaneous breath count. The purpose of this study was to validate the apnea time algorithm by using simulated mechanical ventilation. METHODS A Servo-u ventilator was connected to an ASL 5000 breathing simulator. Ventilator settings were the following: Automode (pressure control to pressure support), pressure control = 10 cm H2O; pressure support = 5 cm H2O; PEEP = 10 cm H2O; breathing frequency = 10, 12, 15, 20 breaths/min; maximum apnea time = 7 and 12 s. Simulator settings were the following: resistance = 10 cm H2O/L/s; compliance = 35 mL/cm H2O; flow trigger model: frequency = 20 breaths/min, trigger flow = 10 L/min, trigger duration = 800 ms. Flow waveforms were recorded, and the observed apnea time limit was compared with the calculated value. The outcome variable was error, defined as the difference between observed and calculated apnea times expressed as a percentage. RESULTS The observed apnea time limit ranged from 3 to 12 s, depending on the mandatory frequency and the spontaneous breath count. The average error ranged from -2 to 0%. CONCLUSIONS The measured apnea time for simulated ventilation settings was within 2% of calculated times. Automode allowed a spontaneous frequency lower than expected based on the mandatory frequency.

中文翻译：

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使用自动模式在通气期间自动调整呼吸暂停时间。

背景技术自动模式是伺服呼吸机的一项功能，可在强制呼吸和自主呼吸之间自动切换。自主呼吸抑制强制呼吸直至呼吸暂停。从最后一次自主呼吸到第一次强制呼吸的时间段是根据最大呼吸暂停时间设置、强制呼吸频率设置和自主呼吸计数计算出的呼吸暂停时间限制来自动调整的。本研究的目的是通过使用模拟机械通气来验证呼吸暂停时间算法。方法 将 Servo-u 呼吸机连接到 ASL 5000 呼吸模拟器。呼吸机设置如下：自动模式（压力控制到压力支持），压力控制 = 10 cm H2O；压力支持= 5 cm H2O；PEEP = 10 厘米水柱；呼吸频率=10、12、15、20次/分钟；最大呼吸暂停时间 = 7 和 12 秒。模拟器设置如下：阻力 = 10 cm H2O/L/s；顺应性 = 35 mL/cm H2O；流量触发模型：频率 = 20 次呼吸/分钟，触发流量 = 10 L/min，触发持续时间 = 800 ms。记录流量波形，并将观察到的呼吸暂停时间限制与计算值进行比较。结果变量是误差，定义为观察到的呼吸暂停时间与计算的呼吸暂停时间之间的差异，以百分比表示。结果观察到的呼吸暂停时间限制范围为 3 至 12 秒，具体取决于强制频率和自主呼吸计数。平均误差范围为-2% 至0%。结论 模拟通气设置的测量呼吸暂停时间在计算时间的 2% 以内。自动模式允许自发频率低于基于强制频率的预期。