无创正压通气时不同呼气触发灵敏度设置对呼气同步的影响

Effect on inspiratory cycling-off synchronization with different expiratory trigger sensitivity level during pressure-support ventilation： a lung model study

目的 观察无创正压通气时不同呼气触发灵敏度（ETS）设置对呼气同步的影响.方法 使用Series 1101机械肺模拟器（美国Hans Rudolph公司）分别模拟高气道阻力和低胸肺顺应性状态,对BiPAP Synchrony（美国Philips Respironics公司）和Flexo ST 30[美国Curative公司/凯迪泰（北京）医疗科技有限公司]两款呼吸机进行测试.双水平正压呼吸机以压力支持通气模式运行,参数为15cmH2O（1 cmH2O =0.098 kPa）的压力支持及5 cmH2O的呼气末正压,后备通气频率为10次/min.收集在泄漏量为24～ 28 L/min时的通气参数.结果 在高气道阻力模型时,BiPAP Synchrony和FlexoST 30两款呼吸机均呈现为呼气延迟切换,其中采用自动调节触发灵敏度（Auto-Trak）技术的BiPAPSynchrony呼吸机呼气延迟切换时间较短[（68.9±13.3）比（121.4±13.2） ms,P＜0.05].随着ETS水平的改变,Flexo ST 30的潮气量和吸气时间逐渐增大,呼气峰流量也随之增高.在低胸肺顺应性状态下,两款呼吸机的吸气峰流量和呼气峰流量均显著增高,且出现呼气过早切换现象,潮气量和吸气时间明显减小;Flexo ST 30的ETS水平为最低时,出现轻度呼气切换延迟,延迟时间为（64.3±15.3）ms.结论 不同型号呼吸机的呼气切换同步性能不同,调整ETS可减少呼气不同步的发生.AutoTrak技术有助于简化操作,对呼气同步的影响较小.

Objective To compare the inspiratory cycling-off synchronization with different expiratory trigger sensitivity （ETS） setting during noninvasive pressure support ventilation （PSV） under the conditions of system leak.Methods Ventilators were connected to a lung model （Hans Rudolph Series1101 simulator）.And its mechanics was set in two models of obstructive and restrictive ventilatory dysfunction.All ventilators were set at 15 cmH2O （1 cmH2O =0.098 kPa） pressure support and 5 cmH2O positive endexpiratory pressure （PEEP）.Tests were conducted at the level of air leaks （24-28 L/min）.Cycling delay time,tidal volume and airflow were collected.Results Compared with Curative Flexo ST 30 with the ETS setting at the most sensitive level,the use of digital Auto-TrakTM system （Respironics Synchrony） was associated with milder delay cycling （（68.9 ± 13.3） vs （121.4 ± 13.2） ms,P 〈 0.05） in obstructive condition.The tidal volume （VT）,inspiratory time （TI vent） and peak expiratory flow （PEF） increased after adjusting the ETS level.Premature cycling was detected in restrictive condition with both ventilators.Peak inspiratory flow （PIF） and PEF significantly increased as VT and TI vent decreased.Delay cycling （（64.3 ± 15.3） ms） was present in Flexo ST 30 when ETS was at most insensitive level.Conclusions There are significant differences in performances and cycling-off in obstructive and restrictive conditions among 2 bilevel ventilators.And it may be due to the software of algorithm.Modifications of ETS can affect the ventilatory parameters to improve patient-ventilator synchrony in the presence of air leaks.The Auto-Trak system during PSV show similar results and better synchronzation compared with conventional adjustments.