持续雾化吸入气流导致呼吸机无效触发的?呼吸力学原因分析
Reason analysis of ineffective triggering caused by a continuous nebulization airflow in mechanical ventilation
目的 以呼吸力学方法分析雾化吸入导致无效触发的原因.方法 将模拟肺连接PB840呼吸机,同时回路中接入氧气驱动雾化器,在雾化关闭或打开时分别在不同流量触发模式〔流量触发灵敏度(VTrig)?3?L/min及5?L/min〕与压力触发模式〔压力触发灵敏度(PTrig)2?cmH2O及4?cmH2O,1?cmH2O=0.098?kPa〕下,手动牵拉模肺触发一次有效送气.通过调节呼吸机显示屏内的曲线幅度,观察不同触发情况下流量与回路压力的对应关系及特点.应用呼吸力学方法分析达到有效触发所需要的最低肺泡内压(Pa)及Pa在触发期间的变化幅度.结果 ①?流量触发模式下,无雾化时Pa需要从呼气末正压(PEEP)或内源性呼气末正压(PEEPi)降至"PEEP-VTrigR"水平,式中R为气道阻力,此时跨度为"VTrigR"或"PEEPi-PEEP+VTrigR";有雾化时Pa需要从PEEP或PEEPi降至"PEEP-(VTrig+N)R"水平,式中N为雾化气流流量,此时跨度为"(VTrig+N)R"或"PEEPi-PEEP+(VTrig+N)R".②?压力触发模式下,无雾化时Pa需要从PEEP或PEEPi降至"PEEP-PTrig-1R"水平,此时跨度为"PTrig+1R"或"PEEPi-PEEP+PTrig+1R";有雾化时Pa需要从PEEP或PEEPi降至"PEEP-PTrig-(N+1)R"水平,此时跨度为"PTrig+(N+1)R"或"PEEPi-PEEP+PTrig+(N+1)R".结论雾化吸入气流增加了机械通气时的吸气触发难度,PEEPi的存在也加重了吸气触发难度.
更多Objective? To? analyze? the? ineffective? triggering? caused? by? nebulization? in? the? way? of?respiratory?mechanics.? Methods? A?test-lung?and?an?oxygen-driven?jet?nebulizer?were?connected?to?the?circuit?in?a?PB840?ventilator.?The?test-lung?was?pulled?outwards?in?manual?way?till?an?inspiration?was?effectively?triggered?separately?in?different?flow-trigger?modes?[flow-trigger?sensitivity?(VTrig)?3?L/min?and?5?L/min]?and?pressure-trigger?modes?[pressure-trigger?sensitivity?(PTrig)?2?cmH2O?and?4?cmH2O,?1?cmH2O?=?0.098?kPa]?with?the?nebulizer?being?closed?and?opened?in?turn.?The?corresponding?relationship?and?characteristics?between?the?flow?and?pressure?in?the?circuit?under?different?triggering?conditions?were?observed?by?adjusting?the?curve?amplitude?in?the?screen.?The?minimum?alveolar?pressure?(Pa)?which?could?cause?an?effective?triggering?and?the?variation?span?of?Pa?during?the?triggering?period?were?analyzed?in?respiratory?mechanics.? Results? ①?In?flow-trigger?mode:?Pa?was?pulled?down? from? positive? end-expiratory? pressure? (PEEP)? or? intrinsic? positive? end-expiratory? pressure? (PEEPi)? to?"PEEP-VTrigR"?(R?meant?airway?resistance)?without?nebulization,?and?the?span?of?Pa?was?"VTrigR"?or?"PEEPi-PEEP+VTrigR".?Pa?was?pulled?down?from?PEEP?or?PEEPi?to?"PEEP-(VTrig+N)?R"?(N?meant?nebulization?airflow)?with?nebulization,?and?the?span?of?Pa?was?"(VTrig+N)?R"?or?"PEEPi-PEEP+(VTrig+N)?R".?②?In?pressure-trigger?mode:?Pa?was?pulled?down?from?PEEP?or?PEEPi?to?"PEEP-PTrig-1R"?without?nebulization,?and?the?span?of?Pa?was?"PTrig+1R"?or?"PEEPi-PEEP+PTrig+1R".?Pa?was?pulled?down?from?PEEP?or?PEEPi?to?"PEEP-PTrig-(N+1)?R"?with?nebulization,?and?the?span?of?Pa?was?"PTrig+(N+1)?R"?or?"PEEPi-PEEP+PTrig+(N+1)?R".? ?Conclusions? Nebulization?airflow?increases?the?difficulty?of?inspiratory?triggering?in?mechanical?ventilation.?PEEPi?makes?it?more?difficult.
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