From the Department of Anesthesiology and Critical Care, Medical Center-University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany.
Anesth Analg. 2017 Oct;125(4):1246-1252. doi: 10.1213/ANE.0000000000001991.
Traditionally, mechanical ventilation is achieved via active lung inflation during inspiration and passive lung emptying during expiration. By contrast, the novel FLEX (FLow-controlled EXpiration) ventilator mode actively decreases the rate of lung emptying. We investigated whether FLEX can be used during intraoperative mechanical ventilation of lung-healthy patients.
In 30 adult patients scheduled for neurosurgical procedures, we studied respiratory system mechanics, regional ventilation, oxygenation, and hemodynamics during ventilation with and without FLEX at positive end-expiratory pressure (PEEP) of 5 and 7 cm H2O. The FLEX system was integrated into the expiratory limb and modified the expiratory flow profile by continuously changing expiratory resistance according to a computer-controlled algorithm.
Mean airway pressure increased with PEEP by 1.9 cm H2O and with FLEX by 1 cm H2O (all P < .001). The expiratory peak flow was 42% lower with FLEX than without FLEX (P < .001). FLEX caused significant shifts in aeration from ventral to the dorsal lung regions. Respiratory mechanics, end-tidal carbon dioxide partial pressure, oxygenation, and hemodynamics were independent from FLEX and PEEP. We observed no critical incidents or FLEX malfunctions in any measurement that would have required an intervention or termination of the FLEX mode.
FLEX can be used in lung-healthy patients who are mechanically ventilated during general anesthesia. FLEX improves the homogeneous distribution of ventilation in the lungs.
传统上，机械通气是通过吸气时主动肺充气和呼气时被动肺排空来实现的。相比之下，新型 FLEX（流量控制呼气）通气模式主动降低肺排空速度。我们研究了 FLEX 是否可用于肺健康患者的术中机械通气。
在 30 名计划接受神经外科手术的成年患者中，我们在呼气末正压通气（PEEP）为 5 和 7 cm H2O 时，研究了 FLEX 通气和无 FLEX 通气时的呼吸系统力学、区域通气、氧合和血液动力学。FLEX 系统集成到呼气支路上，并通过根据计算机控制算法连续改变呼气阻力来改变呼气流量曲线。
平均气道压力随 PEEP 增加 1.9 cm H2O，随 FLEX 增加 1 cm H2O（均 P <.001）。与无 FLEX 相比，FLEX 时呼气峰流速降低 42%（P <.001）。FLEX 导致通气从肺的腹侧向背侧区域显著转移。呼吸力学、呼气末二氧化碳分压、氧合和血液动力学与 FLEX 和 PEEP 无关。我们没有观察到任何会需要干预或终止 FLEX 模式的关键事件或 FLEX 故障。
FLEX 可用于在全身麻醉期间接受机械通气的肺健康患者。FLEX 可改善肺部通气的均匀分布。
