在Bench模型中模拟未插管呼吸暂停患者梗阻气道的通气策略

背景Smart Bag MO是一种设计用于成人的流量限制型球囊面罩装置，它可减少在无气道保护的情况下发生胃反流的风险。其在严重气道梗阻时的应用特性尚不明确。方法建立Bench模型以模拟无气道保护情况下发生呼吸暂停的患者，分别使用流量限制型球囊装置和标准球囊装置通气。测定并对比两者在气道阻力为4、10、20cmH2O·L-1·S-1时的呼吸力学和潮气量。结果使用流量限制型球囊装置较标准球囊装置能延长吸气时间。流量限制型球囊装置和标准球囊装置在模拟无气道梗阻组中肺潮气量分别为750±70ml和780±30ml（无统计学差异）；模拟中度气道梗阻组中肺潮气量分别为800±70ml和850±20ml（无统计学差异）；模拟严重气道梗阻组中肺潮气量分别为210±20ml和170±10ml（P〈0．01）。流量限制球囊装置和标准球囊装置在模拟无气道梗阻组中气道峰压分别为15±2cmH2O和22±4cmH2O（P〈0．01）；模拟中度气道梗阻组中气道峰压分别为22±1cmH2O和39±7cmH，O（P〈0．01）；模拟严重气道梗阻组中气道峰压分别为26±1cmH，O和61±3cmH，O（P〈0．01）。流量限制球囊装置和标准球囊装置在模拟无气道梗阻组中的胃胀气速率为0ml／min；模拟中度气道梗阻组中速率分别为0ml／min和200±20ml／min（P〈0．01）；模拟严重气道梗阻组中速率分别为0ml／min和1240±50ml／min（P〈0．01）。结论在模拟严重气道梗阻组中，与标准球囊装置相比，流量限制型球囊装置能延长吸气时间、增大潮气量、降低气道压并能避免胃胀气的发生。

BACKGROUND： The Smart Bag MO is an adult flow-limited bag-valve device designed to reduce the risk of stomach inflation in an unprotected airway. Its properties in severe airway obstruction are as yet unknown. METHODS： In a bench model, we evaluated respiratory mechanics and delivered tidal volumes although ventilating at airway resistances of 4, 10, and 20 cm H2O·L-1·S-1 once with a flow-limited bag-valve device and once with a standard bag-valve device to simulate a respiratory arrest patient with an unprotected airway. RESULTS： Inspiratory times were always longer with the flowlimited bag-valve device than with the standard bag-valve device. Lung tidal volume in the simulated unobstructed airway was 750 ± 70 ml using the flow-limited bag-valve device versus 780 ±30 ml using the standard bag-valve device （n.s.）; in the simulated medium obstructed airway it was 800 ± 70 versus 850 ±20 ml （n.s.）, and in the simulated severely obstructed airway it was 210 ± 20 versus 170 ± 10 ml （P 〈0. 01 ）. Peak airway pressure in the simulated unobstructed airway was 15 ± 2 cm H2O using the flow-limited bag-valve device versus 22 ±4 cm H2O using the standard bag-valve device （P 〈 0. 01 ）; in the simulated medium obstructed airway it was 22 ± 1 versus 39 ± 7 cm H20 （P 〈 0. 01 ）, and in the simulated severely obstructed airway it was 26 ± 1 versus 61 ± 3 cm H20 （P 〈 0.01 ）. Stomach inflation in the simulated unobstructed airway was 0 ml/min using both bag-valve devices; in the simulated medium obstructed airway it was 0 ml/min for the flow-limited bag-valve device versus 200 ±20 ml/min for the standard bag-valve device （P 〈 0. 01 ）, and in the simulated severely obstructed airway it was 0 versus 1240 ±50 ml/min （P 〈 0.01 ）. CONCLUSION： In a simulated severely obstructed unprotected airway, the use of a flow-limited bag-valve device resulted in longer inspiratory times, higher tidal volumes, lower inspiratory pressures, and no stomach inflation compared with a standard bag-valve device.