【罂粟摘要】低氧血症患者接受高流量鼻腔氧疗期间气道压力的测量：一项随机对照交叉试验
低氧血症患者接受高流量鼻腔氧疗期间气道压力的测量：一项随机对照交叉试验
贵州医科大学 高鸿教授课题组
翻译：佟睿 编辑：佟睿 审校：曹莹
人们认识到，高流量鼻腔氧疗可以防止气道管理过程中出现血氧饱和度降低。对自然呼吸患者的研究表明，鼻咽部的流速和气道正压几乎呈线性关系。气道正压被认为是解释高流量鼻腔氧疗效果的可能机制之一。然而，目前仍缺乏在全麻下高流量鼻腔氧疗对窒息成人气道所产生压力的数据。这项随机对照交叉试验调查了麻醉和瘫痪状态下呼吸暂停患者接受高流量鼻腔氧疗期间，不同流速所产生的气道压力，比较了闭口和张口时的压力。在麻醉药物和肌松药物诱导后，使用持续的颌骨推力使气道通畅。使用连接压力传感器的光纤导管测量右主支气管、气管中部和咽部的气道压力。每次测量都是根据闭口或张口和不同的流速随机进行的。试验纳入了20例接受择期手术的患者[均数(标准差)年龄为38(18)岁，体重指数为25.0(3.3)kg·m-2]，其中包含9名女性，患者ASA分级1级(35%)，2级(55%)，3级(10%)。闭口和流速增加时气道压力呈非线性增加，而张口时气道压力的增加可以忽略不计。气道压力保持在10cmH2O以下，即使闭嘴，流速也可达80L·min-1；导管位置对其无影响。这项研究表明，闭嘴时的气道压力增加取决于流速。张开嘴巴时，产生的压力可以忽略不计。这些数据质疑了气道正压作为呼吸暂停期间维持氧合重要机制的合理性。
Measurement of airway pressure during high-flow nasal therapy in apnoeic oxygenation: a randomised controlled crossover trial
Summary
It is recognised that high-flow nasal therapy can prevent desaturation during airway management. Studies in spontaneously breathing patients show an almost linear relationship between flow rate and positive airway pressure in the nasopharynx. Positive airway pressure has been suggested as one of the possible mechanisms explaining how high-flow nasal therapy works. However, data on pressures generated by high-flow nasal therapy in apnoeic adults under general anaesthesia are absent. This randomised controlled crossover trial investigated airway pressures generated by different flow rates during high-flow nasal therapy in anaesthetised and paralysed apnoeic patients, comparing pressures with closed and open mouths. Following induction of anaesthesia and neuromuscular blockade, a continuous jaw thrust was used to enable airway patency. Airway pressure was measured in the right main bronchus, the middle of the trachea and the pharynx, using a fibreoptically-placed catheter connected to a pressure transducer. Each measurement was randomised with respect to closed or open mouth and different flow rates. Twenty patients undergoing elective surgery were included (mean (SD) age 38 (18) years, BMI 25.0 (3.3) kg.m-2, nine women, ASA physical status 1 (35%), 2 (55%), 3 (10%). While closed mouths and increasing flow rates demonstrated non-linear increases in pressure, the pressure increase was negligible with an open mouth. Airway pressures remained below 10 cmH2O even with closed mouths and flow rates up to 80 l.min-1; they were not influenced by catheter position. This study shows an increase in airway pressures with closed mouths that depends on flow rate. The generated pressure is negligible with an open mouth. These data question positive airway pressure as an important mechanism for maintenance of oxygenation during apnoea.
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