HFT Nasal Cannula 临床研究(5)

for apnea of prematurity using ventilator-generated conventional CPAP or nasal cannula at flow rates of up to 2.5 L/min.The study found that the nasal cannula flow required to generate comparable positive distending pressure varied with patient weight according to the formula:

考虑到缺乏任何同行评审刊审评HHFNC和产生的压力，回顾和推断无湿度低流速鼻套管的两个实验数据是有意义的。第一个被观测的食道内压和胸腹运动是在13个早产新生儿中由外直径为0.2 或 0.3 cm的鼻套管传递0.5–2 L/min气流产生的。13较小的鼻套管在任何流速下都没有产生气压或调节胸腹运动状况，然而，外直径0.3cm的鼻套管根据气流量的增加和胸腹运动异步性减小而传递内腔扩张正压。产生的平均压力为2 L/min流速率下9.8 cm氧气。我们推断出鼻套管气流能传递内腔扩张正压并能极大的改变呼吸模式，这引起了我们对新生儿日常输氧不加区分的治疗使用、尺寸选择和鼻套管安全性能的极大关心。第二个实验针对40名早产儿利用CPAP治疗早产导致的呼吸暂停，传统的CPAP呼吸机或鼻套管流速率达到2.5 L/min。14研究表明按

照以下公式，随着患者体重的不同鼻套管流量需产生相当的扩张正压：

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Flow (L/min) = 0.92 + (0.68 × Weight [in kg]) 流速 (L/min) = 0.92 + (0.68 × 体重 [kg])

The difficulty in determining what, if any, pressure might be produced by HHFNC in different circumstances is underscored

by the variable findings in these studies. Arguably the most relevant would be the latter 2 studies of nonhumidified low-flow nasal cannula, given the study populations and the details available from the full publications. Both these studies show that at relatively modest nonhumidified nasal cannula flow rates of 1.5—2 L/min, pressures of approximately 6—10 cm H2O can be generated in even moderately preterm neonates. In attempting to extrapolate these data to HHFNC, it is interesting to note that a study of healthy adult volunteers on nasal mask CPAP found that in the presence of a significant mouth leak with resultant unidirectional air flow, effective heated humidification substantially decreased resistance across the nasal airway.This would result in more effective transmission of generated CPAP to the distal patient airway. Similarly, it suggests that even higher pressures than those documented in the non-humidified low-flow nasal cannula studies might be delivered to the distal airway with effective heated humidification using the Vapotherm or other HHFNC device.

如果说这些实验中有困难的话，就是HHFNC在不同的环境下产生的压力结果是不一样的。相关可被论证的要算后面的2个考虑到患者类型和所有出版物中可利用信息的无增湿流速鼻套管实验。这些实验都表

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明相对适度的无增湿鼻套管流速为1.5—2 L/min时，适度早产儿中产生的气压约为6—10 cm氧气。为了推断出HHFNC这些数据，值得一提的是一项关于健康的成人志愿者使用鼻罩式CPAP的研究结果表明，在单向气流合成口腔漏气的情况下通过鼻腔导气管很大程度上有效的减少了加温加湿阻力。这会导致CPAP向患者导气管末端产生更有效的传送。同样的，这一研究指出，比文件记录中无增湿低流速鼻套管研究更大的气压可能利用Vapotherm或其他HHFNC设备向导气管末端传递有效的加温加湿气体。

As to the possible physiological and/or clinical effects of any generated airway pressure when using nasal cannula flow, it has been demonstrated that each of variable-flow CPAP, continuous-flow CPAP, and CPAP provided via adapted nasal cannula produce measurable changes in lung volume at set CPAP pressures of 4, 6, and 8 cm H2O in neonates.It should be noted that the adapted nasal cannula in this study was connected to a ventilator set to deliver CPAP with a continuous gas flow of 6 L/min, rather than the typical setup for HHFNC in which flow is adjusted and no airway pressure is set or monitored. In addition, although the adapted nasal cannula was able to recruit lung volume, it did so at the cost of increased respiratory effort and oxygen requirement when compared with

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the variable-flow and continuous-flow CPAP. As such, the potential would seem to exist for clinically relevant physiologic effects secondary to airway pressure generation produced by HHFNC use. Depending on the degree of such effects, they might be helpful, harmful, or of little or no consequence clinically.

至于使用鼻套管流速产生的导气管压力对于生理学和/或临床的效果，我们需论证在新生儿中，经合适的鼻套管分别在变速流CPAP、持续流CPAP和CPAP情况下，设置CPAP压力值为4 cm, 6 cm,和8 cm氧气时肺容量的变化。值得注意的是本实验中的合适的鼻套管是与呼吸机连接，传递6 L/min的连续气流CPAP，而非特别靠调节流量和设置无气道压力的HHFNC。另外，虽然合适的鼻套管能够补充恢复肺活量，但这是以比较变速流和持续流CPAP时增强的呼吸运作和供氧需求为代价的。就其本身而论，与临床相关的生理性效果似乎存在的可能性次于使用HHFNC所产生的气道压。根据这种效果的程度不同，它们可能是有益的、有害的或只有很少（没有）临床研究价值。

Although the latter study sheds some light on the potential effects of nasal cannula flow on lung recruitment, there is no published evidence at this stage to answer the question directly whether or not HHFNC is able to increase and/or maintain FRC, as has been shown to be the primary effect of CPAP.

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Similarly, the secondary physiologic benefits of CPAP have also not been specifically demonstrated in any studies of HHFNC. 即使后一个实验对鼻套管流速恢复肺功能的潜在效果有一定的启示作用，但现阶段还没有官方论证直接回答HHFNC是否能增加和/或维持FRC，就像展示CPAP的初始效应一样。

IS HHFNC THERAPY A FORM OF CPAP?: CONCLUSIONS HHFNC是 CPAP的一种表现形式吗？：结论

It seems clear that humidified high-flow gas via nasal cannula does indeed produce positive airway pressure, and that this pressure is:

显然，增湿高流速气体经鼻套管的确产生气道正压通气，这种气压是： . variable (and may range from trivial to excessive); . 可变的（可能量范围从极少到超多） . relatively unpredictable; . 相对的不可预知 . unregulated; . 不规范的

. related to flow, prong size, and patient size, and likely to effective heated humidification; and …… 此处隐藏：3017字，全部文档内容请下载后查看。喜欢就下载吧 ……