HFT Nasal Cannula 临床研究(3)

年1月至2007年1月国际市场上的Vapotherm仪器全部召回。下文中将就此问题详细讨论。

Following the withdrawal of Vapotherm from the market, there were widespread anecdotal reports of individual neonatal and pediatric centers putting together their own systems for delivery of HHFNC using the basic components of a humidifier, respiratory circuit, adapter, and nasal cannula. The efficacy of such systems and the safety of this practice are highly questionable, especially given the relative lack of evidence of efficacy and safety for even the approved products, as noted later in this review. As such, this practice is not recommended. Subsequently, Fisher & Paykel Healthcare (Auckland, New Zealand) released the RT329 Infant Oxygen Delivery System designed to deliver humidified gas (37°C, 44 mg/L) via nasal cannula at flow rates between 0.3 and 8 L/min.This system is marketed in tandem with the FDA-approved Fisher & Paykel (F&P) MR850 humidifier. Given the apparent growing popularity of HHFNC use, it is likely that additional similar products will be released in the market in the relatively near future. 随着市场上的Vapotherm被召回，一些轶事报道关于一些私人儿科中心将他们自己的设备组合起来，利用加湿器、呼吸管道、适配器和鼻

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套管等基础部件来组装使用HHFNC疗法。这种组装系统的有效性和安全性值得高度怀疑，尤其已被认证的产品都出现无法证明其有效性和安全性，这个问题我们在后面会谈到。同样，这种设备的应用不被推荐。随后，Fisher & Paykel Healthcare（奥克兰，新西兰）发布经鼻套管流速率在0.3 L/min和 8 L/min之间提供增湿气体（37°C, 44 mg/L）的 RT329婴儿供氧系统。7此系统需同通过FDA认证的(F&P) MR850增湿器配套使用。鉴于HHFNC越来越受到大众青睐，很可能在不久的将来一些类似的产品会出现在市场上

Although differences exist in the specifics of the Vapotherm and F&P systems, they, and presumably most of the custom-built center-specific devices previously mentioned, share the following basic design attributes:

虽然Vapotherm和F&P系统在一些细节上有所区别，还有之前提及的个人制定、儿科中心特有的仪器，它们的设计都遵循以下属性特征：

1 A humidifier to effectively warm and humidify respiratory gases.

1.通过加湿器有效的提供增温增湿的呼吸气

2 A respiratory circuit with a means to maintain the temperature—and, by extension, the humidity, thereby preventing excessive precipitation or “rainout”—of the delivered gas until the distal end of the circuit. Vapotherm achieves this by means of a sleeve of recirculated warmed water encasing the delivery tube, and the F&P RT329 by means of a

heated wire coil that extends to the end of the circuit. 2.呼吸环道和一种维持已传送气体温度的工具---相关的还有湿度，以防止沉淀物过量或“雨洗效应”---直到环道末端。Vapotherm通过循环暖水套包住传输管来实现这一功能，F&P RT329通过加热延伸至环道末端的线圈来实现这一功能。

3 A nasal cannula with adapter that connects to the delivery circuit. Of note, the cannula design is such that there is little or no excess tubing between the end of the delivery circuit and the actual nasal prongs, thereby minimizing further any potential for gas cooling and precipitation.

3.鼻套管配合适配器连接到输气环路。值得注意的是，套管的设计长度几乎不会超过传输环道末端到鼻塞之间，因此能最大程度上避免气体冷却和沉淀物的产生。

HHFNC therapy is provided by delivering high-flow gases (in the ranges recommended by the manufacturers, generally between 2 and 8 L/min) via the humidifier and supplied circuit to the nasal cannula that has been secured to the face with the cannula prongs in the nares. Although no uniformly accepted guidelines exist, cannula prongs should be of an external diameter smaller than the internal diameter of the nares in order to prevent an occlusive seal between prongs and nares that might predispose

to excessive airway pressure generation. Gas flow rate is adjusted according to clinical response, generally being increased for increasing respiratory distress or oxygen requirement and decreased for improving respiratory distress or decreasing oxygen requirement.

HHFNC疗法提供高流速气体（厂商推荐通常在2 L/min和 8 L/min之间）经增湿器和可用环道安全的输送到鼻孔里的鼻插管。尽管这些操作指南并没有被一致认同，但是套管塞外径应小于鼻孔内径，这是为了防止堵塞封闭鼻塞和鼻孔而可能产生导气管压力过大。气流速根据临床反应来调节，通常在呼吸窘迫和供氧需要增多时气流速增大，呼吸窘迫改善和供养需求减少时气流速减小。

The exact mechanism of action of HHFNC remains to be elucidated. Aside from the basic concept of being able to provide humidified respiratory gases and an increased fractional inspired oxygen concentration, it has been speculated that HHFNC may work by, among other mechanisms, providing airway pressure, improving mucosal perfusion, or stimulation of respiratory drive.

HHFNC精准的作用机制有待说明。除能够提供基本的增湿呼吸气和增加部分氧气浓度以外，据推测HHFNC在其他机制中可提供气道压力、改善粘膜灌注或刺激吸气机制。