Sinha Ian P, McBride Antonia K S, Smith Rachel, Fernandes Ricardo M
From the Respiratory Unit, Alder Hey Children's Hospital, Liverpool, England.
From the Respiratory Unit, Alder Hey Children's Hospital, Liverpool, England.
Chest. 2015 Sep;148(3):810-823. doi: 10.1378/chest.14-1589.
Severe respiratory failure develops in some infants with bronchiolitis because of a complex pathophysiologic process involving increased airways resistance, alveolar atelectasis, muscle fatigue, and hypoxemia due to mismatch between ventilation and perfusion. Nasal CPAP and high-flow nasal cannula (HFNC) oxygen may improve the work of breathing and oxygenation. Although the mechanisms behind these noninvasive modalities of respiratory support are not well understood, they may help infants by way of distending pressure and delivery of high concentrations of warmed and humidified oxygen. Observational studies of varying quality have suggested that CPAP and HFNC may confer direct physiologic benefits to infants with bronchiolitis and that their use has reduced the need for intubation. No trials to our knowledge, however, have compared CPAP with HFNC in bronchiolitis. Two randomized trials compared CPAP with oxygen delivered by low-flow nasal cannula or face mask and found some improvements in blood gas results and some physiologic parameters, but these trials were unable to demonstrate a reduction in the need for intubation. Two trials evaluated HFNC in bronchiolitis (one comparing it with headbox oxygen, the other with nebulized hypertonic saline), with the results not seeming to suggest important clinical or physiologic benefits. In this article, we review the pathophysiology of respiratory failure in bronchiolitis, discuss these trials in detail, and consider how future research studies may be designed to best evaluate CPAP and HFNC in bronchiolitis.
一些患细支气管炎的婴儿会出现严重呼吸衰竭，这是由于复杂的病理生理过程所致，该过程涉及气道阻力增加、肺泡萎陷、肌肉疲劳以及因通气与灌注不匹配导致的低氧血症。鼻持续气道正压通气（CPAP）和高流量鼻导管（HFNC）吸氧可改善呼吸功和氧合。尽管这些无创呼吸支持方式背后的机制尚未完全明确，但它们可能通过扩张压力以及输送高浓度的温热湿化氧气来帮助婴儿。质量参差不齐的观察性研究表明，CPAP和HFNC可能给患细支气管炎的婴儿带来直接的生理益处，且其使用减少了插管需求。然而，据我们所知，尚无试验在细支气管炎中比较CPAP和HFNC。两项随机试验将CPAP与通过低流量鼻导管或面罩输送的氧气进行了比较，发现血气结果和一些生理参数有一定改善，但这些试验未能证明插管需求减少。两项试验评估了HFNC在细支气管炎中的应用（一项将其与头罩吸氧比较，另一项与雾化高渗盐水比较），结果似乎并未显示出重要的临床或生理益处。在本文中，我们回顾细支气管炎呼吸衰竭的病理生理学，详细讨论这些试验，并思考未来的研究可如何设计，以最佳地评估CPAP和HFNC在细支气管炎中的应用。
