Background

Non-invasive ventilation (NIV) is preferred as the initial ventilatory support to treat acute hypercapnic respiratory failure in patients with chronic obstructive pulmonary disease (COPD). High-flow nasal cannula (HFNC) may be an alternative method; however, the effects of HFNC in hypercapnic COPD are not well known. This preliminary study aimed at assessing the physiologic effects of HFNC at different flow rates in hypercapnic COPD and to compare it with NIV.

Methods

A prospective physiologic study enrolled 12 hypercapnic COPD patients who had initially required NIV, and were ventilated with HFNC at flow rates increasing from 10 to 50 L/min for 15 min in each step. The primary outcome was the effort to breathe estimated by a simplified esophageal pressure–time product (sPTP_es). The other studied variables were respiratory rate, oxygen saturation (SpO₂), and transcutaneous CO₂ pressure (PtcCO₂).

Results

Before NIV initiation, the median [interquartile range] pH was 7.36 [7.28–7.37] with a PaCO₂ of 51 [42–60] mmHg. sPTP_es per minute was significantly lower with HFNC at 30 L/min than 10 and 20 L/min (p < 0.001), and did not significantly differ with NIV (median inspiratory/expiratory positive airway pressure of 11 [10–12] and [5–5] cmH₂O, respectively). At 50 L/min, sPTPes per minute increased compared to 30 L/min half of the patients. Respiratory rate was lower (p = 0.003) and SpO₂ was higher (p = 0.028) with higher flows (30–50 L/min) compared to flow rate of 10 L/min and not different than with NIV. No significant differences in PtcCO₂ between NIV and HFNC at different flow rates were observed (p = 0.335).

Conclusions

Applying HFNC at 30 L/min for a short duration reduces inspiratory effort in comparison to 10 and 20 L/min, and resulted in similar effect than NIV delivered at modest levels of pressure support in hypercapnic COPD with mild to moderate exacerbation. Higher flow rates reduce respiratory rate but sometimes increase the effort to breathe. Using HFNC at 30 L/min in hypercapnic COPD patients should be further evaluated. Trial registration Thai Clinical Trials Registry, TCTR20160902001. Registered 31 August 2016, http://www.clinicaltrials.in.th/index.php?tp=regtrials&menu=trialsearch&smenu=fulltext&task=search&task2=view1&id=2008.

中文翻译：

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高流量鼻导管和无创通气对慢性阻塞性肺疾病高碳酸血症患者吸气努力的影响：初步研究

背景

优选使用无创通气（NIV）作为治疗慢性阻塞性肺疾病（COPD）患者的急性高碳酸血症性呼吸衰竭的初始通气支持。高流量鼻导管（HFNC）可能是一种替代方法；然而，HFNC在高碳酸血症COPD中的作用尚不清楚。这项初步研究旨在评估高碳酸血症性COPD患者不同流速下HFNC的生理效应，并将其与NIV进行比较。

方法

一项前瞻性生理学研究招募了12例最初需要NIV的高碳酸血症COPD患者，并以HFNC进行通气，每个步骤的流速从10 L / min增加至50 L / min，持续15分钟。主要结果是通过简化的食道压力-时间乘积（sPTP _es）估算的呼吸努力。其他研究的变量是呼吸率，血氧饱和度（SPO ₂），和经皮CO ₂压力（PtcCO ₂）。

结果

在开始NIV之前，中位[四分位间距] pH为7.36 [7.28-7.37]，PaCO ₂为51 [42-60] mmHg。HFNC在30 L / min时每分钟的sPTP _es显着低于10和20 L / min（p  <0.001），而与NIV则无显着差异（中位吸气/呼气正气道压力为11 [10–12]和[5–5] cmH ₂ O）。在50 L / min时，每分钟sPTPes增加，而一半的患者为30 L / min。与流量为10 L / min的流量相比，流量较高（30–50 L / min）的呼吸速率较低（p  = 0.003），SpO ₂较高（p  = 0.028），与NIV相同。PtcCO ₂无明显差异在不同流速下观察到NIV和HFNC之间的差值（p  = 0.335）。

结论

与10和20 L / min相比，短时间以30 L / min的频率应用HFNC可以减少吸气量，并且与轻度至中度加重的高碳酸血症COPD中适度压力支持下的NIV产生的效果相似。较高的流速会降低呼吸频率，但有时会增加呼吸强度。高碳酸血症COPD患者应以30 L / min的频率使用HFNC。试验注册泰国临床试验注册中心（TCTR20160902001）。注册于2016年8月31日，http://www.clinicaltrials.in.th/index.php?tp=regtrials&menu=trialsearch&smenu=fulltext&task=search&task2=view1&id=2008。