Data_Sheet_1_Nasal High Flow at 25 L/min or Expiratory Resistive Load Do Not Improve Regional Lung Function in Patients With COPD: A Functional CT Imaging Study.docx

BackgroundNasal high flow (NHF) is a non-invasive breathing therapy that is based on the delivery via a large-caliber nasal cannula of heated and humidified air at flow rates that exceed peak inspiratory flow. It is thought that positive airway pressure generated by NHF can help reduce gas trapping and improve regional lung ventilation. There are no data to confirm this hypothesis at flow rates applicable in stable chronic obstructive pulmonary disease (COPD) patients.
MethodsIn this study, we used non-rigid registration of computed tomography (CT) images acquired at maximal expiration and inspiration to compute regional lung attenuation changes (ΔHU), and lung displacement (LD), indices of regional lung ventilation. Parametric response maps (Galban et al., 2012) were also computed in each experimental condition. Eight COPD patients were assessed at baseline (BL) and after 5 min of NHF and expiratory resistive loading (ERL).
ResultsΔHU was: BL (median, IQR): 85 (67.2, 102.8); NHF: 90.7 (57.4, 97.6); ERL: 74.6 (46.4, 89.6) HU (p = 0.531); and LD: 27.8 (22.3, 39.3); 17.6 (15.4, 27.9); and 20.4 (16.6, 23.6) mm (p = 0.120) in the 3 conditions, respectively. No significant difference in trapping was observed. Respiratory rate significantly decreased with both treatments [BL: 17.3 (16.4, 18.9); NHF: 13.7; ERL: 11.4 (9.6, 13.2) bpm; and p < 0.001].
ConclusionNeither NHF at 25 L/min nor ERL significantly improved the regional lung ventilation of stable COPD patients with gas trapping, based on functional lung CT imaging. Further study including more subjects is needed to assess the potential effect of NHF on regional lung function at higher flow rates.
Clinical Trial Registrationwww.clinicaltrials.gov/under, identifier NCT03821311.

背景：鼻高流量通气（Nasal high flow, NHF）是一种无创呼吸治疗技术，其通过大口径鼻导管输送流速高于吸气峰值流量的加温湿化气体。目前学界认为，鼻高流量通气产生的气道正压可帮助减少气体陷闭并改善区域肺通气功能，但针对稳定期慢性阻塞性肺疾病（chronic obstructive pulmonary disease, COPD）患者适用的流速范围内，尚无相关数据证实这一假说。

方法：本研究对最大呼气相与吸气相采集的计算机断层扫描（computed tomography, CT）图像开展非刚性配准，计算区域肺衰减变化值（ΔHU）与肺位移量（lung displacement, LD）这两项区域肺通气指标。同时在各实验条件下计算参数响应图（Galban等，2012）。本研究纳入8名COPD患者，分别在基线状态（BL）、鼻高流量通气治疗5分钟后以及呼气阻力负荷（expiratory resistive loading, ERL）干预后进行评估。

结果：三种实验条件下的区域肺衰减变化值（ΔHU）分别为：基线状态[中位数，四分位距（IQR）]：85（67.2, 102.8）；鼻高流量通气组：90.7（57.4, 97.6）；呼气阻力负荷组：74.6（46.4, 89.6）亨斯菲尔德单位（HU），组间比较p=0.531。肺位移量（LD）分别为27.8（22.3, 39.3）、17.6（15.4, 27.9）和20.4（16.6, 23.6）毫米，组间比较p=0.120。未观察到气体陷闭情况存在显著组间差异。两种干预方式均使呼吸频率显著降低[基线状态：17.3（16.4, 18.9）；鼻高流量通气组：13.7；呼气阻力负荷组：11.4（9.6, 13.2）次/分钟；p < 0.001]。

结论：基于功能性肺CT成像结果，无论是25L/min流速的鼻高流量通气还是呼气阻力负荷干预，均未显著改善伴气体陷闭的稳定期COPD患者的区域肺通气功能。未来需纳入更多受试者开展进一步研究，以评估高流速下鼻高流量通气对区域肺功能的潜在影响。

临床试验注册：本研究已在www.clinicaltrials.gov注册，注册号为NCT03821311。