Shamohammadi Hossein, Weaver Liam, Saffaran Sina, Tonelli Roberto, Laviola Marianna, Laffey John G, Camporota Luigi, Scott Timothy E, Hardman Jonathan G, Clini Enrico, Bates Declan G
School of Engineering, University of Warwick, Coventry, CV4 7AL, UK.
Respiratory Diseases Unit, Department of Medical and Surgical Sciences, University Hospital of Modena, University of Modena and Reggio Emilia, Modena, Italy.
Respir Res. 2025 Jan 8;26(1):9. doi: 10.1186/s12931-025-03096-x.
High flow nasal cannula (HFNC) therapy is an increasingly popular mode of non-invasive respiratory support for the treatment of patients with acute hypoxemic respiratory failure (AHRF). Previous experimental studies in healthy subjects have established that HFNC generates flow-dependent positive airway pressures, but no data is available on the levels of mean airway pressure (mP) or positive end-expiratory pressure (PEEP) generated by HFNC therapy in AHRF patients. We aimed to estimate the airway pressures generated by HFNC at different flow rates in patients with AHRF, whose functional lung volume may be significantly reduced compared to healthy subjects due to alveolar consolidation and/or collapse.
We developed a high-fidelity mechanistic computational model of the cardiopulmonary system during HFNC therapy using data from healthy subjects, and then measured the mP and PEEP levels produced when different amounts of alveolar consolidation/collapse were incorporated into the model.
When calibrated to represent normal lung physiology in healthy subjects, our model recapitulates the airway pressures produced by HFNC at different flow rates in healthy volunteers who were breathing normally, with their mouths closed or open. When different amounts of alveolar consolidation/collapse are implemented in the model to reflect the pathophysiology of AHRF, the mP and PEEP produced by HFNC at all flow rates increase as the functional lung volume decreases (up to a mP of 11.53 and a PEEP of 11.41 cmHO at 60 L/min with the mouth closed when 50% of the model's alveolar compartments are non-aerated). When the model was matched to individual patient data from a cohort of 58 patients with AHRF receiving HFNC at 60 L/min, the mean (standard deviation) of the mP / PEEP produced by HFNC in the models of these patients was 8.56 (1.50) / 8.92 (1.49) cmHO with mouths closed, and 1.73 (0.31) / 1.36 (0.36) cmHO with mouths open.
Our results suggest that the airway pressures produced by HFNC in patients with AHRF could be higher than is currently assumed based on experimental data from healthy subjects, particularly in patients whose mouths remain closed. Higher levels of PEEP could be beneficial if they lead to alveolar recruitment and improved lung compliance, but could cause alveolar overdistension if they do not, motivating the close monitoring of the effects of HFNC on lung mechanics. Further clinical studies are warranted to directly measure the airway pressures produced by HFNC in patients with different severities of AHRF.
高流量鼻导管（HFNC）治疗是一种越来越受欢迎的无创呼吸支持方式，用于治疗急性低氧性呼吸衰竭（AHRF）患者。先前在健康受试者中进行的实验研究已证实，HFNC会产生流量依赖性气道正压，但目前尚无关于HFNC治疗AHRF患者时产生的平均气道压（mP）或呼气末正压（PEEP）水平的数据。我们旨在评估AHRF患者在不同流速下HFNC产生的气道压力，由于肺泡实变和/或萎陷，与健康受试者相比，这些患者的功能肺容积可能会显著降低。
我们利用来自健康受试者的数据，开发了一个HFNC治疗期间心肺系统的高保真机械计算模型，然后测量在模型中纳入不同程度的肺泡实变/萎陷时产生的mP和PEEP水平。
当校准以代表健康受试者的正常肺生理时，我们的模型再现了HFNC在不同流速下对正常呼吸、口闭或口开的健康志愿者产生的气道压力。当在模型中实施不同程度的肺泡实变/萎陷以反映AHRF的病理生理学时，随着功能肺容积的减小，HFNC在所有流速下产生的mP和PEEP都会增加（当模型中50%的肺泡腔未通气时，口闭状态下60 L/min时mP可达11.53，PEEP可达11.41 cmH₂O）。当模型与一组58例接受60 L/min HFNC治疗的AHRF患者的个体数据匹配时，这些患者模型中HFNC产生的mP / PEEP的平均值（标准差）口闭时为8.56（1.50）/ 8.92（1.49）cmH₂O，口开时为1.73（0.31）/ 1.36（0.36）cmH₂O。
我们的结果表明，AHRF患者中HFNC产生的气道压力可能高于目前基于健康受试者实验数据所假设的水平，尤其是口闭的患者。如果较高水平的PEEP能导致肺泡复张并改善肺顺应性则可能有益，但如果不能则可能导致肺泡过度扩张，这促使密切监测HFNC对肺力学的影响。有必要进行进一步的临床研究，以直接测量不同严重程度AHRF患者中HFNC产生的气道压力。
