High-flow therapy: beyond gas exchange!

High-flow therapy (HFT) is increasingly being used in the chronic setting for patients with COPD. In this workshop, our guest speaker Mathieu Delorme outlines how to best use HFT, as well as describing the potential benefits in patients with COPD and chronic respiratory failure.

In patients with chronic respiratory failure, HFT improves mucociliary clearance,¹ improves rehabilitation outcomes,² reduces hypercapnia,³ and reduces exacerbation rates.^4,5 Interestingly, the physiological and clinical benefits of HFT may be observed without any oxygen requirement, but rather are due to the warmed and humidified air. Mathieu Delorme describes how HFT reduces dead space ventilation at flows of greater than 20 L/min,⁶ leading to reduced work of breathing and reduced CO₂ retention.⁷ Mathieu Delorme describes how the humidification requirement is dependent on the flow rate, and there is no formal recommendation for the optimal hygrometry setting. Lower humidification settings have been shown to reduce patient comfort, yet settings must be adjusted to reach the optimal balance between safety and patient comfort. In addition, ambient temperature must be considered. Mathieu Delorme highlights how further research into the optimal HFT settings is required.  

In summary, home HFT provides benefits to patients with COPD and chronic respiratory failure and could be a particularly attractive option for patients who do not tolerate non-invasive ventilation.

References:

1. Hasani A et al. Domiciliary humidification improves lung mucociliary clearance in patients with bronchiectasis. Chron Respir Dis. 2008;5(2):81–86.
2. Bitos K et al. Effect of High-Flow Oxygen on Exercise Performance in COPD Patients. Randomized Trial. Front Med. 2021: doi.org/10.3389/fmed.2020.595450.
3. Bräunlich J et al. Nasal high-flow versus noninvasive ventilation in patients with chronic hypercapnic COPD. Int J Chron Obstruct Pulmon Dis. 2019;14:1411–1421.
4. Rea H et al. The clinical utility of long-term humidification therapy in chronic airway disease. Respir Med. 2010;104(4):525–533.
5. Storgaard LH et al. Long-term effects of oxygen-enriched high-flow nasal cannula treatment in COPD patients with chronic hypoxemic respiratory failure. Int J Chron Obstruct Pulmon Dis. 2018;13:1195–1205.
6. Delorme M et al. Physiologic Effects of High-Flow Nasal Cannula in Healthy Subjects. Respir Care. 2020;65(9):1346–1354.
7. Pisani L et al. Change in pulmonary mechanics and the effect on breathing pattern of high flow oxygen therapy in stable hypercapnic COPD. Thorax. 2017;72(4):373–375.