Nasal high flow oxygen therapy in patients with COPD reduces respiratory rate and tissue carbon dioxide while increasing tidal and end-expiratory lung volumes: a randomised crossover trial

Abstract

Patients with COPD using long-term oxygen therapy (LTOT) over 15 h per day have improved outcomes. As inhalation of dry cold gas is detrimental to mucociliary clearance, humidified nasal high flow (NHF) oxygen may reduce frequency of exacerbations, while improving lung function and quality of life in this cohort. In this randomised crossover study, we assessed short-term physiological responses to NHF therapy in 30 males chronically treated with LTOT. LTOT (2–4 L/min) through nasal cannula was compared with NHF at 30 L/min from an AIRVO through an Optiflow nasal interface with entrained supplemental oxygen. Comparing NHF with LTOT: transcutaneous carbon dioxide (TcCO2) (43.3 vs 46.7 mm Hg, p<0.001), transcutaneous oxygen (TcO2) (97.1 vs 101.2 mm Hg, p=0.01), I:E ratio (0.75 vs 0.86, p=0.02) and respiratory rate (RR) (15.4 vs 19.2 bpm, p<0.001) were lower; and tidal volume (Vt) (0.50 vs 0.40, p=0.003) and end-expiratory lung volume (EELV) (174% vs 113%, p<0.001) were higher. EELV is expressed as relative change from baseline (%Δ). Subjective dyspnoea and interface comfort favoured LTOT. NHF decreased TcCO2, I:E ratio and RR, with a concurrent increase in EELV and Vt compared with LTOT. This demonstrates a potential mechanistic rationale behind the improved outcomes observed in long-term treatment with NHF in oxygen-dependent patients.Trial registration numberACTRN12613000028707.

Change in pulmonary mechanics and the effect on breathing pattern of high flow oxygen therapy in stable hypercapnic COPD

“…In patients with acute respiratory failure, compared with standard oxygen therapy, HFOT was repeatedly shown to improve comfort, avoid mucosal dryness and injury, and deliver a more reliable and stable fraction of inspired oxygen (FiO 2 ) 1. In a study performed in patients with stable COPD, HFOT reduced the arterial carbon dioxide oxygen tension (PaCO 2 ), increased end-expiratory and tidal volumes (VTs), and decreased respiratory rate 2. This makes HFOT an appealing form of treatment in patients with stable chronic hypercapnic respiratory failure (CHRF).…”

Nasal high flow therapy: a novel treatment rather than a more expensive oxygen device

“…These mechanisms lead to improved exercise performance with fewer symptoms and better gas exchange [85,88,89], improved lung mechanics [90] with less respiratory muscle load [91] and less work of breathing [86]. Since NIV is used currently as a treatment option in patients with COPD and chronic hypercapnia [92], it seems that NHF could be used instead of NIV in the least tolerant and compliant patients, or in association with NIV, to reduce mask-related side-effects [89].…”

Non-Invasive Ventilation as an Adjunct to Exercise Training in Chronic Ventilatory Failure: A Narrative Review

“…High-flow nasal cannula (HFNC) can deliver up to 60 L/min of reheated, humidified air via nasal cannula, with or without additional oxygen. Above a flow of 20 L/min, HFNC generates a positive pressure in the upper airways [74], inducing an increase in alveolar ventilation, improvements in gas exchange and a reduction in WOB in patients with COPD [75, 76]. Preliminary reports indicate that HFNC may improve exercise performance, oxygen saturation and perceived symptoms in patients with severe COPD and ventilatory limitation [77].…”