Article Text

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
  1. John F Fraser1,
  2. Amy J Spooner1,
  3. Kimble R Dunster1,2,
  4. Chris M Anstey1,3,
  5. Amanda Corley1
  1. 1Critical Care Research Group, The Prince Charles Hospital and University of Queensland, Brisbane, Australia
  2. 2Biomedical Engineering and Medical Physics, Science and Engineering Faculty, Queensland University of Technology, Brisbane, Australia
  3. 3Intensive Care Unit, Nambour General Hospital, Nambour, Australia
  1. Correspondence to Amanda Corley, Critical Care Research Group, Level 5 CSB, The Prince Charles Hospital, Rode Rd, Chermside, Brisbane, QLD 4032, Australia; amanda.corley{at}


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 number ACTRN12613000028707.

  • Long Term Oxygen Therapy (LTOT)
  • COPD Exacerbations
  • Non invasive ventilation

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