X3.2.1 Humidified nasal high flow therapy (hNHF)

Humidified nasal high flow therapy (hNHF) delivering flows of up to 60 L/minute has been used successfully for the management of acute hypoxaemic respiratory failure, while in acute exacerbations of COPD associated with hypercapnia and acidemia, NIV is accepted as standard of care (see below).

In a multi-centre Italian study of hNHF, (Optiflow and MR850 or Airvo) patients (n=80) with mild-moderate AECOPD and hypercapnia (PaCO2> 55mmHg, pH 7.25-7.35) before support were randomised to receive NIV or hNHF, with oxygen titrated to oxygen saturations of 88-92%. hNHF was statistically non-inferior to NIV as initial ventilatory support in reducing PaCO2 at 2 hrs (-6.8mmHg HFNT + 8.7, v -9.5 mmHg +8.5), p=0.4, considering a non- inferiority margin of 10 mmHg. However, by 6 hours 32% of patients in hNHF group had switched to NIV due to worsening or no improvement of respiratory failure; n=1 due to intolerance, while from the NIV group only one patient switched to hNHF due to intolerance and one to invasive ventilation. The authors of this study concluded that further trials with a superiority design examining patient related outcome measures are needed. NIV remains standard of care at present as it has been consistently shown to reduce mortality (Cortegiani 2020) [evidence level I].