Nasal high-Flow (NHF) improves ventilation in patients with interstitial lung disease (ILD)

Introduction: Acute hypercapnic respiratory failure has a poor prognosis in patients with interstitial lung disease (ILD). Recent data demonstrated a positive effect of nasal high-flow (NHF) in patients with acute hypoxemic respiratory failure. Preliminary data show also benefits in several hypercapnic chronic lung diseases. Objectives: The aim of this study was to characterize flow dependent changes in mean airway pressure, breathing volumes, breathing frequency and decrease in PCO2. Methods: Mean airway pressure was measured in the nasopharyngeal space. To evaluate breathing volumes a polysomnographic device was used (16 patients). All subjects received 20, 30, 40, 50 l/min and - to illustrate the effects - nCPAP and nBiPAP. Capillary blood gas analyses were performed in 25 hypercapnic ILD subjects before and 5 hours after the use of NHF. Additionally, comfort and dyspnea during the use of NHF were surveyed. Results: NHF resulted in a small flow-dependent increase in mean airway pressure. Tidal volume was unchanged and breathing rate decreased. The calculated minute volume decreased by 20 and 30 l/min NHF breathing. In spite of this fact, hypercapnia decreased at a flow rate of 24 l/min. Additionally, an improvement in dyspnea was observed. Conclusions: NHF leads to a reduction of paCO2. This is most likely achieved by a washout of the respiratory tract and a reduction of functional dead space. NHF enhances effectiveness of breathing in ILD patients by reduction of respiratory rate. In summary, NHF works as an effective ventilatory support device in hypercapnic ILD patients.