Background. Fibrotic interstitial lung disease ( f-ILD) is characterized by impaired pulmonary gas exchange, increased ventilatory demand and disabling dyspnea. Conventional O 2 therapy at rest improves patients’ oxygenation but not ventilatory requirements. Nasal high-flow (NHF) with or without supplemental O 2 may reduce ventilatory demand but its acute physiological and perceptual benefits remain unclear in f-ILD. Methods. Fifteen naïve patients (partial pressure of arterial O 2 = 57±12 mmHg) underwent, in a randomized, single-blind, cross-over trial, six bouts of 7-min exposure: room air; conventional O 2 fraction of inspired O 2 (FiO 2 )=0.5 or 1.0; NHF air (30 L·min-1, FiO 2 =0.21); and NHFO 2 (30 L·min⁻¹, FiO 2 =0.3 or 0.5). Breathing pattern (respiratory plethysmography), O 2 saturation (SpO 2 ) and dyspnea intensity (Borg CR-10) and qualitative descriptors were compared across conditions. Results. SpO 2 improved in O 2 -enriched conditions (≥98%) vs air and NHF air (~92%; p<0.001). NHF air , NHFO 2 with FiO 2 =0.3 and FiO 2 =0.5 lessened ventilation vs room air (7.8±3.0, 7.1±3.3, 7.0±2.5 and 9.3±3.0 L·min -1 , respectively; all p≤0.044), but conventional O 2 had no significant effect. Respiratory rate only decreased with NHFO 2 with FiO 2 =0.3 vs air (20±6 vs 23±5 breaths·min-1; p=0.008). Dyspnea intensity was greater with NHF modalities vs conventional O 2 (~1 Borg unit; all p≤0.030); qualitative descriptors did not differ across conditions. Conclusion. In moderately-hypoxemic patients with f-ILD, NHF (regardless of O 2 enrichment) but not conventional O 2 therapy lessened resting ventilatory requirements. Concurrently, NHF increased dyspnea intensity despite preserved qualitative dimensions, suggesting dissociation between physiological and perceptual responses in this population. These findings highlight the need for individualized strategies when implementing NHFO 2 in naïve patients with f-ILD.
Thivent et al. (Thu,) studied this question.