Dyspnoea relief as an inherent benefit of high flow nasal cannula therapy: A laboratory randomized trial in healthy humans

Abstract Background and Objective Persistent dyspnoea is a public health issue for which the therapeutic arsenal is limited. This study tested high‐flow nasal cannula therapy (HFNT) as a means to alleviate experimental dyspnoea. Methods Thirty‐two healthy subjects underwent an experimental dyspnoea induced by thoracoabdominal elastic loading. HFNT was administered with alternately FiO 2 of 100% (HFNT100) or 21% (HFNT21). The sensory (S‐VAS) and affective (A‐VAS) components of dyspnoea, transcutaneous CO 2 pressure (PtcCO 2 ), pulse‐oximetry oxygen saturation (SpO 2 ), heart rate, respiratory rate and skin galvanometry were monitored continuously. Three experimental sessions of 8 min were conducted: the first session consisted in familiarization with the experimental dyspnoea and the next two sessions tested the effects of HFNT100 and HFNT21 alternatively in a randomized order. Results HFNT21 and HFNT100 significantly reduced dyspnoea, respectively of ∆A‐VAS = 0.80 cm [−0.02–1.5]; p = 0.007 and ∆A‐VAS = 1.00 cm [0.08–1.75]; p < 0.0001; ∆S‐VAS = 0.70 cm [−0.15–1.98]), p < 0.0001 and ∆S‐VAS = 0.70 cm [0.08–1.95]), p = 0.0002) with no significant difference between HFNT21 and HFNT100. HFNT did not significantly alter the respiratory rate or the heart rate, reduced PtcCO 2 only on room air and GSR under both experimental conditions. Conclusion HFNT was associated with a statistically significant reduction in the intensity of the sensory and affective components of dyspnoea, independent of oxygen addition. This relief of laboratory dyspnoea could result from a reduction of afferent‐reafferent mismatch.