Physiological effects of high-flow nasal cannula during sustained high-intensity exercise in healthy volunteers: a randomised crossover trial

Introduction High-flow nasal cannula (HFNC) has increased exercise capacity in patients with chronic respiratory diseases. However, it remains unknown whether HFNC impacts respiratory physiological variables during exercise. This study aimed to evaluate the effect of HFNC on respiratory physiological variables during sustained high-intensity exercise in healthy volunteers.

Methods We performed a single-center, open-label, and randomised crossover trial to compare HFNC (60 L·min⁻¹) and Sham-HFNC (2 L·min⁻¹) interventions during a constant work-rate exercise (CWRET) through randomised order. The primary outcome was ΔPes, and the secondary outcomes were other variables of inspiratory effort, ventilation distribution, ventilatory variables, and clinical assessment. We evaluated volunteers at seven-time points (Baseline= T0; CWRET= T1-T2-T3 (minutes: 1′, 4′ and 6′); Cooldown-period= T4-T5-T6 (minutes: 1′; 6′;10′)) in both interventions.

Results Fourteen healthy volunteers (50% women; age: 22 [21–27] years) were enrolled. Mean differences in ΔPes decreased to favor the HFNC intervention compared to Sham-HFNC at T2 (−2.8 cmH2O; 95%CI −5.3 to −0.3), as well as the sPTPmin at T2 (−86.1 cmH2O×s·min⁻¹;95%CI −146.2 to −26.1), and T3 (−79.9 cmH2O×s·min⁻¹;95%CI −142.3 to −17.6). The standard deviation of the regional ventilation delay index was also lower with HFNC compared to Sham-HFNC (T1: −1.38; 95%CI −1.93 to −0.83; T2: −0.71; 95%CI −1.27 to −0.16). There was decreased dyspnea to favor the HFNC, but sPTP-per-breath, spatial distribution ventilation indexes, ventilatory variables, and clinical assessments were nonsignificant between interventions.

Conclusion HFNC intervention reduces respiratory effort, dyspnea and improves temporal ventilation distribution in healthy volunteers during CWRET.