Cool facial airflow hastens exertion recovery in chronic breathlessness: randomised crossover trial of different fan airflow speeds.

Objectives: Facial airflow from a hand-held fan (fan) hastens recovery from exertional breathlessness. We aimed to determine the effect of different airflow speeds on recovery from exertional breathlessness in patients with chronic breathlessness.

Methods: A prospective, unblinded, randomised crossover trial. Participants with chronic breathlessness (modified Medical Research Council ≥3) completed five 1 min sit-to-stand (STS) tests to induce breathlessness. After each STS test, participants used a fan with one of four airflow speeds or control (no fan) during 10 min recovery. Numerical Rating Scale (NRS) breathlessness intensity, airflow pleasantness, heart rate, oxygen saturation and facial skin temperature were recorded.

Results: 10 participants were recruited (n=1 withdrew due to health concerns) and 9 (mean±SD age 66±14 years; 5 men; 8 chronic obstructive pulmonary disease, 1 long covid) completed the trial. Per-protocol analysis identified no difference in NRS breathlessness recovery across fan speeds (p>0.05). Sensitivity analysis (n=1 excluded due to low exertional NRS breathlessness post STS test) identified a significant interaction effect for fan speed over time (p=0.010). Fan speed 2.85 m/s reduced NRS breathlessness compared with control at minutes 4-8 during recovery (p<0.05), whereas fan speeds 1.98 m/s, 3.70 m/s and 4.91 m/s only differed from control after 7 min recovery (p<0.05). The perceived most pleasant and preferred airflow rate was 2.85 m/s. NRS pleasantness decreased with faster airflow speeds, suggesting a ceiling limit to net benefit.

Conclusion: Our novel data suggest the optimal airflow speed to hasten recovery from exertional breathlessness in people with chronic breathlessness is 2.85 m/s. Net benefit reduces at higher flow rates.