Breathlessness dimensions should be evaluated in relation to the level of exertion: A clinical study.

Background/aim: Exertional breathlessness is a dominating symptom in cardiorespiratory disease, limiting exercise capacity. Multidimensional measurement has been proposed to capture breathlessness, but it is unknown whether it is useful to differentiate people with abnormal vs normal exertional breathlessness intensity.

Methods: This was a secondary analysis of a randomized controlled trial of outpatients aged ≥ 18 years performing a symptom-limited cycle incremental exercise test (IET). Breathlessness sensations at end of IET were identified using the multidimensional dyspnea profile (MDP) 30-min post-exercise and compared between people with abnormally high breathlessness (Borg 0-10 rating > upper limit of normal [ULN]) and people within normal ranges (≤ ULN) in relation to the percentage of predicted peak power output defined by normative reference equations.

Results: Of 92 participants, 20 (22 %) had abnormally high breathlessness. Compared with those with normal breathlessness (n = 72 [78 %]), the abnormal group reported higher symptom intensity at peak exercise (7.9 ± 1.7 vs 6.3 ± 1.4 Borg units; p < 0.001) and had lower peak power output 129 ± 52 W vs 167 ± 55 W; p < 0.001). Differences between those with normal, and abnormal exertional breathlessness regarding MDP ratings were not statistically significant (all p > 0.05): overall unpleasantness, 4.1 ± 2.3 vs 4.7 ± 1.6; immediate perception, 10.9 ± 2.8 vs 11.5 ± 1.8; and emotional response, 4.1 ± 7.6 vs 3.2 ± 7.5. MDP ratings had no relation to peak power output.

Conclusion: Breathlessness dimensions are similar at the peak of a standardized IET and cannot differentiate between people with normal and abnormally high exertional breathlessness.