Assessment of multiple dimensions of dyspnea during cardiopulmonary exercise testing (CPET) in healthy adults

Background: Dyspnea is a complex sensation with sensory and affective dimensions contributing to the overall perceptual experience. Multidimensional dyspnea assessment tools have numerous items and rating scales making them unsuitable for use during CPET. This study aimed to determine whether healthy volunteers could reliably discriminate and separately rate dyspnea intensity (SI), sensory qualities ('work/effort' [SQWORK ], 'unsatisfied inspiration' [SQUI ]) and unpleasantness (UN) when evaluated during CPET using Borg's 0-10 category ratio scale. Methods: In a randomized crossover study, 15 healthy adults aged 22±2 years performed six repeat CPETs (25 W/2-min) with six dyspnea assessment protocols randomized for order: simultaneous ratings of 1) SI, SQWORK , SQUI , UN [DYSPALL ]; or 2) SI, UN only; and 3-6) SI, SQWORL , SQUI , and UN each alone. Dyspnea responses were compared between protocols with an alpha of 0.05. Results: Participants rated the dimensions of exertional dyspnea consistent across protocols, with the exception of SI rated modestly but significantly higher at peak exercise when rated alone compared to the DYSPALL protocol (0.8 Borg units, p<0.05). During CPET, ratings of SI and SQWORK were similar across protocols and significantly greater than ratings of UN and SQUI , which were also rated similarly. Conclusion: Dyspnea intensity and unpleasantness were rated as separable constructs during CPET, which were associated with perceptions of 'work/effort' and 'unsatisfied inspiration', respectively. Two separate rating scales (SI and UN) may be sufficient to assess the multiple dimensions of dyspnea during CPET in clinical and research contexts.