Background The current theory of dyspnea perception presumes a multidimensional conception of dyspnea.However,its validity in patients with cardiopulmonary dyspnea has not been investigated.Methods A respiratory symptom checklist incorporating spontaneously reported descriptors of sensory experiences of breathing discomfort,affective aspects,and behavioral items was administered to 396 patients with asthma,chronic obstructive pulmonary disease (COPD),diffuse parenchymal lung disease,pulmonary vascular disease,chronic heart failure,and medically unexplained dyspnea.Symptom factors measuring different qualitative components of dyspnea were derived by a principal component analysis.The separation of patient groups was achieved by a variance analysis on symptom factors.Results Seven factors appeared to measure three dimensions of dyspnea:sensory (difficulty breathing and phase of respiration,depth and frequency of breathing,urge to breathe,wheeze),affective (chest tightness,anxiety),and behavioral (refraining from physical activity) dimensions.Difficulty breathing and phase of respiration occurred more often in COPD,followed by asthma (R2=0.12).Urge to breathe was unique for patients with medically unexplained dyspnea (R2=0.12).Wheeze occurred most frequently in asthma,followed by COPD and heart failure (R2=0.17).Chest tightness was specifically linked to medically unexplained dyspnea and asthma (R2=0.04).Anxiety characterized medically unexplained dyspnea (R2=0.08).Refraining from physical activity appeared more often in heart failure,pulmonary vascular disease,and COPD (R2=0.15).Conclusions Three dimensions with seven qualitative components of dyspnea appeared in cardiopulmonary disease and the components under each dimension allowed separation of different patient groups.These findings may serve as a validation on the multiple dimensions of cardiopulmonary dyspnea.