There is growing awareness that dyspnoea, like pain, is a multidimensional experience, but measurement instruments have not kept pace. The Multidimensional Dyspnea Profile (MDP) assesses overall breathing discomfort, sensory qualities, and emotional responses in laboratory and clinical settings. Here we provide the MDP, review published evidence regarding its measurement properties and discuss its use and interpretation. The MDP assesses dyspnoea during a specific time or a particular activity (focus period) and is designed to examine individual items that are theoretically aligned with separate mechanisms. In contrast, other multidimensional dyspnoea scales assess recalled recent dyspnoea over a period of days using aggregate scores.Previous psychophysical and psychometric studies using the MDP show that: 1) subjects exposed to different laboratory stimuli could discriminate between air hunger and work/effort sensation, and found air hunger more unpleasant; 2) the MDP immediate unpleasantness scale (A1) was convergent with common dyspnoea scales; 3) in emergency department patients, two domains were distinguished (immediate perception, emotional response); 4) test–retest reliability over hours was high; 5) the instrument responded to opioid treatment of experimental dyspnoea and to clinical improvement; 6) convergent validity with common instruments was good; and 7) items responded differently from one another as predicted for multiple dimensions.

BackgroundLaboratory-induced dyspnea (breathing discomfort) in healthy subjects is widely used to study perceptual mechanisms, yet the relationship between laboratory-induced dyspnea in healthy volunteers and spontaneous dyspnea in patients with chronic lung disease is not well established. We compared affective responses to dyspnea 1) in COPD patients vs. healthy volunteers (HV) undergoing the same laboratory stimulus; 2) in COPD during laboratory dyspnea vs. during activities of daily living (ADL).MethodsWe induced moderate and high dyspnea levels in 13 COPD patients and 12 HV by increasing end-tidal CO2 (PETCO2) during restricted ventilation, evoking air hunger. We used the multidimensional dyspnea profile (MDP) to measure intensity of sensory qualities (e.g., air hunger (AH) and work/effort (W/E)) as well as immediate discomfort (A1) and secondary emotions (A2). Ten of the COPD subjects also completed the MDP outside the laboratory following dyspnea evoked by ADL.ResultsCOPD patients and HV reported similar levels of immediate discomfort relative to sensory intensity. COPD patients and HV reported anxiety and frustration during laboratory-induced dyspnea; variation among individuals far outweighed the small differences between subject groups. COPD patients reported similar intensities of sensory qualities, discomfort, and emotions during ADL vs. during moderate laboratory dyspnea. Patients with COPD described limiting ADL to avoid greater dyspnea.ConclusionsIn this pilot study, we found no evidence that a history of COPD alters the affective response to laboratory-induced dyspnea, and no difference in affective response between dyspnea evoked by this laboratory model and dyspnea evoked by ADL.

1 2 : A number of laboratory respiratory interventions have been used to evoke respiratory discomfort. Laboratory interventions Rationale provide greater control, but an important question is often raised: How does the laboratory experience compare to dyspnea experienced by pulmonary patients in daily life (wild-type dyspnea)?: We measured multiple aspects of dyspnea using the Multidimensional Methods Dyspnea Profile (MDP) in COPD patients during a laboratory intervention (hypercapnia during limited ventilation, which predominantly evokes air hunger), and sent the same patients home with the MDP to record daily experiences. All scales in the MDP range from 0 to 10.: The mean sensory intensity (SI) of laboratory dyspnea we imposed was comparable to the mean intensity of dyspnea experienced Results in the wild (5.4 vs 6.5). Across individuals, matching was not perfect -differences between lab ratings and wild ratings ranged from 0 to 3 (of 10). To account for these small differences in the intensity of sensation we assessed immediate unpleasantness (A1) and emotional response (A2; the average of 5 negative emotions) as ratios to SI. The mean ratios were similar between lab and wild type dyspnea (A1 to SI .97 vs .97; A2 to SI .17 vs .20). Examination of the range of responses among individuals revealed more detail: There was variation amongst individuals in the ratio of A1 to SI (range .7 to 1.22) -this variation was independent of situation, i.e., an individual's A1/SI ratio in the laboratory was a good predictor of that individual's A1/SI ratio in the wild -see left-hand figure below. The degree of unpleasantness rated at a given sensory intensity is thus an individual characteristic. In contrast, the A2/SI ratio was highly dependent on situation, i.e., an individual's emotional response to induced dyspnea in the lab did not predict his or her emotional response to dyspnea in the wild. Some individuals had a much stronger response in the lab, others had a much stronger response in the wild; see right-hand figure.: Conclusions Thus, air hunger induced in the laboratory is a reasonable model of wild-type dyspnea -similar intensity and unpleasantness can be evoked in the lab, and the relationship between them is similar to dyspnea in the wild. Average emotional response is similar in the lab, but the wide situational variation in individual emotional responses suggests caution in interpretation of emotional factors in laboratory experiments.

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