Impact of Pulmonary Rehabilitation on the Major Dimensions of Dyspnea in COPD

Figures & data

Table 1.  Domains of dyspnea measurement

Domain	Definiti on	Measurements
Sensory-perceptual experience	What breathing feels like	• Intensity ratings (Borg scale) of dyspnea during a standardized physical task, i.e., CWR cycle
		• Intensity ratings (Borg scale) of dyspnea at the end of CWR cycle, 6MWT and ESWT
		• Selection of qualitative dyspnea descriptors at the end of CWR cycle, 6MWT and ESWT
Affective distress	How distressing breathing feels; focus can be either immediate (e.g., unpleasantness) or evaluative (e.g., judgments of meaning or consequences)	• Intensity ratings (Borg scale) of dyspnea-related anxiety during CWR cycle exercise
		• COPD self-efficacy scale (CSES)
Symptom impact	How dyspnea affects functional ability, disability, quality of life or health status	• MRC dyspnea scale
		• BDI / TDI
		• CRQ dyspnea component
		• SGRQ activity component

Abbreviations: 6MWT, 6-minute walk test; BDI, Baseline Dyspnea Index; CRQ, Chronic Respiratory Questionnaire; CSES, COPD Self-Efficacy Scale; CWR, constant-work rate; ESWT, endurance shuttle walk test; MRC, Medical Research Council; SGRQ, St. George's Respiratory Questionnaire; TDI, Transition Dyspnea Index.

Table 2.  Subject characteristics at study entry

	CTRL (n = 28)	PR (n = 20)	p-value*
Sex, M:F (% male)	16:12 (57)	11:9 (55)	0.883
Age, years	66 ± 7	68 ± 6	0.386
Height, cm	170 ± 11	167 ± 8	0.257
Weight, kg	83.8 ± 16.1	75.6 ± 18.5	0.111
Body mass index, kg/m2	28.9 ± 4.3	26.7 ± 4.9	0.114
Smoking pack-years	57 ± 29	61 ± 42	0.675
Smoking status, %current	21%	10%	0.295
BDI, focal score	5.9 ± 1.4	6.3 ± 1.2	0.300
Peak incremental work rate, watts	68 ± 29	71 ± 31	0.721
Peak incremental VO2, L/min	1.21 ± 0.49	1.12 ± 0.48	0.529
Peak incremental VO2, % predicted maximum	64 ± 21	66 ± 18	0.508
Peak incremental VE, L/min	41.5 ± 10.2	41.7 ± 14.6	0.969
Reason for stopping exercise, %:			0.971
Breathing	39	35
Legs	25	30
Both breathing and legs	32	30
Other	4	5
FEV1/FVC, %	42 ± 10	41 ± 11	0.581
FEV1, L	1.23 ± 0.52	1.16 ± 0.40	0.752
FEV1, % predicted	48 ± 19	48 ± 12	0.801
FRC, % predicted	151 ± 34	148 ± 39	0.860
RV, %predicted	181 ± 53	167 ± 47	0.384
TLC, %predicted	121 ± 14	118 ± 19	0.465
sRaw, % predicted	613 ± 324	537 ± 297	0.499
DLCO, % predicted	57 ± 22	57 ± 17	0.918
MIPFRC, % predicted	82 ± 25	82 ± 29	0.719
MEPTLC, % predicted	76 ± 18	74 ± 19	0.935

Mean ± SD unless otherwise specified.

*p-value for between-group comparisons by unpaired t-test or chi-square analysis.

Abbreviations: BDI, Baseline Dyspnea Index; DLCO, diffusing capacity of the lung for carbon monoxide; FEV1, forced expired volume in 1 s; FRC, functional residual capacity; FVC, forced vital capacity; MIPFRC, maximum inspiratory mouth pressure measured at FRC; MEPTLC, maximum expiratory mouth pressure measured at TLC; RV, residual volume; sRaw, specific airway resistance; TLC, total lung capacity; VE, minute ventilation; VO2, oxygen consumption.

Figure 1.  Ventilatory responses to CWR cycle exercise in response to pulmonary rehabilitation (PR) or usual care control (CTRL). Data plotted are means ± SEM for measurements collected at steady-state rest, isotime and peak exercise. Fb, breathing frequency.

Table 3.  Anthropometric and pulmonary function measurements of subjects who completed the study

	CTRL (n = 24)		PR (n = 17)
	Pre	Post	Pre	Post
Sex, M:F (% male)	13:11 (54)		9:8 (53)
Age, yrs	66 ± 7		67 ± 5
Height, cm	170 ± 11		168 ± 9
Body mass index, kg/m2	29.1 ± 4.3	29.6 ± 4.1	27.3 ± 6.5	27.9 ± 5.5
FEV1/FVC, %	40 ± 10	41 ± 11	44 ± 10	45 ± 10
FEV1, % predicted	49 ± 19	51 ± 22	51 ± 14	52 ± 14
FRC, % predicted	150 ± 30	148 ± 28	143 ± 34	145 ± 37
RV, %predicted	175 ± 52	171 ± 45	160 ± 44	164 ± 50
TLC, %predicted	121 ± 12	121 ± 11	115 ± 17	117 ± 18
sRaw, % predicted	604 ± 256	602 ± 363	525 ± 402	487 ± 321
DLCO, %predicted	57 ± 24	55 ± 20	58 ± 18	58 ± 17
MIPFRC, %predicted	80 ± 26	87 ± 28 *	84 ± 30	97 ± 31 *
MEPTLC, %predicted	78 ± 20	79 ± 19	77 ± 18	79 ± 15

Mean ± SD.

*p < 0.05 within-group difference post- versus pre-intervention.

†p < 0.05 between-group difference in post-pre change by repeated measures ANOVA.

Abbreviations: DLCO, diffusing capacity of the lung for carbon monoxide; FEV1, forced expired volume in 1 s; FRC, functional residual capacity; FVC, forced vital capacity; MIPFRC, maximum inspiratory mouth pressure measured at FRC; MEPTLC, maximum expiratory mouth pressure measured at TLC; RV, residual volume; sRaw, specific airway resistance; TLC, total lung capacity.

Table 4.  Questionnaires and functional tasks

	CTRL (n = 24)		PR (n = 17)
	Pre	Post	Pre	Post
MRC dyspnea scale, 1-5	2.9 ± 1.0	3.0 ± 1.0	2.9 ± 0.8	2.2 ± 0.6 *†
BDI:
Focal score	6.0 ± 1.5	6.0 ± 2.1	6.1 ± 1.1	7.9 ± 1.5*†
Functional impairment	2.1 ± 1.0	2.1 ± 0.9	2.3 ± 0.6	2.9 ± 0.7*†
Magnitude of effort	2.0 ± 0.7	2.2 ± 0.8	2.1 ± 0.7	2.6 ± 0.8*
Magnitude of task	1.8 ± 0.5	1.8 ± 0.5	1.8 ± 0.4	2.3 ± 0.6*†
TDI:
Focal score	n/a	0.3 ± 2.1	n/a	3.8 ± 2.3 †
Functional impairment		0.0 ± 0.7		1.1 ± 1.1 †
Magnitude of effort		0.3 ± 1.2		1.5 ± 1.1 †
Magnitude of task		0.0 ± 0.7		1.4 ± 0.8 †
CRQ:
Total	18.3 ± 4.1	18.0 ± 3.5	16.9 ± 3.2	19.8 ± 3.9*†
Dyspnea	3.4 ± 1.2	3.4 ± 1.4	2.7 ± 0.7	3.9 ± 1.0 *†
Fatigue	4.5 ± 1.3	4.2 ± 1.2	4.0 ± 1.3	5.0 ± 1.0 *†
Emotion	5.1 ± 1.1	5.2 ± 1.1	5.0 ± 1.0	5.4 ± 1.0
Mastery	5.3 ± 1.3	5.3 ± 1.3	5.1 ± 1.1	5.5 ± 1.4
SGRQ:
Total	47 ± 14	45 ± 13	50 ± 15	42 ± 17 *
Symptom	61 ± 23	53 ± 20 *	60 ± 21	55 ± 22
Activity	66 ± 17	65 ± 19	67 ± 16	55 ± 18 *†
Impact	32 ± 14	31 ± 14	37 ± 17	30 ± 22
HADS anxiety score	4.5 ± 2.8	4.8 ± 3.2	5.8 ± 3.5	4.1 ± 3.2 *†
HADS depression score	4.2 ± 2.9	4.7 ± 2.9	5.1 ± 3.3	3.0 ± 2.2 *†
COPD Self-Efficacy Scale	109 ± 23	112 ± 22	102 ± 18	122 ± 25 *†
6-min walk self-efficacy	42 ± 22	44 ± 22	42 ± 20	61 ± 24 *†
6-minute walk test:
Distance, m	449 ± 101	448 ± 97	451 ± 83	469 ± 92 *†
Dyspnea, Borg	3.8 ± 1.8	3.8 ± 1.6	3.7 ± 1.8	3.8 ± 1.9
Leg discomfort, Borg	3.1 ± 2.0	3.0 ± 1.8	3.6 ± 2.9	2.7 ± 2.4 *
Endurance shuttle walk test:
Distance, m	487 ± 417	578 ± 537	406 ± 240	662 ± 462 *
Dyspnea, Borg	4.0 ± 1.5	4.3 ± 1.5	5.2 ± 2.3	4.9 ± 2.6
Leg discomfort, Borg	3.4 ± 2.1	3.5 ± 1.8	4.5 ± 3.0	3.8 ± 2.6
CWR cycle test:
Endurance time, s	314 ± 168	372 ± 240	457 ± 484	562 ± 475 *
Dyspnea, Borg	6.1 ± 2.4	5.8 ± 1.9	6.1 ± 2.4	6.2 ± 2.9
Leg discomfort, Borg	5.9 ± 2.8	6.0 ± 2.5	6.5 ± 3.2	5.8 ± 3.1
Quadriceps strength, kg	30 ± 12	31 ± 13	28 ± 14	31 ± 14*

Mean ± SD.

* p < 0.05 within-group difference post- versus pre-intervention.

† p < 0.05 between-group difference in post-pre change by repeated measures ANOVA.

Abbreviations: BDI, Baseline Dyspnea Index; CRQ, Chronic Respiratory Questionnaire; CWR, constant-work rate; HADS, Hospital Anxiety and Depression Scale; MRC, Medical Research 
Council; SGRQ, St. George's Respiratory Questionnaire; TDI, Transition Dyspnea Index.

Figure 2.  Intensity of exertional dyspnea and dyspnea-related anxiety during CWR cycle exercise. Data plotted are means±SEM for measurements collected at steady-state rest, isotime and peak exercise. *p < 0.05 pre- versus post-intervention.

Figure 3.  Measurements of activity-related dyspnea (symptom impact) in response to pulmonary rehabilitation (PR) or usual care control (CTRL). Scores are shown for the Transition Dyspnea Index (TDI) and its components (Functional Impairment, Magnitude of Task, Magnitude of Effort), the Medical Research Council MRC) dyspnea scale, the Chronic Respiratory Questionnaire (CRQ) dyspnea component, and the St. George's Respiratory Questionnaire (SGRQ) activity component. Values are means ± SEM. *p < 0.05 within- and between-group difference; †p < 0.05 within-group difference for change with intervention.