Detecting Improvements in Dyspnea in COPD Using a Three-Minute Constant Rate Shuttle Walking Protocol

Figures & data

Figure 1.  Dyspnea (panel A) and leg fatigue (panel B) Borg scores (mean ± SEM) during the 3-minute constant rate shuttle walking test under both experimental conditions (ipratropium bromide [triangles] and placebo [circles]). *p < 0.01. Symptom scores were obtained at the highest speed that was carried through for the whole 3 minutes under both experimental conditions by each individual patient (2.5 km/hr = 3 patients; 4.0 km/hr = 30 patients; 6.0 km/hr = 5 patients, one patient was unable to complete any of the walking speeds).

Table 1.  Baseline characteristics of the study population

	Value	SD
Number of subjects	39	-
Males/females, n	27/12	-
Age (years)	64	5
Body mass index (kg/m^2)	28	5
Current smokers (n)	17	-
GOLD (I/II/III)	1/23/15	-
Pulmonary Function
FEV1 (L)	1.37	0.52
FEV1 (% predicted)	51	14
FVC (% predicted)	94	17
FEV1/FVC (%)	43	11
FRC (% predicted)	141	36
TLC (% predicted)	115	20
RV (% predicted)	152	47
DLCO (% predicted)	53	13

Values are mean ± SD.

Definition of abbreviations: GOLD: Global Initiative for Chronic Obstructive Lung Disease; FEV1: forced expiratory volume in 1 second; FVC: forced vital capacity; FRC: functional residual capacity; TLC: total lung capacity; RV: residual volume; DLco: single-breath diffusing capacity for carbon monoxide.

Table 2.  Physiological responses to the incremental shuttle walking test

	Value	SD
V. O2 peak (L/min)	1.4	0.4
V. O2 peak (mL/kg/min)	17.5	4.1
V. E peak (L/min)	52	19
V. E /MVV (%)	99	20
Peak heart rate	119	20
Distance walked (m)	420	152
Locus of symptom limitation (dyspnea/fatigue)	31/8	-
Peak dyspnea Borg score	5.8	2.4
Peak leg fatigue Borg score	4.7	2.2

Values are mean ± SD.

Definition of abbreviations: V. O2 : oxygen uptake; V. E: minute ventilation; MVV: maximum voluntary ventilation.

Table 3.  Effects of ipratropium bromide on physiologic data at 3 minutes during the 3-minute constant rate shuttle walking test

	Placebo		IB		p-value (placebo vs IB)
	Baseline	3 minutes	Baseline	3 minutes	Baseline	3 minutes
V. E (L/min)	13 ± 4	41 ± 13	13 ± 4	44 ± 12	0.17	<0.01
VT (L)	0.65 ± 0.21	1.15 ± 0.40	0.68 ± 0.18	1.30 ± 0.42	0.19	<0.01
Respiratory rate (min-1)	20 ± 5	32 ± 6	20 ± 5	30 ±6	0.50	0.02
V. O2 (L/min)	0.31 ± 0.12	1.13 ± 0.37	0.31 ± 0.11	1.14 ± 0.40	0.88	0.96
V. CO2 (L/min)	0.30 ± 0.18	1.03 ± 0.42	0.27 ± 0.08	1.19 ± 0.45	0.61	0.40
Heart rate (BPM)	79 ± 18	107 ± 16	81 ± 18	108 ± 16	0.69	0.53
SpO2 (%)	94 ± 2	91 ± 3	94 ± 2	91 ± 5	0.72	0.97

Values are mean ± SD.

Abbreviations: FEV1: forced expiratory volume in 1 second;V. E: minute ventilation; VT: tidal volume; V. O2: oxygen uptake; V. CO2: carbon dioxide excretion; SpO2: oxygen pulse saturation. Physiological values were obtained at the highest speed that was carried through for the whole 3 minutes under both experimental conditions by each individual patient (2.5 km/hr = 3 patients; 4.0 km/hr = 30 patients; 6.0 km/hr = 5 patients, 1 patient was unable to complete any of the walking speed).