Consistency Evaluation of Two Loading Devices in Measuring the Perception of Dyspnea

Figures & data

Figure 1 Consort diagram of the study.

Abbreviations: COPD, chronic obstructive pulmonary disease; MIP, maximum inspiratory pressure; I-TLD, hand-held electronic incremental threshold loading device; C-TLD, traditional threshold loading device.

Figure 2 Load rising modes of the two devices. (A) Load rising mode of C-TLD. (B) Load rising mode of I-TLD.

Abbreviations: I-TLD, hand-held electronic incremental threshold loading device; C-TLD, traditional threshold loading device.

Table 1 General Characteristics of Enrolled COPD and Non-COPD Subjects

Variables	COPD Patients (n = 38)	Non-COPD Subjects (n = 41)
Age (years)	57.5 (40.8–78.1)	54.0 (35.0–67.4)
Gender (male), n (%)	29 (76.3)	21 (51.2)
BMI (kg/m^2)	25.6 (20.7–29.9)	27.4 (20.6–34.1)
Former or current smoker, n (%)	23 (60.5)	17 (41.5)
MIP (cmH2O)	75.5 (27.6–117.2)	73.0 (47.7–148.5)
FEV1/FVC^a, %	63.7 (47.4–69.5)	83.2 (75.5–90.5)
GOLD stage of COPD
GOLD stage I	13 (34.2)	-
GOLD stage II	17 (44.7)	-
GOLD stage III	6 (15.8)	-
GOLD stage IV	2 (5.3)	-

Notes: Data are presented as median (5–95 percentile) or n (%). ^aFEV₁/FVC was measured after bronchodilator inhalation in COPD patients, while it was measured before bronchodilator inhalation in non-COPD subjects.

Abbreviations: COPD, chronic obstructive pulmonary disease; BMI, body mass index; MIP, maximum inspiratory pressure; FEV_1/FVC, ratio of forced expiratory volume in one second to forced vital capacity; GOLD, global initiative for chronic obstructive lung disease.

Table 2 Borg Scores and Slope a Measured by the Two Devices in COPD and Non-COPD Subjects

	C-TLD	I-TLD	p value
COPD patients
Borg scores of 0 cmH2O level	0 (0–1.0)	0 (0–1.0)	1.000
Borg scores of 5 cmH2O level	0.5 (0–3.0)	0.3 (0–2.0)	0.002
Borg scores of 10 cmH2O level	2.0 (0–4.1)	1.5 (0–3.0)	0.039
Borg scores of 20 cmH2O level	3.0 (0.5–7.0)	3.0 (0–5.0)	0.123
Borg scores of 30 cmH2O level	4.0 (0.5–10.0)	4.0 (0.5–9.1)	0.208
Slope a	8.1 (1.6–30.7)	8.1 (1.3–18.3)	0.939
Non-COPD subjects
Borg scores of 0 cmH2O level	0 (0–0)	0 (0–0)	1.000
Borg scores of 5 cmH2O level	0.5 (0–2.9)	0.5 (0–2.0)	0.160
Borg scores of 10 cmH2O level	1.0 (0–4.9)	2.0 (0–3.0)	0.898
Borg scores of 20 cmH2O level	3.0 (0.5–5.9)	3.0 (0.5–4.0)	0.682
Borg scores of 30 cmH2O level	4.0 (0.5–7.9)	3.0 (2.0–5.0)	0.798
Slope a	8.1 (1.2–23.0)	8.3 (4.1–20.9)	0.995
All subjects
Borg scores of 0 cmH2O level	0 (0–0.5)	0 (0–0.5)	1.000
Borg scores of 5 cmH2O level	0.5 (0–3.0)	0.5 (0–2.0)	0.001
Borg scores of 10 cmH2O level	2.0 (0–4.0)	2.0 (0–3.0)	0.202
Borg scores of 20 cmH2O level	3.0 (0.5–7.0)	3.0 (0.5–4.0)	0.151
Borg scores of 30 cmH2O level	4.0 (0.5–9.0)	4.0 (2.0–7.0)	0.292
Slope a	8.1 (1.2–23.0)	8.3 (2.4–18.6)	0.845

Note: Data are presented as median (5–95 percentile).

Abbreviations: slope a, Borg scores vs percentage of oral pressure from the patient’s maximum; COPD, chronic obstructive pulmonary disease; I-TLD, hand-held electronic incremental threshold loading device; C-TLD, traditional threshold loading device.

Figure 3 Distribution of linear regression coefficient (slope a) in the two devices. (A) Distribution of linear regression coefficient (slope a) in patients with COPD. (B) Distribution of linear regression coefficient (slope a) in non-COPD subjects.

Abbreviations: slope a, Borg scores vs percentage of oral pressure from the patient’s maximum; COPD, chronic obstructive pulmonary disease; I-TLD, hand-held electronic incremental threshold loading device; C-TLD, traditional threshold loading device.

Figure 4 Scatter plot of slope a for the two devices. (A) Scatter plot of slope a in patients with COPD. (B) Scatter plot of slope a in non-COPD subjects.

Abbreviations: slope a, Borg scores vs percentage of oral pressure from the patient’s maximum; COPD, chronic obstructive pulmonary disease; I-TLD, hand-held electronic incremental threshold loading device; C-TLD, traditional threshold loading device.

Figure 5 Consistency evaluation of slope a in all subjects for the two devices.

Abbreviation: slope a, Borg scores vs percentage of oral pressure from the patient’s maximum.