COPD phenotypes on computed tomography and its correlation with selected lung function variables in severe patients

Figures & data

Figure 1 Illustrative curves constructed with mean values of each group.

Notes: (A) Control group (ETCO₂=36 mmHg; Slp3=7.3 mmHg/L; V_e =693.2±245.9 mL; (B) airways diseases group (ETCO₂=39.0±6.7 mmHg; Slp3=37.1±15.5 mmHg/L; V_e =508.5 mL); (C) emphysema group (ETCO₂=33.7±6.8 mmHg; Slp3=28.6±12.7 mmHg/L; V_e =652.1 mL). Data from Veronez et al.¹⁵
Abbreviations: ETCO₂, end-tidal CO₂; Slp3, slope of phase 3; V_e, expired volume.

Table 1 Scoring system for CT findings

Category	Absent in RSL all lobes	LSL	ML	LIN	RIL	LIL	Total	Score range
Extension of bronchiectasis: 0= absent; 1= until 50% of the lobe; 2= more than 50%								0–12
Severity of dilatation: 0= absent; 1= mild (lumen slightly greater than the diameter of adjacent vessel); 2= moderate (lumen 2–3× > diameter of adjacent vessel); 3= severe (lumen 3× >diameter of adjacent vessel)								0–18
Peribronchial thickening: 0= absent; 1= mild (airwall thickness equal to adjacent vessel); 2= moderate (airwall thickening > adjacente vessel but ≤2× the diameter of adjacent vessel); 3= severe (airwall thickening >2× diameter of adjacent vessel)								0–18
Tree-in-bud: 0= absent; 1= present								0–6
Mucoid plug: 0= absent; 1= present								0–6
Air trapping (expiratory scan): 0= absent; 1= present; NE = not evaluated								0–6
Fibrotic collapse/consolidation: 0= absent; 1= subsegmentar; 2= segmentar or lobar								0–2
Bullae, n: 0= absent; 1= unilateral (<4); 2= bilateral (<4); 3=≥4								0–3
Emphysema: 0= absent; 1= present								0–6
Total								0–77
PA/Ao ratio: 0≤1; 1>1								0–1

Notes: The ratio score is zero or one. Score zero is equal to PA/Ao ratio ≤1. Score 1 is equal to PA/Ao ratio >1.

Abbreviations: CT, computed tomography; RSL, right superior lobe; LSL, left superior lobe; ML, medium lobe; LIN, lingula; RIL, right inferior lobe; LIL, left inferior lobe; PA, pulmonary artery; Ao, aorta.

Figure 2 Flowchart of patients included in the study.

Table 2 Clinical and functional characteristics of patients (N=65)

Age (years)a	64.15±8.45
Sex (M/F)	43/22 (66.2%/33.8%)
Smoking (pack-years)a	47.4±38.7
BMI (kg/m^2)a	26.3±6.22
SpO2 rest (%)	92.7±3.74
Number of exacerbations/year (last 3 years)a	0.74±0.44
BODEa	4.5±1.86
MRCa	2.8±0.87
Coughb	30 (46%)
Sputum productionb	20 (31%)
Use of domiciliary oxygenb	21 (32%)
Other associated diseasesb	55 (85%)
HBP	34 (52%)
DLP	10 (15%)
PAH	9 (14%)
DM	8 (12%)
Questionnaire SGRQ – general domain (%)a	58.09±15.82
Symptoms score (%)a	55.31±23.48
Activity score (%)a	73.04±16.44
Impact score (%)a	50.42±17.36
Questionnaire AQ20 (1–20)	11.47±3.78
FVC (L)	2.07±0.60
FVC (% predicted)	56.64±13.98
FEV1 (L)	1.15±0.42
FEV1 (% predicted)	39.75±14.11
FEV1/FVC	54.83±11.41
FEF25%–75% (L)	0.58±0.29
FEF25%–75% (% predicted)	22.29±11.08
6MWD (m)	378.61±89.96
6MWD (% predicted)^Citation22	76.7
ΔSpO2 (%)	4.6±4.04
ΔBorg	2.68±2.40
ETCO2	36.22±7.23
Slp2	246.34±118.18
Slp3	32.64±14.64
Slp3/ETCO2	0.90±0.36
Slp3/Ve	0.07±0.05
Ti/Te (s)	0.60±0.15

Notes: All spirometric measurements were obtained after bronchodilator use.

a Data expressed as mean ± standard deviation.

b Categorical variables (yes/no).

Abbreviations: M, male; F, female; BMI, body mass index; SpO₂, peripheral oxygen saturation; BODE, Body mass index, airflow Obstruction, Dyspnea, and Exercise; MRC, Medical Research Council; HBP, high blood pressure; DLP, dyslipidemia; PAH, pulmonary arterial hypertension; DM, diabetes mellitus; SGRQ, Saint George’s Respiratory Questionnaire; AQ20, Airways Questionnaire 20; FVC, forced vital capacity; FEV₁, forced expiratory volume in 1 second; FEF_25%–75%, forced expiratory flow between 25% and 75% of FVC; ΔSpO₂, difference between final and initial peripheral oxygen saturation; ΔBorg, difference between final and initial Borg score of dyspnea; ETCO₂, level of carbon dioxide released at the end of expiration; Slp2, slope of phase 2; Slp3, slope of phase 3; V_e, expiratory volume; T_i, inspiratory time; T_e, expiratory time.

Table 3 HRCT findings of all patients (N=65)

CT findings	Patients with the CT finding (%)	CT score
		Mean ± SD	Median (min–max)
Bronchiectasis (score range: 0–30)	22 (33.8)	7.45±6.25	5.5 (2–22)
Peribronchial thickening (score range: 0–18)	45 (69.2)	3.60±1.68	3 (2–8)
Tree-in-bud/mucoid plugging (score range: 0–12)	4 (6.15)	5±3.16	4.5 (2–6)
Air trappinga (score range: 0–6)	23 (52.3)	3±1.73	2 (2–6)
Bullae (score range: 0–3)	14 (21.5)	1.92±0.91	0–3
Emphysema (score range: 0–6)	45 (69.2)	3.15±2.58	3 (0–6)
CT total score (score range: 0–77)		11.47±10.08	9 (2–50)
PA/Ao >1	11 (16.9)

Note:

a Evaluated in 44 subjects who had expiration scans.

Abbreviations: PA, pulmonary artery; Ao, aorta; CT, computed tomography; min, minimum; max, maximum; HRCT, high-resolution computed tomography; SD, standard deviation.

Table 4 HRCT findings, clinical and functional characteristics of patients according to CT phenotype

Variables	Emphysema (N=34)	Airway disease (N=31)	P-value
	n (%)	n (%)
CT findings
Bronchiectasis	8 (23.5)	14 (45.2)	0.06
Score: 0–30a	3.75±1.98	9.57±6.91	0.009
Peribronchial thickening	19 (55.9)	26 (83.9)	0.01
Score: 0–18a	3.16±1.50	3.92±1.76	0.13
Tree-in-bud/mucoid plug	1 (2.9)	3 (9.7)	0.34
Score: 0–12a	6	4.66±3.78
Air trapping (N=44)b	4/19 (21.1)	19/25 (76)	<0.001
Score: 0–6a	2.75±2.22	3.14±1.62	0.60
Bullae	13 (38.2)	1 (3.2)	<0.001
Emphysema	34 (100)	11 (35.5)	<0.001
Score: 0–6a	5.11±1.66	1.0±1.43	<0.001
CT total score (0–77)	9.76±5.35a	13.35±13.37a	0.99
	9.5 (2–29)c	9 (2–50)c
PA/Ao >1 (Y/N)	6 (17.7)	5 (16.1)
Clinical variables
Age (years)a	64.5±8.4	63.7±8.7	0.750
Sex (M/F)d	24/10	19/12	0.430
Smoking (pack-years)a	51.7±42.6	42.7±34.1	0.390
BMI (kg/m^2)a	24.1±6.0	28.7±5.6	0.002
SpO2 (%)a	92.9±3.8	92.5±3.8	0.720
Exacerbations/yeara	0.7±0.4	0.7±0.5	0.990
BODEa	5.2±1.8	3.8±1.7	0.003
MRCa	2.9±0.8	2.67±0.9	0.480
Coughd	17 (50)	13 (41.9)	0.510
Sputum productiond	9 (26.5)	11 (35.5)	0.430
Use of oxygend	11 (32.4)	10 (32.3)	0.990
Spirometry post-BD
FVC (L)a	2.1±0.7	2.1±0.5	0.710
FVC (% predicted)a	55.7±15.6	57.6±12.2	0.560
FEV1 (L)a	1.1±0.5	1.2±0.4	0.059
FEV1 (% predicted)a	36.6±13.8	43.3±13.8	0.044
FEV1/FVC (%)a	51.1±10.6	58.9±11.0	0.007
FEF25%–75% (% predicted)a	19.4±9.0	25.4±12.4	0.032
6-minute walk test
6MWD (m)a	365.2±82.1	393.4±97.1	0.140
6MWD (% predicted)a	73.2±19.4	80.5±18.1	0.039
ΔSpO2a	4.9±3.9	4.3±4.2	0.440
ΔBorga	2.6±2.3	2.8±2.5	0.930
Volumetric capnography
ETCO2 (mmHg)a	33.7±6.8	39±6.7	<0.001
Slp2 (mmHg/L)a	192.2±68.1	305.7±133.2	<0.001
Slp3 (mmHg/L)a	28.6±12.7	37.1±15.5	0.034
Slp3/Vea	0.1±0.0	0.1±0.1	0.008
Ti/Te (s)a	0.6±0.1	0.6±0.2	0.420

Notes: All the values (mean) were calculated in patients with tomography sign present.

a Values expressed as mean ± standard deviation.

b Evaluated in 44 subjects who had expiration scans.

c Values expressed as median (min–max).

d Categorical variables (yes/no).

Abbreviations: HRCT, high-resolution computed tomography; PA, pulmonary artery; Ao, aorta; M, male; F, female; BMI, body mass index; SpO₂, peripheral oxygen saturation; BODE, Body mass index, airflow Obstruction, Dyspnea, and Exercise; MRC, Medical Research Council; O₂, oxygen; FVC, forced vital capacity; BD, bronchodilator; FEV₁, forced expiratory volume in 1 second; FEF_25%–75%, forced expiratory flow between 25% and 75% of FVC; 6MWD, 6-minute walked distance; ΔSpO₂, difference between final and initial peripheral oxygen saturation; ΔBorg, difference between final and initial Borg score of dyspnea; ETCO₂, level of carbon dioxide released at the end of expiration; Slp2, slope of phase 2; Slp3, slope of phase 3; V_e, expiratory volume; T_i, inspiratory time; T_e, expiratory time; min, minimum; max, maximum; Y, yes; N, no.

Table 5 Comparison of patients according to the presence or absence of air trapping on CT expiratory scans (N=44)

Variables	With air trapping (N=23)	Without air trapping (N=21)	P-value
Clinical variables
Age (years)a	64.9±8.1	65±8.5	0.970
Sex (M/F)b	13/10	16/5	0.170
Smoking (pack-years)a	46.4±37.9	44.6±40.7	0.990
BMI (kg/m^2)a	27.9±5.0	25.7±6.4	0.140
SpO2 (%)a	92±3.9	93.9±3.6	0.080
Exacerbations/yeara	0.8±0.5	0.7±0.4	0.270
BODEa	4.0±1.7	4.6±1.9	0.430
MRCa	2.6±0.9	2.8±0.9	0.790
Cough (Y/N)b	11/12	9/12	0.740
Secretion (Y/N)b	9/14	3/18	0.065
Use of oxygen (Y/N)b	7/16	5/16	0.620
Spirometry post-BD
FVC (L)a	2.0±0.6	2.1±0.6	0.710
FVC (% predicted)a	56±13.3	56.3±15	0.900
FEV1 (L)a	1.1±0.4	1.2±0.5	0.410
FEV1 (% predicted)a	40.6±14.1	41.6±14.9	0.940
FEV1/FVC (%)a	56.6±10.8	57.6±11.6	0.660
FEF25%–75% (% predicted)a	23.2±12.5	23.8±11.5	0.750
Six-minute walk test (6MWT)
6MWD (m)	390.4±92.1	385.8±87.2	0.840
6MWD (% predicted)^Citation22	0.8±0.2	0.8±0.2	1.00
ΔSpO2	4.8±4.2	3.2±3.7	0.250
ΔBorg	3.0±2.8	2.6±2.7	0.760
Volumetric capnography
ETCO2 (mmHg)a	39.1±7.3	34.7±6.3	0.046
Slp2 (mmHg/L)a	286±116.9	225.5±102	0.082
Slp3 (mmHg/L)a	37±13.1	28.4±17.9	0.016
Slp3/Vea	0.1±0.1	0.1±0.1	0.037
Ti/Te (s)a	0.6±0.2	0.6±0.1	0.640

Notes:

a Values expressed as mean ± standard deviation.

b Categorical variables.

Abbreviations: M, male; F, female; BMI, body mass index; SpO₂, peripheral oxygen saturation; BODE, Body mass index, airflow Obstruction, Dyspnea, and Exercise; MRC, Medical Research Council; O₂, oxygen; FVC, forced vital capacity; BD, bronchodilator; FEV₁, forced expiratory volume in 1 second; FEF_25%–75%, forced expiratory flow between 25% and 75% of FVC; 6MWD, 6-minute walked distance; ΔSpO₂, difference between final and initial peripheral oxygen saturation; ΔBorg, difference between final and initial Borg score of dyspnea; ETCO₂, level of carbon dioxide released at the end of expiration; Slp2, slope of phase 2; Slp3, slope of phase 3; V_e, expiratory volume; T_i, inspiratory time; T_e, expiratory time; Y, yes; N, no.

Table 6 Correlation between CT score and spirometric variables, 6MWT and volumetric capnography

Category	Bronchiectasis (0–30)	Peribronchial thickening (0–18)	Tree-in-bud/mucoid plug (0–12)	Air trapping (0–6)	Bullae (0–3)	Emphysema (0–6)	CT total score (0–77)
Spirometry
FVC (L)	r=0.05	r=−0.08	r=−0.04	r=−0.17	r=0.06	r=−0.01	r=−0.09
	P=0.71	P=0.54	P=0.73	P=0.25	P=0.66	P=−0.91	P=0.48
FVC (% predicted value)	r=0.12	r=0.007	r=−0.18	r=−0.12	r=−0.16	r=0.04	r=−0.01
	P=321	P=0.96	P=0.16	P=0.27	P=0.21	P=0.77	P=0.92
FEV1 (L)	r=0.04	r=−0.12	r=−0.08	r=−0.17	r=−0.20	r=−0.15	r=−0.19
	P=0.74	P=0.34	P=0.51	P=0.27	P=0.12	P=0.22	P=0.12
FEV1 (% predicted value)	r=0.09	r=−0.06	r=−0.11	r=−0.06	r=−0.32	r=−0.13	r=−0.11
	P=0.48	P=0.64	P=0.37	P=0.70	P=0.009	P=0.29	P=0.37
FEV1/FVC	r=−0.012	r=−0.12	r=0.04	r=−0.02	r=−0.46	r=−0.29	r=−0.19
	P=0.92	P=0.32	P=0.72	P=0.91	P=0.0001	P=0.02	P=0.12
FEF25%–75% (L)	r=0.02	r=−0.08	r=−0.09	r=−0.08	r=−0.35	r=−0.14	r=−0.15
	P=0.84	P=0.53	P=0.47	P=0.60	P=0.004	P=0.27	P=0.24
ΔFEV1	r=0.06	r=−0.006	r=−0.20	r=−0.03	r=0.05	r=0.03	r=0.02
	P=0.66	P=0.96	P=0.11	P=0.85	P=0.68	P=0.79	P=0.89
Volumetric capnography
Respiratory frequency (BPM)	r=0.07	r=0.14	r=0.14	r=0.04	r=−0.16	r=−0.06	r=0.07
	P=0.56	P=0.27	P=0.27	P=0.80	P=0.21	P=0.63	P=0.59
VCO2	r=−0.21	r=0.006	r=0.14	r=−0.01	r=−0.002	r=−0.02	r=−0.09
	P=0.09	P=0.97	P=0.28	P=0.93	P=0.98	P=0.85	P=0.44
ETCO2	r=0.04	r=0.09	r=0.06	r=0.38	r=−0.19	r=−0.55	r=−0.13
	P=0.78	P=0.45	P=0.65	P=0.009	P=0.11	P≤0.0001	P=0.29
Slp2 (mmHg/L)	r=−0.003	r=−0.04	r=−0.07	r=0.24	r=−0.36	r=−0.55	r=−0.27
	P=0.99	P=0.77	P=0.59	P=0.12	P=0.003	P≤0.0001	P=0.03
Slp3 (mmHg/L)	r=0.24	r=0.22	r=0.05	r=0.34	r=−0.16	r=−0.19	r=0.19
	P=0.05	P=0.08	P=0.69	P=0.02	P=0.22	P=0.14	P=0.13
Slp3/Ve	r=0.02	r=0.15	r=−0.005	r=0.23	r=−0.23	r=−0.26	r=0.07
	P=0.13	P=0.22	P=0.97	P=0.13	P=0.06	P=0.04	P=0.59
Te	r=−0.06	r=−0.12	r=−0.17	r=0.04	r=0.19	r=0.09	r=−0.03
	P=0.66	P=0.35	P=0.17	P=0.81	P=0.14	P=0.46	P=0.84
Ti/Te	r=0.05	r=−0.02	r=0.17	r=−0.10	r=−0.15	r=−0.14	r=−0.11
	P=0.71	P=0.84	P=0.18	P=0.50	P=0.24	P=0.26	P=0.36
Tobin	r=0.09	r=0.13	r=0.06	r=0.05	r=−0.23	r=−0.18	r=0.009
	P=0.47	P=0.29	P=0.65	P=0.73	P=0.06	P=0.15	P=0.94

Abbreviations: CT, computed tomography; 6MWT, 6-minute walk test; FVC, forced vital capacity; FEV₁, forced expiratory volume in 1 second; FEF_25%–75%, forced expiratory flow between 25% and 75% of FVC; BPM, breaths per minute; ETCO₂, level of carbon dioxide released at the end of expiration; Slp2, slope of phase 2; Slp3, slope of phase 3; V_e, expiratory volume; T_i, inspiratory time; T_e, expiratory time.

VeronezLMoreiraMMPereiraMCVolumetric capnography for the evaluation of pulmonary disease in adult patients with cystic fibrosis and noncystic fibrosis bronchiectasisLung2010188326326820049470

 PubMed Web of Science ®Google Scholar

EnrightPLSherrillDLReference equations for the six-minute walk in healthy adultsAm J Respir Crit Care Med19981585 Pt 1138413879817683

 PubMed Web of Science ®Google Scholar