Is intrathoracic tracheal collapsibility correlated to clinical phenotypes and sex in patients with COPD?

Figures & data

Figure 1 Application of the proposed algorithms on the CT scans of a COPD patient.

Notes: For the sake of simplicity, the results (in red) are superimposed on a CT slice at about 1 cm above the carina (A–D) and at a lower level (E and F). Inspiratory CT slices are shown on the top row, whereas corresponding expiratory CT slices are on the bottom row. Panels A and B show the lung segmentation results employed for lung volume computation (delta volume =0.42). Panels C and D show trachea segmentation results used to measure tracheal collapsibility (35.8%). Panels E and F display the lung area with density values below −950 Hounsfield units in the inspiratory scan (%LAA_−950insp =5.6%) and below −910 Hounsfield units in the expiratory scan (%LAA_−910exp =4.1%).
Abbreviations: COPD, chronic obstructive pulmonary disease; CT, computed tomography.

Table 1 Anthropometric data, smoke exposure, pulmonary function, and presence of purulent sputum in 69 patients with COPD subdivided according to the predominant mechanism of air flow limitation and sex

	All patients (n=69)	Predominant airway phenotype (n=28)	Predominant emphysema phenotype (n=41)	P	Males (n=42)	Females (n=27)	P
Age (years)	67±9	66±8	66±10	NS	67±9	66±9	NS
BMI (kg/m^2)	25±4	27±4	24±4	<0.01	25±4	25±4	NS
Packs/year	42±23	35±24	47±22	<0.05	41±18	44±30	NS
FEV1%	61±27	73±23	53±26	<0.001	54±25	73±25	<0.01
FRC%	126±31	111±25	137±30	<0.001	131±33	120±24	NS
DLCO%	69±22	85±18	57±16	<0.0001	67±22	69±21	NS
Presence of purulent sputum	16/69	12/28	4/41	<0.01	11/42	5/27	NS

Notes: Data are mean ± SD for continuous variables and proportion for categorical values. Sputum purulence (entered as 1 when present and 0 when absent in the regression equation employed to phenotype patients with COPD). Packs/year is the mean number of daily cigarettes × number of years/20.

Abbreviations: BMI, body mass index (weight/height²); COPD, chronic obstructive pulmonary disease; DL_CO%, lung diffusing capacity for carbon monoxide (% of predicted); FEV₁%, forced expiratory volume in one second (% of predicted); FRC%, functional residual capacity (% of predicted); NS, not significant; SD, standard deviation.

Table 2 CT quantitative densitometric data, airway wall thickness, inspiratory–expiratory volume variation, and tracheal collapsibility in 69 patients with COPD subdivided according to the predominant mechanism of air flow limitation and sex

	All patients (n=69)	Predominant airway phenotype (n=28)	Predominant emphysema phenotype (n=41)	P	Males (n=42)	Females (n=27)	P
%LAA−950insp	11.7±13	5±5	16.3±15	<0.001	15±15	7±8	<0.05
%LAA−910exp	12.7±15	4±0.1	16.9±16	<0.01	16±16	7±11	<0.05
AWTPi10 (mm)	3.84±0.11	3.85±0.12	3.83±0.08	NS	3.87±0.09	3.80±0.09	<0.05
Delta volume	0.30±0.13	0.36±0.10	0.26±0.13	0.001	0.29±0.14	0.32±0.10	NS
Tracheal collapsibility (%)	14.4±12	19±13	11.4±10	<0.01	12±10	18±14	<0.05

Notes: Data are mean ± SD. Delta volume is ([inspiratory CT volume – expiratory CT volume]/inspiratory CT volume). Intrathoracic tracheal collapsibility (%) is ([inspiratory tracheal volume – expiratory tracheal volume]/inspiratory tracheal volume) ×100.

Abbreviations: AWTPi10 (mm), average wall thickness of an extrapolated airway with an internal perimeter of 10 mm; COPD, chronic obstructive pulmonary disease; CT, computed tomography; %LAA_−910exp, percentage of total lung area with attenuation values below −910 Hounsfield units at maximal expiration; %LAA_−950insp, percentage of total lung area with attenuation values below −950 Hounsfield units at maximal inspiration; NS, not significant; SD, standard deviation.

Table 3 Relationships of intrathoracic tracheal collapsibility with functional parameters indicative of airflow obstruction and hyperinflation

Intrathoracic tracheal collapsibility (%)	All patients (n=69)	Predominant airway phenotype (n=28)	Predominant emphysema phenotype (n=41)	Males (n=42)	Females (n=27)
FEV1%	r=0.44	r=0.39	r=0.37	r=0.32	r=0.49
	P<0.0001	P<0.05	P<0.05	P<0.05	P<0.05
FRC%	r= −0.43	NS	r= −0.54	r= −0.57	NS
	P<0.001		P<0.001	P<0.0001

Abbreviations: FEV₁%, forced expiratory volume in one second (% of predicted); FRC%, functional residual capacity (% of predicted); NS, not significant.

Table 4 Relationships of intrathoracic tracheal collapsibility with CT thresholds of lung inspiratory and expiratory density (%LAA_−950insp and %LAA_−910exp, respectively)

Intrathoracic tracheal collapsibility (%)	All patients (n=69)	Predominant airway phenotype (n=28)	Predominant emphysema phenotype (n=41)	Males (n=42)	Females (n=27)
%LAA−950insp	r= −0.43	r= −0.29	r= −0.43	r= −0.37	r= −0.54
	P<0.001	NS	P<0.01	P<0.05	P<0.01
%LAA−910exp	r= −0.57	r= −0.54	r= −0.37	r= −0.46	r= −0.57
	P<0.0001	P<0.01	P<0.05	P<0.01	P<0.0001

Abbreviations: CT, computed tomography; %LAA_–910exp, percentage of total lung area with attenuation values below −910 Hounsfield units at maximal expiration; %LAA_−950insp, percentage of total lung area with attenuation values below −950 Hounsfield units at maximal inspiration; NS, not significant.

Figure 2 Relationship of intrathoracic tracheal collapsibility with delta volume ([inspiratory CT volume – expiratory CT volume]/inspiratory CT volume) in 69 patients with COPD (A); 28 of whom were classified as being affected by predominant airway disease (B); 41 of whom were classified as being affected by predominant emphysema (C); males (D); and females (E).

Abbreviations: COPD, chronic obstructive pulmonary disease; CT, computed tomography.

Figure 3 Intrathoracic tracheal collapsibility in males and females with COPD according to predominant airway disease and predominant emphysema.

Note: **P<0.001 among females.
Abbreviation: COPD, chronic obstructive pulmonary disease.

Table 5 Predictive models of intrathoracic tracheal collapsibility by multivariate regression analysis of clinical history data (cough, wheezing, dyspnea), pulmonary function, and CT variables in the whole set of patients with COPD and in the examined subsets

Estimates of intrathoracic tracheal collapsibility	Predictors	Coefficients	R/R^2
All patients (n=69)	Delta volume	49.6	0.70/0.49
	%LAA−910exp	−0.217
	Intercept	2.176
Predominant airway phenotype (n=28)	Delta volume	75.26	0.60/0.36
	Intercept	−8.465
Predominant emphysema phenotype (n=41)	Delta volume	36.46	0.78/0.61
	BMI	0.684
	FRC	−0.089
	Intercept	−2.445
Males (n=42)	Delta volume	36.49	0.69/0.48
	BMI	0.648
	Intercept	−14.81
Females (n=27)	Delta volume	111.1	0.77/0.59
	Intercept	−17.96

Abbreviations: BMI, body mass index; COPD, chronic obstructive pulmonary disease; CT, computed tomography; FRC, functional residual capacity; %LAA_−910exp, percentage of total lung area with attenuation values below −910 Hounsfield units at maximal expiration.

BoisellePMTracheomalacia: functional imaging of the large airways with multidetector-row CTBoisellePMWhiteCSNew Techniques in Cardiothoracic ImagingNew York, NYInforma2007177185

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