Prevalence of Tracheal Collapse in an Emphysema Cohort as Measured With End-expiration CT

Rationale and Objectives

To retrospectively investigate the prevalence of tracheal collapse in an emphysema cohort. The occurrence of a large degree of tracheal collapse may have important implications for the clinical management of respiratory symptoms and air trapping in patients with emphysema.

Materials and Methods

Paired full-inspiratory and end-expiratory thin-section volumetric computed tomographic scans were available for 1071 long-term smokers with clinically and physiologically confirmed emphysema. The percentage reduction in the cross-sectional tracheal luminal area from full-inspiration to end-expiration was automatically computed at 2.5-mm intervals along the centerline of the trachea using customized software.

Results

Maximal tracheal collapse did not follow a normal distribution in the emphysema cohort ( P < .0001, skewness/kurtosis tests for normality); the median collapse was 18% (intraquartile range, 11%–30%). Statistically significant differences were found in the distribution of maximal collapse by gender ( P < .005, Wilcoxon rank sum test). Overall, 10.5% of men and 17.1% of women showed evidence of tracheomalacia on the basis of the criterion of a reduction of 50% or greater in cross-sectional tracheal luminal area at end-expiration.

Conclusion

This study offers insights into the prevalence of tracheal collapse in a cohort of patients with emphysema; future work is needed to determine the possible relationship between tracheal collapse and air trapping in subjects with emphysema.

A high degree of tracheal collapse is associated with tracheomalacia, which can be diagnosed in both children and adults ( ). Tracheomalacia can be congenital or acquired; associated symptoms include dyspnea, wheeze, cough, sputum production, and hemoptysis. Investigators have suggested a correlation between tracheobronchomalacia and chronic inflammation and irritants, such as cigarette smoke ( ). Because of its nonspecific symptoms, it may be an underdiagnosed condition.

Bronchoscopy is considered the gold standard for diagnosing tracheobronchomalacia ( ); a reduction in the cross-sectional luminal area of the trachea greater than 50% is considered indicative of tracheomalacia. The reported prevalence of the disease has ranged from 1% to 13% for all subjects referred for bronchoscopic evaluation ( ) and as high as 23% for subjects with histories of chronic bronchitis ( ). The condition is commonly associated with increased age and chronic obstructive pulmonary disease ( ).

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Materials and methods

Patients

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CT Scanning Protocol

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Measurement of Tracheal Collapse

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Statistical Analysis

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Results

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Table 1

Summary of Measurements

Variable All Subjects ⁎ Men Women_P_ Value † (n = 1071) (n = 267) (n = 164) Age (y) — 64 ± 7 62 ± 8 <0.005 Measurement LA TLC (mm 2 ) 268 ± 64 296 ± 60 221 ± 38 <0.001 LA RV (mm 2 ) 224 ± 74 253 ± 70 179 ± 54 <0.001 ΔLA avg (%) 16 ± 19 14 ± 17 19 ± 20 <0.03 ΔLA max (%) 25 ± 20 22 ± 19 28 ± 21 <0.003 Subjects with maximal tracheal collapse ≥28% 27.7% (297) 21.3% (57) 35.4% (58) ≥50% 13.4% (143) 10.5% (28) 17.1% (28) ≥70% 5.1% (55) 4.9% (13) 6.7% (11)

avg: average; LA: luminal area; max: maximal; RV: residual volume; TLC: total lung capacity.

Data are expressed as mean ± SD or as percentage (number). Significant differences were found between the genders.

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Discussion

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Conclusion

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References

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Prevalence of Tracheal Collapse in an Emphysema Cohort as Measured With End-expiration CT

Rationale and Objectives

Materials and Methods

Results

Conclusion

Materials and methods

Patients

CT Scanning Protocol

Measurement of Tracheal Collapse

Statistical Analysis

Results

Discussion

Conclusion

References

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