Thitiporn Suwatanapongched MD, Abstract Co-Author: Nothing to Disclose

Chayanin Thongprasert MD, Presenter: Nothing to Disclose

Siwaporn Lertpongpiroon MD, Abstract Co-Author: Nothing to Disclose

Sumalee Kiatboonsri MD, Abstract Co-Author: Nothing to Disclose

To determine the frequency and severity of expiratory air trapping (ATexp) during acute asthmatic attack (AAA), by using a semi-quantitative CT scoring method, and to evaluate the relationship between the CT score and bronchial wall thickness (BWT), expiratory bronchial collapse (BCexp) and clinical characteristics.

The frequency, pattern and extent grading of ATexp and the degree of BWT and BCexp (% reduction in bronchial cross-sectional area or luminal width) were retrospectively determined from the twelve zones of the six-chosen levels of 36 paired inspiratory-expiratory CT performed during AAA. Pearson correlations between the total-ATexp score (summed scores of pattern grading x extent grading) with BWT, BCexp and clinical characteristics and performance of the score under receiver-operating-characteristic (ROC) analysis were calculated.

All patients had ATexp. The total-ATexp score (mean±SD, 110.1±43.4; range, 8-166) was higher in the lower lung zones (p=0.002) and was correlated with patient’s age (r=0.331, p=0.049), BMI (r=-0.375, p=0.024), %predicted peak expiratory flow rate (PEFR) (r=-0.332, p=0.048), and BWT (r=0.338, p=0.048), but was not correlated with BCexp. Patients with age >60 years (p=0.025), BMI <28 kg/m2 (p=0.039), and severe AAA (p=0.039) had higher total-ATexp scores. With area under ROC curve of 0.724 (95% CI, 0.582-0.866), the total-ATexp score of 110 could distinguish severe AAA (PEFR <60 %predicted) from less-severe AAA (sensitivity, 92.9%; specificity, 59.1%).

ATexp invariably occurred during AAA with a greater severity in the lower lungs and in patients with age >60 years, BMI <28 kg/m2, and severe AAA. The total-ATexp was not correlated with BCexp.

The findings suggested the role of small airways in AAA. Hence, newly developed drugs or devices enabling drugs to target the small airways should have benefits in these patients.

Suwatanapongched, T, Thongprasert, C, Lertpongpiroon, S, Kiatboonsri, S, Determination of Expiratory Air-trapping and Expiratory Collapse of the Large- and Medium-sized Bronchi during the Episode of Acute Asthmatic Attack.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14003497.html