Abstract Rationale Excessive dynamic airway collapse (EDAC) is a term applied to individuals identified with functional collapse of large airways. It is the anterior motion of the posterior tracheal membrane into the airway lumen ( 75%) during expiration. 1,2 This prospective study aimed to identify significant airway collapse (EDAC) in patients with audible wheezing and a negative upper airway exam. Methods This study included active-duty military patients aged 18 to 50 years with a primary complaint of exertional dyspnea with reported audible wheezing, and a negative upper airway exam. In addition, none of the participants had a confirmed diagnosis of obstructive lung disease. Each patient underwent an evaluation with complete pulmonary function testing (PFT), a dynamic HRCT scan with inspiratory/expiratory views, exercise laryngoscopy and exercise bronchoscopy to examine tracheal and large airway motion during cycle ergometry. Results Of the 16 participants enrolled, seven (43%) had EDAC. Among those with EDAC, six were male, and the average age was 38 years old; four (57%) exhibited audible wheezing during testing. Only one participant (14%) met the 75% diagnostic threshold on CT. When reviewing the EDAC patients, the average forced vital capacity (FVC), forced expiratory volume in one second (FEV1), and FEV1/FVC ratios were 95%, 87%, and 74%, respectively. Additionally, the average bronchodilator response and forced expiratory flow 25-75 were 5% and 71%. The average total lung capacity, residual volume, and diffusion capacity for carbon monoxide were 103%, 110%, and 94%. The impulse oscillometry data for all seven EDAC patients had increased R5 compared to the referenced values, and five out of the seven had increased R20s. We reviewed six of the EDAC patients’ CTs and measured the percent collapse at the level of the aorta by using the anterior-posterior diameter and calculating the area in both inspiratory and expiratory views, with an average collapse of 41%. Conclusion This study expanded on the original article by Weinstein et al. 3 by evaluating participants with reported wheezing during exertion and negative laryngoscopy. This small study highlights that EDAC is likely to have a higher prevalence (43%) in select groups including those without evidence of obstructive lung disease. It also demonstrates the need for further research to develop a more sensitive dynamic CT protocol for identifying patients with EDAC. This abstract is funded by: None
Springer et al. (Fri,) studied this question.