A previously underrecognized condition, expiratory central airway collapse (ECAC), is gaining attention for its potential to mimic asthma and chronic obstructive pulmonary disease (COPD), leading to misdiagnosis and delayed appropriate treatment. This dynamic airway obstruction occurs when the central airways—the trachea and main bronchi—narrow during exhalation, hindering airflow. While not a new phenomenon, recent research is shedding light on the prevalence, diagnosis, and management of ECAC, particularly in individuals with a history of respiratory symptoms.
The challenge lies in differentiating ECAC from more common respiratory illnesses. Symptoms like shortness of breath, wheezing, and cough can overlap significantly, making accurate diagnosis difficult without specialized testing. ECAC is thought to be caused by a combination of factors, including weakened airway support structures and increased external pressure during forceful exhalation. This can be exacerbated by conditions like obesity, age-related changes in connective tissue, and certain anatomical predispositions.
Understanding the mechanics of ECAC is crucial. Unlike asthma or COPD, where the obstruction originates from within the airways due to inflammation or mucus buildup, ECAC is an external compression. During normal breathing, the airways remain open due to the support of cartilage and surrounding tissues. However, in individuals with ECAC, these support structures may be insufficient, causing the airways to collapse inward during the increased pressure of exhalation. This collapse restricts airflow, leading to the characteristic symptoms.
Traditional pulmonary function tests, while helpful in identifying airflow obstruction, often fail to pinpoint ECAC as the underlying cause. Spirometry, for example, may present reduced expiratory flow rates, but it doesn’t reveal the specific mechanism of obstruction. More advanced imaging techniques are needed for accurate diagnosis.
Dynamic CT scans, performed during active breathing, are considered the gold standard for identifying ECAC. These scans capture images of the airways in motion, allowing clinicians to visualize the collapse during exhalation. The degree of collapse can be quantified, providing valuable information for assessing the severity of the condition.
Researchers are also exploring the use of other imaging modalities, such as dynamic MRI, but CT scans currently offer the best resolution and detail for visualizing the central airways. The key is to capture the airways *during* the act of breathing, not just in a static image. This dynamic assessment is what differentiates ECAC diagnosis from standard imaging.
Who is at Risk for Expiratory Central Airway Collapse?
While ECAC can affect individuals of any age, certain populations are more susceptible. Obesity is a significant risk factor, as excess weight can increase external pressure on the airways. A 2025 study highlighted in the New England Journal of Medicine demonstrated a strong correlation between body mass index (BMI) and the severity of ECAC .
Older adults are also at increased risk due to age-related changes in connective tissue, which can weaken airway support structures. Individuals with certain anatomical features, such as a narrow trachea or a prominent sternum, may also be predisposed to ECAC. Those with a history of frequent forceful coughing or straining may contribute to the development of the condition over time.
It’s important to note that ECAC doesn’t necessarily develop in isolation. It can coexist with other respiratory conditions, such as asthma and COPD, complicating the diagnostic picture. In these cases, it’s crucial to determine the relative contribution of each condition to the patient’s symptoms.
Treatment Options and Future Directions
Currently, there is no single, definitive treatment for ECAC. Management strategies focus on alleviating symptoms and improving airflow. Positive airway pressure (PAP) therapy, such as continuous positive airway pressure (CPAP) or bilevel positive airway pressure (BiPAP), is often used to splint the airways open during exhalation. This external support can prevent or reduce the degree of collapse, improving breathing.
Weight loss, when appropriate, can also be beneficial in reducing external pressure on the airways. In some cases, surgical interventions may be considered, such as tracheostomy or airway stenting, but these are typically reserved for severe cases that don’t respond to conservative management.
Recent advancements in respiratory medicine have also led to the development of new therapies targeting airway support. For example, research is underway to explore the use of airway-strengthening medications and minimally invasive procedures to reinforce airway structures. The efficacy and safety of an mRNA-based RSV PreF vaccine in older adults has also been demonstrated, potentially reducing the incidence of RSV-associated lower respiratory tract disease, which could exacerbate ECAC symptoms .
The Importance of Accurate Diagnosis
Misdiagnosis of ECAC as asthma or COPD can lead to ineffective treatment and prolonged suffering. Patients may be prescribed bronchodilators or inhaled corticosteroids, which address airway inflammation and constriction but do little to alleviate the external compression caused by ECAC.
clinicians should consider ECAC in the differential diagnosis of patients with unexplained respiratory symptoms, particularly those with risk factors such as obesity or age-related changes. A high index of suspicion, coupled with appropriate imaging studies, is essential for accurate diagnosis and timely intervention.
As research continues to unravel the complexities of expiratory central airway collapse, we can expect to see further refinements in diagnostic techniques and treatment strategies. The next major update on ECAC research is anticipated at the American Thoracic Society International Conference in May 2026, where preliminary results from several ongoing clinical trials will be presented.
Do you have experience with respiratory conditions or know someone who might benefit from learning more about expiratory central airway collapse? Share your thoughts and questions in the comments below.
Disclaimer: This article is for informational purposes only and should not be considered medical advice. Please consult with a qualified healthcare professional for any health concerns or before making any decisions related to your health or treatment.
