From the Guidelines
Decreased expiration in the lungs is primarily caused by obstructive lung diseases, such as chronic obstructive pulmonary disease (COPD), which can lead to airway collapse and reduced elastic recoil, as well as neuromuscular disorders that weaken respiratory muscles, as supported by the most recent study 1.
Causes of Decreased Expiration
The main causes of decreased expiration in the lungs include:
- Chronic obstructive pulmonary disease (COPD), which encompasses emphysema and chronic bronchitis
- Asthma, which causes bronchospasm and inflammation that narrows airways
- Bronchiectasis and cystic fibrosis, which can lead to airway obstruction
- Neuromuscular disorders, such as myasthenia gravis or muscular dystrophy, which can weaken respiratory muscles needed for effective exhalation
Pathophysiology
In COPD, destruction of alveolar walls (emphysema) or inflammation and mucus hypersecretion (chronic bronchitis) can lead to airway collapse during exhalation, as explained in 1. The loss of elastic recoil and the increased airway resistance can cause gas trapping and dynamic hyperinflation, leading to decreased expiration.
Treatment
Treatment depends on the underlying cause, but often includes:
- Bronchodilators, such as albuterol (2 puffs every 4-6 hours as needed) or long-acting agents like tiotropium (18mcg once daily)
- Anti-inflammatory medications, such as inhaled corticosteroids
- Oxygen therapy in severe cases These conditions impair exhalation because they either physically obstruct airways or reduce the elastic recoil of lung tissue that normally helps push air out during passive exhalation, as supported by 1 and 1.
From the Research
Causes of Decreased Expiration in Lungs
- Decreased expiration in lungs can be caused by various factors, including chronic obstructive pulmonary disease (COPD) which is characterized by expiratory flow limitation (EFL) due to progressive airflow obstruction 2.
- Other factors that may contribute to decreased expiration include acute exacerbations of COPD, which can result in increased airway resistance and inspiratory effort, further leading to dynamic hyperinflation 2.
- Environmental exposures, infections (viral and bacterial), or bronchial inflammation can also trigger COPD exacerbations, leading to worsening respiratory failure requiring mechanical ventilation (MV) 2, 3.
- In addition, the exacerbation of other respiratory diseases and non-respiratory diseases (e.g., heart failure, thromboembolism) can also contribute to decreased expiration 3.
- Asthma is another inflammatory disease characterized by airway obstruction, which can also lead to decreased expiration, especially in patients with overlap between COPD and asthma 4.
Mechanisms of Decreased Expiration
- The mechanisms that cause expiratory flow limitation (EFL) in COPD are central to understanding the physiopathology of the disease, and include dynamic inflation due to incomplete emptying of the lungs, resulting in auto-positive end-expiratory pressure (PEEP) or PEEPi 2.
- Airflow obstruction, which is a hallmark of COPD, can also lead to decreased expiration by increasing airway resistance and reducing lung function 5, 6.
- The use of inhaler therapy, counseling, and pharmacotherapy for smoking cessation, pulmonary rehabilitation, and treatment of comorbidities can help manage COPD and improve lung function, including expiration 5, 6.