From the Guidelines
Lung elasticity and resistance are critical components that determine the effectiveness of breathing, with elasticity referring to the lungs' ability to stretch and recoil, and resistance describing the opposition to airflow through the respiratory tract. The most recent and highest quality study, 1, highlights the importance of understanding these properties in the context of chronic obstructive pulmonary disease (COPD). According to this study, the hallmark pathophysiological features of COPD include small airway luminal narrowing, caused by inflammation and remodelling, and small airway collapse due to the loss of supporting alveolar attachments. There is also destruction of peripheral airways and parenchyma, with the latter reducing the elastic recoil of the lungs during expiration. Collectively, these features cause increased small airway resistance, reduced expiratory flow, and gas trapping on expiration. Key factors influencing lung elasticity and resistance include:
- Destruction of elastic tissue in emphysema, reducing the lungs' recoil ability
- Excessive scarring in pulmonary fibrosis, decreasing elasticity and making the lungs stiff
- Airway narrowing from bronchospasm, inflammation, or mucus accumulation in diseases like asthma or chronic bronchitis, significantly increasing resistance
- The role of surfactant in reducing surface tension and making breathing easier Understanding the relationship between lung elasticity and resistance is essential for explaining why certain respiratory diseases cause specific symptoms and for guiding treatment approaches aimed at improving airflow and reducing the work of breathing, as noted in 1 and 1. The most effective approach to managing COPD and other respiratory diseases involves addressing both lung elasticity and resistance, through a combination of pharmacological and non-pharmacological interventions, with the goal of improving morbidity, mortality, and quality of life. In clinical practice, this may involve the use of bronchodilators, anti-inflammatory medications, and pulmonary rehabilitation programs, as well as lifestyle modifications such as smoking cessation and regular exercise. By prioritizing the management of lung elasticity and resistance, healthcare providers can help patients with respiratory diseases breathe more easily and improve their overall health outcomes.
From the Research
Lung Elasticity and Resistance
- Lung elasticity refers to the ability of the lungs to expand and contract during breathing, while resistance refers to the opposition to airflow in the airways 2.
- Reduced lung elastic recoil and increased lung compliance have been observed in patients with asthma, which can lead to fixed airflow obstruction (FAO) 2.
- FAO in asthma occurs despite optimal inhaled treatment and no smoking history, and remains a significant problem, particularly with increasing age and duration of asthma 2.
Factors Affecting Lung Elasticity and Resistance
- Increased lung compliance and loss of lung elastic recoil relate to airflow obstruction in older non-smoking asthmatic subjects, independent of ageing 2.
- Respiratory system resistance at 5 Hz (Rrs5) and respiratory system reactance at 5 Hz (Xrs5) are measures of lung resistance and reactance, which can be used to assess lung function 2.
- Forced expiratory volume in 1 s/forced vital capacity (FEV1/FVC) is a measure of lung function that can be used to diagnose and monitor respiratory diseases such as COPD and asthma 3, 4, 5.
Treatment Options for COPD and Asthma
- Bronchodilators, including long-acting β2-agonists and long-acting muscarinic antagonists, are the mainstay for treatment of patients with COPD to prevent exacerbations or reduce symptoms 3.
- Formoterol is a highly selective and potent β2-agonist that relaxes airway smooth muscle to significantly improve lung function, and is an effective and safe treatment option for patients with moderate to severe COPD 3, 6.
- Combination therapy with inhaled corticosteroids and long-acting β2-agonists, such as budesonide/formoterol, can be more effective than monotherapy in preventing exacerbations and improving lung function in patients with COPD and asthma 4, 5.