Emphysema definition
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Understanding Emphysema: Definition and Key Characteristics
Definition of Emphysema
Emphysema is a chronic lung condition characterized by the abnormal, permanent enlargement of airspaces distal to the terminal bronchiole, accompanied by the destruction of their walls without obvious fibrosis . This definition, which has been widely accepted since a 1984 workshop funded by the National Heart, Lung, and Blood Institute, emphasizes the anatomical changes in the lung tissue.
Anatomical and Morphological Aspects
The disease primarily affects the gas-exchanging parts of the lung, known as the acinus, leading to the destruction of respiratory tissue. Emphysema can be classified based on the part of the acinus that is predominantly involved. For instance, proximal acinar emphysema affects the respiratory bronchioles, while panacinar emphysema involves the entire acinus uniformly. Distal acinar emphysema, on the other hand, primarily affects the alveolar ducts and sacs.
Pathophysiology and Symptoms
Emphysema results in the loss of elasticity in lung tissue due to the destruction of structures supporting the alveoli and the capillaries feeding them. This leads to the collapse of small airways during exhalation, trapping air in the lungs and impeding airflow. Common symptoms include shortness of breath, hyperventilation, and an expanded chest.
Diagnostic Criteria
Diagnosis of emphysema is typically achieved through high-resolution CT scans of the thorax, which can reveal the characteristic enlargement and destruction of distal airspaces. Advanced forms of the disease are associated with severe respiratory insufficiency. Additionally, the presence of giant bullae, which are large air-filled spaces, can be indicative of isolated forms of emphysema.
Historical and Evolving Definitions
Historically, the term "emphysema" has been used to describe various morbid states of the lung, leading to confusion among medical professionals. However, the consensus has shifted towards defining emphysema strictly in morphological terms, focusing on the destruction of alveolar walls and the permanent enlargement of airspaces. This shift has helped standardize the diagnosis and understanding of the disease.
Conclusion
Emphysema is a chronic lung disease marked by the permanent enlargement of airspaces and the destruction of their walls, leading to significant respiratory impairment. Understanding its anatomical and morphological characteristics is crucial for accurate diagnosis and effective management. Despite advancements in medical imaging and diagnostic criteria, emphysema remains a complex condition requiring ongoing research and clinical attention.
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