From the Guidelines
Trapped lung is primarily caused by the formation of a fibrous peel or membrane over the visceral pleura, preventing the lung from fully expanding, and can occur as a result of pleural thickening, proximal endobronchial obstruction, or chronic atelectasis, as noted in the study by 1. The condition typically develops as a complication of long-standing pleural effusions, particularly when fluid remains in the pleural space for extended periods. Common causes include:
- Malignant pleural effusions
- Complicated parapneumonic effusions
- Hemothorax
- Empyema
- Tuberculosis
- Previous thoracic surgeries Inflammation in the pleural space triggers fibroblast proliferation and collagen deposition, creating a restrictive membrane that limits lung expansion, as discussed in the study by 1. Recurrent thoracentesis procedures can also contribute to trapped lung development. Unlike pleural effusions caused by active disease processes, trapped lung represents a mechanical problem where the lung cannot expand to fill the pleural space even after fluid removal. The diagnosis is often made when patients experience chest pain during thoracentesis or when imaging shows persistent pleural space despite drainage attempts. Treatment depends on symptom severity and may include observation for mild cases or surgical decortication for severe symptoms, though there is no medication that directly treats the underlying fibrotic process, as mentioned in the study by 1 and further discussed in the study by 1. It is essential to note that the management of trapped lung is complex and requires a comprehensive approach, taking into account the underlying cause and the patient's overall condition. In some cases, indwelling pleural catheters or pleuroperitoneal shunts may provide symptomatic relief, as suggested in the study by 1. However, the choice of treatment should be individualized and based on the latest evidence and clinical guidelines. Overall, trapped lung is a serious condition that requires prompt diagnosis and treatment to improve patient outcomes and quality of life.
From the Research
Causes of Trapped Lung
The causes of trapped lung can be attributed to various factors, including:
- Fibrinous or granulomatous pleuritis, which can lead to a restricting fibrous visceral pleural peel, preventing the lung from expanding and filling the thoracic cavity 2
- Inadequately treated parapneumonic effusion, which is the most common cause of trapped lung today 2
- Cardiac surgery, chest trauma, and other inflammatory processes involving the pleura, which can also contribute to the development of trapped lung 2
- Malignant pleural effusions and inflammatory pleural diseases, such as pleural infection (e.g. empyema and complicated parapneumonic effusion) and noninfectious fibrinous pleuritis, which can cause unexpandable lung due to pleural disease 3
- Remote pleural inflammation resulting in a mature fibrous membrane overlying the visceral pleura, preventing full expansion of the lung, also known as defective healing of the pleural space 3
- Pneumothorax, which can cause trapped lung, although this is rarely reported 4
Associated Conditions
Trapped lung can be associated with various conditions, including:
- Chronic, benign, unilateral pleural effusion 2
- Malignant pleural effusion 5
- Breast cancer, which is a common diagnosis in patients with trapped lung syndrome 5
- Dyspnea, which is a significant symptom of trapped lung, impacting the patient's quality of life 5, 6
Diagnosis and Treatment
The diagnosis of trapped lung requires documentation of chronicity and stability, and the absence of an active inflammatory or malignant pleural process, bronchial obstruction, or severe underlying lung disease 2. Treatment options include thoracoscopic decortication, which is the only available therapy for trapped lung 2, and pleural catheter insertion, which can provide effective palliation for malignant pleural effusion associated with trapped lung syndrome 5.