What are the causes of pulmonary restriction (pulmonary function test abnormality)?

From the Guidelines

Pulmonary restriction is a serious condition that requires prompt diagnosis and treatment to prevent complications and maintain optimal respiratory function, and the most recent and highest quality study 1 recommends routine evaluation and monitoring of pulmonary function in patients with osteogenesis imperfecta. Pulmonary restriction is a breathing disorder characterized by reduced lung expansion and decreased total lung capacity. It occurs when the lungs cannot fully expand during inhalation, resulting in decreased lung volumes and impaired gas exchange. Common causes include obesity, chest wall abnormalities, neuromuscular diseases, interstitial lung diseases, and pleural disorders. Patients typically experience shortness of breath, especially during physical activity, decreased exercise tolerance, and rapid, shallow breathing.

Diagnosis and Treatment

Diagnosis involves pulmonary function tests showing reduced lung volumes with a preserved FEV1/FVC ratio. Treatment focuses on addressing the underlying cause, such as weight loss for obesity-related restriction, medications for inflammatory conditions, oxygen therapy for hypoxemia, pulmonary rehabilitation to improve breathing efficiency, and in some cases, surgical interventions.

• The severity of pulmonary restriction varies widely depending on the cause, with some conditions being reversible while others may progressively worsen over time.
• Early diagnosis and appropriate management are essential to prevent complications and maintain optimal respiratory function.
• According to the study 1, breathing impairments in osteogenesis imperfecta are due to the thorax, including bones, lungs, airways, and respiratory muscles, and it is recommended to use guides and motivators for pulmonary tests in children.
• The study 1 also highlights the importance of interpreting pulmonary function tests critically, especially in patients with osteogenesis imperfecta, as artifactual values of FVC higher than expected can lead to potential misinterpretation and overestimation of real pulmonary function.
• Additionally, the study 1 suggests that pulmonary rehabilitation programs should address body composition abnormalities, which are frequently present and underrecognized in chronic lung disease, and intervention may be in the form of caloric, physiologic, pharmacologic, or combination therapy. In summary, pulmonary restriction requires a comprehensive approach to diagnosis and treatment, taking into account the underlying cause and individual patient needs, and the most recent and highest quality study 1 provides valuable recommendations for lung function guidance in osteogenesis imperfecta.

From the Research

Definition and Diagnosis of Pulmonary Restriction

• Pulmonary restriction refers to a condition where the lungs are unable to expand fully, resulting in reduced lung volume and capacity for gas exchange 2.
• The diagnosis of pulmonary restriction can be made using spirometric measurements, such as Forced Vital Capacity (FVC) and Forced Expiratory Volume in one second (FEV1), as well as lung volume measurements 2.

Spirometric Criteria for Diagnosing Pulmonary Restriction

• A study found that the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of FVC<lower limit of normal (LLN) to diagnose restriction based on lung volume measurement criteria were 88.6%, 56.8%, 39.9%, and 93.9%, respectively 2.
• The same study found that the sensitivity, specificity, PPV, and NPV of FVC<LLN and FEV1/FVC>or=normal to diagnose restriction based on lung volume criteria were 72.4%, 87.1%, 64.4%, and 90.7%, respectively 2.

Pulmonary Rehabilitation and Restrictive Lung Diseases

• Pulmonary rehabilitation is a multidisciplinary treatment that includes exercise training, self-management education, and psychosocial and nutritional intervention, and is now a standard of care for chronic obstructive pulmonary disease (COPD) and other chronic respiratory diseases 3, 4.
• However, the evidence on pulmonary rehabilitation for restrictive lung diseases is limited, and more research is needed to determine its effectiveness in these conditions 3, 4.

Imaging Techniques for Evaluating Pulmonary Restriction

• High-resolution CT scans can be used to evaluate the extent and pattern of fibrosis in patients with pulmonary sarcoidosis, and can provide valuable information on pulmonary function and survival 5.
• A study found that the presence of basal subpleural honeycombing on HRCT scans was associated with worse pulmonary function and worse survival in patients with stage IV pulmonary sarcoidosis 5.