General practitioners (GPs) often use spirometry to assess lung function. While this can be helpful in detecting abnormalities, it doesn’t always provide the full picture. Complex lung function testing, available through specialised respiratory clinics, provides a more detailed assessment and helps distinguish between different types of lung diseases.

Why Is Complex Lung Function Testing Prioritised?

Spirometry conducted in a GP setting can indicate whether there is an obstruction in airflow, but it lacks the specificity needed for a comprehensive diagnosis. Complex lung function testing offers:

• More detailed measurement of lung volumes, gas exchange, and airway resistance.
• The ability to differentiate between obstructive and restrictive lung diseases.
• A more precise diagnosis, leading to better treatment planning.

Understanding Restrictive vs Obstructive Lung Diseases

Lung diseases can broadly be categorised into two groups: restrictive lung diseases and obstructive lung diseases.

Restrictive Lung Diseases

These conditions limit the lungs’ ability to expand, reducing overall lung volume and making it difficult to take in a full breath. This results from lung stiffness, weakened respiratory muscles, or structural abnormalities. Common examples include pulmonary fibrosis, sarcoidosis, and pleural diseases.

Obstructive Lung Diseases

These conditions make it difficult to exhale all the air from the lungs due to narrowed or blocked airways. This leads to air trapping and increased effort in breathing out. Common examples include asthma, chronic obstructive pulmonary disease, (COPD), and bronchiectasis.

Lesser-Known Lung Conditions Causing Shortness of Breath

Lesser-Known Restrictive Lung Conditions

• Idiopathic Pulmonary Fibrosis (IPF): The cause of IPF is unknown, but it is linked to environmental and genetic factors. This lung condition causes progressive shortness of breath, dry cough, and fatigue, and can be diagnosed with high-resolution CT scans and complex lung function tests showing reduced lung volume and impaired gas exchange.
• Sarcoidosis: An inflammatory disease which causes granulomas in the lungs and other organs and can cause symptoms like breathlessness, dry cough, chest pain, and sometimes systemic symptoms like fever or weight loss. Diagnosis includes chest imaging, biopsy, and lung function testing revealing restrictive lung patterns.
• Hypersensitivity Pneumonitis: Caused by inhalation of organic particles (e.g., mould, bird droppings) triggering an immune response, creating symptoms of shortness of breath, flu-like symptoms, and chronic lung inflammation. This lung condition can be diagnosed by exposure history, lung imaging, and pulmonary function testing showing restrictive disease patterns.
• Pleural Effusion: This lung condition is caused by fluid accumulation in the pleural space due to infection, cancer, or heart failure. Symptoms include shortness of breath, chest pain, and reduced lung expansion, and it can be diagnosed with a chest X-ray, ultrasound, and thoracentesis (fluid analysis).

Lesser-Known Obstructive Lung Conditions

• Bronchiolitis Obliterans (BO): Often caused by inhalation of toxic fumes, viral infections, or post-lung transplant rejection. Symptoms include progressive shortness of breath, dry cough, and wheezing. Diagnosis of BO often involves complex lung function tests to reveal airflow obstruction that does not significantly improve bronchodilators.
• Alpha-1 Antitrypsin Deficiency (AATD): AATD is a genetic disorder leading to early-onset emphysema, causing progressive breathlessness, chronic cough, and frequent lung infections. AATD can be diagnosed by blood tests to measure alpha-1 antitrypsin levels which are confirmed by lung function testing.
• Tracheobronchomalacia (TBM): TBM is caused by weakening or collapse of the airway walls, often congenital or acquired from chronic inflammation. Symptoms include shortness of breath, a barking cough, and difficulty clearing secretions, and it is diagnosed by dynamic airway imaging combined with lung function testing.

Why Accurate Diagnosis Matters

Misdiagnosing shortness of breath as asthma or anxiety can lead to inadequate treatment and worsening of the actual underlying condition. Proper lung function testing ensures that the correct diagnosis is made, allowing for targeted treatment plans that address the root cause of the condition rather than just managing symptoms. Timely and appropriate interventions can also slow disease progression, leading to improved patient outcomes.

Lung Function Testing at North Brisbane Sleep and Thoracic

At North Brisbane Sleep and Thoracic, we offer comprehensive lung function testing to accurately diagnose and manage respiratory conditions. Our state-of-the-art testing includes:

• Diffusion capacity testing to assess gas exchange efficiency in the lungs.
• FeNO testing to evaluate nitric oxide gas levels, particularly useful for asthma diagnosis.
• Spirometry to determine the amount of air being inhaled and exhaled.
• Lung volumes testing using body plethysmography to measure total lung capacity and residual volume.

Our expert team ensures that patients receive accurate diagnoses and personalised treatment plans, improving overall respiratory health and quality of life.

Shortness of breath is a symptom with a broad range of potential causes beyond just asthma or anxiety. Lesser-known lung conditions, both obstructive and restrictive, can significantly impact respiratory health and require advanced diagnostic testing for accurate identification. Complex lung function testing plays a critical role in distinguishing between these conditions, leading to better patient care. If you or someone you know experiences unexplained shortness of breath, consulting a respiratory specialist for comprehensive lung function testing can make all the difference in receiving the right diagnosis and treatment.