Dyspnoea – Shortness of Breath: Causes, Symptoms & Treatment

What is Dyspnoea?

Dyspnoea (from Greek: dys = difficult, pnoe = breath) is the subjective sensation of breathlessness, shortness of breath, or laboured breathing. Patients often describe it as not being able to get enough air, or as an uncomfortable effort to breathe. Dyspnoea is not a disease in itself but a symptom that may indicate a wide range of underlying medical conditions.

Causes

Dyspnoea can be triggered by disorders of various organ systems. The most common causes are grouped as follows:

Pulmonary Causes (Lungs)

• Asthma: Episodes of breathlessness caused by airway narrowing
• Chronic Obstructive Pulmonary Disease (COPD): Progressive limitation of airflow
• Pulmonary Embolism: Blockage of a pulmonary artery by a blood clot
• Pneumonia: Inflammatory changes in lung tissue
• Pneumothorax: Air entering the pleural space causing lung collapse

Cardiac Causes (Heart)

• Heart Failure: Reduced pumping capacity of the heart leads to fluid accumulation in the lungs
• Myocardial Infarction (Heart Attack): Acute disruption of blood supply to the heart
• Cardiac Arrhythmias: Irregular heartbeat impairing oxygen delivery

Other Causes

• Anaemia: Reduced oxygen-carrying capacity of the blood
• Obesity and overweight
• Anxiety disorders and panic attacks
• Poisoning or metabolic imbalances

Symptoms and Associated Findings

While dyspnoea itself is a symptom, it may be accompanied by other signs that point to the underlying cause:

• Tightness or pressure in the chest
• Coughing or wheezing (stridor)
• Bluish discolouration of the lips or fingernails (cyanosis)
• Rapid heart rate (tachycardia)
• Dizziness or altered consciousness
• Leg swelling in cases of heart failure

Classification

The severity of dyspnoea is commonly assessed using the NYHA Classification (New York Heart Association), especially in cardiac conditions:

• NYHA Class I: No symptoms during ordinary physical activity
• NYHA Class II: Slight limitation during more strenuous activity
• NYHA Class III: Marked limitation even during mild activity
• NYHA Class IV: Breathlessness at rest

A distinction is also made between acute dyspnoea (sudden onset) and chronic dyspnoea (persisting over weeks or months).

Diagnosis

A variety of diagnostic tools are used to identify the cause of dyspnoea:

• Medical history and physical examination: Assessment of onset, duration, triggers, and associated symptoms
• Spirometry (lung function test): Measurement of breathing capacity and airflow
• Blood gas analysis: Measurement of oxygen and carbon dioxide levels in the blood
• Chest X-ray: Assessment of the heart and lungs
• ECG (Electrocardiogram): Evaluation of cardiac function
• Echocardiography: Ultrasound examination of the heart
• Blood tests: e.g. D-dimers for suspected pulmonary embolism, full blood count for anaemia

Treatment

Treatment of dyspnoea is always directed at the underlying cause:

• Bronchodilators and corticosteroids for asthma or COPD
• Diuretics for heart failure to reduce fluid buildup
• Anticoagulants for pulmonary embolism
• Antibiotics for pneumonia
• Oxygen therapy when blood oxygen levels are significantly reduced
• Breathing exercises and pulmonary rehabilitation for chronic conditions

In cases of acute, severe breathlessness, immediate medical attention is required. In an emergency, call 911 (US) or your local emergency number.

When to See a Doctor?

Dyspnoea should always be evaluated by a physician, especially if it occurs suddenly, is present at rest, is accompanied by chest pain or loss of consciousness, or is progressively worsening. Acute dyspnoea is a medical emergency.

References

1. World Health Organization (WHO): Chronic respiratory diseases. Available at: https://www.who.int/news-room/fact-sheets/detail/chronic-obstructive-pulmonary-disease-(copd)
2. Loscalzo, J. et al.: Harrison's Principles of Internal Medicine, 21st Edition. McGraw-Hill Education, 2022.
3. Parshall, M. B. et al.: An Official American Thoracic Society Statement: Update on the Mechanisms, Assessment, and Management of Dyspnea. American Journal of Respiratory and Critical Care Medicine, 2012; 185(4): 435-452.