What Is the Most Common Cause of Dyspnea?

Dyspnea is the medical term for shortness of breath or difficulty breathing.

What Are Symptoms of Dyspnea?

Dyspnea is shortness of breath or difficulty breathing and is a symptom of other medical conditions. Dyspnea may be acute (sudden dyspnea) or chronic (long-term dyspnea).

When a person feels short of breath, other symptoms may include:

• Inability to breathe deeply
• Sense you cannot inhale deeply
• Tightness in the chest
• Increased effort to breathe
• “Air hunger”
• Sensation of rapid, shallow breathing 
• Sense of heavy breathing
• Feeling of suffocation

Additional symptoms that may accompany dyspnea, depending on the cause, include: 

• Cough
• Sputum production
• Nasal congestion
• Chest pain
• Swelling of extremities 
• Raynaud’s phenomenon (poor circulation to the extremities)
• Joint swelling
• Muscle weakness 

There are numerous causes for dyspnea. 

The most common causes of chronic dyspnea include: 

• Asthma
• Chronic obstructive pulmonary disease (COPD), which includes emphysema and chronic bronchitis
• Interstitial lung disease 
• Heart dysfunction 
• Obesity/deconditioning due to lack of physical activity

Acute dyspnea that comes on over minutes to hours is usually due to a limited number of conditions, including:

• Cardiovascular causes
• Reduced blood flow in cardiac arteries (acute myocardial ischemia)
• Heart failure
• Cardiac tamponade
• Acute coronary syndrome (ACS) 
• High output failure
• Cardiomyopathy
• Arrhythmia
• Valvular dysfunction

Respiratory causes

• Bronchospasm
• Blood clot in the lung (pulmonary embolism, or PE)
• Pneumothorax
• Lung infection such as bronchitis, pneumonia
• Upper airway obstruction such as aspiration, severe allergic reaction (anaphylaxis), foreign objects lodged in the upper airways
• Acute respiratory distress syndrome (ARDS)
• Hemorrhage 
• Hyperventilation

Neurologic causes

• Stroke
• Neuromuscular disease

Toxic/metabolic causes

• Toxic ingestion
• Diabetic ketoacidosis
• Sepsis
• Anemia
• Carbon monoxide poisoning
• Salicylate poisoning
• Organophosphate poisoning
• Acute chest syndrome

Other causes

• Angioedema
• Neck trauma
• Rib fractures
• Flail chest
• Anxiety
• Pneumomediastinum
• Lung tumor
• Pleural effusion
• Intra-abdominal process
• Ascites
• Pregnancy

Diagnosis of dyspnea usually begins with a history, if the patient is able to speak, and a physical examination. In the physical exam, the doctor will check

• Respiratory rate
• Pulse oximetry
• Abnormal breath sounds such as stridor, wheezing, crackles
• Cardiovascular signs such as abnormal heart rhythm, heart murmur, muffled or distant heart sounds, and other signs
• Blood pressure drops when inhaling (pulsus paradoxus)
• Skin for discoloration that may show signs of low blood oxygen (hypoxia) or poor blood flow, signs of an allergic reaction, or evidence of trauma
• Swelling of extremities

Tests that may be indicated to help diagnose the cause of acute dyspnea include: 

• Chest X-ray
• Ultrasound
• Electrocardiogram (ECG) 
• Cardiac biomarkers 
• Brain natriuretic peptide (BNP) 
• D-dimer 
• Arterial and venous blood gas
• Carbon dioxide monitoring 
• Chest computerized tomography scan (CT) 
• Pulmonary ventilation/perfusion (V/Q) scan
• Multidetector computed tomography (MDCT) scan of the chest 
• Peak flow and pulmonary function tests (PFTs) 
• Negative inspiratory force (NIF) 

Tests for chronic dyspnea depend on the suspected cause and may include: 

• Blood tests 
  • Complete blood count 
  • Glucose, blood urea nitrogen, creatinine, electrolytes
  • Thyroid stimulating hormone (TSH)
• Spirometry pre and post inhaled bronchodilator OR full pulmonary function tests (PFTs)
• Pulse oximetry during ambulation at a normal pace over approximately 200 meters and/or up two to three flights of stairs
• Chest X-ray
• Electrocardiogram (ECG)
• Plasma BNP or NT-pro BNP

Treatment for acute severe dyspnea in an emergency setting usually includes

• Oxygen 
• Determining if the patient needs emergency airway management and ventilatory support
• Establishing the most likely causes of the dyspnea and initiating treatment

Treatment for chronic dyspnea varies widely depending on the cause. For example

• If chronic dyspnea is caused by asthma, that may be treated with medications such as bronchodilators or inhaled steroids 
• If chronic dyspnea is caused by a blood clot (pulmonary embolism), you may need blood thinners
• If chronic dyspnea is caused by fluid in the lungs, that fluid may need to be drained

Complications of dyspnea include:

• Low blood oxygen (hypoxia)
• Loss of consciousness
• Cognitive impairment

Some causes of dyspnea may be prevented, and in doing so, this will prevent dyspnea from developing or worsening. 

• Don’t smoke or quit smoking
• Lose weight and maintain a healthy weight
• Avoid allergens
• Practice stress reduction techniques