Bronchospasm

What happens during bronchospasm

Airways are lined with a layer of smooth muscle. In bronchospasm, this muscle contracts strongly, narrowing the airway. Air can get in, but it struggles to get out, so it becomes trapped in the lungs. The narrowed airways produce a whistling wheeze, mostly when breathing out. Bronchospasm often occurs along with airway inflammation and mucus, which narrow the airways further.

Symptoms

• wheezing
• shortness of breath
• chest tightness
• coughing, often worse at night or with exercise
• difficulty breathing out fully
• fatigue from the effort of breathing

In severe bronchospasm, breathing becomes very hard, the person may only manage single words, and wheezing may become quieter because little air is moving.

Causes and triggers

• Asthma: the most common cause. Triggers include allergens (pollen, dust mites, pets, mold), viral colds, cold air, exercise, smoke and strong smells.
• COPD: flare-ups, often from infections or pollution.
• Exercise-induced bronchoconstriction: narrowing during or shortly after exercise, especially in cold, dry air. Many people with asthma have it, and some people have it without other asthma symptoms.
• Respiratory infections: viral infections and acute bronchitis can cause wheeze even in people without asthma.
• Allergic reactions and anaphylaxis to foods, stings or medicines.
• Medicines: non-selective beta blockers (including some eye drops), aspirin and NSAIDs in people with aspirin-exacerbated respiratory disease.
• Irritants: cigarette smoke, chemicals, fumes and workplace dusts (occupational asthma).
• Anesthesia and airway procedures: irritation of the airway during intubation.
• Gastroesophageal reflux in some people.

Conditions that mimic bronchospasm

Vocal cord dysfunction causes noisy breathing in (rather than out) from the throat. Heart failure can cause "cardiac asthma." Inhaled foreign bodies cause one-sided wheeze. These need different treatment.

Diagnosis

• Examination: wheeze heard with a stethoscope, breathing rate and oxygen level.
• Spirometry: measures how much air you can blow out in one second (FEV1). Improvement after a bronchodilator confirms reversible bronchospasm.
• Peak flow monitoring at home.
• Exercise or methacholine challenge tests to detect airway sensitivity when spirometry is normal.
• Allergy tests and chest X-ray in selected cases.

Treatment

Quick relief

• Short-acting beta-agonists (SABAs) such as albuterol relax airway muscles within minutes. They are used with a spacer or nebulizer.
• ICS-formoterol inhalers are now recommended by GINA as reliever therapy for many adults and teens with asthma.
• Ipratropium, another bronchodilator, is added in emergencies or used in COPD.

Emergency treatment

Oxygen, repeated nebulized bronchodilators, oral or IV steroids, IV magnesium, and in anaphylaxis, intramuscular epinephrine. Severe cases may need intensive care.

Prevention

• Inhaled corticosteroids reduce airway inflammation and are the foundation of asthma control.
• Long-acting bronchodilators for asthma (with steroids) and COPD.
• Leukotriene modifiers and biologic therapies for some people with severe asthma.
• For exercise: warm up, use a reliever inhaler 5 to 20 minutes before exercise if advised, and cover the mouth in cold air.
• Avoid triggers and stop smoking.
• Vaccinations against flu, COVID-19 and pneumococcus reduce infection triggers.
• Have a written action plan that says what to do as symptoms change.

Outlook

Bronchospasm is usually fully reversible with treatment. Good control of asthma and COPD prevents most episodes. Frequent reliever use is a sign that control needs improving.

Frequently asked questions

What is the difference between bronchospasm and asthma?

Bronchospasm is the tightening of airway muscles. Asthma is a long-term condition of inflamed, sensitive airways that causes repeated episodes of bronchospasm. Bronchospasm can also happen without asthma, for example with infections, allergic reactions or exercise.

How long does bronchospasm last?

Mild bronchospasm often eases within minutes of using a quick-relief inhaler. Exercise-induced episodes usually settle within 30 to 60 minutes. Bronchospasm with an infection or poorly controlled asthma can recur for days and may need steroids.

Can bronchospasm happen without asthma?

Yes. Viral infections, bronchitis, allergic reactions, smoke and fume exposure, certain medicines and anesthesia can cause bronchospasm in people without asthma. Recurrent episodes should be assessed, because asthma may be the underlying cause.

What is the fastest way to stop bronchospasm?

Use a short-acting bronchodilator inhaler such as albuterol, ideally through a spacer, as your action plan directs. Sit upright and breathe slowly. If symptoms do not improve quickly or are severe, call 911 or your local emergency number.