Acute Bronchospasm

What happens during acute bronchospasm

The airways (bronchi and smaller bronchioles) are tubes wrapped in a thin layer of smooth muscle. In bronchospasm this muscle suddenly contracts. Three things narrow the tubes at once:

1. Muscle contraction squeezes the airway from outside.
2. Swelling of the airway lining (inflammation) thickens the wall.
3. Mucus builds up inside the tube.

Breathing out becomes harder than breathing in, because airways naturally narrow as you exhale. Air gets trapped in the lungs, which is why people feel unable to take a full breath even though the problem is getting air out.

"Acute" means it comes on suddenly, over minutes to hours, as opposed to the slow, fixed narrowing of long-term lung disease. In medical coding, acute bronchospasm has its own ICD-10-CM code (J98.01), used when bronchospasm is diagnosed without a more specific cause such as an asthma attack.

Acute bronchospasm symptoms

• Wheezing: a high-pitched whistle, loudest when breathing out
• Chest tightness: a band-like squeeze across the chest
• Shortness of breath: feeling unable to get enough air, often with fast breathing
• Cough: usually dry, sometimes the only symptom, especially at night or after exercise
• Prolonged breathing out: exhaling takes noticeably longer than inhaling
• Using extra muscles to breathe: the neck muscles tighten and the skin between the ribs pulls in
• Anxiety and a fast heart rate, made worse by quick-relief inhalers, which can cause shakiness

Signs of a severe episode

• Speaking only in single words or short phrases
• Sitting bolt upright, leaning forward, unable to lie down
• A breathing rate over about 25 to 30 breaths a minute in adults
• Very little wheeze despite great effort (the "silent chest")
• Blue lips, confusion or drowsiness

Causes and triggers

Asthma

Asthma is the most common cause. People with asthma have airways that are inflamed and overly sensitive, so they clamp down in response to triggers that would not affect others. Common triggers include colds and flu, pollen, dust mites, pet dander, mold, smoke, cold air, exercise and strong smells.

Allergic reactions and anaphylaxis

In anaphylaxis, chemicals released by immune cells cause airway muscle to contract within minutes of exposure to a trigger such as peanuts, shellfish, insect stings or some medicines. Bronchospasm with hives, facial swelling, vomiting or a drop in blood pressure needs epinephrine immediately.

Respiratory infections

Viral infections inflame the airways and can cause bronchospasm even in people without asthma. Examples include acute bronchitis in adults and bronchiolitis in babies, usually caused by RSV. Wheezing may last a few weeks after the infection.

COPD flare-ups

In COPD, the airways are permanently narrowed, and an infection or pollution can tighten them further. This is called an exacerbation.

Exercise-induced bronchoconstriction

Breathing large volumes of cold, dry air during exercise dries the airway lining and triggers narrowing. Symptoms usually peak 5 to 15 minutes after stopping exercise and settle within an hour. It is common in people with asthma and in winter athletes.

Medicines

• Aspirin and NSAIDs such as ibuprofen trigger attacks in a subset of people with asthma and nasal polyps (aspirin-exacerbated respiratory disease).
• Beta blockers, including eye drops for glaucoma, can trigger bronchospasm in people with asthma.
• Some inhaled medicines can paradoxically cause bronchospasm right after use.

During anesthesia and surgery

Placing a breathing tube, airway secretions, or reactions to anesthetic drugs can cause bronchospasm during surgery. Anesthesia teams watch for it closely, especially in people with asthma, COPD or a recent cold, and treat it immediately.

Irritants

Smoke, vaping, chlorine, ammonia, workplace dusts and fumes, and very cold air can all trigger it. Some people develop occupational asthma from repeated workplace exposure.

Conditions that mimic bronchospasm

How bronchospasm is diagnosed

During an acute episode, diagnosis is clinical and treatment starts straight away. A clinician listens for wheeze, counts your breathing rate, checks how well you can speak, and measures oxygen levels with a finger pulse oximeter. Peak flow (how hard you can blow out) shows how narrow the airways are. In severe episodes, blood gas tests and a chest X-ray look for complications such as pneumonia or a collapsed lung.

Once the episode has passed, spirometry confirms airway narrowing that improves after a bronchodilator, which is the hallmark of asthma. Other tests include FeNO (a breath test for airway inflammation), allergy testing, and exercise or methacholine challenge tests when the diagnosis is uncertain.

Treatment of acute bronchospasm

Immediate relief

• Short-acting bronchodilators: albuterol (salbutamol) relaxes the airway muscle within minutes. It is given by inhaler with a spacer, or by a nebulizer in severe cases. For many people with asthma, current guidelines favor a combined steroid and formoterol inhaler as the reliever.
• Ipratropium: a second type of bronchodilator added in moderate to severe attacks and COPD flare-ups.
• Oxygen: to keep blood oxygen at a safe level.
• Steroids: a short course of oral or IV steroids reduces airway inflammation. They take several hours to work and help prevent relapse.
• Epinephrine: the first treatment when bronchospasm is part of anaphylaxis, given by injection into the thigh muscle.
• Hospital treatments: magnesium given into a vein, and rarely, breathing support with a ventilator.

If you have a reliever inhaler and a written action plan, use it as directed. Sit upright, take slow breaths, and use a spacer. If you do not improve quickly, or need the inhaler again within minutes, call 911 or your local emergency number.

Preventing further episodes

• Daily controller medicines such as inhaled corticosteroids reduce airway sensitivity in asthma.
• Identify and avoid triggers, including smoke, allergens and medicines that caused reactions.
• Before exercise, a reliever inhaler 10 to 15 minutes beforehand and a gradual warm-up prevent most exercise-induced symptoms.
• Vaccinations: flu, COVID-19, pneumococcal and RSV vaccines (where recommended) reduce infection-triggered flare-ups.
• Check inhaler technique with a pharmacist or nurse. Poor technique is a very common reason inhalers seem not to work.
• Stop smoking and avoid vaping.

Complications and outlook

Most episodes resolve fully with treatment. Risks of a severe or untreated episode include low oxygen levels, exhaustion of the breathing muscles, a collapsed lung (pneumothorax) and, rarely, respiratory arrest. People who have needed hospital or intensive care for bronchospasm, or who use a reliever inhaler very often, are at higher risk of future severe attacks and should have their treatment reviewed.

Frequently asked questions

What is acute bronchospasm?

Acute bronchospasm is a sudden contraction of the smooth muscle around the airways. The airways narrow, causing wheezing, coughing, chest tightness and breathlessness. It is most often caused by asthma, but allergic reactions, chest infections, COPD, exercise, irritants and certain medicines can also trigger it.

What are the symptoms of acute bronchospasm?

The main symptoms are wheezing, chest tightness, coughing and shortness of breath, often coming on over minutes. Breathing out takes longer than breathing in. Severe episodes cause difficulty speaking, blue lips, confusion, and sometimes a quiet chest because so little air is moving. These need emergency care.

How long does bronchospasm last?

A mild episode often settles within minutes of using a quick-relief inhaler. Exercise-induced bronchospasm usually clears within an hour. Bronchospasm caused by a viral infection can come and go for 2 to 3 weeks. A severe attack may need hours to days of hospital treatment.

Can you have bronchospasm without asthma?

Yes. Viral infections such as bronchitis, allergic reactions, COPD, smoke and chemical fumes, exercise in cold air, beta blocker medicines and anesthesia can all cause bronchospasm in people who do not have asthma. Repeated episodes, however, should be investigated for asthma.

Is bronchospasm an emergency?

It can be. Call 911 or your local emergency number if you cannot speak in full sentences, your lips turn blue, your reliever inhaler does not help, or the wheeze comes with facial swelling or hives. Mild episodes that clear fully with your usual inhaler can be managed at home with an action plan.

What is the difference between bronchospasm and bronchitis?

Bronchospasm is the sudden tightening of the airway muscles. Bronchitis is inflammation of the airways, usually from a viral infection, causing a cough with mucus. Bronchitis can trigger bronchospasm, which is why some people wheeze during a chest infection.