Asthma
A patient with asthma may tell you that their chest feels tight, that they cannot quite get a full breath or that they have been coughing through the night. By the time you listen to their chest the next morning, they may sound almost normal. That variability is very characteristic of asthma. The airways can narrow considerably when symptoms flare and then open again as the episode settles or treatment takes effect.
What is happening inside those airways is more than a brief spasm of the bronchi. The smooth muscle around them tightens, the airway lining becomes inflamed and swollen, and mucus takes up some of the space that is left. Put those changes together and the opening available for air becomes much smaller.
What is happening inside the airway?
Air can still enter the lungs, but getting it back out through narrowed bronchi takes longer. During expiration the pressure inside the chest rises and naturally tends to narrow the intrathoracic airways. If those airways are already tight and inflamed, expiration becomes even more difficult. The patient breathes out for longer, may start using accessory muscles and can trap air behind the narrowed airways.
The wheeze comes from air moving through those narrowed airways. It is tempting to judge an asthma attack by how loud the wheeze is, but that can be misleading. Wheeze needs moving air. If the obstruction becomes so severe that very little air is getting through, the chest may actually become quieter. A patient who is exhausted, struggling to speak and has very poor air entry has not improved because the wheeze has disappeared. A silent chest in that situation is a life-threatening sign.
Asthmatic airways are also unusually responsive to things that may have little effect on somebody else. A viral infection, pollen, cold air, exercise, smoke, vaping or air pollution can provoke symptoms. For some people the pattern is linked to work, which is why asking whether symptoms improve on days off or during holidays can reveal something that a chest examination cannot. Some medicines, including non-selective beta-blockers and non-steroidal anti-inflammatory drugs in susceptible people, can also provoke bronchospasm.
The bronchi and the way air moves through the wider respiratory tract are explored in Bleepbook's Respiratory Anatomy: From the Nose to the Alveoli.
Asthma can look normal between episodes
This is one of the reasons asthma is not diagnosed from wheeze alone. Wheeze, cough, breathlessness and chest tightness occur in other conditions, and a person with asthma may have no wheeze at all when they are well. The pattern around the symptoms is often more revealing: waking at night, coughing in the early morning, symptoms during exercise, repeated episodes after viral infections, or periods when breathing is completely normal.
Objective tests help show what cannot always be heard with a stethoscope. Fractional exhaled nitric oxide (FeNO) and the blood eosinophil count can provide evidence of the type of airway inflammation seen in many people with asthma. Spirometry looks at how air moves out of the lungs. If airflow obstruction is present, testing before and after a bronchodilator can show whether it improves when the airways relax. Peak expiratory flow readings taken over time can also reveal variability when a single set of tests has not given a clear answer.
A normal test does not automatically close the door on asthma. Someone tested on a good day may have relatively normal lung function, and inhaled corticosteroids can reduce the inflammation that diagnostic testing is trying to demonstrate. The history, examination and objective findings therefore have to be considered together. If the patient is acutely unwell, stabilising their breathing takes priority over completing the perfect diagnostic sequence.
Why the inhaler treatment has changed
For years, many people thought of the blue short-acting beta2 agonist (SABA) inhaler as the asthma inhaler. It can make somebody feel better quickly because it relaxes bronchial smooth muscle and opens the airway, but look back at what is happening in asthma and you can see what it does not treat: the airway inflammation.
That is why current UK guidance no longer recommends treating asthma with a SABA alone. For newly diagnosed asthma in people aged 12 and over, BTS, NICE and SIGN recommend low-dose inhaled corticosteroid (ICS)/formoterol used when symptoms occur. This is anti-inflammatory reliever (AIR) therapy. Formoterol provides rapid bronchodilation while the inhaled corticosteroid treats the inflammatory part of the disease at the same time.
If symptoms are not adequately controlled with as-needed AIR therapy, the same ICS/formoterol combination can be used as maintenance and reliever therapy (MART), where the patient takes regular maintenance doses and also uses the inhaler for symptom relief. Children have age-specific pathways, so they should not simply be placed on an adult regimen at a smaller dose. The current guideline, product licence and local formulary need to be followed.
Before assuming that somebody needs stronger treatment, watch them use their inhaler. A prescription can be completely appropriate on paper and still deliver very little medicine to the lungs if the technique is wrong. Ask whether doses are being missed, how often symptoms are waking them, how frequently they need reliever treatment and whether anything in their environment is making control more difficult. Those conversations often tell you more about their asthma than simply asking whether they are “taking their inhalers”.
When the patient in front of you is getting worse
During an asthma attack, the patient is trying to move air through increasingly narrow airways. You may see the respiratory rate rise, expiration become prolonged and accessory muscles come into use. Speech gives you useful information without any equipment: somebody who has to stop after a few words because they need to breathe is telling you, very visibly, how hard they are working.
Peak expiratory flow can help judge the severity of an attack when the patient can perform it properly, and oxygen saturation tells you about oxygenation, but neither should pull your attention away from the patient. Look at their work of breathing. Listen to the amount of air entering both lungs. Notice whether they can speak, whether they are becoming exhausted and whether their condition is changing after treatment.
Carbon dioxide can be particularly easy to misunderstand. Early in a significant attack the patient is often breathing quickly and blowing off carbon dioxide, so the arterial carbon dioxide level may be low. If they continue to struggle, the respiratory muscles can tire and ventilation starts to fail. Carbon dioxide then moves back towards the normal range and may eventually rise. In a patient with severe asthma, a “normal” carbon dioxide can therefore be a warning that they are tiring rather than a reassuring result.
A silent chest, cyanosis, poor respiratory effort, hypotension, arrhythmia, exhaustion or altered consciousness should make the severity unmistakable. These are life-threatening features requiring emergency treatment and escalation. Acute treatment may include inhaled bronchodilators, oxygen when required, systemic corticosteroids and ipratropium in severe attacks, with further management determined by the patient's response and the emergency pathway being followed.
And then reassess. A nebuliser has been given, but is more air moving now? Can the patient speak more comfortably? Has the respiratory rate changed? Are they less exhausted? What has happened to their oxygen saturation and peak flow where appropriate? The sound of the chest only makes sense alongside the rest of the patient. Less wheeze is reassuring when airflow and breathing improve. Less wheeze with worsening air entry and increasing fatigue is something very different.
Good asthma care happens between attacks too
Someone can have normal observations in clinic and still have poorly controlled asthma. Night waking, avoiding exercise, stopping repeatedly on stairs, missing work or university, or repeatedly reaching for a reliever inhaler all tell you how much the condition is affecting everyday life.
Inhaler technique deserves to be seen rather than assumed. Pressurised metered-dose inhalers and dry-powder inhalers are used differently, and someone can have used the same device for years while making a small error that reduces how much medicine reaches the lungs.
A personalised asthma action plan gives the patient something practical to work from when symptoms change: what they normally take, what deterioration looks like for them, what to do when symptoms increase and when to seek help. After an exacerbation, the job is not finished when the wheeze settles. It is an opportunity to work out what contributed to the attack, review treatment and technique, and reduce the chance of the patient returning with the same problem.
References
British Thoracic Society, National Institute for Health and Care Excellence and Scottish Intercollegiate Guidelines Network (2024, updated 2025) Asthma: diagnosis, monitoring and chronic asthma management. NICE guideline NG245.
Global Initiative for Asthma (2026) Global Strategy for Asthma Management and Prevention.
Global Initiative for Asthma (2026) Summary Guide for Asthma Management and Prevention.
NHS Asthma.
NHS How and when to use salbutamol inhalers.
Asthma + Lung UK (2026) Asthma action plans and guidance notes for healthcare professionals.
Asthma + Lung UK Completing an AIR asthma action plan with your patients.
Asthma + Lung UK Completing a MART asthma action plan with your patients.