Acute shortness of breath (dyspnoea): causes, red flags and what to do

NICE CKS defines breathlessness as a subjective, distressing awareness of difficulty with breathing. Acute means it has developed over minutes. The NHS says shortness of breath might not be anything to worry about but sometimes it can be serious. It is a symptom of many different problems because breathing depends on the airways, the lungs, the heart, the blood and the nervous system.

A useful practical point is the difference between breathlessness from exertion, which many people experience when unfit or overweight, and breathlessness that occurs at rest, on lying flat or on minimal effort. The NHS asks people to see a GP if breathlessness gets worse with normal activities or when lying down.

CKS groups the common causes into cardiac, pulmonary and other. The table below adds what each often looks like.

The NHS divides the advice into levels. For 999 or A&E: severe difficulty breathing, chest tightness or heaviness, pain spreading to arms, back, neck or jaw, lips or skin turning pale, blue or grey (easier to see on the palms of the hands on brown or black skin), and sudden confusion. For NHS 111: more breathless than usual, feeling or being sick, coughing up blood, pain or swelling in one leg, and heart palpitations. For a GP: breathlessness that worsens with normal activities or on lying down, shortness of breath with swollen ankles, and a cough lasting 3 weeks or more.

The NHS heart failure page lists breathlessness when lying down or doing everyday activity, coughing up frothy pink phlegm and sudden weight gain as reasons for an urgent appointment or 111, and the NHS pulmonary embolism page lists chest or upper back pain, a very fast heartbeat or someone passing out with breathing difficulty as 999 triggers.

NICE CKS guidance on cough and chest pain names a respiratory rate above 30 breaths a minute, a heart rate above 130, a systolic blood pressure below 90, oxygen saturation below 92 per cent, altered consciousness and use of the accessory breathing muscles, particularly if becoming exhausted, as signs of serious illness that call for emergency admission.

• Struggling to speak in full sentences, gasping or choking.

• Chest tightness or heaviness, or pain spreading to arm, back, neck or jaw.

• Blue, grey or very pale lips or skin.

• Sudden confusion, drowsiness or collapse.

• Coughing up blood, or pain and swelling in one leg.

• A known asthma attack that is not responding to the reliever inhaler.

• For a child: grunting, sucking in under the ribs, floppiness, unresponsiveness.

CKS says the first step is an airway, breathing and circulation check, including blood pressure, pulse, breathing rate, temperature, level of consciousness and oxygen saturation, to decide whether emergency admission is needed. If it is not, a medical history and cardiovascular, respiratory and neurological examination follow.

The history includes how fast the breathlessness developed, whether it is worse lying flat or at night, chest pain, cough, wheeze, leg swelling, fever, smoking, previous heart or lung disease, medicines, allergies and recent immobility, surgery or flights. If emergency admission is indicated and oxygen saturation is 94 per cent or less, CKS says oxygen should be given while awaiting transfer, provided there is no risk of hypercapnia.

The NHS says a GP may arrange blood tests and a chest X-ray, and breathing tests such as spirometry for suspected asthma or COPD. For suspected heart problems an ECG, blood tests and an echocardiogram are typical, as the NHS describes for heart attack and heart failure. For a suspected pulmonary embolism the NHS says people go to hospital, where an anticoagulant injection is usually given before test results.

Depending on the picture, a peak flow reading, an oxygen saturation check, a full blood count for anaemia and a thyroid test may also be used.

For an asthma attack the NHS advises sitting up straight and staying calm, using the blue reliever inhaler at 1 puff every 30 to 60 seconds until you feel better up to a maximum of 10 puffs, or following your personal asthma action plan, and calling 999 if you feel worse at any time, do not improve after the maximum dose or have no inhaler.

In other cases, sit upright, loosen tight clothing, stay with the person, and do not drive yourself to hospital: the NHS says to ask someone to drive you or call 999, and to bring any medicines you take.

Emergency services for the red flags above; NHS 111 when breathlessness is more than usual or comes with sickness, blood in phlegm, leg pain and swelling or palpitations; a GP for breathlessness that is gradually worse with activity, on lying down or with ankle swelling. The NHS says you are not wasting anyone's time by getting it checked out.