Asthma and SpO2: what your oxygen reading means

A pulse oximeter adds useful information, yet symptoms, ability to speak, breathing effort and response to reliever medicine matter too. Follow the personal action plan provided by your clinician rather than waiting for the number to change.

The clip shines light through a fingertip to estimate oxygen saturation and usually displays a pulse rate. Asthma narrows the airways; oxygen may remain normal early in a flare even while wheezing, cough or chest tightness is worsening.

Cold hands, movement, nail products, poor circulation and an ill-fitting sensor can distort a result. A single unexpected value should be checked again under better conditions, but severe symptoms take priority over repeated measurements.

Sit still, warm the hand, remove nail polish if practical, place the sensor securely and allow the display to settle. Record the reading alongside symptoms, reliever use and any peak-flow result if peak flow is part of your plan.

Use prescribed inhalers exactly as directed. If symptoms do not improve as your action plan predicts, obtain medical advice even when the oximeter appears reassuring. Do not borrow oxygen or change controller doses solely because of a home reading.

Call emergency services for severe breathlessness, blue or grey lips, confusion, collapse, exhaustion, marked difficulty speaking, or symptoms that keep worsening despite prescribed reliever treatment. Seek urgent assessment for a persistently lower-than-usual oxygen reading, especially with visible breathing effort.

Do not drive yourself if breathing is severely impaired. Continue the emergency steps in your asthma action plan while help is being arranged.

Ask whether home oxygen monitoring is useful for you, what your usual reading is, which symptoms should trigger your action plan, and whether you should also use a peak-flow meter. Bring the device to an appointment if its results seem inconsistent.