What should you know about an oxygen spirometer?

During spirometry, you breathe through a mouthpiece connected to the spirometer. You take a deep breath and blow out as hard and fully as you can, sometimes more than once. The device records airflow and the amount of air moved. A clinician may use the pattern to assess conditions such as asthma or chronic obstructive pulmonary disease, or to check how breathing changes over time.

Blood oxygen is assessed separately with a pulse oximeter, commonly a small sensor placed on a fingertip. It estimates oxygen saturation and pulse rate. Cold fingers, movement, nail products, or poor circulation can affect the reading, so the number needs to be interpreted alongside your symptoms and examination.

Wear loose clothing and follow the clinic's instructions about eating, smoking, and medicines. Tell the clinician if you have chest pain, feel unwell, or have recently had surgery or a serious infection, because forceful blowing may need to be delayed or adapted. Sit upright, seal your lips around the mouthpiece, and follow the instructions carefully; a poor seal or hesitant effort can make the result less useful.

Do not change inhalers or other prescribed treatment solely because of a home oxygen reading or spirometry result. Bring the device or a record of readings to an appointment if a clinician has asked you to monitor at home.

Seek urgent medical help for severe or rapidly worsening breathlessness, blue or grey lips, new confusion, fainting, or chest pain. If a pulse oximeter reading is unexpectedly low or keeps falling, repeat it with a warm, still finger and seek prompt clinical advice rather than relying on the device alone. Contact a clinician soon for ongoing breathlessness, wheezing, a persistent cough, or a noticeable reduction in exercise tolerance.

Ask whether you need spirometry, pulse oximetry, or both; what the results show about your breathing; whether any medicines should be paused before testing; and which symptoms or home readings should prompt urgent help. You can also ask how to use your monitor correctly and when your results should be reviewed.