Quick answer
Pulse oximetry is a quick, non-invasive measurement that estimates blood oxygen saturation and pulse using a sensor, usually placed on a finger. The number should not be interpreted alone: symptoms, peripheral circulation, movement, and other factors can affect the reading.
What is pulse oximetry?
Pulse oximetry provides a non-invasive estimate of oxygen saturation and pulse.
When may it be recommended?
It is useful in respiratory illness, post-infection monitoring, shortness of breath, sleep apnea, or before further testing.
What happens during the service?
A sensor is placed on the finger. The reading is interpreted together with symptoms and clinical examination.
How should you prepare?
- Rest for a few minutes before the measurement when clinically appropriate.
- Warm cold hands and keep the finger still while the reading stabilises.
- Remove dark nail polish or an artificial nail from the measured finger where possible.
- Tell the clinician if you have circulation problems or use supplemental oxygen.
What limitations and precautions matter?
- Movement, cold hands, reduced circulation, nail polish, and poor sensor position can affect the reading.
- Pulse oximetry estimates oxygenation and does not replace arterial blood gas testing when that is required.
- An apparently normal result does not exclude every respiratory problem and must be assessed with symptoms.
Medical sources
Medical content: Dr. Teaha Cristina · Last editorial review: