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 vital signs monitoring?
Pulse oximetry provides a non-invasive estimate of oxygen saturation and pulse. Vital signs, including blood pressure, are monitored at every consultation. Electrocardiography may be performed, and blood glucose is monitored for patients with diabetes or under observation for diabetes.
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 to measure oxygen saturation and pulse. The readings and other monitored parameters are interpreted together with symptoms and the 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: