A sensor, attached to a device called a pulse oximeter, is clipped to your finger or ear, and then directs a beam of light through the tissue. The device is able to monitor oxygen saturation in the blood by measuring the amount of light absorbed by oxygenated hemoglobin (the oxygen-carrying pigment in red blood cells).

Purpose of the Oximetry

  • To monitor oxygen levels in patients at risk for decreased oxygen saturation in the blood (hypoxemia), including those who are undergoing surgery, cardiac stress testing, or pulmonary function tests; people who are heavily sedated, severely injured, or using a mechanical ventilation machine; and individuals undergoing studies in a sleep laboratory.

Who Performs It

  • A doctor, a nurse, or a technician

Special Concerns

  • A variety of factors may interfere with the results, including extreme changes in temperature, movement of the fingers, severe anemia, and fingernail polish.
  • This test should not be performed on patients who have taken light-activated drugs for photo-dynamic therapy.

Before the Oximetry

  • If you wear nail polish, remove it from at least one fingernail.

What You Experience

  • The person performing the test will rub your fingertip or ear to increase blood circulation, and attach the monitoring sensor.
  • The procedure is painless and noninvasive, and takes a few minutes.

Risks and Complications

  • None

After the Oximetry

  • No special aftercare is needed.

Results

  • If your oxygen levels are insufficient, you may be given supplemental oxygen through a face mask or small prongs that fit in the nose. Additional tests, such as arterial blood gases, may be needed to determine the cause.
  • If you are recovering from surgery with general anesthesia, the results of oximetry will help determine when you are ready for discharge.
  • Decreased oxygen levels during sleep studies may indicate sleep apnea.

Source:

The Johns Hopkins Consumer Guide to Medical Tests

Simeon Margolis, M.D., Ph.D., Medical Editor

Updated by Remedy Health Media

Publication Review By: the Editorial Staff at Healthcommunities.com

Published: 25 Jan 2012

Last Modified: 20 Oct 2014