Pulse Oximetry


Pulse oximetry is the measure of oxygen in a patient's hemoglobin. The purpose of pulse oximetry is to read the oxygen saturation which is the amount of oxygen attached to a hemoglobin molecule. A single hemoglobin molecule can carry a maximum of four oxygen molecules and by average a fit, healthy young person will have a oxygen saturation of 95-99%. Which means that a majority of the hemoglobin molecules are carrying oxygen through the blood stream. This allows someone to read/check to make sure that the patient has a good respiratory rate and that they are receiving enough oxygen throughout their whole body.

A pulse oximeter is a device used for monitoring the percentage of hemoglobin saturated with oxygen. If a patient is suspected to have some sort of oxygen instability or respiratory problems, their doctor may refer them to a pulmonary clinic, or any clinician who provides this equipment. The newer pulse oximeters are given to patients to take home and test themselves in the comfort of their own home. It has a probe, which connects to a body part such as a fingertip, toe, or earlobe, and is also connected by wire to a computerized device. The probe works by shining two lines, one is red and the other is an infrared light. The light passes through the fingers and based on the number of hemoglobin molecules will affect how much light will reach the other side of the finger. More hemoglobin molecules carrying oxygen will absorb more light therefore telling the probe that there is a high concentration of oxygen.

Some benefits of pulse oximetry devices are that it is non-invasive and offers accurate readings within seconds which helps with a speedy patients assessments. Another benefit is that it allows patients with heart conditions to keep track of their current condition and notify doctors when there is a problem.

Some negatives of pulse oximeters is that even with a quick reading they must be used for a long period to give strong reliable information as well a finger that has a weak pulse which could give a poor signal for the device to read. Another negative is the inability to tell if someone is breathing out enough carbon dioxide in comparison to breathing in enough oxygen. Carbon monoxide can also be an issue by attaching itself to hemoglobin and showing a higher saturation then there actually is making a pulse oximeter less useful for those who have been near any sort of fire.

The actual device is usually a little bigger than a hand, and is computerized. While connected to an individual, it displays their data within only a few seconds, showing the pulse, oxygen saturation, and in most cases, the heart rate. With the ease of testing in your own home, it allows people to relax, which gives a more accurate reading. After a patient takes the device home, connects to it overnight, they then bring it back to the clinic where they conduct the readings and results. Assessing a patients oxygen level is imperative if oxygen instability is suspected because life relies on oxygen.


  • A pulse oximeter tests for certain sleep disorders such as Sleep Apnea.

  • It also detects hypoxia, which is the shortage of oxygen in the body.

  • A pulse oximeter is also used in medical environments such as during/after operations, emergency room settings, and more.

Web Resources:

Related Terminology:

  • Hemoglobin - a protein in red blood cells that carries oxygen

  • Hypoxia - the reduction of oxygen specifically in the blood

  • Sleep Apnea - sleep disorder in which breathing repeatedly stops and starts


Attin M, Cardin S, Dee V, Doering L, Dunn D, Ellstrom K, Erickson V, Etchepare M, Gawlinski A, Haley T, Henneman E, Keckeisen M, Malmet M and Olson L (2002) An educational project to improve knowledge related to pulse oximetry American Journal of Critical Care.

Reucroft Stephen and Swain John (2007) What is a pulse oximeter, and what does it measure? Boston.com

Schiffman, George (2007) Oximetry Medicine.net