Pulse Oximetry: Uses and Benefits

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What does pulse oximetry mean?

Pulse Oximetry is a medical technology used for the measurement of the Oxygen level in a person’s blood. Basically, it is a method for monitoring Oxygen Saturation. It was developed by bioengineers Takuo Aoyagi and Michio Kishi in 1972. The device or machinery used for this process is called a Pulse Oximeter. It was first tested in 1975 by a surgeon, Susumu Nakajima and his associates. A Pulse Oximeter is a sensory device that indirectly reads the Oxygen level in the blood of a patient by sending wavelengths of light through a thin part of the patient’s body (the fingertip is the most common part, then the earlobe or a foot in case of an infant) to a photodetector.

An Arterial Blood Gas was the only way a person’s oxygen level could be checked before the creation and adoption of the Pulse Oximeter. The Arterial Blood Gas took several minutes of sample collection and a laboratory process. It wasn’t effective because if there was no oxygenation, the brain will begin to go through damages in Five minutes and brain death also begins in Ten minutes, a time which might be too short for results to be gathered, interpreted and for treatment to be implemented. The Pulse Oximeter and Pulse Oximetry was invented to save the day with a faster process. The Pulse Oximeter also can be incorporated into a multi-parameter patient monitor.

How Pulse Oximeters Work

A Pulse Oximeter in its most common method of application works this way; it send two wavelengths of light through the finger (or thin part of the body where it is placed)  and to a photodetector. The sensors in this device detect how much oxygen is in the blood through the readings  gotten from the way the light passes through the finger. It measures the changes in the absorbances at each of the wavelengths, determining the absorbances due to the pulsing oxygenated blood in the bloodstream only. It is built to omit readings from deoxygenated or venous blood, skin, fat, muscle, bone and even nail polish. This method of reading the Oxygen level is called the Transmissive Pulse Oximetry.

The Transmissive Pulse Oximetry is the most commonly used method. However, there is an alternative method that does not need a thin part of the body to work. It is the Reflectance Pulse Oximetry. It can be useful for applications on places like the forehead, the chest, etc. However, it also has a few limitations in its work.

Advantages of Pulse Oximetry

  • It is particularly convenient. It is useful in any setting rather than the conventional laboratory testing.
  • It is of critical importance in emergency situations. It is very useful for patients with respiratory or cardiac problems, sleep disorders, etc.

Limitations

  • It cannot determine the amount of Oxygen used by a patient nor the metabolism of Oxygen.
  • The detection of hypoventilation is impaired when patient is not breathing room air.
  • Erroneously low readings may occur due to hypoperfusion or a cold limb.
  • It is not a complete measure of circulatory sufficiency.
  • False readings may occur when hemoglobin binds to an element other than oxygen.

 

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