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Pulse Oximeter Information

A pulse oximeter is a medical device that slips onto one's fingertip to measure the oxygen saturation of arterial blood. A pulse oximeter checks the oxygen saturation of blood indirectly. It generally has a monitor attached to it so that oxygenation can be checked continuously. Heart rate can also be checked through these monitors. They are small, light in weight, and can be carried around anywhere. They also come in affordable price ranges.

  1. Hemoglobin Level

    • One hemoglobin molecule is capable of carrying four oxygen molecules. If a hemoglobin molecule contains three molecules of oxygen, then it would be carrying three-fourths of the maximum amount of oxygen a hemoglobin molecule can carry. This is called fraction oxygen saturation. That is the actual amount of oxygen hemoglobin is carrying as a percentage of the maximum possible amount of level of hemoglobin could carry. This is 1.39 militaries of oxygen per milligram of hemoglobin.

    Working Principle

    • A pulse oximeter emits rays of light through a light-emitting diode when it comes in contact with the finger or earlobe of a patient. Red light is shined from diode--an electronic device that has two electrodes. A pulse oximeter also emits infrared light. Red light has a wavelength of 660 nanometers whereas infrared light has a wavelength from 905 to 940 nanometers. Absorption takes place at these wavelengths, and it decides the ratio of oxyhemoglobin--hemoglobin loosely combined with oxygen to deoxyhemoglobin.

    Basic Principle

    • Contraction and expansion of arterial blood vessels takes place with each heartbeat, and the monitor signal of a pulse oximeter changes accordingly. A pulse oximeter detects a slight change in the color caused by a beat of the heart pushing blood through a radial artery of the index and middle fingers. The slight color change only happens when there is a good, strong pulse in the fingers. If the signal level is too low, then the test result may not be reliable.

    Limitations

    • Pulse oximeter tests are normally painless and rarely cause side effects; however, some older models may cause burns, so make sure you use a modern pulse oximeter. Besides, pulse oximeters have a number of limitations that can lead to erroneous readings, especially when the signal is poor. If these limitations are kept aside, there is no harm as such in using pulse oximeters.

    Precautions

    • The fast results and simplicity of pulse oximeters have made them very popular, but one should be fully aware of their limitations. Some of these limitations can be dangerous in the sense that a pulse oximeter can read a good signal and display a good saturation figure, but this reading could be false because of malfunctioning of the device.

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