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What is an Oximeter? [Sep 19,2016]
What is an Oximeter?

What is an Oximeter


Pulse oximeters are medical devices commonly used throughout the healthcare industry. A pulse oximeter (pulse ox) is a small, portable device that is used to non-invasively measure the oxygen saturation levels in the blood. The pulse oximeter will show the % oxygen saturation and the pulse rate of the user.

The Workings of a Pulse Oximeter

The workings of a pulse oximeter are based on the latest processor chip technology, where accuracy is combined with portability. Once oxygen is breathed in the lungs, it enters the blood and attaches to hemoglobin as a means of transportation in the bloodstream. The oxygenated blood then circulates to various tissues in the human body. To understand the workings of a pulse oximeter, it is important to understand that oxygenated blood absorbs light at different levels compared to deoxygenated blood. Pulse oximeters utilize the light absorptive characteristics of hemoglobin and the varying pulsating nature of blood flow to measure oxygenation saturation levels.

Pulse oximeters consist of two (2) light emitting diodes and two (2) light collecting sensors, which are designed to measure the amount of red and infra-red light emerging from tissues traversed by the light rays. Oxygen-rich hemoglobin absorbs more of the infra-red light and the hemoglobin without oxygen absorbs more of the red light. Pulse oximeters calculate SPO2 and pulse rate based on the variations of the infra-red and red light absorption.
Based on Lamber-Beer Law, the light absorbance of a given substance is directly proportional with its density or concentration.  When the light with certain wavelength emits on human tissue, the measured intensity of light after absorption, reflecting and attenuation in tissue can reflect the structure character of the tissue by which the light passes.  Due to the fact that oxygenated hemoglobin (HbO2) and deoxygenated hemoglobin (Hb) have different absorption characteristics, the spectrum range from red to infrared light (600nm~1000nm wavelength), by using these characteristics the SpO2 can be determined.  SpO2 measured by the oximeter is the functional oxygen saturation – a percentage of the hemoglobin that can transport oxygen. 

What is SpO2?

SpO2 is the saturation percentage of oxygen in the blood, so call O2 concentration in the blood; it is defined by the percentage of oxyhemoglobin of the arterial blood.  SpO2 is an important physiological parameter to reflect the respiration function; it is calculated by the following method:
SpO2 = HbO2/(HbO2+ Hb) x 100%
HbO2 are the oxyhemoglobins (oxygenated hemoglobin) while Hb are those hemoglobins which release oxygen.

Directions for Operation

  1. Open the clip and place the finger into the rubber cushions of the device.  It is important that the finger comes in contact with the sensor indicated by a red light. In general, the index finger or ring finger are best for achieving an accurate pulse rate and oxygen saturation level.
  2. Remain still while the device takes the measurement. Moving your hand, fingers or arm may interfere with getting an accurate reading.
  3. Measurement result will be displayed on the screen.  %SpO2:  Percent oxygen saturation.  Pulse beat icon:  BPM or beats per minute. The amount of oxygen in the blood is given in a percentage. For example, if the reading is 100% your blood is saturated with oxygen at 100 percent which is the highest amount possible.  


    • Remove all fingernail polish. Remove any fingernail polish. The pulse oximetry does not work as effectively if placed on a finger with nail polish.
    • Cold fingers may not be able to get a viable reading. Warm the hand by placing a warm towel on it for a few minutes and repeat the above procedure.
    • Very poor circulation will affect the ability for the sensor to pick up a reading.