All you need to know about 'Pulse-Oximeter'

Have we ever thought that a small creature of a few nanometer size can frighten this earth of billions of people? Unfortunately, it happened. Corona Virus came all of a sudden into the picture of our daily life. It has made millions of people sick and snatched away millions of people from their families. The devil virus can immensely damage our lungs. Blood oxygen level falls. But if we can measure the oxygen level in our blood, we can somehow manage the case. Even this can be helpful to save precious lives. 

Pulse-Oximeter is such a wonderful device that can measure the oxygen saturation of blood, to be more precise oxygen saturation of haemoglobin without any invasive procedure.

Contents in this blog post

(Save your time by clicking on the desired section)

• How it works?
• How to use it?
• Precautions to be taken
• Values of SpO2
• False Reading
• Preferred finger and body posture
• Watch the video about Pulse-Oximeter  in Bengali

How it works:

The oximeter works on the principle of spectrophotometry. In the oximeter, there are two light-emitting diodes or LEDs for the red light and the infrared light on the inner aspect of one probe and the respective detector on the inner aspect of the other probe. Red light is absorbed by reduced haemoglobin and infrared light is absorbed by oxygenated haemoglobin. Oximeter calculates the ratio of oxyhaemoglobin to reduced haemoglobin and the value is given as SpO2 or percent saturation of haemoglobin.

How to use it:
Step 1:

Sit on a chair calmly. Hands should be preferably kept on a table without any movement. 

Step 2:

Place your finger properly within the two probes of the oximeter.

Step 3:

Switch on the device.

Step 4:

Within a few seconds, the device will start showing the result. When the value reaches a steady state take the reading. Besides measuring the SpO2, it will measure the pulse rate as well.

Precautions to be taken:
1. There shouldn’t be any movement of the hand.

2. Remove nail polish before measuring.

3. If you have done any physical activity recently like exercise, or running, then take rest for a few minutes before measuring.

4. Avoid very bright light, like open sunlight in the space where you are measuring the SpO2.

Values of SpO2:

SpO2 value is considered to be normal when it is 95% or more. If it becomes between 90% to 94%, you should consult with your doctor. And if the SpO2 value comes to be less than 90%, take it as an emergency condition. In this situation, you have to contact your doctor or nearby health facility without any delay.

False readings:

1. Cold hands can give a falsely low value.
2. Presence of met-hemoglobin in blood will give a falsely low value.
3. The oximeter gives a falsely high value if the carbon monoxide level is high in the blood.

Preferred finger and body posture:
SpO2 can be measured on any finger which fits in the oximeter properly. But, some research has shown that the right middle finger gives the most accurate value in a right-handed person. Research has also shown that sitting in an upright position gives an accurate value of SpO2.

Disclaimer:

This article is a compilation of knowledge that I gathered from different sources. If any part of this article is found similar to any other article in any respect, the same should be treated as mere coincidence only.

Image: Nivedita Kauri YouTube Channel, Stock images, NXP