Basic concepts of pulse oximetry
What does a pulse oximeter mean?
Pulse: Changes in blood vessels with each heartbeat
Oxi : Oxygen
Meter : measurement
A pulse oximeter is a device that measures the rate and amount of oxygen in each beat of the blood arteries.
In what cases is it used?
A pulse oximeter measures the amount of oxygen in a blood vessel. In fact, the device measures the amount of oxygen as the percentage of hemoglobin molecules that are mixed with oxygen relative to the total number of hemoglobin molecules. Most pulse oximeters also display heart rate.
Physiology
Hemoglobin is a protein found in red blood cells. When oxygen enters the blood, it is carried to all parts of the body by hemoglobin (attached to hemoglobin). Hemoglobin to which oxygen is attached is called oxyhemoglobin.
How does it work?
The pulse oximeter probe consists of two parts:
2 low power LEDs
Infrared light with a wavelength of 940 nm and red light with a wavelength of 660 nm
A photodetector
Infrared and red light are emitted alternately by body tissues (for example, from the finger, foot, earlobe, nose, etc.). . .). When light passes through tissue, some of it is absorbed by the tissue. The amount of light absorbed changes each time the blood pulses pass through the sensor (heart rate). Light is absorbed differently by hemoglobin and oxyhemoglobin. The intensity of infrared and red light after passing through the patient’s finger is measured by a photodetector. A pulse oximeter measures the percentage of hemoglobin that is mixed with oxygen. SpO2 is equal to oxyhemoglobin × 100% of the maximum amount of hemoglobin in a time interval of 4 to 8 hours and the heart rate is calculated and displayed according to the pulse rate.
unit of measurement
SpO2 : %
Pulse rate: beats per minute (BPM)
Qualitative Coefficients
Adults
SpO2: % 100-95, Pulse rate: 90-50 BPM
Babies
SpO2: 98-95, Pulse Rate: 180-120 BPM
Some manufacturing companies
AMI, Armstrong, BCI, Comdek, Datascope, Datex-Ohmeda, Digicare, Invivo Research, Island, Masimo, Medlab, Minolta, Nonin Medical, Novametrix, Pace Tech https://t.me/joinchat/LGFNuFbsiWDOnIal9Q65LA
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