How Does A Pulse Oximeter Work?

How Does A Pulse Oximeter Work?

A pulse oximeter is a device which clips onto the patient’s body, usually by the finger but can also be the ear lobe or toe. This device will measure how much oxygen is currently in the patient’s blood, and therefore letting him or her know if they require more oxygen by way of a supplementary oxygen supply. The use of a pulse oximeter is considered to be not intrusive as the device simply clips onto the patient’s body. This is painless and gives a result via digital screen within seconds.

How does this device get its readings?

Many moons ago medical research discovered that blood absorbs light differently depending on the amount of oxygen that is within the blood itself. Due to this a number of devices were created and adapted over the years and as a result, the pulse oximeter was created.

A pulse oximeter’s readings are recorded by the shining of two light wavelengths, one of these will be a visible red beam which can be seen when applying the device to the body and the other is an infrared beam, invisible to the naked eye. These lights will shine through the part of the body in which the device is applied (usually the finger tip) and the photo detector sensor within the device will conduct a mathematical calculation of the ratio of red to infrared light.

This then gives a reading, displaying the amount of oxygen which is contained within the blood. The light which is absorbed by this device is dependent on a few factors such which are as follows;

  • Light’s concentration for absorbing substance
  • Light path’s length in substance absorption

The pulse oximeter tries to notice any changes in absorption as the blood flows along the place the device is applied. It detects pulses as the heart pumps and is able to record when there is a strong or weak pulse. If a weak pulse is present then this may result in the device given a warning message to the user that it is unable to gain an accurate recording. In most cases this device is used at home or portably by the home user and the error will not occur at all, but the due diligence and awareness are required when you are using a pulse oximeter to make sure the most accurate results to be recorded.

Pulse oximeters are non-invasive medical equipment items that have been designed to monitor oxygen levels in the blood. It is also used to monitor a patient’s heart rate. These items are frequently used by anaesthesiologists during surgery. It has proven effective as an early warning system.

In the past, it was necessary to obtain blood samples from patients to check their blood oxygen levels. Many patients fear the method of drawing blood that is required for blood sampling. There are also many patients who for religious reasons are unable to provide blood samples. Pulse oximeters have alleviated these personal problems by providing this important information to doctors without patients having to undergo any invasive procedures.

A pulse oximeter comprises of a small probe which is connected to a computerized unit. The probe is attached to a part of the body that offers good blood flow such as the earlobe or fingertip. The probe contains two light streams, one infrared and one red. A photo detection device is used to receive and measure the streams of light as they pass through the volume of blood. Oxygenated blood absorbs more infrared light than red light. Deoxygenated blood absorbs a larger amount of red light and allows the infrared light to pass through. The oximeter uses these two different wavelengths to calculate the oxygen levels in the patient’s bloodstream.

Non-invasive pulse oximetry is becoming a vital tool in the first stages of diagnosis of congenital heart disease in infants. This is particularly useful in those infants who are showing no other signs of the condition.

There are limitations to this non-invasive method of blood oxygen level monitoring. It does not offer a suitable profile of the blood gas analysis. It cannot be used as a substitute for drawing a blood sample in order to do further tests. It simply acts as an indicator that further investigation may be required to determine the cause of the stunted levels of oxygen in the blood.

It is important that a full medical history of the patient is available as certain pre-existent medical conditions can affect the readings negatively. Excessive patient movement or faulty equipment can also cause false readings.

Pulse oximeters are a proven non-invasive method of determining blood oxygen levels. It does not require any invasive surgery or blood drawing to provide the required information. You may click here for further details in this regard.

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