Pulse Oximetry

What is Pulse Oximetry?

Pulse oximetry is a non-invasive test procedure that is used to measure a person’s oxygen saturation levels in their blood. It works by detecting the amount of oxygen bonded hemoglobin cells that are in a person’s blood stream. Pulse oximetry can accurately detect the efficiency to which oxygenated blood is being carried throughout the body.

Pulse oximetry is an extremely common test procedure performed in many different areas of healthcare. It involves attaching a clip called a pulse oximeter probe to a person’s finger, ear, or toe, which is then able to provide an accurate reading of the amount of oxygenated blood being carried throughout the body.

Uses of Pulse Oximetry

Pulse oximetry provides extremely useful feedback of a person’s condition in order to diagnose issues or to monitors and prevent further complications. Some common uses include:

• Monitoring patient condition during procedures that involve sedation
• Assessing someone’s ability to handle increased activity
• To assess the efficiency of assisted breathing devices such as ventilators or CPAP machines
• Diagnosing pulmonary function conditions such as COPD, heart attacks, asthma or pneumonia
• Observing the effects of lung medications

How Does it Work?

During a pulse oximetry test a clip is placed on a person’s finger, ear lobe, or toe in order to get a reading. The clip is placed on a person’s extremity in order to get a more accurate reading of how well oxygenated blood is being carried throughout the body as these extremities are furthest from the heart.

The clip, or pulse oximeter probe, has a light emitter on one side and a light detector on the other. When the probe is placed on a person’s extremity the light is emitted through the extremity and is then detected by the light detector on the other side of the extremity. The detector is then able to determine the amount of light that has made its way through the extremity, this data is then used to determine the amount of oxygenated blood. This works because hemoglobin cells in the blood that are bonded with an oxygen molecule will absorb more of the light rays than those that are not bonded with an oxygen molecule. Therefore, the less light detected by the light detector, the more oxygenated the blood.

Pulse oximetry is also capable of detecting the rate of a person’s pulse or heart rate. This is done by reading the rate at which blood is being passed between the two sensors located on the pulse oximeter probe.

The Importance of Pulse Oximetry Maintenance

It is important to receive regular maintenance on your pulse oximeters by a trained Biomedical Technologist at least on an annual basis. This will help to ensure that your unit is performing at its best and is adhering to all standards pertaining to the accuracy of which it is providing readings. Without this regular maintenance your pulse oximetry equipment may fall short on the quality of feedback it is providing about the patient’s condition and therefore may lead to further complications or a missed diagnosis.

How TRH Services Will Help

A TRH services trained technologist will verify your pulse oximetry equipment using a series of testing procedures and high-tech biomedical testing equipment in order to verify that your equipment is working at its best and is compliant to all standards. If any test happens to show any discrepancies, we will do our best to correct it and get it up and running at its best again by providing any repairs, replacement parts or calibrations required.

Visual Inspection

The first test procedure done on any piece of equipment is a visual inspection. During the visual inspection we will look for any signs of damage or wear that may indicate some problems with the functionality of the unit or may pose a safety issue. This may include any damage to the power cord or cables, the outer casing of the unit, controls, and the pulse oximeter probe itself.

Electrical Safety

The next test procedure we will perform is an electrical safety test. This is an important test on any piece of electronic equipment, especially those that come in direct contact with the patient, such as pulse oximetry. During the electrical safety test we will test to ensure that the ground resistance as well as leakage currents of the unit are within acceptable ranges according to the standards outlined in IEC 60601, the standards for general requirements for basic safety and essential performance of medical electrical equipment as published by the International Electrotechnical Commission.

Functional Tests

Next, is a functional test where we will test the accuracy of the readings being provided by the pulse oximeter. During this test we will utilize a patient simulator where we will attach the pulse oximeter probe to different finger simulators that are each rated at differing percentages of oxygenated blood. We test at low, mid and high ranges of SpO2 percentages in order to verify a wide range of readings and to test that the equipment will alarm at the appropriate readings. Our tests include an 80%, 90% and 97% oxygenated blood tests. During these tests the reading from the pulse oximeter must be accurate to a minimum of ±1%.

We will also test to ensure that the pulse oximeter is correctly reading pulse rate. This is also done by utilizing the patient simulator along with the finger simulators. Just like the oxygen percentage tests, the BPM test, or beats per minute, will be tested at low, mid, and high ranges for a wider variety of test reading and to ensure proper alarm indications will occur whether the pulse rate is too high or too low. We will test the accuracy of the pulse rate detection by performing test at 30BPM, 60BPM, 120BPM, and 240BPM. The pulse rate readings from the pulse oximeter must be within ±1BPM of the test rate selected on the patient simulator.

Conclusion

Pulse oximetry is a vital tool used in many areas of healthcare used as both a monitoring and assessment tool. Therefore, it is important to keep these units up and running in optimal condition and putting them on a routine maintenance schedule will help with that. TRH Services can provide service on all types of pulse oximetry equipment including, routine preventative maintenance, calibration and repairs.

Here is a listing of some units that we service:

Written By: Nicholas Shiels

Edited By: Tyler Hasenpflug CET