Pulse oximetry is a daily practice in the hospital. From premature babies to elderly patients, and from the ER to the OR, ICU, and nursing ward. The pulse oximeter displays, among other things, the peripheral O2 saturation in the blood: the SpO2 value. This is essential information to assess whether the oxygen saturation is adequate.
How does a pulse oximeter work?
Oxygen is absorbed into the blood via the lungs and distributed throughout the body. A pulse oximeter sensor measures SpO2 via two LEDs (red and infrared) and a photodiode. Oxygen-rich blood allows less light to pass through. The sensor detects how much light is absorbed and calculates the oxygen saturation based on this. In this blog, we focus on the ‘transmissive’ SpO2 measurement.
Important during checking
In addition to visual inspection, heart rate accuracy, and alarms, the SpO2 measurement is particularly crucial. Always use a functional tester (SpO2 simulator). With a human finger, you only test at normal values – it is not calibrated. It is precisely with abnormal values that you want the device to work reliably. You can set a simulator to both high and low SpO2 values and heart rate.
Setting to the correct manufacturer
Always set the correct brand of the SpO2 sensor on the simulator. Each manufacturer has its own R-curve. The simulator must match this. Ensure that the sensor is properly positioned on the test finger. Many simulators indicate whether enough light is being absorbed for a correct simulation.
Pulse amplitude and disturbances
You can test how sensitive the pulse oximeter is by varying the SpO2 value and pulse amplitude on the simulator. The smaller the signal, the more difficult the measurement. You can also simulate ambient light or respiration to see how the device deals with disturbances.
Setting skin type and finger thickness
Simulate different skin types (light, average, dark) and finger thicknesses – for example, also a neonatal foot. The simulator adjusts the light transmission accordingly, so you can assess how the pulse oximeter responds to variations in patient characteristics.
Did you know that the ProSim 8 from Fluke Biomedical can also simulate Masimo Rainbow technology?
