How to use Pulse oximeter? Does it works?

author: Karry

2023-11-08

If it is examined in a hospital, it is more accurate to take arterial blood and measure arterial oxygen saturation (SaO2) by arterial blood gas analysis, after all, this is a direct "blood test". But every oxygen test requires blood, and even in a hospital, you can't do that every time.

If you check your blood oxygen at the hospital, the doctor clips something on your finger to take a reading, which is also a "pulse oximeter."

Our nails and earlobes are transparent and full of capillaries, making them good measuring points. Inside the pulse oximeter are two light-emitting diodes, one is infrared and the other is a light-receiving sensor. Based on the received signal, the bleeding oxygen saturation, known as pulse oxygen saturation (SpO2), can be calculated after calculation. We basically use this product at home, and in hospitals, SpO2 is also used if you just pinch your finger to measure blood oxygen.

Pulse oximeter, Patient Monitor, ICU monitor, oximeter, oximetre, utech-news

How accurate is pulse oximetry?

In 2014, Israeli researchers published a paper in the journal Medical Devices evaluating the accuracy of pulse oximeters on the market. Comparing pulse oximeter with conventional arterial oximeter, the error is considered to be 3% or 4%. This margin of error is "sufficient to detect a significant decline in the patient's respiratory function." However, for special cases, such as clinically assisted oxygen delivery for critical illness, or blood oxygen monitoring for premature infants, this accuracy is not sufficient.

Pulse Oximetry: fundamentals and technology update

So the pulse oximeter does have a certain error, but in the case of our home, it can still help us understand the changes in blood oxygen, help us find the obvious decline in blood oxygen, and remind us to seek medical attention in time.

And recently, with the emergence of smart watches, another new technology has also begun to appear - the previous pulse oximeter is to let the light received through the finger and other parts to measure. But the watch was worn on a thick wrist, and light could not pass through. As a result, smartwatch and bracelet companies such as Apple have replaced the original transmission with reflection.

However, reflex oximetry is only a new technology, so its accuracy has not been widely recognized, including by the FDA, which regulates medical devices in the United States, and has not approved Apple's oximetry to meet medical requirements. But Apple claims its measurements are accurate enough, at least when blood oxygen levels are below 90 percent.

I also asked the students in charge of watch products at Apple specifically for this matter. He said that the electrocardiogram function does need FDA approval to promote, but the blood oxygen function FDA does not care, and Apple is no problem. It's just that the wrist doesn't have the finger lobes.

So my personal recommendation is that if you need to use an oximeter, it is best to use a traditional transmission pulse oximeter (finger type), if not, then use a smart watch to measure, at least as a reference.

Regarding the use of the oximeter, we refer to the FDA manual and give you some recommendations:

After buying it back, it is best to measure your normal blood oxygen data under healthy circumstances and judge the changes after that. Follow the manufacturer's instructions.

When you clip the oximeter to your finger, heat it, relax it, and keep it below your heart level. Remove nail polish from your fingers. Hold still while measuring until the reading stabilizes.

It is best to record the changes in blood oxygen with a pen and paper or mobile phone.

Changes in signs and symptoms are more important than changes in blood oxygen!! Hypoxia is suspected regardless of whether there is a change in the blood oxygen index if:

1. Blue face, lips or nails;
2.Shortness of breath, dyspnea or increased
cough;
3. Restlessness and discomfort;
4. Chest pain or tightness;
5. Pulse quickens dramatically.

The trend of blood oxygen change is more important than the specific number!! Any measuring instrument has a certain amount of error, so we record the data and note that if the oxygen content is lower than the previous value, there is a continuous decline. Changes or trends in measurements may be more meaningful than individual measurements.

Finally, for any product, there will be good or bad, and even fake and shoddy situations, so when buying this medical device, you need to pay more attention to whether there is CE and other international standards recognized.

If you want to learn more about oximeters, please visit: Handheld Pulse Oximeter (chinautech.com)