If you use a fingertip pulse oximeter, you should be aware of certain factors that can affect your readings despite the oximeter functioning properly. In these scenarios, it is important to understand the factors that are at play which could be contributing to inaccurate readings. Before you assume that your device is malfunctioning, take a look at the list we have put together in this article to help you identify some common challenges.
How Fingertip Pulse Oximeters Work
Before we go into the challenges, let us first take a look at how fingertip pulse oximeters work. Making use of photo detectors and light sources, fingertip pulse oximeters use LEDs to beam infrared light through the blood of your fingertip in order to measure the amount of light that is able to travel through your finger. As oxygenated and de-oxygenated blood have a different absorption patterns, oximeters make use of the pattern of these lights to calculate your blood oxygen saturation level.
Challenges that Affect Readings on Fingertip Pulse Oximeters
- Improper Use: While it is common for some people to wear their fingertip pulse oximeter overnight, this is not the correct use for this device. Fingertip pulse oximeters are meant for convenient spot-checks, and should not be used for continuous monitoring.
- Strong external lights: If you are confident your device is functioning properly and you are using it correctly, a factor that can contribute to inaccurate readings is exposure to strong or bright external lights which can interfere with the readings. Make sure that you are in a suitably lit place before taking your reading.
- The presence of carbon monoxide: When carbon monoxide enters a person’s body in however small amounts, it can attach to their hemoglobin cells and replace oxygen molecules. When this happens, a pulse oximeter is unable to tell the difference between hemoglobin and oxygen, and the reading will be the combined value of carbon monoxide and oxygen level. Hence, pulse oximeters should not be used on heavy smokers or someone who has suffered from carbon monoxide poisoning and/or smoke inhalation.
- Low oxygen carrying capacity: In some conditions such as hypothermia and hypotension, a patient may have an acceptable oxygen saturation level. However, they have a low oxygen carrying capacity due to a reduction in blood flow. Hence, the sensor on pulse oximeters may not be able to accurately pick up the wavelength of light, resulting in an abnormal reading or loss of signal.
- Irregular signals: Inaccurate readings can occur if a patient has an irregular heartbeat or is moving about when the reading is being taken.
- Cold fingers: When your fingers are too cold, your flow of blood is reduced. As fingertip pulse oximeters depend on the normal flow of blood to yield accurate results, warm up your hands by running them under warm water or rubbing them together before taking another reading.
- Nail polish: The presence of artificial nails or nail polish, particularly dark colors, can potentially interfere with your reading. Always make sure to have unpolished nails before taking a reading to ensure accurate results.