Last week, Stephanie Williams gave us a great introduction on how to use a pulse oximeter along with the My COPD Action Plan to make sure you are managing your COPD symptoms as well as possible. She shared her thought that everyone with COPD should have a pulse oximeter in their home medicine cabinet (a thought I wholeheartedly agree with). So, now you may be considering buying one yourself. But as you browse local or online stores, you will see a wide variety of options and may have even more questions. Is a color screen important? Do I need Bluetooth? What even is a “plethysmograph?” This post can help you choose the right device for your needs.
How Do Pulse Oximeters Work?
While blood looks like a consistent shade of red, the red blood cells (RBCs) that carry oxygen throughout the body actually change their color a little depending on how much oxygen they are carrying. Each RBC has proteins called hemoglobin. If you picture a train, the RBC is the oxygen “boxcar.” A pulse oximeter works by shining a tiny red light and a tiny infrared light through the blood vessels of your finger. RBCs with empty boxcars absorb more of the red light and RBCs that are carrying oxygen absorb more of the infrared light. The computer built into the oximeter compares how much of each kind of light gets absorbed. This allows the computer to calculate how many boxcars are carrying oxygen, which shows on your pulse oximeter as your oxygen saturation.
Since pulse oximeters are just measuring different colors, they can sometimes be fooled. Nail polish, circulation problems, and even skin tone can affect readings. Some companies use different processes or even add extra lights with different wavelengths to improve accuracy. Still, it is important to remove any polish and warm up your fingers for the best results. Also, adding extra features adds to the overall cost. High-end oximeters like those used in medical facilities can cost close to $300. That may be OK if you have a flexible spending account or health savings account to help with the sticker shock, but that price tag is a bit steep for many.
What Features Do I Really Need?
Many pulse oximeters do not cost much more than your average fast-food value meal. If this is your price range, you should consider some things. These devices may take longer to get accurate readings. They are more likely to be affected by those things like movement and nail polish, so you will need to be extra sure to remove any polish and be at rest before taking any readings. It may also take a little longer to get a reading you can count on. Every pulse oximeter uses the average of the measurements over several seconds to give a readout, but lower-cost models may need to take a longer series to display a number.
Even with bargain oximeters, there is a way to tell whether the reading is accurate. Every oximeter display has either a series of bars or waves that move along with your heartbeat. That is because the oximeter can also measure very small changes in the amount of blood in your blood vessels, a measurement called plethysmography or “pleth.” If you see wild, irregular swings in the pleth readout, it means the oximeter is having problems measuring your oxygen level. This could be due to movement or other issues. When the bar graph pulses consistently, or the waveform is regular and even, the value on the screen is more likely to be correct. Therefore, you should choose a device where the display is easy for you to read.
What Features Are Nice to Have?
Stephanie also mentioned in her Q&A that pulse oximeters only tell you part of the story. However, some pulse oximeters have advanced features that may help as you manage your COPD. For example, many oximeters these days come with a Bluetooth feature. You can connect the pulse oximeter to an app on your phone or tablet to help you keep track of your oxygen status over time. This can help point out times when your oxygen may dip down regularly. This can then help you find possible triggers that cause your symptoms to flare up. Some pulse oximeters have displays that rotate depending on how you hold your finger. This makes them easier to read from different angles. Others are on your wrist (for overnight monitoring) or as a ring for more constant monitoring. None of these options is absolutely necessary but, depending on your situation, you may find them to be helpful.
Which Should You Pick?
There’s no one-size-fits-all answer here. Pulse oximeters are often one of those things where you get what you pay for, but less-expensive models can still be useful. Check with other people you know who have COPD (including in the COPD360social community) for advice, look for a device that meets your needs without breaking your budget, and be sure to check it against the medical equipment at your clinician’s office. Then you will have another tool to help keep your COPD under as much control as possible!