People with high blood pressure benefit from high blood pressure monitors, and people with diabetes use home blood sugar monitors. Should you add a pulse oximeter or a smartwatch to your wellness toolbox?

Pulse oximeters

You may not recognize the name of this gadget, but if you have been to a doctor or a hospital in the past 30 years, you have used one. Medical office and hospital-based pulse oximeters are the clips placed on your finger to measure the amount of oxygen in your blood. This is such an easy, quick, and valuable test that it has been called the fifth vital sign. This device estimates the percent of oxygen saturation in your blood by passing a light through your fingertip.

Pulse oximeters used by doctors and hospitals are regulated by the U.S. Food and Drug Administration and are accurate within about three percentage points. If you have a known lung condition, such as COPD or asthma, your doctor may prescribe an FDA-approved oximeter for you.

Over-the-counter devices

Over-the-counter pulse oximeters are easy to use, but they are less accurate. OTC pulse oximeters have been around for several years, but they really took off during COVID-19 when people became aware that a drop in blood oxygen was a sign of a more serious COVID infection. They give your oxygen saturation as a percentage that you read off the device. A normal reading is 95 to 100 percent saturation. Below 92 percent is the danger zone, and you should contact your health-care provider. Below 88 is very dangerous and requires immediate medical attention.

FDA warning

Due to the rapid increase in the use of these devices, the FDA issued a safety communication in September 2022.It warns that OTC pulse oximeters are not checked or regulated by the FDA, and that users should be aware of certain conditions that may reduce the accuracy of pulse oximetry. These conditions include poor circulation, dark or thick skin, smoking, cool skin temperature, dark fingernail polish, artificial nails, or dirty nails.

Both the FDA and the American Lung Association say that readings from a pulse oximeter alone are not sufficient to diagnose low blood oxygen levels. You should do a few readings to make sure the reading stays the same and check for other signs of low oxygen, like a blue tinge of the nail beds or lips (called cyanosis), shortness of breath, or air hunger (taking deep breaths without felling relieved).

If you already have a long-term lung condition, your normal pulse oximeter reading may be a little low, but normal for you. In that case, look for a drop of three or four percentage points from your normal reading as a warning.

If you decide to try an OTC pulse oximeter, check with your doctor to find out your normal oxygen saturation number, and have your OTC oximeter checked against an FDA-approved office model. Ask your doctor what saturation drop would require either a doctor call or an emergency evaluation.

Bottom line: As long as you know the limitations, you could consider having this device in your home, especially if you have someone at home who may be at risk for lung problems.

Smart watch heart monitor

In 2018, an Apple watch that can do a simplified electrocardiogram (ECG) became available. This watch claims it can detect atrial fibrillation (A-fib), the most common heart rhythm abnormality, called an arrhythmia. There are pros and cons to consider before you spend your money. Like the OTC pulse oximeter, this device is not regulated by the FDA.

Studies suggest that using a smart watch ECG increases the number of people diagnosed with A-fib. A-fib can come and go, and many people with it have no symptoms, so they don’t realize they are in danger of a stroke. Finding out you have A-fib is certainly a big benefit because your doctor can prescribe medications to control it and to reduce your risk of stroke. If you are young and healthy, without any heart condition, the Apple watch is less likely to be beneficial. The risk of A-fib increases with age, affecting about 10 percent of people over age 75 and 20 percent of people over age 80.

Limitations of the Apple Watch

The largest and most recent study of the Apple watch was published in the October 2022 edition of the Canadian Journal of Cardiology. In this study that included 734 patients, Apple watch electrocardiograms (ECGs), which use one sensor, were compared to 12-lead ECGs and evaluated for accuracy by cardiologists.

The key results were that the Apple watch ECGs correctly identified A-fib in about 80 percent of patients, compared with 97 percent for the 12-lead ECG. People who had common and innocent ECG changes due to premature heartbeats were three times more likely to be incorrectly diagnosed with A-fib by the Apple watch. People who had more serious arrhythmias due to other heart conditions were not accurately diagnosed by the Apple watch. The researchers concluded that “smart watches are not yet smart enough.”

If you have risk factors for A-fib, like older age, high blood pressure, obesity, sleep apnea, or diabetes, the benefits of an Apple watch may be worthwhile for you. Your best bet is to talk to your doctor to find out. If you get one, let your doctor know about any Apple watch warnings, but don’t panic. A-fib is not a medical emergency, and the Apple watch ECG could be a false alarm. Also, let your doctor know about other warning signs of A-fib like an irregular pulse, palpitations, lightheadedness, fatigue, shortness of breath, or chest pain.

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