If you have a health condition that affects your breathing, your doctor may recommend that you use a pulse oximeter (also known as an oxygen monitor) at home. The device measures how much oxygen is in your blood by shining a light on your finger and measuring the color of your blood. Blood that has lots of oxygen is bright red, while blood with low levels of oxygen is bluish or purple in color.
The most accurate way to measure your blood oxygen level is through a blood test, but pulse oximeters can be useful in a variety of situations, including when you’re traveling or at higher elevations. Generally speaking, an oxygen saturation reading of 95% to 100% is considered normal for healthy individuals at sea level. However, this number can be lower in people with lung diseases like COPD and pneumonia. Your healthcare provider will let you know what a normal level is for your situation.
What is a normal reading on a finger pulse oximeter?
Using the oximeter at home is easy enough, but it’s important to follow the manufacturer’s instructions for the best results. Make sure your finger is warm and relaxed, and that it is held below the heart. Remove any nail polish or artificial nails from the finger being tested and keep it still so the oximeter can read your heart rate and oxygen level. Wait a few seconds until the reading on the screen stops changing and displays one steady number. Be sure to write down the oxygen level and heart rate numbers, along with the date and time, so you can track changes and report them to your healthcare team.
Pulse oximeters are most accurate on the fingers or toes because they have high vascular density. However, it’s important to be aware that factors that interfere with pulse wave amplitude (a measure of blood flow) such as severe hypotension, cold extremities, Raynaud disease or motion can affect the oximeter’s accuracy. Most hospital-grade oximeters are designed to be able to read through these conditions, but over-the-counter devices may not.
Over-the-counter pulse oximeters typically aren’t as accurate as those used in hospitals, and they shouldn’t be relied on to diagnose a health problem or predict when you’ll need medical care. If you notice your oxygen level or heart rate decreasing, it’s important to contact your healthcare team right away.
The best practice is to take measurements of your heart rate and oxygen level three times a day at the same time each day. Record your findings in a diary and bring the completed journal with you to each appointment. To download a pulse oximeter diary, click here. Then, you can easily see the trends and patterns in your symptom readings. This information will help your healthcare team determine if there are any changes in your symptoms that warrant further evaluation or advice from the medical team. This information can also help you track whether or not your medications are working.