What is pulse oximetry?
Pulse oximetry measures the amount of oxygen saturation in your blood (blood oxygen saturation level). The noninvasive test uses a portable device called a pulse oximeter. The device clips to your finger to read your blood oxygen saturation level and your pulse rate.
Your blood oxygen saturation level is an indicator of how well your heart and lungs are functioning. If you have a heart or lung condition, you will need to watch for signs of low blood oxygen (hypoxemia). Your provider may recommend you track your levels using a pulse oximeter at home.
Understanding blood oxygen saturation
Your organs need oxygen to function. Red blood cells carry a specific balance of oxygen. Your blood oxygen saturation level is calculated by comparing the percentage of oxygenated cells to deoxygenated cells in your blood.
How pulse oximetry works
Pulse oximetry tests use a pulse oximeter device clipped to your finger to measure the oxygen saturation in your blood.
A pulse oximeter uses a sensor with red and infrared light to rapidly measure the percentage of oxygen in your blood. It uses a gentle clamp and is commonly clipped to your finger.
The pulse oximeter calculates your saturation levels by analyzing how much light passes through your tissue. The amount of oxygen in your tissues will affect how well it absorbs the light. It’s a painless test and pulse oximeter readings are usually displayed within seconds.
Benefits of pulse oximetry
Pulse oximetry testing is a convenient method to track your blood oxygen saturation levels and alert you if you need medical intervention. These pulse oximeter readings help your doctor know if your treatments – such as supplemental oxygen or medication – are working and help indicate any potential complications.
Who needs oxygen saturation monitoring?
Pulse oximeters are commonly used to gather vital signs during physical exams. They are also used by pulmonologists, cardiologists and in urgent care settings.
If you have a heart or lung condition, it’s important to track your oxygen saturation levels at home. Pulse oximeters may be prescribed by your doctor or purchased over-the counter.
Pulse oximetry is beneficial for those with conditions such as:
- Acute respiratory distress syndrome (ARDS)
- Anemia
- Asthma
- Chronic obstructive pulmonary disease (COPD)
- Heart failure
- Lung cancer
- Pneumonia
How to use a pulse oximeter
It’s important to follow the instructions for your pulse oximeter. To help you get the most accurate pulse oximeter readings, follow the below steps:
- Remove any jewelry, nail polish or false nails
- Rest for at least five minutes before you use the pulse oximeter
- Warm your hands to room temperature
- Place your hand below your heart level
- Clip the pulse oximeter to your middle or index finger
- Hold still and switch your pulse oximeter on, following your device’s instructions
Interpreting pulse oximetry readings
Pulse oximeters display your blood oxygen saturation level number and your pulse rate. It’s recommended that you take your readings a few times and record the average result.
Typically, a normal oxygen saturation range is between 95-100%. Ask your doctor what saturation level and pulse rate you should be experiencing.
Contact your doctor if you have concerning pulse oximeter readings or are experiencing signs of hypoxemia.
Symptoms of hypoxemia
Hypoxemia is a low level of oxygen in the blood. Depending on the severity and duration, it can be life-threatening.
Symptoms of hypoxemia include:
- Anxiety
- Bluish skin
- Confusion
- Difficulty breathing or shortness of breath
- Headache
- Rapid breathing or heart rate
- Restlessness
How accurate are pulse oximeters?
Pulse oximeters are usually precise. However, the Food and Drug Administration found in February 2021 that you may have inconsistent pulse oximeter readings if you have:
- Dark skin pigmentation
- Thick skin
- Poor circulation