What is SpO2 and normal oxygen level?
SpO2, also known as “blood oxygen saturation”, is the amount of oxygen flowing through your blood.
Your body receives its supply of oxygen through the process of breathing or respiration which involves an exchange of gases. During the exchange of gases, you inhale oxygen from the atmosphere and exhale carbon dioxide. Your lungs take in oxygen that binds to haemoglobin (a protein found in red blood cells that carry oxygen) and is then transported throughout the body through the bloodstream.
It is vital to maintain an optimum level of blood oxygen to carry out various body functions efficiently. Studies suggest that your normal SpO2 levels have to be anywhere between 95% to 100%.
A drop in your SpO2 levels can lead to severe health conditions and complications.
How to measure your SpO2 levels?
There are several ways of measuring the normal oxygen levels of your blood. The simplest and commonest way is to use a pulse oximeter, also known as “oximeter”.
A pulse oximeter is a small, portable medical device that uses sensors to detect oxygen saturation levels in your blood. It is clipped to your index or middle finger and the percentage of oxygen level is displayed on a screen.
Pulse oximeters are widely used in medical facilities and at home to keep a track of blood oxygen levels.
Recently, over the last 1.5 years, the demand and awareness about pulse oximeters have significantly increased. Due to the COVID-19 infection, keeping a track of your oxygen saturation levels has become a part of daily routine in most households, even more during the ongoing second wave of the coronavirus pandemic in India.
How does COVID-19 infection impact your SpO2 levels?
COVID-19 is a serious respiratory disease and studies suggest that SARS-CoV-2, the virus that causes COVID-19, can attack and damage the walls and linings of the air sacs in your lungs.
When your body tries to fight this foreign entrant, your lungs become inflamed and as a result, it becomes harder for you to breathe in room air. This, in turn, impacts the supply of oxygenated blood to your body and can result in a significant drop in your SpO2 levels.
While SpO2 levels between 95 to 100% are considered healthy, readings below 95% can lead to hypoxemia (a condition when oxygen saturation levels are lower than normal), which starves your body for oxygen.
Note: If a patient is infected with COVID-19 and readings consistently fall below 95%, it indicates a severe infection and the person should seek immediate medical advice. In such cases, it becomes imperative to monitor the patients’ SpO2 levels continuously.
Besides critically ill patients, keeping a track of blood oxygen levels for all COVID-19 positive patients is recommended.
Here are a few commonly asked questions about tracking SpO2 levels in all COVID-19 patients:
1. How many times a day should you check your oxygen saturation if you are infected with COVID-19?
Experts recommend that if you test positive for COVID-19, you should monitor your SpO2 levels, once every four hours and correctly note down or document both oxygen saturation and body temperature (measured by a thermometer).
Each time you check your SpO2 levels, ensure to rest for 5 minutes, then take an average of 3 to 4 readings, with a gap of 1 minute each. This will give you the most accurate/reliable reading.
2. How to ensure your oximeter is working properly?
Pulse oximeters are battery-operated devices and there are chances that your instrument is defective or not working properly. If you suspect the instrument is faulty, check the batteries and instruction manual of the device.
Ensure to buy a high-quality, standard pulse oximeter. If you suspect that the pulse oximeter is showing wrong readings, you can rest for 5 minutes and try again or you can try taking the reading by placing the oximeter on any other finger.
To validate, check the oxygen saturation of a trusted nearby person.
3. What is the correct method of checking your SpO2 levels using an oximeter?
Sit properly with your back straight in a comfortable position. Ensure your index finger or middle finger is dry and there is no paint, nail polish or varnish applied to your finger or there is no injury to the finger.
Clip the device to your finger and check if it is not too loose or too tight. Wait for a few seconds for the device to give you a reading. Do not take a reading under direct sunlight.
If you think the reading is wrong, you can clip the device to any finger to cross-check.
A pulse oximeter is not a way to determine or confirm if you have the COVID-19 infection. Having one at home will come in handy and can be useful to check your oxygen saturation if you have COVID-19 symptoms or while you are getting treated for COVID-19 at home.
Consult your doctor immediately if your SpO2 readings are consistently below 95%.
References:
1. Luks, A. and Swenson, E., 2020. Pulse Oximetry for Monitoring Patients with COVID-19 at Home. Potential Pitfalls and Practical Guidance. Annals of the American Thoracic Society, 17(9), pp.1040-1046.
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