Blood Oxygen Saturation (SpO2) Explained

Sep 26, 2017 by | health, education, healthy living, science, disease prevention

What Is Blood Oxygen Saturation?

Red blood cells travel through the body’s arteries and veins, transporting oxygen from the lungs to every cell and tissue. Oxygen is carried through the blood stream by attaching itself to hemoglobin, an iron-rich molecule inside red blood cells. When the blood flows past oxygen-hungry cells and tissues, hemoglobin releases its oxygen payload. Carbon Dioxide, produced by cell metabolism, is dissolved in the blood and circulates back to the lungs where it is released as fresh oxygen attaches to hemoglobin and the cycle is repeated.

Blood Oxygen Saturation (SpO2) is a measurement of how much oxygen the red blood cells in the body’s arteries are carrying. Each hemoglobin molecule can carry four oxygen atoms and SpO2 is the percentage of hemoglobin molecules carrying a full load of oxygen. Shown as a percentage, normal SpO2 readings are between 95-100%, with anything lower than 90% providing cause for concern.

Understanding blood oxygen saturation (SpO2) graph

Pulse oximeters use levels of red and infrared light to determine SpO2. The level of red and infrared light absorbed by hemoglobin molecules with oxygen molecules attached (HbO2) differs from the level of red and infrared light absorbed by hemoglobin molecules with no oxygen attached (Hg). The difference between absorption using a red light and an infrared light is used to calculate SpO2. It is using this method that iHeart is able to calculate SpO2.

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Blood that is poorly saturated with oxygen can cause the following symptoms:

  • Trouble breathing/shortness of breath
  • Increased heart rate
  • Headache/confusion
  • Chest pain

Persistent low SpO2 is called Hypoxemia and can lead to health issues including organ failure. Blood oxygen saturation is an indicator of heart and lung health, with lower readings suggesting that the tester is unfit and/or may be suffering from illness.

Knowledge Is Power

A pulse oximeter is a device capable of quickly assessing the amount of oxygen in arterial blood. Oximeters clip onto a fingertip and SpO2 is measured and displayed as a percentage within a few seconds.

The first thing that anyone should do if they’re noticing consistently low SpO2 readings is consult a Doctor. Oxygen supplementation may be recommended if the Doctor deems it necessary but this is considered medication and must be prescribed. Lifestyle choices greatly influence lung health; regular exercise and a healthy diet are recommended to improve overall health including health of the lungs.

The Effect of Smoking on SpO2

One of the biggest negative influencers of lung health is smoking. Smokers will experience drastic increases in both mental and physical health if they can gain control of their habit including improved mood regulation, increased lung capacity and fitness levels, and an increase in general energy.

There are a number of resources available to help with controlling a smoking habit and most countries have a government program in place to aid its population. Canadians, Americans, and residents of the UK can click to access some of their government programs. A quick “quit smoking” search on Google will produce the most popular results in your area if you’re located outside of these regions.

iHeart is a fingertip pulse oximeter and mobile app capable of measuring blood oxygen saturation levels, as well as heart rate and aortic pulse wave velocity. iHeart then takes this information to determine a person's internal age; an indication of their overall internal health and risk for cardiovascular and brain disease.

Learn More About iHeart

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