CO2 Blood Levels

What is CO2’s effect in your blood?

It results in a drop in blood oxygen levels, known as desaturations which are measured to assess the extent of the problem. Normal blood oxygen levels in humans are considered 95-100 percent. If the level is below 90 percent, it is considered low resulting in hypoxemia.

What is Oxygen saturation?

It’s a term used referring to the fraction of oxygen-saturated haemoglobin relative to total haemoglobin (unsaturated + saturated) in the blood. The human body requires and regulates a very precise and specific balance of oxygen in the blood. Normal blood oxygen levels in humans are considered 95-100 percent. When the level is below 90 %, it is considered low resulting in hypoxemia. Blood oxygen levels below 80 % may compromise organ function, such as the brain and heart, and should be promptly addressed. Continued low oxygen levels may lead to respiratory or cardiac arrest. Oxygen therapy may be used to assist in raising blood oxygen levels. Oxygenation occurs when oxygen molecules (O2) enter the tissues of the body. For example, blood is oxygenated in the lungs, where oxygen molecules travel from the air and into the blood. Oxygenation is commonly used to refer to medical oxygen saturation.

What is Hypoxemia (low blood oxygen)?

Hypoxemia is a below-normal level of oxygen in your blood, specifically in the arteries. It is a sign of a problem related to breathing or circulation, and may result in various symptoms, such as shortness of breath. Hypoxemia is determined by measuring the oxygen level in a blood sample taken from an artery (arterial blood gas). It can also be estimated by measuring the oxygen saturation of your blood using a pulse oximeter — a small device that clips to your finger. 

  • Normal arterial oxygen is approximately 75 to 100 millimetres of mercury (mm Hg).
  • Values under 60 mm Hg usually indicate the need for supplemental oxygen.
  • Normal pulse oximeter readings usually range from 95 to 100 percent.
  • Values under 90 percent are considered low.


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