What Occurs When Oxygen Saturation Levels Are High?

Oxygen can be a double-edged sword. On one hand, we need oxygen to survive. On the other hand, when exposed to higher concentrations of oxygen, the saturation levels increase and can pose life-threatening health problems. While oxygen makes up nearly 21 per cent of the air we normally breathe, its when we are exposed to higher levels of oxygen for an extended period of time that creates the issues.


Oxygen saturation is the amount of oxygen blood carries that attaches to the haemoglobin molecules, and is also called oxyhemoglobin. Medical professionals typically express it as a percentage, such as 98 per cent. Oxygen saturation is also called SpO2.

Normal Levels

Typically, a range of 96-100 per cent saturation is considered normal. The general healthy range, though, is 95-98 per cent. A person cannot reach 100 per cent saturation on room air alone; supplemental oxygen would be needed. A person can receive 100 per cent saturation typically in a clinical or hospital setting through a face mask with a supplemental oxygen attachment.

High Levels

According to Favorite Plus, "oxygen, like any drug, can have toxic effects." So if a pulse oximeter (a device that measures oxygen saturation) steadily displays 100 per cent saturation, patients may be receiving superfluous amounts of oxygen. However, 100 per cent saturation may be acceptable for certain conditions, such as anaemia, where oxygen has problems being carried in the blood.

Oxygen Toxicity

Oxygen toxicity, also called oxygen poisoning or oxygen intoxication, is defined as too much oxygen in body tissues. This results when a person inhales too much concentrated oxygen, as in when receiving oxygen therapy.


There are two main types of oxygen toxicity: Central Nervous System (CNS) Toxicity and Pulmonary Toxicity. Named for the systems of the body they affect, these two types mainly affect deep-sea divers but can affect other people as well, including those receiving hyperbaric oxygen, and premature babies.

CNS Toxicity symptoms include vision changes, nausea, hearing changes, irritability, anxiety, confusion, muscle twitching, dizziness and convulsions. Pulmonary toxicity occurs in lungs consistently exposed to high levels of oxygen and it deteriorates rapidly, as in tracheobronchitis and alveolar damage.

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