SpO2

SpO₂ is the measure of the amount of oxygen in the blood. It stands for Saturation of peripheral Oxygen (O₂) and is normally measured with a Pulse Oximeter.

1 Effects of hypoxia

Low levels of SpO₂ effect brain functioning, as shown in the following table.

SpO2	Description	Effect	Notes
100-80%	Mild Hypoxia	Normal brain functioning	This mild level of hypoxia does not affect the functioning of the brain, but some people can be sensitive enough to detect changes.
80-60%	Moderate Hypoxia	Decreasing brain function	Vision can be altered, including tunnel vision. Coordination is impaired in things like handwriting will deteriorate. Below 80% the skin may become blue (cyanosis). Mental functioning is impaired, sometimes creating euphoria or tranquility, including indifference to everything including pain. At this level some people become fixated on whatever they were doing when the hypoxia began, which can be dangerous. Memory and speech can also be impaired. There may be older treat visual hallucinations, feelings of depersonalization and even out of body experiences.
60-40%	Severe hypoxia	Muscle paralysis	Apparent unconsciousness.
<40%	Extreme hypoxia	Unconsciousness and eventually death

2 Hypoxia at altitude

The following table gives an idea of different SpO₂ levels at different altitudes. However, the Intermittent Hypoxic Exposure can increase SpO₂ levels at a given altitude.

Altitude(feet)	Altitude(meters)	Air Pressure(mmHg)	Oxygen Pressure(mmHg)	Oxygen Pressure(% pressure at sea level)	Human SpO2(%)
0	0	760	160	21%	96%
5,000	1,524	632	133	17.5%	95%
7,500	2,286	575	121	16%	93%
10,000	3,048	523	110	14.5%	89%
12,500	3,810	474	99.5	13.1%	87%
14,000	4,267	446	93.7	12.3%	83%
16,500	5,029	403	84.6	11.1%	77%
20,000	6,096	349	73.3	9.6%	65%
25,000	7,620	282	59.2	7.8%	<60%