SpO2
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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[1], 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[2] gives an idea of different SpO2 levels at different altitudes. However, the Intermittent Hypoxic Exposure can increase SpO2 levels at a given altitude[3].
| 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% |
3 References
- ↑ anesthesia and hypoxia http://www.anesthesiaweb.org/hypoxia.php
- ↑ anesthesia and hypoxia http://www.anesthesiaweb.org/hypoxia.php Originally from "The Pilot: An Air Breathing Mammal," Mehler, Stanley R. MD, Human Factors Bulletin, Flight Safety Foundation, 1981.
- ↑ The Effect of Dynamic Intermittent Hypoxic Conditioning on Arterial Oxygen Saturation http://www.wemjournal.org/article/S1080-6032%2809%2970080-8/abstract
