Syncope (medicine)  

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Syncope is the medical term for fainting, a sudden, usually temporary, loss of consciousness generally caused by insufficient oxygen in the brain either through cerebral hypoxia or through hypotension, but possibly for other reasons. Typical symptoms progress through dizziness, clamminess of the skin, a dimming of vision or greyout, possibly tinnitus, complete loss of vision, weakness of limbs to physical collapse. These symptoms falling short of complete collapse, or a fall down, may be referred to as a syncoptic episode.

Syncope due to hypoxia will normally occur if the air breathed contains less than 16% oxygen at atmospheric pressure. Less than 11% oxygen in the air at this pressure can lead to death by suffocation. However, the amount of oxygen in the air is dependent on the partial pressure of oxygen, meaning that, if a person inhales pressurized gas, e.g., while scuba diving, a breathing gas containing less than 16% oxygen can still contain enough to prevent hypoxia. On the other hand, mountaineers, pilots, and astronauts breathe oxygen-enriched gas because the partial pressure of oxygen in normal air mixture is not enough to prevent hypoxia, since the total pressure is reduced at high altitude. Syncope due to hypoxia can also occur because the lungs are not working properly, because a person is not breathing, because the blood is not circulating, or because the blood's ability to transport oxygen is destroyed or blocked, e.g., by carbon monoxide, which, if present, binds itself to the blood's hemoglobin.

Definition

A pre- or near-syncope is diagnosed if the individual can remember events during the loss of consciousness (i.e., reports remembering dizziness, blurred vision, and muscle weakness, and the fall previous to hitting his or her head and losing consciousness). If the individual remembers feeling dizzy and loss of vision, but not the fall, then it is considered a syncoptic episode.

As loss of consciousness is a symptom for a variety of conditions and syncope is difficult to rule out outside of a hospital, a thorough examination is required in order to determine the cause, including interviews with witnesses as well as evaluation with an electrocardiogram.




Unless indicated otherwise, the text in this article is either based on Wikipedia article "Syncope (medicine)" or another language Wikipedia page thereof used under the terms of the GNU Free Documentation License; or on research by Jahsonic and friends. See Art and Popular Culture's copyright notice.

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