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Syncope ((syncope ⓘ), commonly known as fainting or passing out, is a loss of consciousness and muscle strength characterized by a fast onset, short duration, and spontaneous recovery. [1] It is caused by a decrease in blood flow to the brain , typically from low blood pressure . [ 1 ]
Heat syncope is fainting or dizziness as a result of overheating (syncope is the medical term for fainting). It is a type of heat illness. The basic symptom of heat syncope is fainting, with or without mental confusion. [1] Heat syncope is caused by peripheral vessel dilation, resulting in diminished blood flow to the brain and dehydration.
Hyperventilation, paradoxically: self-induced hypocapnia, such as in the fainting game or in shallow water blackout. Overexertion; Panic attack; Recovery is usually rapid. A greyout can be readily reversed by lying down as the cardiovascular system does not need to work against gravity for blood to reach the brain.
Episodes of vasovagal syncope are typically recurrent and usually occur when the predisposed person is exposed to a specific trigger. Before losing consciousness, the individual frequently experiences early signs or symptoms such as lightheadedness, nausea, the feeling of being extremely hot or cold (accompanied by sweating), ringing in the ears, an uncomfortable feeling in the heart, fuzzy ...
Freediving blackout, breath-hold blackout, [1] or apnea blackout is a class of hypoxic blackout, a loss of consciousness caused by cerebral hypoxia towards the end of a breath-hold (freedive or dynamic apnea) dive, when the swimmer does not necessarily experience an urgent need to breathe and has no other obvious medical condition that might have caused it.
The symptoms of a TIA can resolve within a few minutes, unlike a stroke. TIAs share the same underlying etiology as strokes; a disruption of cerebral blood flow. TIAs and strokes present with the same symptoms such as contralateral paralysis (opposite side of body from affected brain hemisphere), or sudden weakness or numbness.
Even when marked, hypocapnia is normally well tolerated. Symptoms include tingling sensation (usually in the limbs), abnormal heartbeat, painful muscle cramps, and seizures. Acute hypocapnia causes hypocapnic alkalosis, which causes cerebral vasoconstriction leading to cerebral hypoxia, and this can cause transient dizziness, fainting, and ...
In theory, atrioventricular blockade or sinus arrest due to profound parasympathetic dominance might result in syncope or sudden cardiac death, but these rhythms tend to be rapidly reversed by lung stretch receptor activation associated with breathing. As such, a vagally produced arrest scenario is likelier during entrapment submersion than in ...