Greyout

Common card · No. 358478

A greyout is a transient loss of vision characterized by a perceived dimming of light and colour, sometimes accompanied by a loss of peripheral vision. It is a precursor to fainting or a blackout and is caused by hypoxia (low brain oxygen level), often due to a loss of blood pressure. Greyouts have a variety of possible causes: Shock, such as hypovolemia, even in mild form such as when drawing blood. Standing up suddenly (see orthostatic hypotension), especially if sick, hangover, or experiencing low blood pressure. Fatigue Hyperventilation, paradoxically: self-induced hypocapnia, such as in the fainting game or in shallow water blackout. Overexertion Severe episodes of coughing or sneezing Panic attack Possible symptoms include: blurred vision tunnel vision dizziness loss of balance lightheadedness sudden feeling of exhaustion breathing accelerates into short quick breaths respiratory acidosis (“hot breath”) heart rate spikes rapidly blood pressure drops oxygen saturation plummets Recovery...

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