<P> People at risk of suspension trauma include people using industrial harnesses (fall arrest systems, abseiling systems, confined space systems), people using harnesses for sporting purposes (caving, climbing, parachuting, etc .), stunt performers, circus performers, and occupations that require the use of harnesses and suspension systems in general . Suspension shock can also occur in medical environments, for similar reasons . </P> <P> The most common cause is accidents in which the person remains motionless suspended in a harness for longer periods of time . Motionlessness may have several causes including fatigue, hypoglycemia, hypothermia or traumatic brain injury . </P> <P> Onset of symptoms may be after just a few minutes, but usually occurs after at least 20 minutes of free hanging . Typical symptoms are pallor, sweating, shortness of breath, blurred vision, dizziness, nausea, hypotension and numbness of the legs . Eventually it leads to fainting, which may result in death due to oxygen deprivation of the brain . </P> <P> If someone is stranded in a harness, but is not unconscious or injured, and has something to kick against or stand on (such as a rock ledge or caving leg - loops) it is helpful for them to use their leg muscles by pushing against it every so often, to keep the blood pumping back to the torso . If the person is stranded in mid-air or is exhausted, then keeping the legs moving can be both beneficial and rather dangerous . On the one hand, exercising the leg muscles will keep the blood returning to the torso, but on the other hand, as the movements become weaker the leg muscles will continue to demand blood yet they will become much less effective at returning it to the body, and the moment the victim ceases moving their legs, the blood will immediately start to pool . "Pedaling an imaginary bicycle" should only be used as a last - ditch effort to prolong consciousness, because as soon as the "pedaling" stops, fainting will shortly follow . If it is impossible to rescue someone immediately, then it is necessary to raise their legs to a sitting position, which can be done with a loop of rigging tape behind the knees or specialized equipment from a rescue kit . </P>

How long does it take for suspension trauma to set in
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