2. Suspension Trauma

Suspension Trauma (Aka Harness Hang Syndrome)

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, hypoglycaemia (the medical condition of having an unusually low level of sugar in the blood), hypothermia (unusually low body temperature) or traumatic brain injury.

Suspension trauma (also called Orthostatic (upright position) Intolerance or Harness Hang Syndrome) is the loss of consciousness due to a victim being held upright with limited movement for a period of time, which can rapidly lead to death if not properly recognised and treated.

Too much blood gets trapped in your legs and you cannot adequately supply your brain with sufficient oxygen. Obviously, your heart is pumping blood into your legs, but gravity is also helping to ‘pull’ that blood towards the ground and keep it there. Clearly, the blood can’t be allowed to stay in the legs. So, to return it to the heart the body depends on 4 major methods:

1. The one-way valves in your veins.  Veins are the blood vessels that bring blood back to the heart, and they’re filled with valves that only let blood flow in one direction: towards the heart.
2. Your Skeletal-Muscle Pump.  In this case, referring primarily to your leg muscles, every time your muscles contract, they get shorter and thicker and press against anything else around them (like your veins and the blood contained therein). The compression of the veins causes the blood to get pushed out of the way, and because of the one-way valves preventing backflow, this means towards the heart.
3. Your smooth muscles.  Your veins also have small muscles surrounding them classified as smooth muscles (tunica media). These muscles control the diameter of the blood vessels and affect what’s known as the “tone” of your vascular system. When these muscles contract, the diameter of the veins decreases, raising the blood pressure. Remember that the one-way valves keep blood flowing towards the heart, so if the same volume of blood keeps entering a smaller pipe, the blood’s velocity will have to increase, returning blood more quickly to the heart.
4. In suspension trauma,  there are two key factors (and a possible third) which come into play, each of which severely impairs blood from returning to your heart to supply oxygen to the brain:

• • A lack of movement
  • Body weight in the harness compressing veins
  • A build-up of toxins in the blood