If someone using personal fall protection equipment (PPE) is suspended in a safety harness too long without moving, there is a risk that he/she may suffer from life-threatening suspension trauma. This is a real danger, if people are left suspended in their safety harnesses because their blood then runs into their extremities. As their movements are confined, their blood is not transported through their bodies in the normal way. As they cannot touch the ground, the muscle-pumping function of their legs is not stimulated. In addition, the safety harness straps prevent the backflow of blood - or cuts the blood supply off completely. This results in an interruption of the backflow through the veins so that there is no longer enough blood available to supply the vital organs with oxygen.
If a person suspended in a safety harness is not quickly rescued, he/she might suffer a life-threatening (orthostatic) shock and cells may die off. If the oxygen supply to the person who has had the accident is cut off, he/she will quickly become unconscious (if not already in an unconscious state as a result of the fall). Once unconscious, the person who has had the accident cannot make any attempts to rescue him/herself and is totally defenceless against suspension trauma. The DGUV insurance association states that the rescue operation must be completed within 15 to 20 minutes. If the individual concerned is unconscious, the rescue operation must be initiated immediately and no time lost.
Even if the individual who is hanging helplessly is rescued quickly, there are a few important points to be aware of. The most important is not to lie this person down flat as this would cause too much blood to run back into his/her torso from the veins in their legs. In the worst case, this could overburden the heart muscle and cause kidney failure, i.e. the rescue operation itself could result in the death of the person concerned. BGR/GUV-R 199 “Rescuing individuals from heights or depths using fall protection equipment” therefore recommends:
”Even if there are no outward signs of injury, the person who has been rescued should be brought into the “W” squatting position. This person should only very slowly be brought into a horizontal position. Lying this person down flat suddenly puts this person’s life in jeopardy. It is recommended to have this person examined immediately by a doctor in order to assess his/her condition.”
Of course, this squatting position may only be used for people who are fully conscious. As soon as the accident victim loses consciousness, first aid emergency measures must be carried out.
If the individual suspended in a safety harness is still conscious and can move, the most effective way to prevent orthostatic shock is to get this person to move his/her legs - ideally by getting him/her to keep pushing his/herself up against any object that provides suitable resistance. Slings and loops are an extremely efficient method of being able to at least postpone the onset of suspension trauma. Another option is to use an adjustable hoisting rope attached to the safety harness. The suspended individual can then place his/her feet in the loop to keep the muscle pump function of his/her legs working.
Anyone who has mastered different knots can also use a prusik knot as a foot sling in an emergency. In addition, manufacturers also offer special, compact slings which can be attached to a safety harness. These can be stored easily, for example in a protective pocket attached to the safety harness, prior to commencing work.