Injuries from falling are only part of the dangers faced by those working at heights. Harness suspension presents with similar symptoms and complications associated with crush injuries, and the resulting lack of blood flow to the vital organs leading to orthostatic intolerance is widely proven to cause death.
Whilst hanging in a harness, the tourniquet effect of the leg webbing, coupled with the effect of gravity and an inability to release the pressure of the webbing on the legs, leads to the condition known as VENOUS POOLING. The body and leg muscles are unable or severerly restricted from pumping blood back into the heart. When in suspension, a harness simply restricts blood flow back to the heart even if the harness has a cradle or sub pelvic bum strap for the buttocks.
Initial symptoms of orthostatic intolerance are tingling or numbness in the legs, nausea, dizziness, sweating, palpitations, and confusion. Fainting occurs next, which, in a harness, will serve to exacerbate the suspension trauma by eliminating movement altogether while still keeping the subject upright. Research has found that after losing consciousness while suspended in a harmess, brain damage and death can occur within four to six minutes (1).
Even if a climber or worker is rescued alive in their harness after suffering orthostatic intolerance, they are still in grave danger due to the large amount of deoxygenated blood in their legs that may cause a heart attack or kidney failure when it returns to the body's vital organs. Research by Flora and Holzl found that of eight rock climbers who were alive after hanging in a harness (from periods of half an hour to eight hours) all died after they were rescued, surviving from half an hour to eleven days (2).
While each individuals tolerance to suspension varies, everyone is susceptible meaning that using a harness designed to enable blood flow in the event of prolonged suspension is critical, as is their quick rescue and recovery.
The LINQ range of lanyards from the well know and trusted Pro Choice Safety Gear are specifically designed to reduce the likelihood of orthostatic intolerance. Featuring a unique Standing Step Harness they eliminate the tourniquet effect and allow the wearer to stand and stimulate the muscles that pump blood back to the body's vital organs. The resulting increased blood flow reduces the risk of suspension trauma and associated dangers.
(1) Nelson B. Climbing harnesses. How long can you safely hang from your harness? (1979)
Off Belay Magazine (USA) (August 1979)
(2) Flora G and Holzl HR. Fatal and non-fatal accidents involving falls into the rope (1972)
Papers of the Second International Conference of Mountain Rescue Doctors (Austria) (1972)
Information taken from LINQ Height Safety product catalog