Roger B. Mortimer, MD’s article “Risks and Management of Prolonged Suspension in an Alpine Harness”, in the journal Wilderness & Environmental Medicine, sheds light on the nature and dangers of prolonged suspension. While the study focused on recreational climbers and cavers in alpine environments, its findings are equally applicable to workers who may suffer suspension trauma as a result of dangling in an industrial fall arrest harness following a fall.
In the study, the dangers of
“suspension trauma, shock leading potentially to death, induced by hanging passively in a harness”
“secondary to the failure of the venous pump to return sufficient column to central circulation in someone limp or inactive”
When a fallen person is suspended in a harness, they are suspended at an angle close to vertical, causing blood to pool in the legs, causing swelling of the legs and lowering the blood pressure in central circulation. The mechanism is similar to how a soldier on parade will faint as a result of a similar pooling of blood. However, a fainted soldier will collapse to the ground and allow blood to re-circulate; the suspended climber or worker remains in an upright or near-upright position, allowing the situation to worsen. The dangers of remaining in such a position are significant: The shortest suspensions leading to death described in the article were a mere half-hour to 35 minutes. This demonstrates that suspension trauma has nothing to do with the design of the harness but with the stationary position of the casualty.
With this understanding a possible way to prevent suspension trauma is to train workers to move their legs while suspended; keeping the venous pump functioning allowing blood to return to the heart and therefore recirculate through the body, maintaining blood pressure and limiting the collection of any toxins created through cell metabolism or cellular damage.
Individuals left suspended for extended periods (over 3 hours) very occasionally suffered “rescue deaths”, dying minutes to hours after being released from their harnesses. The article argues that, contrary to some suggestions that this is the result of a sudden surge of blood from the legs or a similar forcible return to a normal state which the body’s systems cannot handle, these deaths are the result of the trauma incurred during the suspension itself. As Mortimer says, “the most likely scenario is that those who died after rescue died despite rescue, not because of it”. Concerns about avoiding rescue death have delayed rescue efforts, possibly contributing to the complications resulting from suspension. Post fall protocols should therefor focus on the transportation of the casualty to medical facilities as soon as possible for treatment.
Mortimer notes that, unlike the cavers and climbers in the study
“[i]n the industrial setting, a hanging person can more easily self-rescue and is much more likely to have other workers present who can accomplish a rescue quickly”
However, the speed with which prolonged suspension can cause complications or even death demonstrate that the creation and execution of retrieval plans for fallen workers in harnesses is as important a part of Fall Protection training as the attachment and use of the harnesses themselves.