Earlier this year in Texas two window washers became stranded on the side of a commercial building approximately 15 stories above ground. They were working off of a mobile scaffold which failed.
Thankfully, the workers were complying with safety regulations and wearing harnesses, which were rigged to safety lines. The result was two very viable victims who were dangling on the side of the building as opposed to two fatalities that were critically injured on the ground or hanging precariously on the scaffolding.
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On the surface, this sounds like a stable rescue sequence with relatively benign hazards to the victims. However, there is an underlying mechanism that presents a significant risk to the workers and it is extremely time and equipment sensitive: suspension trauma.
Suspension trauma is also referred to as orthostatic intolerance. Here’s how OSHA defines this trauma.
Orthostatic intolerance may be defined as “the development of symptoms such as light-headedness, palpitations, tremulousness, poor concentration, fatigue, nausea, dizziness, headache, sweating, weakness and occasionally fainting during upright standing.” While in a sedentary position, blood can accumulate in the veins, which is commonly called “venous pooling,” and cause orthostatic intolerance.
In the veins, blood normally is moved back to the heart through one-way valves using the normal muscular activity associated with limb movement. If the legs are immobile, then these “muscle pumps” do not operate effectively, and blood can accumulate. Since veins can expand, a large volume of blood may accumulate in the veins.
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An accumulation of blood in the legs reduces the amount of blood in circulation. The body reacts to this reduction by speeding up the heart rate in an attempt to maintain sufficient blood flow to the brain. If the blood supply is significantly reduced, this reaction will not be effective. The body will abruptly slow the heart rate and blood pressure will diminish in the arteries.
During severe venous pooling, the reduction in quantity and/or quality (oxygen content) of blood flowing to the brain causes fainting. This reduction also can have an effect on other vital organs, such as the kidneys. The kidneys are very sensitive to blood oxygen, and renal failure can occur with excessive venous pooling. If these conditions continue, they potentially may be fatal.