Working at Height Risks - Suspension Trauma
One of the methods of protecting workers from a fall is fall arrest which relies on personal protective equipment (PPE), including a fall protection harness and lanyard which connects a worker to an anchor point. Should the worker fall, the lanyard absorbs the energy of the fall and the worker is prevented from hitting the ground. Once the fall has been arrested the worker is left suspended in the fall protection harness and this is when suspension trauma can begin to rear its ugly head. Today we’re going to take a closer look at suspension trauma (both during the suspension and when the worker has been brought safely down) and some ways that we can protect ourselves and others from this hazard.
Suspension trauma (aka orthostatic intolerance or harness hang syndrome) occurs while the worker is suspended in a hanging position waiting for rescue. When hanging in a harness this way, the leg straps of the harness support the weight of the body which can lead to cutting off circulation to the femoral arteries on the inside of the legs. Moreover, because the leg muscles are not being used to stand, they are not contracting and preventing the veins from expanding, leading to vasodilation. The blood gathers in the legs (venous pooling) instead of being returned to the heart.
This loss of circulation makes the heart work harder to ensure blood flow to the brain and vital organs, causing nausea, unconsciousness and a drop in both blood pressure and heart rate – circulatory shock. The lungs can no longer deliver oxygen to the trapped legs and the cells being to undergo anaerobic respiration, during which glucose (blood sugar) breaks down into lactic acid in a process known as lactic acidosis. The lactic acid in the stagnant blood in the legs so that when the worker has been rescued, the sudden restoration of circulation floods the body with high levels of acid, overwhelming the liver and kidneys and sometimes causing heart failure. It’s often the case that dialysis is needed to protect the kidneys after incidents of this type so if suspension trauma is a possibility, it’s essential that any medical personnel in attendance be made aware of this fact.
Suspension trauma can be fatal within as little as 30 minutes of the initial fall so having an effective rescue plan and procedure in place is vital when working with PPE of this type. It’s vital that the personnel and equipment necessary is able to be deployed immediately the fall has taken place to minimise the risk and prevent the worse effects of suspension trauma from taking hold. If the worker is still conscious whilst awaiting rescue, he should be encouraged to move his legs slowly if possible to stimulate circulation of blood in the legs.
Next week we’ll take a look at some of the things that can be done to decrease the likelihood of suspension trauma following a fall.