WHERE a risk assessment identifies the possibility of a fall from height, there is increasing awareness in industry of the steps required to protect those who might be exposed to that risk.
The four essential points to cover include A – Anchor point, B – Body harness, C – Connector and D – Decelerator, together with competency based operator training.
Michael Biddle, chairman of the FPMA (Fall Protection Manufacturers Association) and general manager of Capital Safety, knows that additional risks are created once an accidental fall has happened, leading to the fifth essential point of fall protection: E – Emergency rescue.
“It’s essential to have in place a detailed rescue plan to minimise potential harm,” Biddle said.
“If the user remains suspended after the arrest of an accidental fall, there’s an additional risk in the period between the fall arrest and the rescue. This risk is known as suspension trauma or orthostatic intolerance.
Like all risks, the minimisation or elimination of the possibility of suspension trauma must be considered in order to maximise personal safety.
The rescue plan needs to include appropriate equipment, as well as minimising the time that the worker is suspended.
Suspension Trauma – what is it?
In simple terms, the onset of suspension trauma begins where the body is at rest in a vertical state with the lower body motionless.
Under normal conditions, blood is pumped from the heart to all parts of the body. In the lower parts of the body, the outward flow is assisted by gravity and the return flow is enhanced by the contraction of muscles in the leg acting on the veins and pumping the blood, against gravity, back to the heart.
However, when a person is suspended in a fall arrest-rated full body harness, the legs are immobile and the muscle assistance to the return blood flow is impaired.
The blood begins to pool in the legs. The veins themselves begin to expand under pressure increasing the pooling and causing the total system blood flow to slow.
If this continues, blood pressure drops and the brain does not receive adequate flows of oxygenated blood resulting in the onset of unconsciousness.
These results are most often seen where military personnel have to stand at attention, motionless, for periods of time. The blood pools in their legs, blood oxygen to the brain falls and they faint.
But in this example, the fainting person slumps to the ground and the effect of gravity and the motionless legs on the blood flow are removed. Oxygenated blood begins to flow immediately and consciousness returns.
However, the person suspended in the harness remains suspended and relatively motionless. If this continues, oxygenated blood flows remain low and toxins build in the pooled blood.
There is no definitive suspension time before the onset of unconsciousness, but experiments have shown that it can be as short as five minutes – and if rescue is not quick, the person may die.
Fortunately, in a real fall situation, unless the worker is hurt during the fall, the likelihood of unconsciousness and subsequent motionless, is unlikely.
By struggling, the legs will keep moving and assist the return blood flow. To a certain degree, this can increase the possible suspension time and delay the onset of suspension trauma.
Which harness is best?
Harness designs manufactured by FPMA members are geared in two ways: to spreading the forces generated in arresting a fall over the whole body, and to minimising the restrictions to legs while in suspension.
The selection and correct fitting of a full body harness is an important part of increasing suspension time. Workers should fit the harness to their own body.
This means selecting the right size of harness for their body shape and properly fitting the harness using all the adjustment straps.
Particular care needs to be taken in positioning the rear and frontal fall arrest D-rings and the sub pelvic strap, to ensure a proper sharing of fall arrest loads across the body. Care should also be taken to position leg buckles in areas least likely to cause pressure on the legs.
Manufacturers now offer various forms of suspension straps that can then be deployed by the operator if a fall has taken place. These straps – generally attached to the waist strap of the harness – form suspended loops that can be adjusted by the operator to suit his leg length.
Feet are placed into the strap loop allowing the suspended person to alternate between pushing against the loop to activate the leg muscles and relaxing. By doing this, blood pooling is minimised, flow is maintained and the brain continues to receive oxygenated blood preventing unconsciousness.
Once the rescue has been effected
While the FPMA is not accredited to give medical advice, it should be noted that people rescued from suspension should NOT be immediately placed in a horizontal recovery position as this could be life threatening.
If the blood that has accumulated in the legs flows abruptly into the heart it can create the risk of heart failure due to overstrain. Additionally, the toxins released from the pooled blood can cause severe failure of other internal organs.
Those rescued should be placed in a sitting position and professional medical advice should be sought. Continuous monitoring of the respiration and circulation is necessary. Transfer to the horizontal posture should take place only gradually.
* Gordon Cadzow is secretary of the FPMA, which comprises all leading Australian companies in the design and manufacture of fall protection equipment, 02 9875 3240, www.fpma.com.au.