Introduction
It is well known that the Work at Height Regulations 2005 are concerned with working safely at heights:
• avoiding work at height, where it is reasonably practicable to be do so
• preventing falls from height, where it is reasonably practicable to be do so
• mitigating the effects of falls from height, where it is reasonably practicable to be do so
Regulation 4 of the Work at Height Regulations 2005 deals with organisation and planning: Regulation 4(1) states that: every employer shall ensure that work at height is -
(a) properly planned;
(b) appropriately supervised; and
(c) carried out in a manner which is so far as is reasonably practicable safe, and that its planning includes the selection of work equipment in accordance with regulation 7
Regulation 4(2) states that: Reference in paragraph (1) to planning of work includes planning for emergencies and rescue.
All too frequently, the emergency planning element is often not considered when work at height is being planned. Largely, this is because:
• there is a general lack of awareness of suspension trauma and its consequences
• employers often fail to appreciate where and when rescue provision is required
• employers often fail to provide adequate rescue equipment or appreciate what is suitable equipment for use in rescue
One of the reasons why planning for rescue in work at height situations is important is suspension trauma (a special case of orthostatic intolerance and sometimes known as harness hang syndrome). Orthostatic intolerance is a normal and natural reaction to being upright and immobile. In such cases, a complex combination of blood pooling in the legs and cardiorespiratory restriction leads to unconsciousness. Orthostatic intolerance can occur in several sets of circumstances, such as:
• being suspended in a harness
• being trapped upright within a confined space
• being secured to a vertical stretcher or litter (such as in mountain rescue)
• many situations where people are forced to remain standing without the ability or room to move
A classic manifestation of acute orthostatic intolerance is a soldier who faints after standing rigidly at attention for an extended period of time. Suspension trauma presents an immediate threat of death to anyone immobilised in a vertical position.
Causes of suspension trauma
When people stand upright, the heart alone cannot cope with pumping the blood around the body. In particular, it can't draw blood back up, against the force of gravity, from the legs and feet. To aid the heart, our veins (the blood vessels that return blood to the heart) are very elastic and have a series of (non-return) valves at regular intervals. As people move around, the veins are squeezed by the muscles around them, a process that is important for helping to push blood back up towards the heart. If people are in an upright position for a while without working their leg muscles, then the blood doesn't get pumped back up from the lower body. Instead it collects in the veins of the lower body (venous pooling), and so reduces the amount of blood available for circulation. This reduces the quantity and the quality of blood available to the brain, which can result in loss of consciousness. This loss of consciousness is an important survival mechanism in these circumstances as when people faint, they fall over. Once they are lying down, the heart can circulate their blood quite satisfactorily, returning oxygen to the brain with no harm done.
Suspension trauma is the name given to the situation that occurs when people faint but cannot fall over, causing the body to remain upright. This is a serious problem, because if the body stays upright after losing consciousness, then the blood flow is not restored. In such circumstances, the suspended person is at serious risk as the reduced blood flow can lead to serious brain and/or kidney damage, and ultimately to death. If it is allowed to develop unchecked, it can be fatal in a very short time (a matter of minutes).
Only a short time
In averages cases, it takes somewhere between five and twenty minutes for the first signs of shock to be felt by the casually. If their legs are held perfectly still (such as if they are unconscious) then the first signs of shock may be apparent after about three minutes. If they are not rescued, a few minutes after this they the casualty will faint and shortly after this they will die. If a suspended person is to be rescued, then the rescue must be carried out quickly, preferably within ten minutes of the start of suspension.
Planning for rescue
By their nature, rescue operations are carried out under extreme pressure. Consideration should be given to all aspects of the rescue process. Elements to consider would include the type of equipment required, the demands placed upon the rescuer, the training the rescuer will require to carry out the rescue and how the effectiveness of the rescue system as a whole can be maintained
Following a fall and a person being suspended in a harness, it is clear that even if they are uninjured by the fall there is a relatively short time available during which to rescue them. Following the fall, there is only a short time before the onset of shock and suspension trauma is life threatening. It is essential, therefore, that the means of rescuing them fallen person has been planned before the event.
Even is the casualty cannot be released form suspension immediately, they can be aided by others if they can be reached safely or if they are still conscious. If possible, lift their knees into a sitting position using a rope, sling, or other items. If the casualty is hanging in a harness and is unable to escape, there are some things that they can do to prevent the onset of suspension trauma. In particular, they cam wiggle their toes and move their legs. This will move the muscles in the legs and will help to squeeze the blood back up towards the heart. This may be enough to prevent the onset suspension trauma.
First Aid
When somebody has been rescued from suspension, do not let them lie down and do not lay them down. The first action of the first aider on site when the casualty is released from suspension should be to place them in a sitting position with their body upright and their legs flat, or bent at the knees. The exact angle of the knees is not critical, the important issue is that their body is upright, and the legs are no longer dangling. This posture will reduce the pooling effect of gravity, but will keep most of the pooled blood in the legs, preventing reflow and splinting (see below). The casualty should be kept in this position for at least 45 minutes. The casualty must not be allowed to stand up, exercise, drink or eat. They should be kept calm and relaxed as this will help to reduce the effects of stress on the heart rate. The casualty should be sent to hospital, even if they are not experiencing any ill health.
The first aider must also be mindful of other injuries that have been sustained, such as spinal injuries, choking, etc.
Causes of death after an otherwise successful rescue
Casualties who have developed suspension trauma may be at risk from reflow syndrome. This is the name given to the potentially fatal situation caused when the pooled that has blood in the veins in the legs is allowed to flow back into their body. The blood that has pooled in the veins in the legs will have the nutrients and the oxygen in it used up by the leg muscles. Once this has been used up the leg muscles will respire anaerobically and the blood will accumulate the toxic breakdown products of this anaerobic metabolism
Another of the problems with treating suspension trauma casualties is overloading or splinting of the heart muscle. Lying the casualty down will cause about 60% of blood volume to return very quickly to the heart and may fill it with blood such that the pumping action is not possible. This overloading of the heart muscle can cause immediate death. During and after rescue, it is important that the casualty is not carried or laid horizontally or allowed to lie down.
Summary
Suspension trauma is a potential cause of death in all cases of vertical suspension. It may result in the death of a person who has fallen and whose fall has been arrested by their fall arrest equipment and who is otherwise unhurt. In order to prevent fatalities from suspension trauma, employers need to ensure that casualties can be rescued promptly (within ten minutes) and that the first aiders known how to deal with (suspected) suspension trauma cases.
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