Height Rescue Guidance & Planning

Categories: Height Rescue Tags: Rescue Planning

When operatives are suspended in mid-air after a fall, their lives hang in the balance – even if they have survived the fall without a scratch. Every second counts. The intention of this guidance is to help you fully understand the implications of an operative falling, being arrested and then suspended by a harness, which initially saves them, but minutes later may kill them due to suspension intolerance. More than just helping to understand why this happens, this guidance will show what action should be taken to prevent a fallen operative dying from suspension intolerance. It will also clearly outline the current law with which must be complied with to discharge our legal responsibility.

“Harnesses can become deadly whenever an operative is suspended for durations of over five minutes in an upright posture with the legs relaxed straight beneath the body.”


After five minutes a fall casualty is highly likely to be unconscious but operatives attending the scene may not realise the seriousness of the situation. A mere 10 minutes later a dead body could be hauled up. The cause of this problem is called suspension intolerance (Previously referred to as suspension trauma).

In March 2004, OSHA (US equivalent of the UK Health and Safety Executive) issued a health and safety bulletin outlining the dangers of prolonged, upright suspension. The bulletin warned of the risk of “orthostatic intolerance “and “suspension intolerance” and refers to some of the potential health hazards – death being the chief one – experienced by operatives who are suspended upright by fall arrest equipment after a fall.


Unless the operative is rescued promptly using established safe procedures, suspension intolerance caused by orthostatic intolerance could occur and result in serious or fatal injury as the brain, kidneys and other organs are deprived of oxygen. Most users of fall protection equipment are unaware of the hazard of suspension intolerance.


Death from suspension intolerance is caused by orthostatic intolerance and is the result of venous pooling. This can occur any time a person is required to stand still for prolonged periods and may be worsened by heat and dehydration. Major blood vessels pass through the muscles in the legs. The movement of these muscles assists circulation by squeezing the blood back up towards the heart. If the muscles stop moving, gravity pulls the blood down into the legs
Eventually, enough blood accumulates (venous pooling) so that return blood flow to the right chamber of the heart is reduced as the heart can only pump the blood available, so its output begins to fall. The heart then speeds up to maintain sufficient blood flow to the brain but, if the blood supply to the heart is restricted enough, the higher pulse and faster breathing is ineffective and the body abruptly slows the heart. The result is fainting.

The moment a person loses consciousness they collapse and become horizontal so the time spent in a vertical position while unconscious is minimal and, as blood flow improves – the result of being horizontal – the person returns to consciousness and recovery is likely to be rapid. When a person is suspended in a harness in which their legs are immobile, unlike fainting, the person does not or cannot naturally move into a horizontal position, then gravity pulls blood into the lower legs. In a harness, the operative can’t fall into a horizontal posture, so the reduced heart rate causes the brain’s blood supply to fall below the critical level. During excessive venous pooling, cardiac output and arterial pressure fall to levels, which can critically reduce the quantity and/or the quality of oxygenated blood flowing to the brain.

Three Things That Occur Which Aggravate The Problem:

  1. The operative is suspended in an upright posture with legs dangling.
  2.  The safety harness straps exert pressure on leg veins (femoral arteries), compressing them and reducing blood flow back to the heart.
  3. The harness keeps the operative in an upright position, regardless of loss of consciousness

This includes not only a potentially fatal reduced blood flow to the brain, but also the other vital organs, such as the kidneys. The kidneys are highly sensitive to blood oxygen levels and renal failure as a result of excessive venous pooling is a real possibility.

Injuries suffered during the fall, or the shock resulting from the experience of the fall, can increase the onset and severity of venous pooling and orthostatic intolerance, as can physical and environmental factors such as fatigue, dehydration, hypothermia, cardiovascular disease, respiratory disease and blood loss. The time spent in an unmoving suspended position, with the legs below the
heart, is what kills.


Operatives face considerable danger after a fall, through the lack of a thought-out, detailed and fully implemented rescue plan. It is now a legal requirement of the ‘Work at Height Regulations 2005’ to have a rescue plan. The best rescue strategy is to take every possible precaution to prevent operatives from falling in the first place. But the reality is that falls happen, and a rescue plan is an essential component of the company overall fall protection method statement and risk assessment. The lack of any form of a pre-conceived post-fall rescue plan not only puts the fall victim at risk but also puts rescuers in harm’s way. Whenever there are unplanned attempts to rescue, second or third injuries or fatalities may not be uncommon.