By Maurice a AMPHOUX
At first, nobody can believe that it can be deadly dangerous to remain hanging passively in a well-designed harness. It is, however, a proven truth, albeit generally not known, and it is to remind and stress the consequences of this fact that I want to mention it today.
I shall first mention why the habitual users of this equipment cannot understand their danger. Then I shall mention why some disbelieving people – and I was one of them – have been led to change their minds. Lastly, I shall emphasise the resulting consequences, in my opinion, of which I would like to convince you.
Let us first see why habitual users of such equipment find it hard to admit that it can be dangerous.
We have all seen pruners or linesmen working installed on supporting systems. They often have feet against the tree trunk or the electric pole on which they are working and are therefore only partially supported on their bottoms. Their holding tether [or strap] is at an angle and helps support on their feet. But it is quite possible, even if it is less convenient; that the tether is vertical and that all the body weight is supported by the holding system. This is not convenient for working, owing to the lack of a fulcrum and of a horizontal component. It is the equivalent of working in a state of weightlessness. But it is perfectly bearable without malaise, for several dozen minutes if necessary.
In building and public works, it is also a common situation in order to carry out brief or urgent repairs on a sloping roof, even on a gable or a façade. In France this was still recently the usual technique to install or repair the gutter or down pipes. The worker used a knotted rope on which he was moving a small plank used as a seat. This looked like a swing and was called the old name of “working the ‘escarpolette’ [old French word for swing] way”. It is no longer authorised unless completed with anti-fall harness and a vertical supplementary support. But this is still a perfectly tolerated hanging working way. Cavers readily use light pelvic harnesses with forward fastening which facilitate their progress along the ropes. Their explorations often require lots of materials which have to be transported then brought back up after use. This requires often working dangling in space for relaying and that can last several hours. With a well thought out and well-adjusted harness, it does not create any notable lack of comfort. In mountain climbing this type of situation is less common but can occur, for example when anchoring pitons in a climbing path. Similar techniques are now also sometimes used in the upkeep of some unusual modern architectural constructions, as for example, the cleaning of the well known glass pyramid of The Lourve in Paris. And as far as parachutists are concerned, it is never coming down held by their harnesses, which causes any difficulty.
Therefore none of these sportsmen or these professionals, none of those who design and supply this equipment would have dreamed of incriminating it.
With the team I was supervising some years ago, we got interested in the system for stopping falls with the building workers. We rapidly came to the conclusion that the traditional belts were incompatible with any fall and even more so with maintaining the holding, be it only for the time to wait for help. And we could not exclude falls of the order of four metres. This is the range of fall of a worker at the highest sold cramping point. The fall being able to happen as well through toppling head first as feet first, the only reasonable solution for any fall stopping system was the complete anti-fall harness as defined in the standard EN361.
But still it was necessary to ensure that the hanging support did not cause any problem after the fall. None of the successive equipment elaborated and previously tried seemed bearable for long, including the pelvic harness which imposes a considerable effort to remain in a sitting position with the help of the arms. And then it was necessary to foresee the case, especially unfavourable but still possible though rare, of a fall caused by an impact resulting in loss of consciousness, or a fall resulting in an impact against the substructures with the same consequences: impossibility to make help easier and prolonged maintaining in passive suspension and total muscular relaxation. But with the knowledge of the experiments mentioned earlier, we anticipated that a complete harness would be comfortable and we tried, without any special precaution, a well adapted parachute harness … until loss of consciousness of the subject. Surprised, but in no way worried by this transitory and unexplained malaise, we started again with other subjects and other harnesses, under telecardiographic control. The result repeated itself for each one with sudden modification of the cardiac rhythm without warning symptoms with delays varying from two to twelve minutes. The national research institute on security confirmed these results. Because of lack of means of resuscitation, we did not dare continue these trials but we did publish our data.
These data alerted two quite different teams. One was Jim Brinkley’s who called upon the remarkable installations of the physiology laboratory of the US Air Force to contribute in sufficient safety conditions and which confirmed our results. The other one was that of the French Federation of Speleology. In spite of their initial absolute scepticism, they carried out several trial campaigns, including in a hospital service, of cardiac resuscitation to try and find an explanation and some preventative means. They first showed that high quality sports people, in perfect physical condition, and capable of excellent muscular relaxation, lost consciousness in a few minutes, always without warning signs. Some trials in various hanging positions have shown that the low position of the lower limbs was a determining factor. They also collected some stories of subjects who died while hanging and which could be explained as well by this type of fainting as by exhaustion or exposure.
In fact several hypotheses have been raised to explain the observed troubles. It was possible to invoke the inevitable compression of the tops of the thighs on most of the harnesses tried. Even if that compression was light, it was possible that there was a disturbance with return [blood] circulation and cardiac depression caused by the accumulation of the waste products. But the troubles occurred just as much with certain harness models in which the buttock straps are kept in place by straps which did not compress at this level. This type of compression is, however, to be feared even with a well-adapted harness, if it shifts during the fall. A second hypothesis has been raised during some trials where the hanging straps were in lateral contact with the neck and could have stimulated the carotid baroreceptors. But this arrangement is unusual.
The most probable hypothesis therefore is that absence of muscular contractions more than the compression’s lead to an important blood stasia at the level of the lower limbs. Besides there exists constantly a certain local cyanosis. The lowering of the amount of circulating blood may determine a certain degree of cerebral anoxia aggravated by the trouble of the cardiac rhythm which stems from the same mechanisms. This hypothesis has been largely confirmed by basic knowledge in resuscitation anesthesia. Surgical operations under general anesthesia are only carried out in low legs position for certain special types, more particularly the intra-cranial operations. Anesthetists know that the moment when a patient is brought back to the horizontal position is often delicate and must be especially watched, often necessitating hyper-oxygenation and cardiac support.
Thus the mortal risk of keeping an unconscious subject suspended in his harness is confirmed and explained.
The lessons to be learned from these observations follow:
The first is that this risk is difficult to believe. None of those we have met and who are used to this equipment could believe from the start that, in some particular circumstances it could become deadly dangerous. Indeed we would not advise anybody to repeat the experiment. Some years ago, the demonstrator of a major French manufacturer was in the habit of letting himself fall 4 metres with harness and shock absorber in all safety conditions; he possibly holds the record of several thousand falls without an accident. To convince him I had to let him hang in his workshop while we continued to exchange jokes until I had to release him urgently. I would not dare to do it again under any circumstances. It is necessary to accept the common evidence of our four teams, so different from each other.
Another difficulty stems from the fact that it is an uncommon risk. It is difficult to estimate the probability, at least for workers. Falls without harnesses, with their deadly consequences, do not exceed a few dozen per year in our country. Falls with a stopping system are probably of the same order, but not counted because generally without consequences. Falls with loss of consciousness are probably rarer still. But there is absolutely no reason why the few deaths that might stem from them be attributed to their real cause. The lack of knowledge of this type of accident has therefore every chance of continuing unless the necessary publicity is given.
As regards mountain climbing, there is cause to think that it is similar. Certainly falling is pqart6 of the game and is less unusual than a work accident. But it is often restrained, anticipated for a few seconds and happens in front of experienced witnesses. The probability of remaining in a state of prolonged suspension leading to loss of consciousness is small and, eventually, will find in case of death an obvious explanation between the triggering trauma and cold [or ‘exposure’] without thinking of an enquiry which would have only scientific interest … A similar accident while parachuting or paragliding would have no more reason to be investigated.
The case of caving [speleology] is slightly different, to the extent where staying in suspension is a frequent occurrence, but the falling is unusual. On the other hand it seems that the often very physically demanding conditions in the course of several days could lead to an exhausted state rendering the climb back up dangerous. In any case the risk did not seem negligible to the French Federation of Speleology which has given precise instruction that any subject losing consciousness while in suspension be very urgently rescued, un-hung or toppled over head down and given mouth to mouth resuscitation.
On second thoughts, this should become evident. No first aid worker, nobody, even with little knowledge would imagine leaving a person in a fainting fit in an armchair. He or she would immediately be put in a lying position which would often be sufficient to bring back consciousness. Without doubt one could die in one’s armchair if fainting without a witness…
The un-clipping of an unconscious subject from his harness after a fall can only be rapidly effected if this intervention has been planned ahead and the necessary equipment and personnel are on standby. This means that no one should plan an operation necessitating the use of a harness without perfect knowledge of the rescue conditions and implications involved. The organiser and operator must just been sufficiently trained.
All these difficulties are added to the other reasons to make provision, at work at least, for the use of protective systems against falls, even small ones, must be limited to cases where no collective solution can be organised and, in this case, to the individual protective equipment prohibiting any fall that those limiting the consequence.
So it is an infrequent risk, but deadly; a risk easy to remedy if one is forewarned, but a risk difficult to admit. It is therefore important that the information be widely spread to all interested parties. This is the reason for my intervention, for my insistence. If this results in saving a few lives which otherwise would have been stupidly sacrificed, I will not regret having bored you a few minutes with my stories.
[This is the translated text from French of a recorded lecture at the International Fall Protection Symposium, Germany, September 1998, courtesy Peter Ferguson]