Volume 1 N u m b e r 3 REPORTS OF MEETINGS 245

DESIGN CRITERIA F O R T H E E M E R G E N C Y A M B U L A N C E

International Seminar arranged by the Medical Commission on Accident Prevention held at The Royal College of Surgeons of England, 30 September, 1969"

G. M. Mackay (Department of Transportation and Environmental Planning, University of Birmingham) described the study undertaken by the department and reported some of its findings. Six hundred and forty-three accidents had been studied, of which 32 had proved fatal.

There was a striking difference between urban accidents, which provided 73 per cent of the series, and those occurring in the country. Those killed by urban accidents were motor cyclists or pedestrians and from the 12 cases reported only 1 gave any reason to think that anything could have been done to save life. Rural accidents occurred at higher speed and affected the occupants of vehicles. Ambulances took an average of 19 minutes to arrive, as against 7 minutes in towns, and roughly 5 per cent of passengers were trapped for 6 minutes to 2 hours (mean, 34 minutes) because of deformation of the vehicle. While it appeared likely that 43 per cent of those that died might have benefited from medical treatment at the place of accident this was not the same as say- ing that nearly half the deaths could have been prevented.

Dr. Mackay's study led him to press for better trained and equipped ambulance crews; he was doubtful whether medical teams could often arrive in time. He went on to recommend that ambulances should carry simple extractive gear and one or two stretchers that could be tilted head down- wards and be raised and lowered, should have plenty of good lights, and should have a turning circle of 44 feet diameter.

R. Snook (Senior Casualty Officer, Accident and Ambulance Research Centre, Bath): Bath has a specially equipped Land Rover for crash rescue work and at one time or another every piece of its £3000- 4000 worth of equipment has been used. Its principal purpose is to provide access to the trapped casualty so that he may be removed or, if necessary, be given medical support until he can be removed. Good lighting plays a very important part in this.

It had been found that it was both expensive and unnecessary to equip an ambulance, as the Millar working party had recommended, with rescue gear that was accessible from outside the vehicle.

Experience in Bath supported the policy of making a doctor available with suitable equipment. He referred favourably to a 50/50 mixture of nitrous oxide and oxygen, which was superior to an injected analgesic drug such as pethidine. All persons in pain were comforted by it, none was rendered unconscious, the blood-pressure did not fall, and its effect passed off rapidly when inhalation ceased. It could be used for the pain of either disease or injury.

Equipment needed for the treatment of the patient should, when possible, be made to clip onto the trolley. The exhaustible sort of conforming mattress had

*The full proceedings will be published by the Medical Commission on Accident Prevention.

proved useful as a general splint for the patient on a trolley although there were occasions when its bulk made it awkward to use.

He favoured having patients travel feet first in ambulances.

D. E. Argent (Senior Anaesthetist, St. Mary's General Hospital, Portsmouth): Experiments had shown that an Army 3-ton lorry could subject passen- gers to acceleration of up to 5 G.; figures of 4 G. had been recorded with an Army ambulance, 3 G. with a civilian ambulance travelling at 35 m.p.h., as against a mere 0'4 G. with a hovercraft.

It was essential that patients could be tilted head downwards when necessary and that an effective sucker should be immediately available. He was strongly in favour of means of direct communication between the ambulance's crew and the hospital to which they were travelling.

J. D. Farrington (Chairman, Subcommittee on Transportation of Injured, Committee of Trauma, American College of Surgeons) described the sort of equipment that was required and dealt at some length with the process of releasing and removing a t~apped casualty without hurting him. He illustrated and described the use of long and short spinal boards. Both were light and smooth so that they would slide easily beneath or behind the casualty. The short board provided effective and comfortable support for head, neck, and trunk by means of collar, head- band, and body straps. From the hips up the patient could be moved in one piece and travel in safety, on the side if necessary. The long board could be used as a stretcher.

One disadvantage of the stronger locks that had been introduced to prevent car doors from bursting open was that they could seriously impede rescue gear.

P. S. London (Surgeon, Birmingham Accident Hospital) confined his remarks to the subjects of the comfort of the patient and the convenience of his attendants in the vehicle. He wondered whether enough attention has been given to the comfort of a passenger who cannot see out and is therefore un- prepared for changes of speed or direction and, being recumbent, is in any case hardly able to brace himself against any of the many accelerations to which the vehicle is subject.

The Austin Motor Company, as it then was, devised an ingeniously suspended stretcher that reduced the motion of the vehicle to a very gentle swaying that was acutely nauseating for some persons and therefore unacceptable.

It was desirable that ride characteristics should be designed with the recumbent and helpless person and not a seated passenger in mind and with due regard to the nauseating effects of too much damping.

Space Inside the vehicle one should have enough space

to move comfortably around a centrally placed

246 INJURY; THE BRITISH JOURNAL OF ACCIDENT SURGERY Injury

Jan. 1970

stretcher. During a journey the attendant is on his own with the patient and must therefore be able to reach anything that he needs without leaving the head of a patient who may be unconscious and develop obstruction to his breathing at any time. Being 6 feet tall, the speaker appreciated the import- ance of headroom.

Equipment Some emergency equipment may take its power

from the ambulance but lamps, suckers, and other electrical gear may be needed some way from the vehicle and should not be entirely dependent upon it for power.

Apart from the usual kit an emergency ambulance may have to carry the bulky equipment of a rescue team for heart attacks or respiratory failure.

Loading The easiest way to load an ambulance is to walk

straight into it, having lowered its rear, at least, to the ground. An alternative, if not too reminiscent of a hearse, is to slide the stretcher in on rollers. Unless it can be raised a foot or more the currently popular stretcher trolley is too low for the comfort and convenience of the attendant should he need to carry out more active treatment.

An ambulance is generally thought of as a vehicle used for carrying sick and injured persons. The vehicles used by the ambulance services of Great Britain have three principal tasks:--

1. To carry persons to and from hospital for treat- ment or other appointments as out-patients. They are for all practical purposes small public services vehicles.

2. To carry recumbent persons to and from or between hospitals.

3. To convey seriously ill or seriously injured persons to hospital.

Many of the 140 or so ambulance services of Britain have, for reasons of economy, to use some, at least, of their vehicles for all three purposes, which means that the seriously ill or injured passenger is worst served because he has to travel in a vehicle designed for much greater loads.

The needs of an emergency ambulance are easily stated but the fact that this is an international meeting underlines the difficulties of even trying to meet them.

Jerry Esposito (Director of the School for Emer- gency Medical Technicians, University of Pittsburgh Health Centre) dealt with the shortcomings that existed in ambulance work in the United States, where services were provided by private companies that might also perform the not unconnected functions of undertakers, by police departments, by hospitals, and by other bodies.

Recommendations for ambulances included a good ride and internal dimensions of 115 in. in length, 54 in. minimum head room, and 26 in. between stretchers; they were widely ignored.

When, in 1967, it was decided in Pennsylvania to offer extra pay for crews that had had 10 hours' training and could as a result use sheets, blankets, and bed pans it was found that 70 per cent of the crews had not had even this much training! He blamed the public for its failure to provide adequate support or stimulus for the equipment, training, and organization required. In discussion Dr. Poulsen said that in Denmark initial training in hospital for ambulance crews was to be increased from 2 to 3

months and refresher training to 2 weeks instead of 1 week every other year.

Rex Binning (Senior Consultant Anaesthetist, Brighton and Lewes Group of Hospitals) described the resuscitation service that Brighton was about to start for cardiac emergencies. The equipment was carried in 3 cases; one for the airways, one for intra- venous infusion, and one for drugs. The equipment needed to be portable, reliable, and easily maintained. It was picked up with the doctor, who held himself in readiness for prompt departure at short notice.

John E. BaerwaM (Director, Highway Traffic Safety Centre, University of Illinois) dealt with the specifica- tions for American ambulances but had to admit that their knowledge of what was required had too many gaps in it to act as a proper basis for a full specifica- tion.

Allan Brown (Consultant Anaesthetist, Department of Surgical Neurology, Edinburgh) emphasized the importance of making the training of ambulance crews as realistic as possible, particularly when it dealt with handling the patient during the most dangerous period--just after the accident had occurred. He was strongly in favour of having crews spend time working in hospital because this not only enabled them to increase their knowledge and under- standing of the effects of disease and injury, it made for the necessary good relations between hospital staff and the members of the ambulance service.

Eberhard G~gler (University Surgical Clinic, Heidelberg, Germany) began by putting the cost of ambulances in perspective; Heidelberg had more dust carts than ambulances and spent much more on each dust cart than on each ambulance.

In Heidelberg the duty surgeon was on continuous call for a week, during which period he was in radio communication with the emergency control centre and had an official car at his immediate disposal whenever he was called out. A special ambulance went independently to the accident. This vehicle carried a central support for the patient and emergency medical equipment. The mobile operating unit that had been in use previously had been abandoned when it became clear that the place for major surgery was a properly equipped and staffed operating suite.

The doctor arrived an average of 9 minutes after being summoned, having travelled an average distance of 7 kilometres. In about 1000 such calls Dr. G6gler estimated that 34 persons would have died without the surgical service provided by himself and his colleagues.

In the discussion that followed these papers it was agreed that although the suction achieved by using the exhaust manifold of the ambulance engine could reach 400 mm. Hg it was unwise not to have a reliable alternative.

Mr. London said that the success of radio com- munication between ambulance crews and the receiv- ing hospital depended to a large extent upon there being at the hospital a doctor who was in fact capable of dealing successfully with the crews' calls for advice. Dr. Poulsen pointed out that the best way to ensure that doctors and ambulance men spoke the same language was to bring them together in hospital.

E. IV. Still (Assistant Managing Director, Normal- air Garrett Company, Yeovil) chided the medical profession for not giving designers and engineers the

Volume I Number 3 REPORTS OF MEETINGS 247

precise specifications without which they could not work. He then went on to describe means of cooling ambulances in hot climates.

John Oliver (Research Engineer, Ride and Handling Section, Motor Industries Research Association) dealt with the ride characteristics of passenger cars, which served to emphasize the lack of attention paid to the needs of the recumbent patient.

C. H. G. Mills (Group Research Head (Acoustics), Motor Industries Research Association) spoke about noise in motor vehicles. The amount of noise a particular vehicle would make was not something than could be predicted although it could be reduced. Ambulances were only a little noisier than motor cars, unless the two-tone horn was used (80-85 decibels). It was not thought that in the ordinary way the noise made by an ambulance was harmful to the patient, who might have subsequently to tolerate sounds of up to 60 decibels in hospital.

K. Hamilton-Smith (Assistant Chief Designer, Harry Ferguson Research, Coventry): The much criticized rear-wheel drive was cheaper than front- wheel drive but it did not allow a very low floor and it meant that antiskid devices would be put on only the rear wheels. Front-wheel drive was more expen- sive and produced less traction because the front wheels were more lightly loaded than the rear. In the case of four-wheel drive it was usual for only the rear wheels to be driven while the vehicle was on a made- up road. His company's system of four-wheel drive provided good traction, allowed antiskid devices on all four wheels, so making for stability when braking, and it kept the front axle light by applying only a third of the power to it. It was not much more expensive than a suitable system of front-wheel drive but he admitted that it required a higher floor than would otherwise be possible. An automatic gearbox was a valuabIe aid to easier and smoother driving.

Anthol O, Smallhorn (Research Manager, Ogle Design Limited) had set about devising the sort of vehicle that would meet the requirements stated in the Millar working party's report on equipment. The model vehicle on display was to be regarded as nothing more than a three-dimensional drawing. He favoured conveying the patient on a trolley upon which should rest a simple pole-and-canvas stretcher for use if needed. For purposes of observation he thought that a trolley 19 in. wide would be sufficient but if the patient was going to need treatment 33 in. was a more suitable width. It should in any case be 77 in. long and allow a 30 ° head-down tilt of its entire length and a 60 ° upward tilt of half its length. The 15 in. high floor was easily reached by means of a ramp.

Inside dimensions of the proposed vehicle were 73×73×117in. Cupboards were set over the wheels and provided 18 cu. ft. of storage space. Two trolleys could be carried if necessary; oxygen was piped to the head end. The rear door was 42 in. wide; part was lowered to provide a ramp and the rest lifted up, with a ' winter door ' inside it. He was in favour of having windows, but with blinds. A 2-1itre engine would allow a payload of 1500 lb. and speeds of up to 70 m.p.h.

Mr. Marklew (Dennis Brothers) described the ambulance that his company had built and had sup- plied to two services for trial. It would carry one or two trolleys; there was negligible pitch and roll and having found that a full load caused a tilt of only 2 ° it was considered that there was no need for a levelling device. The floor was 18 in. high. The unsprung weight was low; suspension was by coil springs with hydraulic damping to adjust the ride. Antiskid devices were fitted to the rear wheels only, which were twin. Front-wheel drive was made by a 2'8-1itre Jaguar engine using 35 type Borg-Warner trans- mission, which was a standard attachment. All the parts were already produced in abundance, which helped to keep the price down.

L. Bruce Archer (Department of Industrial Design (Engineering) Research, Royal College of Art) spoke of the theory of problems and their solution. No solution could be attempted until a problem had developed to the point at which it could be defined. It was not at first necessary to be certain on all points; it was reasonable to work from assumptions but they had to be proved at some stage. Designers and testers must work together in development. More than half the cost of development was incurred after the working prototype had been built.

It was not always possible to reconcile all the re- quirements but it should be possible to achieve a satisfactory result by balancing the degree of accep- tability of one or more features against what was theoretically best. Existing laws and established customs often have to be accepted but may need to be changed, from which it follows that the public and the commercial participants in a particular scheme may have to be educated.

There was general expression of gratitude to Mr. John Ogler, Chairman of Ogle Design Ltd., who had provided the means of calling the seminar together.

[Comment: In all the addresses and discussion there was no explicit definition of an emergency ambulance. In Britain it is perhaps best defined as the sort of ambulance that would answer a 999 call, in which case it has to be accepted that much more often than not the special features of the vehicle, equipment, and crew would go unused.] P.S.L.