Vacuum mattress
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A vacuum mattress is a medical device used for the immobilisation of patients, especially in case of vertebra, a pelvis or a limb trauma (especially for femur trauma), as well for hand transportation of patients on short distances (it replaces the stretcher). It was invented by Loed and Haederlé, who called it "shell" mattress (matelas coquille in French).
It consists in a sealed polymer bag (bigger than an adult human body) that encloses small polystyrene balls, with a valve, straps and handles. It is washable and invisible to X-rays.
When the mattress is under air, the ball are free and the mattress can be moulded; usually, the vacuum mattress is put on a stretcher, the patient is put on the mattress (e.g. with a scoop stretcher), and the sides of the mattress are moulded around the patient. Then, the air is pumped through the valve and the valve is closed; the atmospheric pressure presses the balls together and the mattress becomes hard and rigid; the straps are tied.
A sheet is usually put on the vacuum mattress, for three reasons:
- to protect the mattress: the casualty might have broken glass on their clothes, or a jewel that might puncture the mattress;
- to avoid the direct contact of the skin with plastic, e.g. for a sweating casualty;
- to help the patient transfer at the emergency room.
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Use of the vacuum mattress
The full spine immobilisation (splint) is performed with:
- a rigid cervical collar
- a vacuum mattress
- a stretcher under it (the longitudinal stiffness of the mattress alone is not sufficient).
Preparation of the vacuum mattress
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The vacuum mattress is put on a stretcher, or possibly on a long spine board. The straps are put under the mattress, along its side, so they do not reach the ground. Then, the polystyrene balls are distributed evenly through the mattress by shaking its surface: a part with less balls would be less rigid. It is also possible to concentrate the balls in a given place to make this part more rigid. Finally, a sheet is put on the mattress. The sheet is folded so it will be possible to pull it to wrap the casualty into it; the profile has an S-shape.
The team member also checks that the pump (manual or electrical) works in the right direction.
Moulding the mattress
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There are three ways to put the casualty on the vacuum mattress:
- lifting the casualty and pushing the stretcher under it; a method with five team members (four lifting and one pushing the stretcher) should be used when a spine or a pelvis trauma are suspected;
- the casualty is lifted with a scoop stretcher: the scoop stretcher is pus on the mattress and opened to release the casualty;
- the casualty is lifted on a long spine board: the board is put on the mattress, the casualty is lifted (best with four team members) and one team member removes the board.
In all cases, the vacuum valve is up and at the feet of the casualty.
Once the casualty is on the mattress, the sheet is wrapped around him/her, and the sides of the mattress are folded against his/hers body; the top of the head must be kept clear (the mattress could retract when pumping out the air and thus compress the spine). The air is pumped until the mattress is rigid; then the valve is closed, and the traps are fastened.
When only three team members are available and there is no scoop stretcher, the following procedure can be used :
- the vacuum mattress is put besides the casualty, on a protecting ground sheet, and partially depressed (three manual pumping) to make it more rigid and thinner; a sheet is put on the mattress, closer to the casualty;
- the casualty is put on his/her side, with a procedure that is similar to the recovery position;
- the team member at the legs pushes the mattress against the back of the casualty; the ground sheet helps sliding the mattress on he floor;
- the casualty is put on his/her back, overlapping the side of the mattress;
- the casualty is centered on the mattress; the sheet helps sliding the casualty on the mattress;
- the straps are tied to mould the mattress; the team leader moulds the sides of the head manually;
- the air is pumped;
- a long spine board is placed in the axis of the mattress; two team members face each other and hold the mattress' handles at the head and at the thighs; they lift a few centimeters, the ground sheet is removed and the board is slided under the mattress, to ensure a longitudinal rigidity;
- the board can then be lifted (with the mattress on it), and be put on the stretcher.
While the lifting methods can induce a flexing of the spine, this rolling method can be hazardous for several reasons: risk of a torsion of the spine when rolling, risk when sliding the casualty on the mattress, risk of anteversion of the hips (and thus of flexing of the spine) due to the weight of the legs when lifting the mattress to slide the board.
Advantages and disadvantages
The vacuum mattress is an alternative to the use of a long spine board. Its advantages are:
- it is comfortable;
- it is adapted to all traumas, included spine and femoral traumas;
- the victim feels secured;
- it can be used instead of a stretcher for hand transportation (with the handles, e.g. in stairs) when longitudinal rigidity is not critical, or on short distances with six team members.
It drawbacks are:
- it is relatively fragile, and becomes useless at any degradation (the vacuum requires a perfectly sealed envelope);
- therefore, it cannot be used alone as a scoop device (it must be put on a stretcher).
- it is heavier than a board;