Vacuum mattress

A vacuum mattress, or vacmat, is a medical device used for the immobilisation of patients, especially in case of a vertebra, pelvis or limb trauma (especially for femur trauma). It is also used for manual transportation of patients for short distances (it replaces the stretcher). It was invented by Loed and Haederlé, who called it "shell" mattress ("matelas coquille" in French).
Medical uses.
The full spine immobilisation (splint) is performed with: a rigid cervical collar, a vacuum mattress, and a stretcher under it (the longitudinal stiffness of the mattress alone is not sufficient).
Preparation of the vacuum mattress.
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 section with fewer balls would be less rigid, conversely if balls are concentrated at any given point this becomes more rigid.) A sheet is put on the mattress, folded so it will be possible to pull it to wrap the casualty into using an S-fold and finally a team member should double-check the pump (manual or electrical) is set to either pump air out of the bag.
Moulding the mattress.
There are three ways to put the casualty on the vacuum mattress:
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 their 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 straps are fastened.
When only three team members are available and there is no scoop stretcher, the following procedure can be used:
While the lifting methods can induce a flexing of the spine, this rolling method can be hazardous for several reasons: the risk of a torsion of the spine when rolling, the risk when sliding the casualty on the mattress, the 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:
Its drawbacks include:
Operation.
A vacuum mattress consists of a sealed air-tight (typically polymer) bag enclosing small beads (typically polystyrene balls) and fitted with one or more valves. While at ambient air pressure, the beads free to move, but when the mattress has been moulded and the air evacuated, external atmospheric pressure locks the beads in place (jamming) and the mattress becomes rigid.
When used medically this principle allows a patient who is put onto the mattress (e.g. with a scoop stretcher), the sides of the mattress arranged around the patient and when the air inside is evacuated the mattress forms a conformal cradle allowing an injury to be stabilised, straps fastened, and the patient protected sufficiently well that they can be transported.
For this reason the bag is typically bigger than an adult human body (though the same principle may be employed to create an 'instant' cast to stabilise an injured limb). In use, a sheet is usually put on the vacuum mattress to: