Originally Posted by: daveolley 
MPH
Out of interest I copied this from the JRCALC Clinical Practice Guide.
Complications of spinal board use
The concern of placing patients on a board for long periods is centred around pressure area problems. In Pre-hospital context this does not present a practical problem but care to remove debris from under the patient, and keys and other sharp objects in the patient's pockets should be taken.
Are you saying that placing someone on their back is less of a problem regarding pressure areas than placing them on their side?
an interestingly selective quote there Dave,
in the introduction to the section of neck and back trauma in JRCALC it states that people should spend no longer than 45 minutes on an unpadded long extrication board , based on a Cochrane review.
in the section on transporting patients with a suspected spinal injury it suggests if the patient will be immobilised for more than 30 minutes that a vacuum mattress should be used .
the simple fact is that placing anyone immobile on a hard surface and then preventing them from moving and pressure relieving - whether by immobility or by restraint presents problems with the microcirculation - especially if there is already impaired circulation by virtue of shock or neurological issues both in terms of local vascular tone in the microcirculation and in the general vasculature . However you position someone who is unconscious and/or unable to pressure relieve you will create pressure po where bones are not overlaid by a thick layer of muscle and/or fat and create a localised pressure point to the skin between the bone and the hard surface.
In terms of should this be taught on first aid courses for the public i'd suggest that in general perhaps not but as with anything there are factors where you do have to consider this e.g. outdoor activities or those who work in remote areas where response times may be prolonged - and remote is in terms of time to help not necessarily distance to the road - some industrial settings may qualify as 'remote' due the difficult access even if you can get rescuers and their vehicles close to the injury site ...