Hi Barry,
The problem with relative movement in a profiling bed is the same as
that in a reclining (as opposed to tilting) chair. That is, because the
pelvis and hence the spine rotate relative to the hip joint (which is
infront of the chair/bed recline joint), the head moves in an arc that
deviates progressively from that described by the equivalent position
(i.e. radius) on the chair/bed. This is normally seen as the head
sliding down the backrest/bed surface. As far as I am aware there would
be no papers that state that raising the knees would stop this as they'd
be wrong.
The easiest way of combatting this problem is to mount the switch/sensor
on the patient e.g. breastplate, chin switch, etc. but it may well be
that in this case you are unable to do that.
Hope that helps.
Cheers
Jeff
______________________________________________
Dr. Jeffrey D. Morris
Head of Electronic Assistive Technology
Medical Physics & Clinical Engineering Directorate
University Hospital of Wales
Cardiff & Vale NHS Trust
Tel: 029-2031-3931
FAX: 029-2031-3785
e-Mail: [log in to unmask]
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