On Tue, 24 Jan 2012 17:22:10 -0000, "'Mike'"
wrote:

All electrically operated life-support machines invariably have an
alternate power source that will switch in automatically in the event
of a mains failure.

Dream on!

Bill

Bill the emphasis is on "electrically operated life-support machines". Maybe
not in your home but in hospitals, .. yes.

It is *especially* true in the case of life support machines designed
to be used at home. Hospitals will always have staff on hand to
manually operate a ventilator etc. should the power fail, but the
designer of a life-support machine meant for home use cannot rely on
the fact that someone with the necessary knowlege will be on hand
within minutes in the event of a power cut, and so the design of
backup systems and fail-safe failure modes is even more important.

Any domestic life support machine that is designed so that it would
kill the patient in the event of a mains power outage would not be fit
for purpose.

--
Cynic