Lee Corbin writes:
[quoting Stathis]
> > It may also reassure you that in the worst possible case - the patient
>is
> > actually awake, but paralysed - the pain experienced is nowhere near
>what
> > you would imagine a fully awake person with no drugs on board would
> > experience. I once met a young girl, about 10, who had apparently been
>awake
> > during the first part of a cardiac operation, when her chest was being
>cut
> > open with an electric saw. What does it feel like when your chest is
>being
> > cut open with an electric saw? It is "an itchy, scratchy sort of
>feeling."
> > Thank God for fentanyl!
>
>Ditto!
>
>Thanks for the clinical explanations.
>
>The "physiological stress" you mention above: it happens when
>grave surgery is inflicted on tissue? Is it the body's violent
>reaction to take emergency action in some way when it senses
>something really bad is happening? How does fentanyl (in this
>case) work? By locally suppressing the body's reaction, or
>what?
Fentanyl is an artificial opioid type analgesic, like morphine or heroin,
differing mainly in that it has a relatively short half-life in the body.
Huge doses of fentanyl are used in cardiac surgery because it is a
relatively benign drug which doesn't adversely affect the cardiovascular
system like volatile anaesthetics, for example. (Heroin is also a very
benign drug, which causes no long term ill effects even after decades of
regular use, something most people don't know.) Opioids don't work locally,
but rather on the central nervous system: the pain signals are generated and
travel up the peripheral nerves as per usual (even in someone under a GA),
but in the awake patient the unpleasantness of the pain is diminished ("I
can still feel the pain, but it doesn't bother me"), along with the
associated reflex release of adrenaline and other stress hormones; in the
anaesthetised patient, it is just the release of stress hormones which is
reduced.
--Stathis Papaioannou
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Received on Mon Jul 04 2005 - 19:55:54 PDT