It's reassuring to know that there is much debate, on exactly, which
inotrope to use!
Is this a personal, intuitive thing?
I like to think of things like; a 'wide open circulation', that needs
'tightening' (sepsis), with the use of predominately alpha action
(Noradrenaline and Adrenalin to an extent). Or a failing pump that requires
a positive inotrope; doputamine, with adrenaline to counteract the side
effects of opening up the circulation;if required because of low BP!
Of course nitrates are used to 'off load the heart', and presumably decrease
LV diastolic filling pressures (ultimately, leading to over-stretch, and
hence decreased LV function, if LV ED pressures are raised - {but who knows
whats going off, without PA line}). I understand that this is predominately
the mode of action of of Frusemide; with an early vasodilation effect.
However, later this leads to a later diuresis, leading to a relative
decrease in intravascular volume, which impairs LVF by decreasing LV stretch
(negative effect of Starlings Law).{Also an effect of judicious use of
Diamorphine - which decreases alpha activity - inhibits catecholamines - and
acts as venodilator -[Parodox - to use of adrenalin]}
Does anyone ever use Noradrenaline without PA line?
For that matter does anyone ever use inotropes blindly without CVP?
LVF is likely to be due to pump failure ( beware of valve problems)- so
logically can you make a broken pump, pump harder with inotropes? You
maximise efficiency, according to Starlings' Law - maximise stretch, by
judicious use of fluids and inotropes and nitrates....all seems to point to
intuitive
experience.............................................................a
difficult field.
Physiologists - correct me if I'm wrong in my rational use of
inotropes...please!!
Confused?
Thoughts on a post card...............
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