just going to try and generate a bit of
a mind map about kidney disease now
kidney disease can be chronic kidney
disease and we call this CKD these days
chronic kidney disease but they can also
be acute kidney disease which we now
call acute kidney injury what Aki now
acute kidney injury can be subdivided
and the classic subdivisions are pre
renal within the kidney itself intra
renal also called intrinsic and the
third classification is the post renal
so we have these classifications of the
etiology the cause of acute kidney
injury acute kidney injury is a sudden
reduction in renal function typically
over day is normally about 24 or 48
hours really
and we call the acute kidney injury we
used to call the acute renal failure now
we need to try and order the causes of
this condition so let's think about Cree
we know first of all pre renal causes
now this is caused primarily by reduced
renal perfusion
perfusion is the way that the blood
flows through an organ how its perfused
with blood so this reduced renal
perfusion now why is this well there can
be reduced renal perfusion because of
fluid loss fluid loss resulting in low
volumes of blood low volumes of fluid in
the body all together this would be
hypovolemia so there can be this
hypovolemia hypo low vol ii Mir a emi a
in the blood of course if you watch them
in the stage you don't put the egg
whereas in the UK we put the egg now
this can be caused by hemorrhage there
can be bleeding internal or external
bleeding of course you don't have to see
the blood remember hemorrhage can be
onto the floor and four more four more
places the thoracic cavity the abdominal
cavity the pelvic cavity and bleeding
into the limbs from the long bones and
burns also cause a lot of phenols
extensive burns dehydration
so we might think for example of
diarrhea or vomiting leading to
dehydration leading to hypovolemia but
as well as fluid loss there can also be
abnormal distribution of body fluids so
it's kind of right that can be enough
fluid there it's just that the fluid is
in the in the wrong place so why might
this happen well one possibility is
cardiac failure or cardio bolus let's
say cardiogenic shock first so in
cardiogenic shock the heart is unable to
pump out enough blood to maintain the
perfusion of the tissues of the body and
heart failure is also true because in
heart failure again ha cardiac output is
insufficient to maintain the metabolic
demands of the tissue of the body and
because the heart pump can't pump out
the fluid they can't deal with the
venous return so the fluid accumulates
or the blood accumulates in the venous
return so it's not so much that there's
a shortage of blood but there's tumors
blood in the venous system and not
enough in the arterial system so
cardiogenic shock and heart failure
now also allergic allergic shock of its
prolong because an allergic shock
there's a vasodilator and that drops the
blood pressure and when you drop the
blood pressure you drop the perfusion of
the tissues including
a fusion of their kidneys these these
are sometimes called distributive shocks
though the fluid is not properly
distributed as it should be in the
physiological situation
another possibility is a septic shock
now septic shock
is associated with a ventilation and
reduce blood pressure of course shock is
reduced perfusion of the tissues for
vascular reasons but as well as that in
in septic shock
if the sepsis then you get bacterial
toxins in the blood misses toxins that
make us sick of course as that's why
bacteria make you sick and that has a
great effect the toxins have a great
effect on the intra renal causes there
you the toxins produced by severe
systemic sepsis a going to greatly
sensitize many of the tissues in the
kidney particularly the endothelial
cells lining the renal tubules can be
very sensitive to the effect of toxins
and that can greatly increase their
susceptibility to something like fluid
loss so I really was seeing that um
acute kidney injury can be
multifactorial and if that usually it is
multifactorial another reason we get
abnormal fluid distributors what we call
a third spacing fluid can be in a third
space now in this context the first
space I guess will be the intracellular
fluid the second compartment will be the
extracellular fluid which includes the
blood and the tissue fluids but anything
that's in a third space where it's not
supposed to be so for example fluid
Klerk humilate in the peritoneal cavity
in pairs
there's plenty of fluid there it's just
in the wrong places is not available to
the circulatory system so there we have
pre renal causes so these are all
proving our causes here so we've got
three renal pre renal reduced perfusion
and all of these things all of these
can be caused as a pre renal failure so
to continue my mind map on another piece
of paper we now want to look at the
intra renal causes so I think we'll
pause briefly there then we'll come back
and look at the intra renal causes