Case Eight - Case One Flashcards
what is AKI
sudden decline in renal function significant enough to produce uraemia, and also often oliguria
what is oliguria
a urine output of <400ml/day
what is a severe AKI defined as
a creatine level of >500umol/L
what is the incidence of AKI
The approximate incidence of AKI is 180 per 1 million; before the age of 50, this value is 17 per 1 million, but as high as 950 per 1 million in those over 80.§
what are the three main categories that causes of AKI be divided into
prerenal
intra-renal
post-renal
what is the most common cause of AKI in the hospital
sepsis
what what is the prerenal causes of AKI
impaired blood flow to the kidney
what may impaired blood flow to the kidney be a result of
hypovolaemia, decreased BP, decreased CO, or vascular disease
what are the clinical signs of prerenal causes of AKI
history of blood/fluid loss,
sepsis leading to vasodilation,
cardiac disease,
postural hypotension,
weak and rapid pulse with low JVP
what are the three intra-renal causes of AKI
- acute tubular necrosis (ATN)
- Nephrotoxicity
- renal parenchymal disease
what is ATN
by far the most common cause of AKI, where toxicity and or ischaemia results in decreased GFR
what is nephrotoxicity causes by
ahminoglycosides
what is renal parenchymal disease a result of
ATN
what are the investigations for AKI
urine dipstick
urine microscopy - red cell casts and red cells
Blood tests- U+E’s - particularly Cr and K+, FBC, free haemoglobin and myoglobin
Kidney function is monitored through urine output analysis and creatinine clearance monitoring – creatinine clearance monitoring is the ideal, i.e. it is a more precise indication of GFR than serum urea monitoring alone!
what is the official definition of AKI
Acute kidney injury is a sudden decline in renal function significant enough to produce uraemia, and also often oliguria – a urine output of <400ml/day, which is the minimum volume required to remove waste products from the blood.
what is the diagnosis criteria for AKI
- there is a rise of serum creatine of >26.5 in <48 hours
OR - there is a rise in serum creatine to >1.5x the baseline level which was previously known or assumed 7 days prior to the presentation
- there is a signifiant reduction in urine output compared to baseline
what is uraemia
a situation where there is enough urea in the blood to cause clinical symptoms, which may include anorexia and lethargy, and later, possible decrease in mental capacity leading to coma
what is the term azotaemia sometimes used for
sometimes used to describe levels of urea above normal but. not high enough to cause clinical signs
what is the mortality of those with an isolated AKI
5-10%
in those with other organ failure that then go into AKI, what is the mortality
50-70%
what are the three questions that need to be asked before diagnosing acute renal failure
- is the renal failure acute?
- is there a urinary tract obstruction?
- is there something rare that might be causing the AKI?
when should chronic renal failure be suspected (three things)
- there is co-existing diabetes
- there is increased blood pressure, and other signs of chronic disease
- small kidneys are apparent on ultrasound with increased echogenicity
what percentage of severe AKIs are due to obstruction
25% - most commonly causes by prostatic hypertrophy
what is the main test for obstruction
USS of the kidneys
renal USS will not detect obstruction but dilation of the calyces, and in 5% of cases, such dilation may not be detected, culminating in a false negative result