Acute Kidney Injury Flashcards
def
AKA acute renal failure
is an acute decline in the GFR from baseline, with or without oligouria/anuria
what might cause AKI
pre-renal: -impaired renal perfusion intrinsic -exposure to nephrotoxins -intrinsic renal disease post-renal: -outflow obstruction
what is the most common AKI
acute tubular necrosis (often caused by sepsis)
why are patients with CAD at risk of AKI
CAD patients undergoining PCI, contrast is used which causes contrast nephropathy
epi
associated with elderly
how are AKI causes classified
pre-renal azotaemia
intrinsic
post-renal
what results in damage in pre-renal causes of AKI
pre-renal azotaemia (high levels of nitrogen rich compounds (urea, creatinine) in the blood
what are causes of pre-renal azotaemia
1 reduced renal perfusion -hypovolaemia -haemorrhage -HF 2 hepatorenal syndrome -this is seen is severe liver disease and is not reponsive to fluid administration (see above) 3 renovascular disease -ACE inhibitors in those with renal artery stenosis can lead to acute tubular necrosis
what is acute tubular necrosis
death of tubular epithelial cells in the renal tubules of the kidney
what are common causes of acute tubular necrosis
low BP
use of nephrotoxic drugs
what are causes of intrinsic AKI
most commonly:
- acute tubular necrosis (nephrotoxins)
- glomerulonephritis
- interstitial nephritis
what category does haemolytic uraemic syndrome fall into
intrinsic AKI
what are causes of post-renal injury
these are due to mechanical obstruction of the urinary outflow tract:
- prostate hyperplasia or tumour
- ascending urinary infection (pyelonephritis)
- urinary retention
glomerulonephritis and pyelonephritis are what kind of AKI causes
glomerulonephritis intrinsic
pyelonephritis post-renal
risk factors
age underlying renal disease malignant HTN DM Na retaining states such as CHF, cirrhosis, nephrotic syndrome nephrotoxins
name some nephrotoxins
aminoglycosides (streptomycin)
NSAIDs
ACE inhibitors
history
reduced urine production
nausea + vomiting
dizziness
SOB, orthopnoea, PND (fluid overload in HF)
if vomiting or dizziness is seen in the history what does it suggest
a pre-renal cause (azotaemia)
what does muscle tenderness, limb ischaemia, seizures in AKI suggest
rhabdomyolysis
if fever, rash or joint pain is seen in the history what does it suggest
interstitial nephritis
examination
hypotension + tachycardia (pre-renal azotaemia which may progress to acute tubular necrosis)
pulmonary or peripheral oedema (HF + fluid overload is a risk factor for AKI)
what are signs of uraemia
asterixis
a 65y/o male smoker with HTN, dyslipidaemia, DM presents with chest pain. ECG suggests MI. He is taken for an urgent coronary angiogram. 3/7 later he has developed elevated serum creatinine, oliguria, hyperkalaemia
AKI
a 35y.o man with a history of congenital valvular heart disease undergoes a dental procedure without antibiotic prophylaxis. Several weeks later he presents with fever and respiratory distress. laboratory tests reveal a high serum creatinine and low urine output. Urine analysis reveals more than 20 WBCs, more than 20 RBCs, and red cell casts. Serum ESR is elevated.
AKI
investigations
1 bloods
-high serum creatinine, high serum potassium, metabolic acidosis indicates impaired renal function
-serum urea:creatinine of 20:1 indicates pre-renal azotaemia
2 urine
-infection
-high urine osmolality, low urine Na
what might be seen on an ECG in AKI
signs of hyperkalaemia
tented T waves (earliest sign)
absent p waves + PR lengthens
sinus bradycardia or slow AF
VF (severe hyperkalaemia)
what does glomerular disease typically present with
proteinuria, microscopic haematuria with HTN + oedema
management for pre-renal azotaemia
1 volume expansion +/ transfusion is first line
-reduced renal perfusion must be treated
2 if pt hypotensive give dopamine, adrenaline, noradrenaline
3 if pt fluid overloaded give diuretic such as furosemide
when is crystalloid used and when is colloid used
crystalloid (normal saline) is used most commonly
colloid is used in states of hypoalbuminaemia
management for intrinsic
1 treat underlying condition is first line
if pt is fluid overloaded give diuretic (furosemide) if pt is fluid depleted give crystalloids or colloids
management for post-renal injury
1 bladder catheterisation is first line
2 relieve bladder neck obstruction
complications
hyperphosphataemia
uraemia (lethargy, confusion)
hyperkalaemia which may result in cardiac arrest caused by VF
CKD
prognosis
significant mortality
