AKI Flashcards
What is AKI defined as?
an abrupt (<48hours) reduction in kidney fucntion- increase in creat by >26.4; increase in creat >50%; reduction in UO
What must happen before AKI is diagnosed?
following adequate fluid resus and exclusion of obstruction
What are the 3 main causes of pre-renal AKI?
hypovolaemia; hypotension and renal hypoperfusion
What are causes of hypovolaemia?
haemorrhage; volume depletion eg D&V; burns
What are causes of hypotension?
cardiogenic shock; distributive shock- sepsis or anaphylaxis
What can cause renal hypoperfusion?
NSAIDs; ACEi
What is pre-renal AKI?
reveresible volume depletion leading to oliguria and incrase in creatinine
What is normal UO?
0.5ml/kg/hour
How much of the cardiac output do the kidneys receive?
20%
What does untreated prerenal AKI lead to?
acute tubular necrosis
What are causes of acute tubular necrosis?
decreased renal perfusion- sepsis; severe dehydration
rhabdomyolysis and drug toxicity
How is prerenal AKI treated?
fluid status and if dry- fluid challenge
What is renal AKI?
diseases causing inflammation of damage to renal cells
What are the main categories of renal AKI causes?
vascular; glomerular; interstitial nephritis; tubular injury
How do NSAIDs cause interstital nephritis?
COX inhibitor causes preferential conversion of arachidonic acid to leukotrienes which may then activate helper T cells
What is seen on bloods with drug-induced AIN?
eosinophilia and IgE
What are the risk factors for developing AKI?
age >75; CKD; cardiac failure; PVD; DM; sepsis; poor fluid intake/increased losses; hx of urianry symptoms
What are hte causes of interstital nephritis?
drugs; TB; sarcoid
What are the causes of tubular injury?
ischaemia- prolonged renal hypoperfusion; drugs (gentamicin); contrast; rhabdomyolysis
What are the signs of AKI?
fluid overload; uraemia and itch; pericarditis; oliguria
What are hte initial investigations for AKI?
U&Es- K!; FBC and coag screen- anaemia- CKD; myeloma; abnormal clotting- sepsis; urinalysis; USS- obstruction, size; immunology; protein electrophoresis
What are the indications for urgent renal biopsy?
suspected reapidly progressive GN; positive immunology and AKI
How can you ensure a renal biospy will be safe?
normal clotting; normotensive; no hydronephrosis
What is the treatment of AKI?
establish good perfusion pressure; treat underlying cause- abx if sepsis; stop nephrotoxics
When should dialysis be give nwith AKI?
if patient remains anuric and uraemia; pericardial effusion; hyperalaemia; severe acidosis; fluid overload
What are hte life-threatening complications of AKI?
hyperkalaemia; fluid overload; severe acidosis; uraemic pericardiac effusion; severe uraemia
What causes post-renal AKI?
obstruction
What is the treatment of post-renal AKI?
relieve obstruction by catheter or nephrostomy- refer to urology
What is hyperkalaemia?
> 5.5
What is life-threatening hyperkalaemia?
> 6.5
How is hyperkalaemia assessed?
ECG; muscle weakness
