Acute kidney injury Flashcards
What is the definition of acute kidney injury?
An abrupt reduction in kidney function defined as either an absolute increase in creatinine of 26.4umol/l, a 50% increase in creatinine, or a decrease in urine output
How is acute kidney injury classified?
Pre-renal, renal and post-renal
What is the main underlying cause in pre-renal AKI?
Renal hypoperfusion
Why might ACE inhibitors cause pre-renal AKI? When in particular might this happen?
Block angiotensin II, which acts to maintain GFR by constricting the efferent arteriole. Might be particularly important when volume-depleted (e.g. diarrheoa and vomiting)
Name 5 possible causes of pre-renal AKI.
Hypovolaemia Sepsis Renal artery stenosis Cardiac failure Liver cirrhosis (hepatorenal syndrome)
What does untreated pre-renal AKI lead to?
Acute tubular necrosis
What are the common causes of acute tubular necrosis?
Pre-renal AKI (severe sepsis, dehydration)
Nephrotoxic drugs
Rhabdomyolysis
Contrast agents
How is pre-renal AKI generally managed?
Assess fluid status (JVP/BP/pulse/oedema?/capillary refill)
If hypovolaemic- colloid or crystalloid- give bolus, re-assess and repeat if necessary
What (broadly) are the commonest causes of renal AKI?
Vessel disease (e.g. vasculitis)
Glomerulonephritis
Interstitial nephritis
Acute tubular necrosis (ischaemia, nephrotoxic agents)
What signs/symptoms may be seen in renal AKI?
Constitutional symptoms (e.g. nausea, fatigue, lethargy)
Itch (uraemia)
Fluid overload- gallop rhythm, basal lung crepitations, peripheral oedema
Oliguria
For each of the following investigations into AKI state why they might be carried out:
a) U&Es
b) FBC
c) urinalysis
d) USS
e) antibodies
f) protein electrophoresis/Bence-Jones proteins
a) markers of renal function- is potassium high? (potential complications)
b) anaemia (absence of anaemia suggests acute rather than chronic) Low platelets (HUS,TTP); clotting (septic, DIC)
c) proteinuria suggests GN
d) obstruction (post-renal AKI)
e) vasculitis, lupus, Goodpastures
f) myeloma
What are the urgent indications for renal biopsy?
Suspect rapidly progressive GN; positive immunology and AKI
What are the indications for acute dialysis?
Refractory pulmonary oedema Persistent hyperkalaemia Severe metabolic acidosis Uraemic encephalopathy Uraemic pericarditis
What causes post-renal AKI?
Obstruction leading to hydronephrosis
What ECG changes may be seen in hyperkalaemia?
Tall "tented" T-waves Reduced/Absent P-waves Increased PR interval Widened QRS Sine-sine pattern Asystole
