Acute Kidney Injury Flashcards
What can be used to determine if someone has AKI?
Serum creatinine or urine output
What are the criteria for AKI?
Rise in creatinine >26 micromoles per L within 48h, rise in creatinine >1.5x baseline within 7 days, urine output <0.5ml per kg per h for >6 consecutive days
What are the commonest causes of AKI?
Sepsis, major surgery, cardiogenic shock, other hypovolaemia, drugs, hepatorenal syndrome, obstruction
What are pre-renal causes due to?
Low blood volume or low effective circulating volume
What are renal causes due to?
Glomerular, tubular, interstitial, vascular
What are post-renal causes due to?
Obstruction to urine
What are risk factors for AKI?
HTN, volume depletion, CKD, diabetes, cirrhosis, nephrotoxic meds, cancer, trauma
What can lead to pre-renal AKI?
Decreased vascular volume, decreased cardiac output, systemic vasodilation, renal vasoconstriction
What can cause pre-renal AKI?
Haemorrhage, diarrhoea and vomiting, dehydration, shock, cirrhosis, CCF
What can cause glomerular disease?
Glomerulonephritis
What can cause interstitial disease?
Acute interstitial nephritis
What can cause vessel disease?
Vasculitis, microangiopathic haemolytic anaemia
What are some post-renal causes of AKI?
Problem within renal tract, extrinsic compression
What can cause post-renal AKI?
Stones, BPH, Cancer, pyelonephritis
What are general features of AKI?
Oliguria, high creatinine, hyperkalaemia, uraemia, hypocalcaemia/hyperphosphataemia
What USS result suggests CKD?
Small kidneys
What USS result suggests renal vascular disease?
Asymmetry
What are some differential diagnoses?
CKD, drug side effect
What drugs are nephrotoxic/should be stopped?
NSAIDs, ACEi, ARB, metformin, lithium, digoxin
How do you manage pre-renal AKI?
Correct volume depletion and/or increase renal perfusion via circulatory/cardiac support, treat any underlying sepsis
How do you manage renal AKI?
Refer for biopsy and specialist treatment of intrinsic renal disease
What management is common to all AKI?
Fluid balance, Acidosis, hyperkalaemia, recognition of patients who may need renal replacement
How do you manage hypovolaemia?
500ml crystalloid, reassess, further boluses of 250-500ml with review after each up to 2L
How do you manage hypervolaemia?
Oxygen supplementation if needed, fluid restriction, diuretics if symptomatic
What is mild acidosis?
pH 7.30 - 7.36 with bicarb >20 mmol per L
How do you manage acidosis?
Treat underlying disorder. Can give sodium bicarbonate but be cautious
What are the issues with sodium bicarbonate?
It generates CO2 so you need to make sure patient has adequate ventilation to prevent respiratory acidosis. Can cause an increase in sodium and volume load
What ECG changes can occur in hyperkalaemia?
Tall tented T waves, increased PR interval, small/absent P waves, widened QRS complex, sine wave pattern, asystole
What cardioprotection can you give in hyperkalaemia?
Calcium chloride or calcium gluconate
What can you give to decrease potassium levels?
IV insulin (+ glucose), salbutamol
What renal replacement therapy is available?
Haemodialysis, haemofiltration
What are indications to start renal replacement therapy?
Fluid overload unresponsive to treatment, severe/prolonged acidosis, recurrent/persistent hyperkalaemia despite treatment, uraemia
What is stage 1 AKI?
Serum creatinine >26.5 or 1.5-1.9x baseline. Urine output <0.5 ml per kg per h for 6-12h
What is stage 2 AKI?
2.0-2.9x baseline. Urine output <0.5ml per kg h for >12h
What is stage 3 AKI?
> 353.6 or 3.0x baseline or renal replacement therapy. Urine output <0.3 ml per kg per h for >24h or anuria for >12h
What can cause tubular disease?
Necrosis
What does hyperkalaemia cause?
Arrhythmias, muscle weakness
What does uraemia cause?
Nausea and vomiting, pericarditis, platelet dysfunction
What are some pre-renal specific presentations?
Hypotension, signs of liver/heart failure
What are some intra-renal specific presentations?
Infection, signs of underlying disease
What are some post-renal specific presentatons?
LUTS
What main investigations would you do?
U&E to determine eGFR, Creatinine
What other investigations would you do?
Iron, sodium, urea, fluid state, FBC, urinalysis, USS/KUB CT
What are potential complications?
End stage renal failure, metabolic acidosis, uraemia, CKD
What is the most common cause of AKI?
Acute tubular necrosis
