acute renal failure

Question 1

pre-renal causes

Answer 1

Fluid loss: blood loss, plasma loss, water/electrolyte loss (diarrhoea/vomiting, fluid volume depletion)
Hypotension: MI, septicaemic shock, drugs
Renovascular disease: embolus, dissection, atheroma
Increased renal vascular resistance: hepatorenal syndrome

Question 2

renal causes

Answer 2

Acute-on-chronic kidney failure - precipitated by infection, fluid volume depletion, obstruction, nephrotoxic drugs
Acute renal disease e.g. primary/secondary GN, connective tissue disease
Acute tubular necrosis secondary to ischaemia (hypovolaemia), toxins and drugs (e.g. amino glycoside antibiotics, radiocontrast material, heavy metals), rhabdomyolysis/haemoglobinuria
Tubulointerstitial disease e.g. drugs (PPIs, sulphonamides, cyclosporin A), urate/calcium deposits, phosphate, oxalate, crystal nephropathy
Vascular disease e.g. vasculitis, scleroderma
Myeloma
Acute pyelonephritis

Question 3

post-renal causes

Answer 3

At urethra: e.g. calculus or blood clot, sloughed papillae, trauma, phimosis or paraphimosis
At the bladder neck: e.g. calculus or blood clot, prostatic hypertrophy or cancer
At both ureters: intrauretic (e.g. blood clot, pyogenic debris, calculi), extraureteric e.g. retroperitoneal fibrosis (radiation, methysergide or idiopathic), retroperitoneal/pelvic tumour or surgery, uterine prolapse

Question 4

ix (6)

Answer 4

ECG
FBE, UEC, LFT, CRP/ESR
Electrolytes especially hyperkalaemia and metabolic acidosis
Glucose (if diabetic)
Urine MCS: cells, casts
CXR (volume overload and to exclude other causes of dyspnoea)
Renal ultrasound

Question 5

rx principles

Answer 5

prevention
immediate cessation of medication that is not vital and may exacerbate AKI
medical management
prevent, detect, treat infections

Question 6

prevention

Answer 6

Avoid medications that may cause or increase susceptibility to AKI
Minimise radio contrast nephrotoxicity:
Fluid loading (IV saline) prior to and after the investigation
Cease other potentially nephrotoxic drugs, especially if other risk factors (diabetes, elderly, known renal disease)
Carefully consider benefits vs risks of angiogram

Question 7

medical management

Answer 7

Monitor intravascular volume and prescribe appropriate fluids
Diet - low Na/K, high calories, normal protein
Hyperkalaemia
Low potassium diet, avoid IV fluids containing K
Treat acidosis
If high: resnoium
If dangerously high: IV insulin/dextrose + calcium gluconate + initiate dialysis

Question 8

which infections are more likely and why?

Answer 8

More likely to develop pneumonia, UTI, septicaemia
Due to risk factors: PO, recumbency (–> pneumonia), bladder catheterisation to monitor urine output, IV lines, immune suppression due to uraemia state

Question 9

how to prevent infections

Answer 9

How to prevent: mobilise patient if possible, avoid bladder catheterisation, carefully manage IV lines (aseptic insertion and frequent replacement)