AKI Flashcards
What is AKI
abrupt sustained rise in serum urea and creatinine due to a rapid decline in GFR leading to loss of normal water and solute homeostatis
usually reversible
What is CKD
Long standing and usually progressive impairment in renal function
classification of AKI
renal failure results in reduced excretion of nitrogenous waste of which urea is most commonly measured. A raised serum conc (uraemia) is classified (i) pre renal (ii) renal - instrinsic (iii) post renal
pre renal failure
impaired perfusion of the kidneys due to hypovolaemia, hypotension, impaired cardiac pump efficiency or vasc disease limiting renal blood flow
what is autoregulation
the kidney is usually able to maintain glomerular filtration in spite of a wide variation in the renal perfusion pressure and volume status
in the face of a decreased systemic pressure what does maintenance of a normal GFR depend on
the intrarenal production of prostaglandins and Angiotensin II
what drugs impair renal autoregulation
ACEi and NSAIDs
they inc tendency to develop pre renal failure
rx pre renal failure
prompt fluid replacement
post renal uraemia
both urinary outflow tracts are obstructed or when the tract is obstructed in a pt with a single functional kidney - quickly reversed if obstruction removed
investigations post renal uraemia
all pts with AKI should be examined for evidence of obstruction: enlarged palpable kidneys or bladder, large prostate
and undergo renal US to look for hydronephrosis and dilated ureters
how is bladder outflow obstruction ruled out in post renal uraemia
flushing a catheter
rx of post renal uraemia
by a temp measure eg urethral / supra pubic catheter or percutaneous nephrostomy until definitive rx of the obstructing lesion can be undertaken
Acute uraemia due to renal parenchymal disease - most common cause?
tubular necrosis as a result of renal ischaemia or renal toxins
also acute glomerulonephritis
AKI clinical features
early = asymptomatic
1 - altered urine volume, initially oliguria then increase
2 - hyperkalaemia, metabolic acidosis, hyponatraemia, hypocalcaemia & hyperphosphataemia
3 - symps of uraemia
What is the cause of the following abnormalities in AKI:
hyponatraemia
hypocalcaemia
hyperphosphataemia
hyponatraemia - water overload from continued drinking after the onset of oliguria
hypocalcaemia - reduced renal production of 1,25-dihydroxycholecalciferol
hyperphosphataemia - phosphate retention
What are the symptoms of uraemia experienced in AKI?
Weakness, fatigue, anorexia, nausea, vomiting followed by mental confusion, seizures & coma.
May be pruritis & bruising
Breathlessness from anaemia & pulmonary oedema secondary to volume overload
Pericarditis w severe untreated uraemia
what would you be looking for in blood count in AKI?
anaemia and inc ESR = myeloma or vasculitis as underlying cause
why would you do urine and blood cultures in AKI?
to exclude infection
what looking for in urine dipstick and microscopy AKI?
haematuria & proteinuria on dipstick and red cell casts on microscopy = glomerulonephritis as cause
when should renal biopsy be performed in AKI?
when AKI is unexplained
management AKI
emergency resuscitation
establish aetiology and treat underlying cause
prevention of further damage (if infec, abx. AVOID: hypovolaemia, nephrotic drugs, NSAIDs and ACEi)
Frequent review for dialysis
Careful fluid and electrolyte balance
