AKI

Question 1

What is AKI

Answer 1

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

Question 2

What is CKD

Answer 2

Long standing and usually progressive impairment in renal function

Question 3

classification of AKI

Answer 3

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

Question 4

pre renal failure

Answer 4

impaired perfusion of the kidneys due to hypovolaemia, hypotension, impaired cardiac pump efficiency or vasc disease limiting renal blood flow

Question 5

what is autoregulation

Answer 5

the kidney is usually able to maintain glomerular filtration in spite of a wide variation in the renal perfusion pressure and volume status

Question 6

in the face of a decreased systemic pressure what does maintenance of a normal GFR depend on

Answer 6

the intrarenal production of prostaglandins and Angiotensin II

Question 7

what drugs impair renal autoregulation

Answer 7

ACEi and NSAIDs

they inc tendency to develop pre renal failure

Question 8

rx pre renal failure

Answer 8

prompt fluid replacement

Question 9

post renal uraemia

Answer 9

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

Question 10

investigations post renal uraemia

Answer 10

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

Question 11

how is bladder outflow obstruction ruled out in post renal uraemia

Answer 11

flushing a catheter

Question 12

rx of post renal uraemia

Answer 12

by a temp measure eg urethral / supra pubic catheter or percutaneous nephrostomy until definitive rx of the obstructing lesion can be undertaken

Question 13

Acute uraemia due to renal parenchymal disease - most common cause?

Answer 13

tubular necrosis as a result of renal ischaemia or renal toxins
also acute glomerulonephritis

Question 14

AKI clinical features

Answer 14

early = asymptomatic
1 - altered urine volume, initially oliguria then increase
2 - hyperkalaemia, metabolic acidosis, hyponatraemia, hypocalcaemia & hyperphosphataemia
3 - symps of uraemia

Question 15

What is the cause of the following abnormalities in AKI:
hyponatraemia
hypocalcaemia
hyperphosphataemia

Answer 15

hyponatraemia - water overload from continued drinking after the onset of oliguria
hypocalcaemia - reduced renal production of 1,25-dihydroxycholecalciferol
hyperphosphataemia - phosphate retention

Question 16

What are the symptoms of uraemia experienced in AKI?

Answer 16

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

Question 17

what would you be looking for in blood count in AKI?

Answer 17

anaemia and inc ESR = myeloma or vasculitis as underlying cause

Question 18

why would you do urine and blood cultures in AKI?

Answer 18

to exclude infection

Question 19

what looking for in urine dipstick and microscopy AKI?

Answer 19

haematuria & proteinuria on dipstick and red cell casts on microscopy = glomerulonephritis as cause

Question 20

when should renal biopsy be performed in AKI?

Answer 20

when AKI is unexplained

Question 21

management AKI

Answer 21

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