Acute Kidney Injury

Question 1

def

Answer 1

AKA acute renal failure

is an acute decline in the GFR from baseline, with or without oligouria/anuria

Question 2

what might cause AKI

Answer 2

pre-renal:
-impaired renal perfusion
intrinsic
-exposure to nephrotoxins
-intrinsic renal disease
post-renal:
-outflow obstruction

Question 3

what is the most common AKI

Answer 3

acute tubular necrosis (often caused by sepsis)

Question 4

why are patients with CAD at risk of AKI

Answer 4

CAD patients undergoining PCI, contrast is used which causes contrast nephropathy

Question 5

epi

Answer 5

associated with elderly

Question 6

how are AKI causes classified

Answer 6

pre-renal azotaemia
intrinsic
post-renal

Question 7

what results in damage in pre-renal causes of AKI

Answer 7

pre-renal azotaemia (high levels of nitrogen rich compounds (urea, creatinine) in the blood

Question 8

what are causes of pre-renal azotaemia

Answer 8

1 reduced renal perfusion
-hypovolaemia
-haemorrhage
-HF
2 hepatorenal syndrome
-this is seen is severe liver disease and is not reponsive to fluid administration (see above)
3 renovascular disease
-ACE inhibitors in those with renal artery stenosis can lead to acute tubular necrosis

Question 9

what is acute tubular necrosis

Answer 9

death of tubular epithelial cells in the renal tubules of the kidney

Question 10

what are common causes of acute tubular necrosis

Answer 10

low BP

use of nephrotoxic drugs

Question 11

what are causes of intrinsic AKI

Answer 11

most commonly:

• acute tubular necrosis (nephrotoxins)
• glomerulonephritis
• interstitial nephritis

Question 12

what category does haemolytic uraemic syndrome fall into

Answer 12

intrinsic AKI

Question 13

what are causes of post-renal injury

Answer 13

these are due to mechanical obstruction of the urinary outflow tract:

• prostate hyperplasia or tumour
• ascending urinary infection (pyelonephritis)
• urinary retention

Question 14

glomerulonephritis and pyelonephritis are what kind of AKI causes

Answer 14

glomerulonephritis intrinsic

pyelonephritis post-renal

Question 15

risk factors

Answer 15

age
underlying renal disease
malignant HTN
DM
Na retaining states such as CHF, cirrhosis, nephrotic syndrome
nephrotoxins

Question 16

name some nephrotoxins

Answer 16

aminoglycosides (streptomycin)
NSAIDs
ACE inhibitors

Question 17

history

Answer 17

reduced urine production
nausea + vomiting
dizziness
SOB, orthopnoea, PND (fluid overload in HF)

Question 18

if vomiting or dizziness is seen in the history what does it suggest

Answer 18

a pre-renal cause (azotaemia)

Question 19

what does muscle tenderness, limb ischaemia, seizures in AKI suggest

Answer 19

rhabdomyolysis

Question 20

if fever, rash or joint pain is seen in the history what does it suggest

Answer 20

interstitial nephritis

Question 21

examination

Answer 21

hypotension + tachycardia (pre-renal azotaemia which may progress to acute tubular necrosis)
pulmonary or peripheral oedema (HF + fluid overload is a risk factor for AKI)

Question 22

what are signs of uraemia

Answer 22

asterixis

Question 23

a 65y/o male smoker with HTN, dyslipidaemia, DM presents with chest pain. ECG suggests MI. He is taken for an urgent coronary angiogram. 3/7 later he has developed elevated serum creatinine, oliguria, hyperkalaemia

Answer 23

AKI

Question 24

a 35y.o man with a history of congenital valvular heart disease undergoes a dental procedure without antibiotic prophylaxis. Several weeks later he presents with fever and respiratory distress. laboratory tests reveal a high serum creatinine and low urine output. Urine analysis reveals more than 20 WBCs, more than 20 RBCs, and red cell casts. Serum ESR is elevated.

Answer 24

AKI

Question 25

investigations

Answer 25

1 bloods
-high serum creatinine, high serum potassium, metabolic acidosis indicates impaired renal function
-serum urea:creatinine of 20:1 indicates pre-renal azotaemia
2 urine
-infection
-high urine osmolality, low urine Na

Question 26

what might be seen on an ECG in AKI

Answer 26

signs of hyperkalaemia

tented T waves (earliest sign)
absent p waves + PR lengthens
sinus bradycardia or slow AF
VF (severe hyperkalaemia)

Question 27

what does glomerular disease typically present with

Answer 27

proteinuria, microscopic haematuria with HTN + oedema

Question 28

management for pre-renal azotaemia

Answer 28

1 volume expansion +/ transfusion is first line
-reduced renal perfusion must be treated
2 if pt hypotensive give dopamine, adrenaline, noradrenaline
3 if pt fluid overloaded give diuretic such as furosemide

Question 29

when is crystalloid used and when is colloid used

Answer 29

crystalloid (normal saline) is used most commonly

colloid is used in states of hypoalbuminaemia

Question 30

management for intrinsic

Answer 30

1 treat underlying condition is first line

if pt is fluid overloaded give diuretic (furosemide) if pt is fluid depleted give crystalloids or colloids

Question 31

management for post-renal injury

Answer 31

1 bladder catheterisation is first line

2 relieve bladder neck obstruction

Question 32

complications

Answer 32

hyperphosphataemia
uraemia (lethargy, confusion)
hyperkalaemia which may result in cardiac arrest caused by VF
CKD

Question 33

prognosis

Answer 33

significant mortality