[EMed] Acute Renal Failure

Question 1

what can causes of acute renal failure (ARF) be classified into?

Answer 1

• pre-renal
• post-renal (obstructive)
• renal

Question 2

what are pre-renal causes of ARF?

Answer 2

• hypovolaemia
• shock: cardiogenic, anaphylactic
• heart failure
• renal vasoconstriction / stenosis

*most AKIs are pre-renal in nature

Question 3

what are post-renal (obstructive) causes of ARF?

Answer 3

• calculi
• tumour
• retention
• prolapse

Question 4

what are renal causes of ARF?

Answer 4

specific: myeloma, GN

non-specific:

• ischaemia (e.g. emboli, clot)
• toxins (e.g. nephrotoxic drugs. rhabdomyolysis)
• infection / inflammation (e.g. sepsis)

Question 5

what do you do if you suspect a pt has an AKI?

Answer 5

• hx + exam
• assess fluid status
• basic blood panel
• urine dip
• stage AKI

Question 6

what is the 1st line ix for AKI?

Answer 6

U+Es for serum creatinine, eGFR and creatinine clearance

Question 7

what does AKI severity depend on?

Answer 7

rise in baseline creatinine

Question 8

what is the serum creatinine (µmol/L) for AKI stage 1?

Answer 8

1.5-1.9x baseline

Cr rise >20 in 24 hours

Question 9

what is the urine output (ml/kg/hr) for AKI stage 1?

Answer 9

<0.5 for 6-12 hours

Question 10

what is the serum creatinine (µmol/L) for AKI stage 2?

Answer 10

2.0-2.9x baseline

Question 11

what is the urine output (ml/kg/hr) for AKI stage 2?

Answer 11

<0.5 for >12 hours

Question 12

what is the serum creatinine (µmol/L) for AKI stage 3?

Answer 12

> 3.0x baseline
Cr rise to >300

initiation of RRT!

Question 13

what is the urine output (ml/kg/hr) for AKI stage 3?

Answer 13

<0.3 >24 hours

anuria for >12 hours

Question 14

what will aid in resolving an AKI?

Answer 14

addressing the underlying cause

Question 15

what can be considered if the AKI is refractory to rx?

Answer 15

renal replacement therapy (RRT)

Question 16

what is the base criteria for consideration of RRT?

Answer 16

1. hyperkalaemia (refractory)
2. metabolic acidosis (pH<7.2)
3. resistant pulmonary oedema
4. uraemia with encephalopathy
5. specific toxicology reversal

Question 17

what is the mx for AKI?

Answer 17

1. stop any nephrotoxic drugs and commence IVIs
2. start a strict fluid balance chart (including catheterisation)
3. regular monitoring of U+Es
4. address any electrolyte or pH imbalances
5. nephrology input, if the AKI is resistant to rx for RRT assessment

Question 18

indications for dialysis?

Answer 18

AEIOU

A - acidosis pH<7.2
E - electrolyte: hyperkalaemia (refractory)
I - intoxications: toxicology (very selective)
O - oedema (pulmonary)
U - uraemia: hyperuraemia

Question 19

what are the risk factors for CKD?

Answer 19

• HTN
• DM
• chronic NSAID use
• prolonged AKI
• untreated outflow obstruction
• cardiovascular disease

Question 20

what is the progression of CKD?

Answer 20

sustained decrease in eGFR over 12 months

Question 21

what are the complications of CKD?

Answer 21

• anaemia
• mineral and bone disorders (osteodystrophy)
• acute-on-chronic kidney injury
• fluid overload
• hyperkalaemia
• acidosis

Question 22

what is the eGFR for stage 1 CKD?

Answer 22

> 90

Question 23

what is the eGFR for stage 2 CKD?

Answer 23

60-89

Question 24

what is the eGFR for stage 3a CKD?

Answer 24

45-49

Question 25

what is the eGFR for stage 3b CKD?

Answer 25

30-44

Question 26

what is the eGFR for stage 4 CKD?

Answer 26

15-29

Question 27

what is the eGFR for stage 5 CKD?

Answer 27

<15

Question 28

ECG: absent p waves, tall T waves, broad QRS. dx?

Answer 28

hyperkalaemia

Question 29

sharp chest pain relieved leaning forwards, saddle shaped ST segments. dx?

Answer 29

pericarditis (ischaemic)

Question 30

polyarthropathy, fractures and calcific skin lesions with CKD. dx?

Answer 30

osteodystrophy