Acute kidney injury

Question 1

Definition of AKI?

Answer 1

An abrupt (26.4µmol/l) serum Cr
OR increase in creatinine by >50%
OR a reduction in UO

Question 2

Describe each stage of AKI (1-3) according to serum Cr levels

Answer 2

1. Increase >26µmol/L or
   Increase > 1.5-1.9 x reference Cr
2. Increase > 2 to 2.9 x reference SCr
3. Increase > 3 x reference SCr or increase to > 354
   µmol/L or need for RRT

Question 3

causes of Pre-renal AKI (3 main)

Answer 3

Hypovolaemia
Haemorrhage/ volume depletion (burns)

Hypotension
Cardiogenic shock
Distributive shock (sepsis)

Renal hypoperfusion
NSAIDs/COX-2
ACEi/ARBs
hepatorenal symptoms

Question 4

Presentation of Pre-renal AKI

Answer 4

Reversible vol depletion leading to: oliguria and increased creatinine

Question 5

Describe the action of ACE inhibitors on the kidney

Answer 5

They cause a reduction in angiotensin 2 production so reducing vasoconstriction in the efferent tubules
Vasodilation occurs reducing GFR
might precipitate AKI

Question 6

Briefly describe the pathophysiology of pre-renal AKI

Answer 6

Vol depletion/sepsis
Decreased intravascular volume
Increased ADH/Aldosterone
Salt & water retention
Oliguria
AKI

Question 7

What does AKI progress to when untreated?

Answer 7

Acute tubular necrosis

Question 8

Treatment of a pre-renal AKI?

Answer 8

Asses for hydration

• BP, HR, UO
• JVP, Cap refill, oedema
• pulmonary oedema

Fluid challenge for hypovolaemia
-use crystalloid or colloid
bolus then reassess

Question 9

Causes of renal AKI? (4 main ones)

Answer 9

Vascular

• Vasculitis
• Renovascular disease

Glomerular
-Glomerularnephritis

Interstitial nephritis

• Drugs
• infection (TB)
• Systemic e.g. sarcoid

Tubular injury

• ischaemia
• drugs (gentamicin)
• Contrast
• rhabbdomyolysis

Question 10

symptoms of AKI? (7)

Signs of AKI?

Answer 10

-Anorexia, fatigue, weight loss, lethargy
nausea & vomiting
itch
Fluid overload- oedema and SOB

-Fluid overload (oedema/pulmonary oedema/effusions/high BP)
Uraemia= itch/pericarditis
Oliguria

Question 11

Investigations in AKI and possible findings? (6)

Answer 11

U&Es
Look at K, is it high = emergency

FBC & coagulation
low platelets = haemolytic uraemia syndrome, TTP
abnormal clotting = sepsis?
anaemia = CKD, Myeloma

Urinalysis
haemoprotienuria = GN

USS
obstruction?
size of kidney?

Immunology
ANA- SLE
ANCA- vasculitis
GBM- goodpastures

Protien electrophoresis & BJP
-in myeloma

Question 12

indications for renal biopsy?

• urgent
• semi urgent
• not performed when…

Answer 12

-rapidly progressive GN
Positive immunology + AKI

-unexplained AKI

-abnormal clotting, on warfarin
hypovolaemic
hydronephrosis

Question 13

Treatment of renal AKI?

Answer 13

• establish good perfusion pressure , fluid resuscitate then inotropes
• Treat underlying cause
• stop nephrotoxins
• dialysis if they remain anuric & uraemic

Question 14

Complications of AKI? (5)

Answer 14

Hyperkalaemia 
Fluid Overload (Pulmonary oedema)
Severe Acidosis (pH 40)

Question 15

What is post renal AKI?

Answer 15

due to obstruction of urine flow leading to back pressure (hydronephrosis) and thus loss of conc ability

Question 16

Causes of post renal AKI? (4)

Answer 16

stones
tumours
strictures
Extrinsic pressure

Question 17

Treatment of Post renal AKI? (1)

Answer 17

Relieve obstruction: catheter or nephrostomy

Question 18

Hyperkalaemia

• definition?
• assessment?
• treatment? (4)

Answer 18

• > 5.5
  life threatening = >6.5

-ECG, muscle weakness

-IV access!
Calcium Gluconate 10mls 10% (protects myocardium)
insulin dextrose
salbutamol Nebulised
Calcium resonium (not acute)

Question 19

Urgent indications for heamodialysis?

Answer 19

Hyperkalaemia

severe acidosis 40 + pericardial rub