Acute Kidney Injury

Question 1

AKI risk factors

Answer 1

Age
CKD
Other chronic dx
Emergency surgery
Iodinated contrast
Nephrotoxin exposure eg ahminoglycosides
Oliguria

Question 2

AKI clinical features

Answer 2

May be none if early
Fatigue
Pulmonary and peripheral oedema
Features of uraemia (High levels of urea in the bloodstream causing pericarditis encephalopathy)
N+V
Arrythmia (hyperkalaemia)
Fluid overload
Oliguria

Question 3

AKI stage 1 creatinine and urine levels

Answer 3

Creatinine: 1.5-1.9x baseline
Urine: <0.5ml/kg/h for >6 consecutive hours

Question 4

AKI stage 2 creatinine and urine levels

Answer 4

Creatinine: 2-2.9x
Urine: <0.5ml/kg/h >12 hrs

Question 5

AKI stage 3 creatinine and urine levels

Answer 5

Creatinine: >3x baseline
Urine: <0.3ml/kg/h for >24hr or anuric for 12 hr

Question 6

7 Causes

Answer 6

Sepsis.
Major surgery.
Cardiogenic shock.
Other hypovolaemia.
Drugs.
Hepatorenal syndrome.
Obstruction

Question 7

3 types of AKI

Answer 7

Pre-renal
Renal
post renal

Question 8

Pathology of pre-renal AKI

Answer 8

Hypotension of any cause

Dec vascular volume eg Haemorrhage, D&V, burns, pancreatitis

Dec cardiac output eg Cardiogenic shock, MI

Systemic vasodilation eg Sepsis, drugs

Renal vasoconstriction eg NSAIDs, ACE-i, ARB, hepatorenal syndrome

Question 9

Pathology of renal AKI

Answer 9

Glomerular eg Glomerulonephritis, ATN (prolonged renal hypoperfusion
causing intrinsic renal damage)

Interstitial eg Drug reaction, infection, infiltration (eg sarcoid)

Vessels eg Vasculitis, HUS, TTP, DIC

Question 10

Pathology of post-renal AKI

Answer 10

Within renal tract eg Stone, renal tract malignancy, stricture, clot

Extrinsic compression eg Pelvic malignancy, prostatic hypertrophy, retroperitoneal
fibrosis

Question 11

Symptoms and signs AKI

Answer 11

reduced urine output
pulmonary and peripheral oedema
arrhythmias (secondary to changes in potassium and acid-base balance)
features of uraemia (for example, pericarditis or encephalopathy)

Question 12

AKI investigations

Answer 12

Urgent ABG/VBG for K+
ECG for hyperkalaemic changes i.e. arrythmias (peaked T waves)
Bloods: U+Es, Ca2+, PO43-, FBC, ESR, CRP, clotting, LFTs, CK
U+E’s include: Na+, K+, Urea, creatinine (elevation)

Consider renal screen: protein electrophoresis, hepatitis serology, autoantibodies (ANCA, ANA, anti-GBM), complement, rheumatoid factor, cryoglobulins

Urinalysis: dipstick, send for microscopy, culture, albumin/creatinine ratio

Renal USS: if no identifiable cause for deterioration OR at risk of urinary tract obstruction

a. This is done within 24h of assessment
b. Looking for renal size or obstruction

Question 13

What value of K on VBG requires urgent treatment of AKI?

Answer 13

> 6.5

Question 14

Pre-renal vs ATN(renal) urine sodium and why?

Answer 14

Low vs high
In pre-renal, kidneys hold on to sodium to try and correct low vol!
ATN is intrinsic so there would be high levels of sodium!

Question 15

Drugs to stop in AKI as they worsen renal function?

Answer 15

NSAIDS
Aminoglycosides
ACEi
Ang II receptor antagonists
Diuretics

Question 16

Treating hyperkalaemia in AKI

Answer 16

Stabilisation of cardiac membrane: IV calcium gluconate

Shift K –> intracellular: insulin dextrose infusion and nebuliser salbutamol

Remove K from body: calcium resonium, loop diuretic, dialysis

Question 17

AKI mortality

Answer 17

25-30

Question 18

Fluid management of emergency AKI

Answer 18

Correct hypovolaemia using 0.9% saline, boluses of 250 ml and continuous monitoring of fluid status

If urine output remains low after 2 litres of fluid seek expert advice

Question 19

ECG in hyperkalaemia

Answer 19

tall ‘tented’ T waves; increased PR interval; small or absent
P wave; widened QRS complex