Acute Kidney Injury

Question 1

Who developed the RIFLE criteria?

Answer 1

The Acute Dialysis Quality Improvement Group (ADQI) in 2004

Question 2

What is RISK as defined by the RIFLE criteria?

Answer 2

Increased serum creatinine x 1.5 or GFR decrease > 25%

Or urine output < 0.5ml/kg/hr for 6 hours

Question 3

What is Injury as per the RIFLE criteria?

Answer 3

Increased serum creatinine x 2 or GFR decrease by 50%

Or urine output < 0.5ml/kg/hr for 12 hours

Question 4

What is Failure as per the RIFLE criteria?

Answer 4

Increase creatinine x 3
GFR decrease by 75%
Or urine output < 0.3ml/kg/hr for 24 hours or anuria for 12 hours

Question 5

What is Loss as per the RIFLE criteria?

Answer 5

Complete loss of kidney function for > 4 weeks

Question 6

What is ESKD as per the RIFLE criteria?

Answer 6

ESKD > 3 monthss

Question 7

Who are KIDGO?

Answer 7

Kidney Disease Improving Global Outcomes (KDIGO) Group

They published further international consensus on AKI management and definition in 2012

Question 8

What are the complications of AKI?

Answer 8

Metabolic:
-metabolic acidosis
-hyperkalaemia and cardiac arrythmia
-electrolyte disturbance
-uraemia encephalopathy
Fluid-related:
-tissue fluid overload
- resp failure secondary to pulmonary oedema
-fluid accumulation and prolonged positive fluid balance
Long term:
-increased risk of chronic kidney disease

Question 9

According to the NICE AKI guidelines what are the risk factors for AKI in patients with acute illness?

Answer 9

Critical illness
CKD
Heart failure
Diabetes
Liver disease
Previous AKI
Any neurological, cognitive or physical ability that may prevent the pts ability to access fluids
Aged over 65
Hypovolaemia
Sepsis
Deteriorating early warning score
Urological obstruction
Nephrotoxic drugs
IV contrast
Emergency surgery
Intraperitoneal surgery

Question 10

What specific factors in kids increase their risk of AKI in acute illness?

Answer 10

Severe diarrhoea
Symptoms and signs of nephritis e.g. haematuria, oedema
Haematological malignancy
Young age

Question 11

Which large prospective observational study described the aetiological factors for AKI in critically ill patients?

Answer 11

The BEST kidney study

Question 12

According to the BEST kidney study what are the aetiological factors for AKI in critically ill patients?

Answer 12

Usually multifactorial. Frequent contributing factors include sepsis, surgical insult, low cadiac output states, hypovolaemia, drugs, contrast, other organ failures, abdomical compartment syndrome and mechanical obstruction of the renal tract.
Other causes to be considered include:
Contract, rhabdo, haemaltic uraemic syndrome (HUS) secondary to E.coli 0157, tumour lysis syndrome, glomerulonephritis- e.g. post-streptococcal, IgA nephropahthy and vasculitis; tubulointerstitial nephritis e.g. drug hypersensitivity reaction, infection, sarcoidosis, Sjogren’s; Drugs, which commonly include ACEI, angiotensin 2 receptor blockers, diuretics, aminoglycosides, NSAIDS

Question 13

What are the pathophysical mechanisms behind AKI?

Answer 13

ATN is a histopathological description of tubular changes believed to be the consequence of hypoperfusion and subsequent ischaemic changes
It was previously thought to be the mechanism underlying AKI in critical illness
However this has now been discredited
Likely to be far more complex involving immune-mediated dysfunction

Question 14

Why is early detection of AKI difficult?

Answer 14

By the time serum creatinine rises at least 50% of renal function is already lost

Question 15

Which assays, used in research, are associated with a greater sensitivity of detecting AKI in earlier stages?

Answer 15

Neutrophil gelatinase associated lipocalin

Kidney injury molecule 1

Question 16

How can AKI be prevented?

Answer 16

In patients identified as having an increased risk of AKI renal function should be closely monitored.
Hydration, perfusion and oxygenation delivery should be optimised
Avoid nephtotoxic drugs and agents

Question 17

According to the joint ATS/ERS/ECICM/SCCM/SRLF consensus statement how might you try and prevent AKI when using IV contrast?

Answer 17

Consider risk vs benefits and withold if risk outweighs benefits
Withhold nephrotoxic drugs
Use low or iso-osmolar contrast agents in low volume if able
Consider isotonic sodium bicarb infusion - current evidence isn’t very strong
Consider acetylcysteine infusion in high risk patients however there is also a lack of evidence

Question 18

How might you try and prevent AKI in patients with liver disease

Answer 18

Use albumin resuscitation in patients with SBP and those having large volume abdominal paracentesis

Question 19

How might you consider reducing the risk of AKI in patients undergoing cardiac surgery?

Answer 19

Consider off-pump bypass grafting in less complex patients

Question 20

How might you prevent AKI in patients undergoing cyto-toxic therapy at risk of tumour-lysis syndrome?

Answer 20

Volume loading with IV fluids
Sodium bicarb not currently recommended
Consider prophylaxis with allopurinol or rasburicase

Question 21

How might you prevent AKI in patients with rhamdomyolysis?

Answer 21

Large volume crystalloid resuscitation with the aim of rehydration and driving large volume urine output
Maintain urine pH > 6.5 - normally acheivable with saline and bicarb is currently not recommended
Diuretics with caution - need to avoid dehydration

Question 22

Which patients with rhabdo are most at risk of AKI?

Answer 22

Initial Cr > 150 and CK > 5000 and at high risk of requiring RRT

Question 23

How should you approach a critically unwell patient with AKI?

Answer 23

A+B as needed
Identify and correct hypotension - fluid status assessment, CV support, identify and treat sepsis, address life-threatening issues e.g. hyperkalaemia
Invasive monitoring of cardiac output may be useful
Avoid fluid overload and high CVP decreases renal venous drainage and may cause venous congestion within the kidney

Question 24

What are the key points in the history of a patient with AKI?

Answer 24

D+V and decreased po intake make hypovolaemis more likely
Bloody diarrhoea raises the possibility of HUS
Difficulty passing urine - may suggest obstruction
Haematuria may be caused by glorerulonephritis, renal stones or malignancy
Haemoptysis may suggest Wegners or other systemic vasculitides
Joint pain or rash may suggest SLE
Medications

Question 25

In the absence of a UTI what might protein and blood on the urine dip suggest?

Answer 25

Glomerulonephritis

Question 26

What investigations would you do on a patient with AKI?

Answer 26

FBC, coag, E+E, LFTs, CK, glucose, Ca, PO4, Mg2+
Further tests should be directed by clinical suspicion
e.g. blood cultures, ANCA (vasculitis), ANA (lupus), anti-GBM (Goodpastures)
Renal tract ultrasound (should be within 6 hours if suspected renal tract obstruction or within 24 if not)

Question 27

In which situations might you get a renal review for critical care patients?

Answer 27

AKI with no clear cause
Diagnosis suspected or confirmed requiring specialist treatment e.g. vasculitis, glumerulonephritis
Renal transplant patients
Established AKI requiring ongoing RRT on or approaching critical care discharge

Question 28

In patients with AKI, when do NICE recommend urgent urological opinion?

Answer 28

Pyonephrosis
Obstructed solitary kidney
Bilateral renal tract obstruction
Urological obstruction leading to AKI