ACUTE KIDNEY INJURY

Question 1

WHAT IS ACUTE KIDNEY INJURY?

Answer 1

• decreased renal function that occurs over a period of days to weeks which is reversible

Question 2

WHAT ARE THE RISK FACTORS FOR AKI?

Answer 2

1) older age
2) sepsis
3) prolonged immobilisation - rhabdomyolysis
4) diabetes
5) dehydration

Question 3

WHY DOES SEPSIS INCREASE THE CHANCE OF DEVELOPING AKI?

Answer 3

systemic vasodilation leads to hypovolemia and hypoperfusion of the kidneys

Question 4

WHAT ARE THE PRE-RENAL CAUSES OF AKI?

Answer 4

Hypoperfusion due to:

• medication - ACEI, ARBs and NSAIDS
• sepsis
• renal artery stenosis
• hypovolemia
• heart failure
• MI

Question 5

WHAT ARE THE INTRAHEPATIC CAUSES OF AKI?

Answer 5

1) rhabdomyolysis
2) pyelonephritis - kidney infection
3) nephrotoxins - iodinated contrast, gentamycin, methotrexate

Question 6

WHAT ARE THE POST-RENAL CAUSES OF AKI?

Answer 6

Factors that prevent urine leaving body

1) Benign prostatic hyperplasia
2) Prostate cancer
3) Renal stones
4) Strictures
5) Constipation

Question 7

WHAT ARE THE SIGNS OF:

1) dehydration
2) fluid overload

Answer 7

1) dehydration - reduced skin tugor, dry mucous membrane, low urine output, negative fluid balance, increase capillary refill, low BP and high HR
2) fluid overload - signs of respiratory distress, pulmonary oedema (bi-basal crepitations), headaches, SOB, peripheral oedema (ankles and sacrum)

Question 8

HOW MANY STAGES ARE THERE FOR AKI AND WHAT MEASUREMENTS DOES IT TAKE INTO ACCOUNT?

Answer 8

• 3 stages - stage 1 (50-100% from baseline), stage 2 (100%-200% from baseline), stage 3 (200% above baseline)
• serum creatinine and urine output

Question 9

WHAT IS THE MANAGEMENT OF AKI?

Answer 9

STOP

1) SEPSIS
2) TOXINS - discontinue nephrotoxic drugs
3) OPTIMISE VOLUME STATUS- if dehydrated then give IV fluids, if overloaded give diuretics and aim for euvolaemia
4) PREVENT HARM - haemodynamic monitoring with central venous pressure and arterial line, monitor urine output and daily bloods, catheterise if necessary, avoid hyperglycaemia, drug dosing

Question 10

WHICH 4 COMMON MEDICATIONS DECREASE RENAL FUNCTION?

Answer 10

1) NSAIDs
2) Diuretics
3) Aminoglycosides
4) ACE inhibitors

Question 11

WHICH 4 COMMON MEDICATION CAUSE INCREASE TOXICITY IN KIDNEYS?

Answer 11

1) Opiates
2) Digoxin
3) Lithium
4) Metformin

Question 12

WHAT INVESTIGATIONS WOULD YOU CARRY OUT FOR AKI?

Answer 12

1) Urine dip - proteinuria and haematuria (intrinsic damage)
2) ECG
3) Bloods: FBC (infection), U+E’s (increase urea, creatinine and potassium), creatine kinase (rhabdomyolysis), immunology (ANA, ANCA, anti-GBM)
4) Renal USS
5) CT KUB without contrast - renal stones and stricture
6) CXR (bog standard)- HF, cardiomegaly, effusion, chest infection
7) Abdominal X-ray
8) MRI - contrast not nephrotoxic

Question 13

WHAT WILL U+E’s SHOW?

Answer 13

• increased urea and creatinine

Question 14

WHY DO YOU NEEDS TO BE CAREFUL WHEN PRESCRIBING FLUIDS TO PATIENTS WITH RENAL AND CARDIAC IMPAIRMENT? AND HOW DO YOU MITIGATE THIS RISK?

Answer 14

• risk of fluid overload
• measure U and E before and during fluid prescription for evidence of electrolyte disturbance, fluid overloading and dehydration.

Question 15

WHAT IS NEPHRITIC SYNDROME AND ITS SYMPTOMS?

Answer 15

• glomerular damage

- Haematuria, oedema (to a lesser extent compared to nephrotic syndrome),reduced urine output, hypertension, reduced GFR

Question 16

WHAT IS NEPHROTIC SYNDROME AND ITS SYMPTOMS?

Answer 16

• podocyte damage leading to glomerular charge barrier disruption
• oedema, proteinuria, hypoalbuminaemia, hyperlipidaemia

Question 17

WHAT ARE THE CAUSES OF NEPHRITIC SYNDROME?

Answer 17

• good pastures syndrome (anti-GBM disease)
• ANCA- associated vasculitis
• lupus

Question 18

WHAT ELECTROLTE IMBALANCE CAN AKI CAUSE?

Answer 18

• hyperkalaemia due to reduce K+ secretion into tubules

Question 19

WHY DOES PROLONGED IMMBOLISATION INCREASE THE CHANCE OF DEVELOPING AKI?

Answer 19

Leads to rhabdomyolysis, which is the release of myoglobin as a result of skeletal muscle degradation. Increase myoglobin leads to renal vasoconstriction and direct toxicity to kidney tubular cells.

Question 20

WHY DOES DIABETES INCREASE THE CHANCE OF DEVELOPING AKI?

Answer 20

increase blood glucose and associated hypertension can damage kidney microvasculature leading to reduced renal function

Question 21

WHY DOES DEHYDRATION INCREASE THE CHANCE OF DEVELOPING AKI?

Answer 21

hypovolemia leading to hypoperfusion to the kidneys.

Question 22

WHAT FLUIDS IS GIVEN FOR PATIENT WITH AKI?

Answer 22

500 ml 0.9% NaCl

Question 23

WHAT FLUIDS IS GIVEN FOR HEART FAILURE OR ELDERLY/FRAIL PATIENTS?

Answer 23

250ml 0.9% NaCl