Week 2 - AKI

Question 1

What is acute kidney injury?

Answer 1

Recognised by significant elevation of serum creatinine within hours or days or significant decrease in U/O for >6 hours.

Question 2

What is chronic kidney disease?

Answer 2

When GFR is <60mL/min/1.73m^2 for >3 months with/without evidence of kidney damage.

Question 3

What is the function of the kidneys (excretory)?

Answer 3

• Remove waste products
• Remove excess fluids
• Regulate acid-base balance
• Regulate electrolyte levels

Question 4

What is the function of the kidneys (secretory)?

Answer 4

• Regulate BP
• Regulate RBC
• Regulate calcium uptake

Question 5

What is hyperkalaemia?

Answer 5

A condition in which serum potassium is >5.3mEq/L.

Question 6

Investigations of hyperkalaemia:

Answer 6

• Assess renal function
• Measure urine K+ and Na+ concentrations and urine osmolarity
• Measure complete blood count
• Complete metabolic profile

Question 7

What is acidosis?

Answer 7

Occurs when the renal tubules fail to regenerate bicarbonate and secrete H+ ions into the urine.

Question 8

Describe renal autoregulation.

Answer 8

Controlled by 2 mechanisms
• Myogenic control (BP)
• Via tubuloglomerular feedback system

Question 9

3 causes of renal failure.

Answer 9

• Pre-renal failure
• Intra-renal failure
• Post-renal failure

Question 10

What is pre-renal failure?

Answer 10

• Most common
• Hypovolaemia
• Decreased vascular filling
• Heart failure and cardiogenic shock
• Decreased renal perfusion due to vasoactive drugs of diagnostic agents

Question 11

What is intra-renal failure?

Answer 11

Caused by vascular disorders or acute tubular necrosis.

Question 12

What is post-renal failure?

Answer 12

Caused by obstruction of the urinary tract such as BPH, kidney stones, urinary catheters and cancer.

Question 13

What serum values are indicative of renal disease?

Answer 13

Stage 1
<0.5ml/kg/hr for 6-12 hours
1.5-1.9 x baseline

Stage 2
<0.5ml/kg/hr for >12 hours
2-2.9 x baseline

Stage 3
<0.3ml/kg/hr or Anuria >12 hours
3 x baseline

Question 14

What extra-renal causes may cause these serum values to become elevated?

Answer 14

Raised creatinine and raised urea.

Question 15

4 phases in the clinical course of acute renal failure:

Answer 15

1. Onset
2. Oliguric-anuric
3. Diuretic
4. Recovery

Question 16

What is the onset phase?

Answer 16

• Represents the time from initial insult to cell injury
• Can last from hours to days
• Renal blood flow and O2 consumption at 25%

Question 17

What is oliguric-anuric phase?

Answer 17

• Lasts 8-14 days

* Characterised by damage to the tubular wall and basement membranes

Question 18

What is diuretic phase?

Answer 18

• Appears when the obstruction to tubular flow has passed
• Lasts 7-14 days
• Increase in GFR with

Question 19

What is recovery phase?

Answer 19

• Stabilisation of lab results and can range from 1-12months

* Oedema subsides and tubular cells return to normal function

Question 20

What is the significant use of gentamycin and what should you be monitoring for?

Answer 20

• Nephrotoxic
• Excreted exclusive via kidneys and is toxic to proximal tubule
• Serum creatinine and serum urea need to be monitored however takes 2-3 days
• Monitor U/O more stringently

Question 21

What does peaked T waves indicate?

Answer 21

Hyperkalaemia.