Renal physiology

Question 1

What is the kidneys job?

Answer 1

To maintain normal balance of fluids, electrolytes minerals and acid base.

Question 2

What three principles does the kidney use to function?

Answer 2

Ultrafiltration
Excretion
Selective reabsorption

Question 3

What are the three stages of an acute kidney injury?

Answer 3

Pre-renal
Intra renal
Post renal

Question 4

What is prerenal and it causes?

Answer 4

Were kidneys are insufficiently perfused (reduced flow):
1. Hypervolaemia (haemorrhage, trauma, burns).
2. Pump failure (MI or large PE)
3. Renal vascular damage (AAA cross clamping)
4. Dehydration
5. Liver cirrhosis, sepsis, anaphylaxis

Question 5

What is intra renal and its causes?

Answer 5

Where the renal tubules (acute tubular necrosis ATN) or renal bed (parenchyma) damaged and cannot function.
Due to:
1. Infection ( Glomerulonephritis)
2. Blood vessel damage (vasculitis)
3. Toxins (nephrotoxic agents) gentamycin/CT contrast.
4. Rhabdomyolysis (muscle tissue breakdown)

Question 6

What is post renal and its causes?

Answer 6

Obstruction of outflow of urine (blockage preventing urine from leaving body)
Due to:
1. Kidney stones
2. Enlarged prostate gland
3. Tumour

Question 7

Stages of AKI

Answer 7

Stage 1: UO <0.5ml/kg hrly >6hr
Stage 2: UO <0.5ml/kg hrly >12hr
Stage 3: UO <0.3ml/kg hrly >24hr
Or Anuric >12hrs

Question 8

Signs and symptoms of AKI

Answer 8

Neuro: confusion, reduced GCS, agitation
Cardio: hypertensive, tachy, low Hb
Resp: tachyapneic, pulmonary oedema
Renal:
Gastro: nausea & vomiting, malnourishment
Skin: dry, jaundice

Question 9

Management of AKI using ABCDEFG PROCESS

Answer 9

A - address drugs & remove causative agents
B - boost blood pressure (fluid challenge/inotropes)
C- chart UO hrly
D- dipstick urine, consider diuretic therapy
E- electrolytes, correct hyperkalaemia
F - full blood count, consider transfusions Hb >7g/l or >10 in active bleeding
G - gastrointestinal, Mon blood glucose 4hrly