Fluids

Question 1

Normal requirement of H2O?

Answer 1

1. 5 ml/kg/h

2. 5L/day

Question 2

Normal requirement of Na+?

Answer 2

1-2mmol/kg/24h

70-140mmol

Question 3

Normal requirement of K+?

Answer 3

0.5-1mmol/kg/24h

35-70mmol

Question 4

Normal urine output?

Answer 4

> 0.5ml/kg/hr

35ml/h

Question 5

Contents of sodium chloride (0.9%)

Answer 5

Na+ - 154

Cl- - 154

Question 6

Contents of Hartmann’s solution?

Answer 6

Na - 131
Cl - 111
K - 5
HCO3 - 29

Question 7

Contents of 5% dextrose?

Answer 7

50g glucose

Question 8

What is Hartmann’s solution good for?

Answer 8

Most physiological so is good for replacing plasma loss.

Not good for maintenance fluids as would give too much sodium and not enough potassium

Question 9

What is normal saline good for?

Answer 9

More physiological than dextrose but not as physiological as Hartmann’s.
Too much sodium places massive load on kidneys. Can cause hypercholaraemic acidosis.

Question 10

What is 5% dextrose for?

Answer 10

Good for maintenance fluids (no electrolytes, glucose maintains initial osmolarity)

Question 11

What concentrations of potassium are in pre-made versions of saline and dextrose?

Answer 11

20mmol

40mmol

Question 12

When should you give maintenance fluids?

Answer 12

When patient can’t drink enough

Oral/NG tube fluids are safer as much less likely to cause overload, electrolyte disturbance and don’t require a cannula

Question 13

Contents of dextrose-saline 4%/0.18%?

Answer 13

Na - 30
Cl - 30
Glucose - 40g

Question 14

What is dextrose-saline good for?

Answer 14

Good for maintenance fluids because given at the correct rate, contains approximately correct requirements of sodium.

Becoming preferred for maintenance because delivers daily sodium requirement over the course of the regime rather than all in one bag.

Question 15

What is the traditional maintenance fluid regime?

Answer 15

1 salty + 2 sweet

1L saline 0.9% + 20mmol potassium chloride (8 hours)
1L dextrose 5% + 20mmol potassium chloride (8 hours)
1L dextrose 5% + 20mmol potassium chloride (8 hours)

Question 16

What should you do before prescribing any fluids?

Answer 16

Check U+Es and adjust regime as necessary to correct any electrolyte abnormalities

Question 17

What are the two components of replacing fluid loss?

Answer 17

1. Pre-existing fluid (replaced STAT)

2. Ongoing losses (replace future losses as they occur)

Question 18

What should you replace extracellular fluid with? (D+V, NG aspirates, stomas, burns, pancreatitis)

Answer 18

Fluid similar to EC fluid/plasma - Hartmann’s or saline.

If patient needs a lot of sodium-rich fluid resus, Hartmann’s preferred as it contains less chloride (avoid acidosis)

Question 19

What should you replace normal dehydration with (pyrexia, poor intake)?

Answer 19

Normal maintenance fluids (dextrose-saline)

Question 20

What should you replace blood with?

Answer 20

Blood - if patient continues to bleed they may also need other products (FFP, platelets) to stop the bleeding rather than replace the lost red cells.

Question 21

Classes of shock, how much fluid lost and signs?

Answer 21

1 - 0.75L - minimal, mild tachy
2 - 0.75-1.5L - moderate tachy are hypoT
3 - 1.5-2L - severe tachy and hypoT, confusion
4 - >2L - critical tachy and hypoT

Question 22

Fluids post-op?

Answer 22

K+ is intracellular and can decrease due to cell lysis during surgery.

If K+ is over 4.5, omit for 24 hours.

Question 23

Fluids in sepsis?

Answer 23

Sepsis causes intravascular depletion due to plasma loss due to leaky capillaries/vasodilation.

Replace with crystalloid, but avoid too much sodium and chloride.

Question 24

Fluids in heart failure?

Answer 24

No more than 2L/24 hours. If overload develops –> fluid restriction, furosemide, low sodium diet and daily weights.

Question 25

Causes of low SBP/low urine output in HF?

Answer 25

Must examine because two opposite causes.

1. Dehydration - fluid depleted (give fluids)
2. LVF and overload - (furosemide - will improve LVF and increase SBP and urine output)

Question 26

Fluids in liver failure?

Answer 26

Excess Na+ may cause ascites so ONLY use 5% dextrose

Question 27

Fluids in AKI?

Answer 27

Avoid K+

Question 28

Fluids in chronic renal disease?

Answer 28

Avoid excess fluids, sodium and potassium (kidneys can’t excrete). Avoid Hartmann’s as contains lactate.

Question 29

Fluids in extravasation of plasma (e.g. sepsis)?

Answer 29

Fluids that will maintain intravascular volume (e.g. Hartmann’s solution or colloids) - may need inotropic support

Question 30

Fluids in alcoholics?

Answer 30

MUST given parbinex before giving any 5% dextrose (even if hypoglycaemic). Can precipitate Korsakoff syndrome

Question 31

Fluids in brain haemorrhage?

Answer 31

Avoid dextrose (causes osmotic haematoma swelling) - “dextrose destroys the brain if there’s a bleed”

Saline best

Question 32

Fluids in risk of re-feeding syndrome?

Answer 32

Avoid dextrose as it can precipitate