Fluids and Transfusions Flashcards
How much water does a person need in a day?
25-30ml/kg
How much sodium does a person need in a day?
1-2 mmol/kg
How much potassium does a person need in a day?
0.5-1 mmol/kg
How much chloride does a person need in a day?
1 mmol/kg
How much glucose does a person need in a day?
50-100g
What is the difference between crystalloids and colloids?
- Crystalloids - Ionic
- Colloids - Large molecules e.g. albumin
Why aren’t colloids used so much now? (2)
- Anaphylaxis
- No evidence that they’re any better than crystalloids at resuscitation
How much Na, K, Cl and Bicarb in 0.9 Sodium Chloride? (1 litre)
Na 154 mmol
K (can have 20 or 40 added)
Cl 154 mmol
Bicarb 0
How much Na, K, Cl and Bicarb in 0.5 Dextrose? (1 Litre)
Na 0
K 0 (can have potassium added)
Cl 0
Bicarb 0
How much glucose is in 0.5 dextrose?
50g
How much Na, K, Cl and Bicarb in 0.9 Hartmann’s? (1 litre)
Na 131
K 5
Cl 111
Bicarb 29
How is resuscitation achieved?
500ml normal saline over 15 minutes
What should you look for as a cause of fluid loss?
- Third space losses e.g. obstruction or pancreatitis
- Diuresis
- Tachyp, febrile
- High stoma output
- Electrolyte rich fluid losses
What imbalance does vomiting cause?
Alkalosis
- low H+
- low K
- low Cl
What imbalance does diarrhoea cause?
Acidosis
- low K
Why does vomiting cause alkalosis?
Hydrogen ion loss (stomach acid) so pH rises
When should a patient be transfused?
Hb less than 80
Describe the water distribution in a 70kg male.
42kg is water
2/3 intracellular (28)
Of remaining 14 (extra-c), 3 litres is intravascular
3 litres water + 2 litres RBCs makes 5 litres of blood
What is the normal plasma osmalality?
285-295 mOsmol/kg
What happens to the sugar in dextrose?
Rapid uptake into cells
What happens when hypertonic solution is given?
RBCs shrivel as water moves out
What happens as hypotonic fluid is given?
RBCs swell
Where else can you look to assess a patient’s fluids?
- Mucosa
- BP
- Urine output
- Cap refill
