Fluid Management

Question 1

What is maintenance fluid?

Answer 1

Fluid which replaces insensible losses

Allows excretion of excess solute load in urine

Question 2

What is resuscitation fluid?

Answer 2

Fluid which replaces deficit and ongoing losses (blood, vomit, sweat)

Question 3

In what types of fluid loss is K lost most?

Answer 3

Gastric

Diarrhoea

Question 4

What is the major difference in cation between intra and extracellular fluids?

Answer 4

Potassium
High intra
Loss extra

Question 5

What is tonicity?

Answer 5

The total concentration of solutes that exert an osmotic force across a membrane

Question 6

What is the normal value for [Na]?

Answer 6

135-145

Question 7

What is the normal value for [K]?

Answer 7

3.5 - 5

Question 8

What is the normal value for osmolality?

Answer 8

270-295 mmol/kg

Question 9

Which cation maintains plasma tonicity and ECF volume?

Answer 9

Na

Question 10

What is natriuresis? What mediates it?

Answer 10

Urination of Na and water

Stretch on the atria and release of atrial natriuretic peptide

Question 11

Why are children at risk of hyponatraemia?

Answer 11

Large brain : intra-cranial volume ratio

Question 12

What is the Na threshold at which seizures occur?

Answer 12

120mmol/l

cf to 111mmol/l in adults

Question 13

What is the 4/2/1 rule?

Answer 13

• 4 ml/kg/hr for 0-10 kg
• 2 ml/kg/hr for 10-20 kg
• 1 ml/kg/hr for 20+ kg
• Max 100ml/hr

Question 14

How much energy does 1L of 5% dextrose have in it?

Answer 14

200cal

Question 15

What was the PIMS study?

Answer 15

RCT at RCH comparing plasma-lyte and 5% D with 0.45% in 5% dextrose

• Showed less hyponatraemic in isotonic plasma-lyte

Question 16

What must you consider in prescription of maintenance?

Answer 16

ADH response continues post-op/hospital
4/2/1 rule based on healthy children
Hydration status of children is difficult to assess
Fasting time
Age, nutritional status
Kids eat and drink early

Question 17

How does maintenance change in sick children? Why?

Answer 17

Reduce 4/2/1 rule by 75-50%

Stress response causes retention

Question 18

Which groups are high risk for fluid overload?

Answer 18

Neurological disease
Craniofacial/neurosurg patients, major surgery
Neonates
Children requiring full maintenance fluids
Pneumonia

Question 19

Why do we add dextrose?

Answer 19

Prevent hypoglycaemia and ketosis

Prevent hypotonia induced haemolysis - less of an issue now that we’re using isotonic solutions

Question 20

When do you give TPN?

Answer 20

After a few days of no eating and drinking when the liver glycogen stores are depleted