4. Fluid balance

Question 1

define resuscitation fluid

Answer 1

fluid which replaces deficit and ongoing losses

Question 2

resus principle for diarrhoea/vom vs blood loss?

Answer 2

replace like with like-
diarrhoea/vom> fluid with electrolytes
blood> blood

Question 3

Hartmans vs 0.9% saline for Na, Cl, potassium, etc

Answer 3

Saline- more sodium (154 - normal is 140 +/- 5), Hartmans 129,
Potassium- none in saline, 5 in Hartmans (3.5-5)
Chloride - high in saline (154 cf 95-105); normal in Hartmans (109)
Ca -none in saline, 2 in hartmans (2.2-2.6)
lactate - none in saline, very high in hartmans (29 cf 1)

Question 4

difference bw electrolytes in plasma/interstial fluid and intracellular

Answer 4

more Na and Cl in blood/interst, much more K+ in cells

Question 5

What is the mechanism of hyponatremia in children?

Answer 5

Higher sympathetic drive than adults,
ADH release - due to ‘stress’ of surgery/illness> water retention at kidneys- aquaporin and ^Na reabsorption> cellular swelling> cerebral oedema
> Natriuresis due to volume and ANP release

decreased Na= decreased plasma osmolality> water moves into cells

Question 6

Why are children more at risk from hyponatremia?

Answer 6

Large brain- (brain:skull ratio high)> increased ICP with modest volume increase
hyponatremic encephalopathy for children - at about 120, adults 111.

Question 7

Cause of iatrogenic hyponatremia in children?

Answer 7

too much hypotonic fluid

Question 8

4/2/1 maintenance rule-
buut it’s based on healthy children.
What is the ideal maintenance prescription?

Answer 8

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

maximum = 100ml/hr

more ideal - 2/1/1 and quickly reduce once drinking, and isotonic fluids are much better> much lower risk of hyponatremia