Dehydration

Question 1

When is there an increased risk of dehydration?

Answer 1

• Infants (particularly <6 months or who were low birthweight)
• 6 or more diarrhoeal stools passed in previous 24 hours.
• 3 or more vomits in last 24 hours.
• Unable to tolerate/not offered extra fluids
• Signs of malnutrition

Question 2

What are the degrees of dehydration based on loss of body weight?

Answer 2

• No clinically-detectable dehydration (Usually < 5% loss)
• Clinical dehydrate (5-10% loss)
• Shock (>10% loss)

Question 3

What is isonatraemic dehydration?

Answer 3

Losses of sodium proportional to losses of water therefore plasma sodium remains normal.

Question 4

What is hyponatraemic dehydration and when is it seen?

Answer 4

Children drink large quantities of water/other hypotonic solution, leading to greater net loss of sodium than water, leading to decreased plasma sodium.

Question 5

What is the risk with hyponatraemic dehydration?

Answer 5

Low plasma sodium leads to fluid extravasation into the intracellular compartments, leading to increased intracellular fluid volume, which in the CNS causes an increase in brain volume, which can cause convulsions.

Question 6

When is hypernatraemic dehydration seen?

What is the movement of fluid and the effect of this?

Answer 6

Due to insensible water loss (high fever or hot, dry environment) or profuse, low-sodium diarrhoea.

Fluid moves from intracellular spaces to extracellular space. Signs of extracellular fluid depletion and therefore less obvious and dehydration more difficult to recognise.

Also dangerous as water drawn out of brain and cerebral shrinkage, causing jittery movements, increased muscle tone with hyperreflexia, altered consciousness, seizures and multiple, small cerebral haemorrhages.

Question 7

What is the initial management of clinical dehydration?

Answer 7

Oral rehydration solution - Give often in small doses. Continue breast feeding.
If inadequate or vomiting persists, NG tube ORS.

Question 8

What is the initial management of shock?

Answer 8

IV therapy - rapid infusion 0.9% NaCl solution.

Question 9

What is the management of persistent clinical dehydration or secondary management of shock?

Answer 9

IV therapy - replace fluid deficit and give maintenance fluid. Give 0.9% NaCl with or without 5% glucose. Monitor plasma electrolytes, urea, creatinine and glucose.

Question 10

What is the process after dehydration resolved?

Answer 10

Give full strength milk and reintroduce solid food.
Advise diligent hand washing, towels not to be shared, do not return to childcare facility/school until 48 hours after last episode.