normal requirement of fluids and electrolytes in a dehydrated child

1. FLUIDS &ELCTROLYTES
Prof. Hamida Esahli

3. • Objective:
• Normal fluid and electrolyte requirements in
childhood
• Assessment and management of the
dehydrated child

4. • Dehydration does not cause death, shock does.
• Shock occurs as result of rapid loss of 20ml/kg from the intravascular
space. If the intravascular volume is maintained, clinical dehydration is
only evident after losses of >25ml/kg of total body water.
• It is possible to be shocked and not dehydrated, dehydrated and not
shocked, or dehydrated and shocked
• The treatment of shock requires rapid administration of a bolus of
intravascular fluid, with electrolyte content that approximates to plasma.
• The treatment of dehydration requires gradual replacement of fluids, with
electrolyte content that relates to the electrolyte losses, or to the total
body electrolyte content.
• Damage from electrolyte abnormalities is related to either extreme levels,
or rapid rates of change.
•

5. •
•
•
•
The critical clinical questions are therefore:
Is the patient shocked?
Is the patient dehydrated?
Does the patient have a significant acid–base
abnormality?
• Are there significant electrolyte problems

6. • Cardiovascular signs Tachycardia usually associated with :
• poor volume peripheral pulses
• Poor peripheral perfusion with prolonged capillary refill
time and
• cool peripheries
• Low blood pressure as a pre-terminal sign
• Consequences of poor perfusion:
• Alteration of mental status
• Development of metabolic acidosis with
• compensatory tachypnoea
• Poor urine out

7. Clinical Signs of Dehydration
Signs/sympto
ms
Mild<5%
Moderate
5-10%
Severe >10%
Decrease urine
output
+
+
+
Dry mouth
+/-
+
Notes
+
Decreased skin
turgor
-
+/-
+
Unreliable in
fat children and
in hypertonic
dehydration
Sunken
anterior
fontanelle
-
+
+
Only useful if
fontanell well
patent and in
absence of
meningitis
Sunken eyes
-
+
+
All these clinical signs are individually unreliable. Weight is the only objective
measure of acute fluid losses from the body

8. NORMAL Fluid Requirements
Body weight
Fluid requirement/day
Fluid requirement /hour
First 10kg
100ml/kg
4ml/kg
Second 10kg
50ml/kg
2ml/kg
Subsequent kg
20ml/kg
1ml/kg
Actual volume of insensible fluid loss is related to:
caloric content of feeds, ambient temperature, humidity
of inspired air, presence of pyrexia and the quality of
the skin.
Usually between 0 and 10ml/kg per day are lost in stool
(may exceed 300ml/kg/day in diarrhoea).
Urinary losses are usually between 1-2ml/kg per day
(i.e. approximately 30ml/kg/day).

9. Body Weight
Sodium
mmol/kg/day
Potassium
mmol/kg/day
Energy
(Kcal/day)
FIRST 10KG
2-4
1.5-2.5
110
3.00
Second 10kg
1-2
0.5-1.5
75
1.5
0.5-1
0.2-0.7
30
0.75
Subsequent kg
Protein
(g/kg)
PERCENTAGE DEHYDRATION X WEIGHT X 10
Percentage dehydration means: the number of grams of fluid lost
per 100gm of body weight. Percentage X 10 converts
this volume into ml / kg

10. •
•
•
•
•
Example A 6-kg child is clinically shocked and 10%
dehydrated as a result of gastroenteritis.
Initial therapy
20 ml/kg for shock = 6 × 20 = 120 ml of 0.9% saline given as a rapid
intravenous
• bolus
•
• Estimated fluid therapy over next 24 hours:
• 100ml/kg for 10% dehydration = 100 × 6 = 600 ml
• 100ml/kg for daily maintenance fluid = 100 × 6 = 600 ml
• Rehydration + maintenance = 1200 ml
• ∴ Start with infusion of 1200/24 = 50 ml/h

11. • INITIAL INFORMATION
• An 18 month old boy has had 2 days of vomiting and diarrhoea. He has a
respiratory rate of 24 and a pulse of 120. Capillary filling time is about 2
seconds, and he is alert and responsive
• FURTHER INFORMATION
• His mother says he has only had 2 wet nappies in the previous 24 hours.
FURTHER INFORMATION
• Urea, electrolyte, and glucose estimations show:
• Na 135 mmol/l K
• Urea 18 mg/dl
• Glu
75mg/ dl
•
3.5 mmol/l Cl
95 mmol/l

12. • INITIAL INFORMATION
• An 18 month old boy has a history of 5 days of diarrhoea and
vomiting. He has a respiratory rate of 30, a pulse of 150, and
an initial blood pressure of 80 systolic. Capillary refill time is
about 4 seconds. He has a dry mouth and sunken eyes. His
mother says he is thirsty but can’t keep anything down.
• FURTHER INFORMATION
• Urea, electrolyte, and glucose estimations show: Na 130 mmol/l
• K 3.2 mmol/ l
Cl 90 mmol/l Urea 238 mgl/dl Glu 57 mg/dl
•

13. • The principles in the treatment of hyponatraemia are:
• 1) Treat seizures with 3% NaCl
• 2) Calculate maintenance fluid and estimate fluid
deficit carefully
• 3) Aim to raise serum sodium no more than 8 mmol
per day
• 4) Check potassium, chloride, creatinine and glucose
levels also
• 5) Monitor electrolytes frequently
• 6) Clinically assess hydration and weigh frequently

14. • INITIAL INFORMATION
• A 3 month old baby who has had diarrhoea and
vomiting for 4 days is brought into hospital. His
respiratory rate is 40, pulse150, and capillary refill time
3 seconds. He is pale.
•
•
•
•
•
FURTHER INFORMATION
Urea, electrolyte, and glucose estimations show:
Na 164 mmol/l
K 4.3 mmol/l Cl 115 mmol/l Urea 38.9 mg/dl
Gluc 75 mg/dl

15. • The principles in the treatment of hypernatraemia
are:
• 1) Treat shock first
• 2) Calculate the maintenance fluid and estimate fluid
deficit carefully
• 3) Aim to lower serum sodium at a rate of no more
than 0.5 mmol per hour
• 4) Check calcium and glucose levels also
• 5) Monitor electrolytes frequently
• 6) Clinically assess hydration and weigh frequently

16. • A 4 year old boy who is recovering from chicken pox, is brought into the
Emergency Department having a convulsion. This started 10 minutes
before. He is not febrile.
•
• FURTHER INFORMATION
• His respiratory rate is 16, pulse 120, and capillary refill time
• 1 second. Glucose stick test is in the normal range. His mother says he
has not been going to the toilet as often as usual.
• FURTHER INFORMATION
• Urea, electrolyte, and glucose estimations show: Na 120 mmol/l
• K
3.8 mmol/l Cl
85 mmol/l Urea 3.2 mmol/l Glucose 126
mgl/dl
•

17. Shock
N
Y
Assess%
Crystalloid
20mml/kg
dehydration
Y
Oral rehydration
possible
Maintenance fluids appropriate
to clinical condition
Y
Oral rehydrate
STRAT 0,45%.
Maintenance
+replacement over24h.
Na> 150mmol/L plan to
rehydrate over 48 h.
Consider ongoing fluid losses
Re-evaluate weight, clinical condition and
electrolytes every 4-6 hours and adjust the rate
of fluid and electrolytes
Na<150 mmol/l plan to
rehydrate over 24 hours