61. Paediatric fluid management Flashcards
You are asked to anaesthetise a 6-year-old child who has acute
appendicitis and has been unwell for the past 2 days. There are no
significant findings in your medical or anaesthetic assessment. What
problems do you need to address in the peri-operative period?
The main issues are:
Physiological effects of acute illness (dehydration and SIRS) – does the child
need resuscitation prior to theatre?
Emergency anaesthetic in a child.
Risk of aspiration.
Post-operative analgesia.
How would you assess the degree of dehydration clinically?
Calculation of water deficit due to dehydration using clinical signs is usually
inaccurate and only gives an approximation of the true deficit
A history of vomiting, diarrhoea, poor urine output (wet/dry nappies in
babies) and poor oral intake should be sought
Clinical assessment of dehydration – (Classifications vary)
Mild/no dehydration (<5%)
No clinical signs
Moderate dehydration (5%–10%)
Cool pale peripheries
Prolonged capillary return time
Dry mouth
Decreased skin turgor
Sunken fontanelle (infant)
Severe dehydration (>10%)
Reduced urine output
Reduced blood pressure
Tachycardia present/feeble pulse
Cold, sweaty, grey, cyanosed
Irritability/lethargy
Dry mouth and mucus membranes
Markedly decreased skin turgor
Sunken eyes
Markedly sunken fontanelle (infant
If the child was 10% dehydrated clinically and weighed 20 kg, how
would you calculate the fluid deficit?
If the child was 10% dehydrated clinically and weighed 20 kg, how
would you calculate the fluid deficit?
The formula is: Wt (kg) × % Dehydration × 10
For this child: 20 × 10 × 10 = 2000 ml.
Fluid deficits should be replaced over 24 hours and added to maintenance
fluids.
What fluid would you use?
Resuscitation – bolus doses of 10–20 ml/kg of 0.9% (isotonic) sodium
chloride.
Deficits – infusion over 24 hours of 0.9% sodium chloride with glucose 5%
(isotonic solution) or normal saline alone.
Wouldn’t you use 0.18% (one-fifth) normal saline with glucose 4%.
This is a markedly hypotonic solution and risks hyponatraemia.
Hyponatraemia is particularly problematic in the peri-operative period, but
also with the dehydrated, septic, head injured or a chronically unwell child.
The risks of iatrogenic hyponatraemia have recently been highlighted by
the National Patient Safety Agency.
One-fifth normal saline should be reserved for specialist units such as
cardiac or renal ward
What other considerations are there when it comes to fluid therapy?
U&Es should be monitored at baseline and every 24 hours.
Ongoing losses should be assessed every 4 hours.
Glucose-containing solutions should be administered to prevent
hypoglycaemia in the fasting child.
Potassium should be added at up to 40 mmol/l guided by U&E results.
Enteral fluid administration should be considered regularly and instituted as
soon as tolerated.
General points for fluid replacement
Ongoing losses should be replaced with ‘like-for-like’ fluids that reflect
the electrolyte composition of the fluid being lost.
Losses can usually be replaced with isotonic solutions with or without
the addition of potassium.
There is currently not enough evidence to recommend one glucose
containing solution over another.
2.5% glucose (with 0.45% saline or Hartmann’s) is probably enough to
prevent hypoglycaemia in the fasting child.
Higher concentrations of glucose combinations are hyperosmolar and
may require multiple cannulations or even central access for
prolonged intravenous fluid therapy
How would you provide post-operative analgesia for this child?
Multi-modal analgesia
Paracetamol
15 mg/kg i.v. or
40 mg/kg (p.r.) loading
15 mg/kg maintenance 4–6 hourly
Max 90 mg/kg per day
NSAID such as Diclofenac – 1 mg/kg 8 hourly
Opioids such as morphine
0.15 mg/kg i.v.
0.3 mg/kg p.o. 2–3 hourly
Wound infiltration with local anaesthetic
Bupivicaine 0.25% (up to 2 mg/kg)
Anti-emetics: combination therapy would be reasonable in this case.
Ondansetron 0.15 mg/kg
Dexamethasone 0.15 mg/kg
Fluid requirements
Fluid requirements in infants are greater than in adults or older
children because of their higher metabolic rate and their greater
surface area to weight ratio.
This results in higher insensible water loss.
The reduced renal concentrating capacity also results in increased
obligatory water loss.
Formula for daily maintenance fluid requirements
First 10 kg 4 ml/kg per hour (100 ml/kg per 24 hours)
Second 10 kg 2 ml/kg per hour (50 ml/kg per 24 hours)
Subsequent kgs 1 ml/kg per hour (20 ml/kg per 24 hours)
Solution Osmolarity Sodium content Osmolality Tonicity
(mOsmol/l) (mequiv/l) (compared to plasma)
0.9% sodium chloride 308 154 Isosmolar Isotonic
Hartmann’s solution 278 131 Isosmolar Isotonic
