31 - Prescribing for Children Flashcards
How do you calculate the body surface area of a child?
Normogram or Boyd Method
What is the daily fluid requirements in children and what fluid is used?
- 1st 10kg of bodyweight at 100ml/kg/day
- 2nd 10kg of bodyweight at 50ml/kg/day
- Remaining bodyweight at 20ml/kg/day
The fluid type routinely used is 0.9% NaCl + 5% dextrose with 10mmol KCl
What are the paediatric electrolyte requirements?
- Sodium: 2-4mmol/kg/day
- Potassium: 1-2mmol/kg/day
How do you work out fluid deficit replacement in children?
% Dehydration x Weight (kg) x 10
How do you calculate percentage dehydration?
Mild dehydration (0–5%): 5% weight loss in infants; 3% in children
Moderate dehydration (5–10%): Weight loss of 10% in infants; 6% in children
Severe dehydration (>10%): Weight loss of 15% in infants; 9% in children
If Mary is 5% dehydrated what would you give her?
Maintenance + Correction for dehydration
Use 0.9% sodium chloride with dextrose. If sodium is high then use 0.45%
In an emergency where you cannot weigh the child how do you get an estimated weight?
(Age + 4) * 2 OR Broselow Tape
(ALPS criteria)
What is the WETFLAG pneumonic?
Used when weight unknown for emergencies
Why do we need to write a child’s age on the prescription?
It is legal requirement for all children up to age 12
How does prescription by weight vary for obese children?
Should never exceed adult dose
For example if the dose is stated as 8 mg/kg (max. 300 mg), a child weighing 10 kg should receive 80 mg but a child weighing 40 kg should receive 300 mg (rather than 320 mg).
Why do children need a higher dose per kg of certain drugs compared to adults?
They have a higher metabolic rate
What is the most important parameter to know for paediatric prescriptions?
Weight
How is paracetamol prescribed in children?
Always prescribe in mg not ml
Two suspensions of 120mg/5ml or 250mg/5ml
What are two factors in children that differ to adults that affect oral absorption of drugs?
- GI motility: slower in neonates so slower to absorb
- Gastric pH: until 3 years old higher pH so acidic drugs broken down more quickly
How is absorption in neonates different to infants?
How does drug distribution, metabolism and excretion vary in infants?
- Higher total body water: higher volume of distribution
- Less plasma protein binding
- Low eGFR
- Different phase 1 and 2 enzymes in liver
What drugs are prescribed by BSA rather than weight in children?
- Aciclovir
- Chemotherapy
As a rule of thumb how much does an average baby and 1 year old weigh?
Baby: 3.5kg
Infant: 10kg
How should oral rehydration take place?
Over 4 hours of 50ml/kg plus maintenance
Why are there common prescription errors in paediatrics?
- Individualised doses on age and weight
- Lots of drugs used off label
- Abbreviations
How can we minimise prescription errors in paediatrics?
(image really important)
- Clinical pharmacists
- BNFc
What happens to fluid prescriptions in children with pneumonia?
Givent at 50-80% maintenance due to risk of SIADH
How do you prescribe salbutamol and steroids in an asthma exacerbation?
Always round to 5mg with prednisolone
If there is no IV access in status epilepticus what is first line treatment?
Buccal midazolam
Which children are offered flu vaccine?
- At risk 6months to 2 years
- All 2 years to 15 years
What are the two different types of Epipen and why are they different?
What pain relief is available for children?
Non-pharmacological: cuddling, comforting, distraction, playing
What data base is used for poisoning in children?
ToxBase
How do you calculate what amount of medication to give a child e.g you want to give 60mgs but oney have 120mgs in 5ml
What you want/What you’ve got x What it’s in
60/120 x 5 = 2.5mls
