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Calculate Age

Best Guess Weight Formula

Dose Calculator

Select Medical Condition:

Best Guess method weight:

  • The traditional APLS formula for weight estimation in children is wt in kg = (age + 4) x 2.
  • This formula underestimates weight in developed countries, with the degree of underestimation increasing with age.
  • Researchers have tried to derive more accurate formulas.
  • In the UK, data from over 93,000 children aged 1-16 attending a pediatric emergency department were analyzed.
  • The previously derived formula wt = 3(age) + 7 was compared with the APLS formula.
  • The APLS formula underestimated weight by a mean of 33.4% for children aged 1-16 years.
  • The formula wt = 3(age) + 7 provided a mean underestimate of 6.9% for children aged 1-13 years.
  • The APLS formula has become less accurate due to better-nourished children.
  • Continuing to use the APLS formula, which has no evidence base, is not considered good medical practice.
  • An Australian study on over 70,000 pediatric ED attendances derived new formulas(Tinning K, Acworth J. Make your Best Guess: an updated method for paediatric weight estimation in emergencies. Emerg Med Australas. 2007 Dec;19(6):528-34. doi: 10.1111/j.1742-6723.2007.01026.x. PMID: 18021105.)
  • Best Guess method for age-based weight estimation in paediatric emergencies: validation and comparison with current methods:
    • Infants < 12 months: Weight (kg) = (age in months + 9) / 2
    • Children aged 1-5 years: Weight (kg) = 2 x (age in years + 5)
    • Children aged 5-14 years: Weight (kg) = 4 x age in years

Medication dose calculations

1) Allergic reaction – Cetirizine (Zyrtec) dose:
age 1-2 years 2.5 mg BD (Oral)
age 2-6 years 5 mg once daily or 2.5mg BD (Oral)
age 6-12 years 10 mg once daily or 5mg BD (Oral)
age 12-18 years 10 mg once Daily (Oral)

2) Anaphylaxis – adrenaline IM dose: 10 mcg/kg OR 0.01 mL/kg – 1:1000 (maximum 0.5 mL) – display in mcg and ml

3) Asplenia/Hyposplenism – Antibiotic prophylaxis (Daily antibiotics) – either: 
– Amoxicillin dose: 20 mg/kg (up to 250 mg) orally, daily OR
– Phenoxymethylpenicillin dose: 250 mg(child younger than 1 year: 62.5 mg to 5 years: 125mg) orally, 12-hourly

4). Asthma (Mild/Moderate)

  • Salbutamol : age 1-5 years : 2-6 puffs, age > 6 years 12 puffs
  • Ipratropium:  age 6–11 years: 8 puffs, age 1–5 years: 4 puffs
  • Oral prednisolone: 1 mg/kg (max 50 mg) for 3–5 days

5) Asthma (Severe)

  • Salbutamol continuous nebulisation driven by oxygen
    • age: 1–5 years: use 2 x 2.5 mg nebules
    • age: 6–11 years: 2 x 5 mg nebules
  • ipratropium
    • age: 1–5 years: 500 microg to nebulised solution.
    • age: 6–11 years: 250 microg to nebulised solution
  • Start oxygen- Titrate to target oxygen saturation of at least 95%

6) Bites (animal/human) : Amoxicillin/Clavulanate dose: (400/57 mg/5 mL) 22.5 mg/kg (875 mg) (Amoxicillin component) 0.3 mL/kg (11 mL) oral bd 5 days

7) Cellulitis – Mild/moderate – either: 
– Flucloxacillin dose: 25 mg/kg/dose orally QID (maximum 1 g/dose) (For children who can swallow capsules). OR
– Clindamycin dose: 7.5 mg/kg/dose orally QID (maximum 450 mg/dose) (Previous nmMRSA, History of boils or Aboriginal or Pacific islander descent) OR
– Cefalexin dose: 33 mg/kg (500 mg) oral tds (1 g max for moderate cellulitis) 5–10 days

8) Croup Mild-moderate – Dexamethasone dose: 0.15mg/kg 20, 23, maximum 12mg or Prednisolone (Oral) Day 1: 1mg/kg/day Day 1, then 36hours later another dose

9) Croup Severe or life-threatening

  • Dexamethasone dose: 0.6mg/kg (oral/IV/IM), maximum 12mg  AND
  • Adrenaline (NEB) – 5 mL of undiluted 1:1000 Adrenaline nebulised with oxygen as a single dose.

10) Dental abscess – Often polymicrobial – Amoxicillin dose: 25 mg/kg (500 mg) oral tds -7 days and Dental/surgical management required

11) Giardiasis – Metronidazole dose:30 mg/kg/dose orally once daily (maximum 2 g/dose) for 3 days.

12) Head lice- 1% permethrin liquid or cream rinse, Repeat after one week

13) Impetigo – either: 
– Mupirocin 2% ointment top 8H if localised
– Cefalexin dose: 33 mg/kg (500 mg) oral bd 5 days

14) Lymphadenitis (cervical) – Mild Cefalexin dose: 33 mg/kg (500 mg) oral tds 7 days

15) Meningitis Contact prophylaxis – N. meningitidis – either: 
– Ciprofloxacin dose: 250 mg (age 5–12 years) 500 mg (age ≥12 years) oral single dose for 2 days
– if unable to take tablets: Rifampicin dose: 5 mg/kg ( <1 month) or 10 mg/kg (≥1 month) (max 600 mg) oral bd for 2 days

16) Meningitis Contact prophylaxis – H. influenzae type b: Rifampicin dose: 20 mg/kg (600 mg) oral daily for 2 days

17) Otitis Media – either: 
– Amoxicillin dose: 15 mg/kg up to 500 mg orally – TDS for 5 days OR
– Cefuroxime dose: age 3 months to 2 years: 10mg/g, max 125mg BD for 5 days for 5 days OR
– Cefuroxime dose: age 2 years and older 15mg/kg, max 500mg BD for 5 days for 5 days OR
– Trimepthoprim-Sulfamethoxazole dose: child 1 month or older: 4+20mg/kg – max 160-180mg, BD for 5 days

18) Otitis Media – Persistent dose: Amoxicillin /clavulanic acid dose:22.5mg/kg BD dose for 5 days

19) Pain – Paracetamol (oral) dose: 15 mg/kg/dose (maximum 1 g) QID (Dose based on ideal body weight)

20) Pain – Ibuprofen (oral) dose: 10 mg/kg/dose (maximum 400 mg) Q6h

21) Pain – Oxycodone (oral) dose: 0.1 mg/kg/dose (maximum 5 mg) QID

22) Pertussis – either: 
– Azithromycin dose: 10 mg/kg (500 mg) oral daily (Birth – 6 months), 10 mg/kg oral on Day 1, then 5 mg/kg (250 mg) daily (≥6 months) 5 days OR
– Clarithromycin dose: 7.5 mg/kg (500 mg) oral bd 7 days

23) Pneumonia- Mild (outpatient) – Amoxicillin dose: 25 mg/kg (max 1 g) oral tds – 3-5 days

24) Pneumonia-Moderate (inpatient) – Amoxicillin dose:30 mg/kg (1 g) oral tds 5 days

26) Scabies – Sarcoptes scabiei – Permethrin 5% cream top, One application from neck down; leave on for minimum of 8H (usually overnight), May need to repeat after 7 days
Treat whole family

27) Tonsillitis – either: 
– Phenoxymethylpenicillin dose: 15 mg/kg/dose BD (maximum 500 mg/dose) for 10 days  OR
– Azithromycin dose: 10mg/kg orally once daily for 5 days.

28) Threadworm (Pinworm) – Mebendazole dose:50 mg oral (<10 kg) 100 mg oral (≥10 kg) or Pyrantel 10 mg/kg (1 g) oral

29) Urinary tract infection – either: 
Cefalexin dose: 33 mg/kg (500 mg) oral bd      OR
Trimethoprim dose:4 mg/kg (150 mg) oral bd   OR
Trimethoprim/Sulfamethoxazole dose:(8/40 mg/mL) 0.5 mL/kg (20 mL) oral bd

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the formulas and calculations on the same page

STEP 1 : write HTML code for wordpress a formula/calculator for “calculate age”
variables:
– enter birthday in dd/mm/yyyy
– current date (default have the current date entered)
– current age in years and months

then

STEP 2: write HTML code for wordpress a formula/calculator for “Best Guess weight formula”
where the entered months and years.
Infants 1-11 months: weight (kg) = (age in months + 9)/2
Children 1-4 years: weight (kg) = 2 × (age + 5)
Children 5-14 years: weight (kg) = 4 × age

then 

STEP 3: write HTML code for wordpress a dose calculator, each condition below
based on variable fields
(1) weight in kg or
(2) Age in months or years

the weight field and age field can be left blank, or fill them based on  “calculate age” and “Best Guess weight formula” if already calculated

display the conditions radio switch format