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Essential Paediatric Calculations and Normal Values
Paediatric Calculations and Normal Values for Paediatric patients
Paediatric Weight Calculation Formulae:
| Age | Formula |
| 0-12 months | Weight (in kg) = (0.5 x age in months) + 4 |
| 1-5 years | Weight (in kg) = (2 x age in years) + 8 |
| 6-12 years | Weight (in kg) = (3 x age in years) + 7 |
Endo-Tracheal Tube (ETT) Calculations:
| ETT Size (internal diameter in mm) | ETT Depth (in cm) |
| 4 + Age/4 | Oral intubation: 12 + Age/2 Nasal intubation: 15 + Age/2 |
Maintenance fluid requirements for children older than 1 month:
| Body-weight | 24-hour fluid requirement |
| Under 10 kg | 100ml/kg |
| 10 - 20 kg | 100ml/kg for the first 10kg + 50ml/kg for each 1 kg body-weight over 10 kg |
| Over 20 kg | 100ml/kg for the first 10kg + 50ml/kg for each 1 kg body-weight over 10 kg = 20 ml/kg for each 1 kg body-weight over 20 kg (max. 2litres in females, 2.5litres in males) |
Normal limits of resting respiratory rate by age:
| Age | Respiratory rate (breaths per minute) |
| <1 | 30–40 |
| 1–2 | 25–35 |
| 2–5 | 25–30 |
| 5–12 | 20–25 |
| >12 | 15–20 |
Normal limits of heart rate by age:
| Age | Heart rate (beats per minute) |
| <1 | 110–160 |
| 1–2 | 100–150 |
| 2–5 | 95–140 |
| 5–12 | 80–120 |
| >12 | 60–100 |
Systolic blood pressure by age:
| Age (years) | Systolic BP (mmHg) 50th centile | Systolic BP (mmHg) 5th centile |
| <1 | 80-90 | 65-75 |
| 1–2 | 85-95 | 70-75 |
| 2–5 | 85-100 | 70-80 |
| 5–12 | 90-110 | 80-90 |
| >12 | 100-120 | 90-105 |