Formula & Calculator
Defibrillator Pediatric Energy Dose
Calculates the recommended defibrillation shock energy for a pediatric patient based on body weight.
Interpretation
Energy (J) = 2–4 J/kg × mass (kg). Weight‑based dosing for pediatric defibrillation. Ensures appropriate energy delivery to improve survival and minimise myocardial damage. Used in paediatric resuscitation guidelines.
Variables
| Symbol | Quantity | Unit |
|---|---|---|
| Energy | Shock energy | joules |
| mass | Patient body mass | kg |
What it means
For pediatric patients, the recommended defibrillation energy dose is weight‑based, typically 2‑4 J/kg for the initial shock (biphasic) and higher for subsequent shocks. This formula ensures that the delivered energy is appropriate for the child's size, minimising myocardial damage while maximising defibrillation success. The energy dose is set on the defibrillator (or automatic external defibrillator with pediatric pads). Pediatric pads reduce the delivered energy. This calculation is critical in emergency situations like cardiac arrest to improve survival. Healthcare providers must be familiar with weight estimation and energy selection. Understanding this dose is essential for paediatric resuscitation guidelines (e.g., PALS).
Worked example
Pediatric Defibrillation Energy – Two Examples
Real‑World| Parameter | Value |
|---|---|
| Mass | 10 kg |
| Parameter | Value |
|---|---|
| Mass | 20 kg |
Common mistakes
- Mass in kg: The child’s weight in kilograms – do not use pounds.
- Energy range: Initial shock: 2 J/kg; subsequent shocks: up to 4 J/kg (max 10 J/kg for some guidelines).
- Maximum dose: For paediatric defibrillation, do not exceed adult maximum (e.g., 360 J biphasic).
- Pad placement: Antero‑posterior or anterolateral – ensure correct placement for effective defibrillation.
- Biphasic vs. monophasic: Energy recommendations are usually for biphasic defibrillators – monophasic may require higher energies.
Applications
Pediatric defibrillation energy dose is calculated as 2‑4 Joules per kilogram of body weight, as recommended by resuscitation guidelines (e.g., AHA, ERC). This dose is critical for terminating life‑threatening arrhythmias like ventricular fibrillation or pulseless ventricular tachycardia in children, while avoiding myocardial damage from excessive energy. Emergency physicians, paramedics, and paediatric intensivists use this formula to select the appropriate energy setting on an automated external defibrillator (AED) or manual defibrillator. Accurate dosing improves the chances of successful defibrillation and reduces the risk of post‑resuscitation complications. By following this guideline, healthcare providers can deliver safe and effective paediatric resuscitation.
- Paediatric cardiac arrest resuscitation protocols
- Setting of defibrillator energy in emergency departments and ambulances
- Training for healthcare providers in paediatric advanced life support (PALS)
- Design of paediatric‑specific AED pads and algorithms
- Quality improvement in paediatric resuscitation outcomes
Frequently Asked Questions
The recommended initial energy dose for a pediatric patient is Energy (J) = 2 to 4 J/kg × body weight (kg). The exact dose may vary by protocol; many guidelines recommend an initial dose of 2 J/kg, and subsequent doses of 4 J/kg (up to a maximum of 10 J/kg or adult dose).
Using adult fixed‑energy settings (e.g., 200 J) on a small child without scaling to body weight. This can cause unnecessary myocardial damage. Always use the weight‑based pediatric dose.
Energy = 2 J/kg × 20 kg = 40 J. This would be the first shock. If ineffective, the next shock would be 4 J/kg × 20 = 80 J.
According to the American Heart Association (AHA) and European Resuscitation Council (ERC):
- Use a pediatric‑specific defibrillator (with attenuated energy) if available.
- If a manual defibrillator is used, use the weight‑based dose.
- For infants and children < 8 years, use pediatric pads and dose attenuator.
- If only an adult defibrillator is available, a 2 J/kg dose can be used but may need to be approximated.
The maximum energy dose is usually capped at 10 J/kg or the adult dose (e.g., 200 J for biphasic, 360 J for monophasic), whichever is lower. However, some protocols allow up to 200 J for larger children.
Children have smaller body mass and lower impedance, so they require less energy to achieve defibrillation. A fixed adult dose would deliver too much energy and potentially cause thermal injury to the myocardium.
Use the patient's actual weight if known. If unknown, estimate using age‑based formulas (e.g., weight in kg = (age + 4) × 2 for ages 1‑10 years, or use a length‑based tape like the Broselow tape).
Biphasic defibrillators deliver current in two directions and are more effective at lower energies (e.g., 2‑4 J/kg). Monophasic defibrillators require higher energies (e.g., 4‑10 J/kg). Most modern defibrillators are biphasic. The dose formulas are generally for biphasic; for monophasic, higher doses are used.
- Too low: ineffective defibrillation (persistent arrhythmia).
- Too high: myocardial damage, burns, or other complications.
Record the energy in joules, the number of shocks, and the rhythm before and after. Also note the patient's weight and the source of the weight (actual or estimated).