What is the optimal paddle force during paediatric external defibrillation?
BACKGROUND
Transthoracic impedance (TTI) is a major determinant of transmyocardial current flow, and therefore, the success of defibrillation. European Resuscitation Council (ERC) paediatric guidelines recommend that 'firm' paddle force should be applied to the paddles during defibrillation. No study has yet established the optimal paddle force required to minimise TTI in children of different ages.


METHODS
Eighty patients aged 10 weeks to 17 yrs undergoing general anaesthesia for routine surgery were studied. Using defibrillation paddles placed in an anterior-apical position, TTI (Omega) was measured for increasing values of force from 0.5 kgf (baseline) to 6.5 kgf. The optimal force, the force to achieve 95% of the overall reduction in TTI, was then determined. According to current guidelines, paediatric paddles (surface area 16 cm2) were used for infants (< or =10 kg) and adult paddles (82 cm2) for older children. Optimal force was then calculated for infants < or =10 kg, children >10 kg and < or =8 yrs and children 9-17 yrs age.


RESULTS
Increasing paddle force from 0.5 kgf progressively decreased TTI. Optimal force using paediatric paddles was 2.9 kgf in infants. Optimal force using adult paddles was 5.1 kgf in children >10 kg but < or = 8 yrs and 5.3 kgf in children aged 9-17 yrs.


CONCLUSIONS
Force is an important determinant of TTI and therefore, outcome of defibrillation. It is recommended that a minimum of 3 kgf be applied to paddles when defibrillating infants with paediatric paddles, and a minimum of 5 kgf be applied to all older children when adult paddles are used.
Shackleton Department of Anaesthetics, Southampton University Hospital NHS Trust, Tremona Road, Southampton SO16 6YD, UK. charlesdeakin@doctors.org.uk
Charles D
CD
Deakin
Sarah H
SH
Bennetts
Graham W
GW
Petley
Frank
F
Clewlow
D000293:Adolescent; D002307:Cardiography, Impedance / Q000295:instrumentation; D002648:Child; D002675:Child, Preschool; D004554:Electric Countershock / Q000379:methods*; D006801:Humans; D007223:Infant