External and internal biphasic direct current shock doses for pediatric ventricular fibrillation and pulseless ventricular tachycardia*

Abstract

To determine energy dose and number of biphasic direct current shocks for pediatric ventricular fibrillation (VF) and pulseless ventricular tachycardia (VT). Observation of preshock and postshock rhythms, energy doses, and number of shocks. Pediatric hospital. Shockable ventricular dysrhythmias. None. Forty-eight patients with VF or pulseless VT received external shock at 1.7 ± 0.8 (mean ± SD) J/kg. Return of spontaneous circulation (ROSC) occurred in 23 (48%) patients with 2.0 ± 1.0 J/kg, but 25 (52%) patients remained in VF after 1.5 ± 0.7 J/kg (p = .05). In 24 non-responding patients, additional 1-8 shocks (final dose, 2.8 ± 1.2 J/kg) achieved ROSC in 14 (58%) with 2.6 ± 1.1 J/kg but not in 10 (42%) with 3.2 ± 1.2 J/kg (not significant). Overall, 37 (77%) patients achieved ROSC with 2.2 ± 1.1 J/kg (range, 0.5-5.0 J/kg). Eight patients without ROSC recovered with cardiopulmonary bypass and internal direct current shock. At 13 subsequent episodes of VF or VT among eight patients, five achieved ROSC and survived. In combined first and subsequent resuscitative episodes, doses in the range of 2.5 to < 3 J/kg achieved most cases of ROSC. Survival for > 1 yr was seen in 28 (78%) of 36 patients with VF and seven (58%) of 11 patients with VT, with 35 (73%) overall. Lack of ROSC was associated with multiple shocks (p = .003). Repeated shocks with adhesive pads had significantly less impedance (p < .001). Pads in an anteroposterior position achieved highest ROSC rate. Internal shock for another 48 patients with VF or VT achieved ROSC in 28 (58%) patients with 0.7 ± 0.4 J/kg but not in 20 patients with 0.4 ± 0.3 J/kg (p = .01). Nineteen of the nonresponders who received additional internal 1-9 shocks at 0.6 ± 0.5 J/kg and one patient given extracorporeal membrane oxygenation all recovered, yielding 100% ROSC, but 1-yr survival tallied 43 (90%) patients. The initial biphasic direct current external shock dose of 2 J/kg for VF or pulseless VT is inadequate. Appropriate doses for initial and subsequent shocks seem to be in the range of 3-5 J/kg. Multiple shocks do not favor ROSC. The dose for internal shock is 0.6-0.7 J/kg.