ABSTRACT
<p><b>INTRODUCTION</b>Peak currents are the final arbiter of defibrillation in patients with ventricular fibrillation (VF). However, biphasic defibrillators continue to use energy in joules for electrical conversion in hopes that their impedance compensation properties will address transthoracic impedance (TTI), which must be overcome when a fixed amount of energy is delivered. However, optimal peak currents for conversion of VF remain unclear. We aimed to determine the role of peak current and optimal peak levels for conversion in collapsed VF patients.</p><p><b>METHODS</b>Adult, non-pregnant patients presenting with non-traumatic VF were included in the study. All defibrillations that occurred were included. Impedance values during defibrillation were used to calculate peak current values. The endpoint was return of spontaneous circulation (ROSC).</p><p><b>RESULTS</b>Of the 197 patients analysed, 105 had ROSC. Characteristics of patients with and without ROSC were comparable. Short duration of collapse < 10 minutes correlated positively with ROSC. Generally, patients with average or high TTI converted at lower peak currents. 25% of patients with high TTI converted at 13.3 ± 2.3 A, 22.7% with average TTI at 18.2 ± 2.5 A and 18.6% with low TTI at 27.0 ± 4.7 A (p = 0.729). Highest peak current conversions were at < 15 A and 15-20 A. Of the 44 patients who achieved first-shock ROSC, 33 (75.0%) received < 20 A peak current vs. > 20 A for the remaining 11 (25%) patients (p = 0.002).</p><p><b>CONCLUSION</b>For best effect, priming biphasic defibrillators to deliver specific peak currents should be considered.</p>
ABSTRACT
<p><b>INTRODUCTION</b>Early use of mechanical cardiopulmonary resuscitation (CPR) for out-of-hospital cardiac arrest (OHCA) may improve survival outcomes. Current evidence for such devices uses outcomes from an intention-to-treat (ITT) perspective. We aimed to determine whether early use of mechanical CPR using a LUCAS 2 device results in better outcomes.</p><p><b>METHODS</b>A prospective, randomised, multicentre study was conducted over one year with LUCAS 2 devices in 14 ambulances and manual CPR in 32 ambulances to manage OHCA. The primary outcome was return of spontaneous circulation (ROSC). Secondary outcomes were survival at 24 hours, discharge from hospital and 30 days.</p><p><b>RESULTS</b>Of the 1,274 patients recruited, 1,191 were eligible for analysis. 889 had manual CPR and 302 had LUCAS CPR. From an ITT perspective, outcomes for manual and LUCAS CPR were: ROSC 29.2% and 31.1% (odds ratio [OR] 1.09, 95% confidence interval [CI] 0.82-1.45; p = 0.537); 24-hour survival 11.2% and 13.2% (OR 1.20, 95% CI 0.81-1.78; p = 0.352); survival to discharge 3.6% and 4.3% (OR 1.20, 95% CI 0.62-2.33; p = 0.579); and 30-day survival 3.0% and 4.0% (OR 1.32, 95% CI 0.66-2.64; p = 0.430), respectively. By as-treated analysis, outcomes for manual, early LUCAS and late LUCAS CPR were: ROSC 28.0%, 36.9% and 24.5%; 24-hour survival 10.6%, 15.5% and 8.2%; survival to discharge 2.9%, 5.8% and 2.0%; and 30-day survival 2.4%, 5.8% and 0.0%, respectively. Adjusted OR for survival with early LUCAS vs. manual CPR was 1.47 after adjustment for other variables (p = 0.026).</p><p><b>CONCLUSION</b>This study showed a survival benefit with LUCAS CPR as compared to manual CPR only, when the device was applied early on-site.</p>