Estimating the 95% effective defibrillation dose

Minimum-squared-error (MinSE) testing protocols and a MinSE estimator that accurately estimate the voltage that defibrillates 95% of the time (the ED95) are presented. The MinSE experimental procedures, presented in the form of lookup tables, detail the response to successful and unsuccessful trials. The lookup tables also show the ED95 estimates calculated from the observed results using the MinSE estimator. The MinSE estimator and experimental procedure were evaluated in a study of five dogs (19-25 kg, heart weights 139.3-236.9 gm) using nonthoracotomy implantable defibrillator electrodes and a biphasic defibrillation waveform (3.5 ms first phase, 2.0 ms second phase). For ED95 between 0.0 and 800.0 V, the measured RMS error was 15% of the mean measured ED95 for the MinSE, four-test-shock, ED95 estimates. If the protocols are designed with an ED95 population distribution assumption for animals of the same species and size, and defibrillation is constrained to one electrode configuration and waveform, the estimates improve by 3.8%. The MinSE approach can be extended to a variety of defibrillation parameter estimation problems