Philips introduced the first biphasic waveform for an external defibrillator in 1996, ever since, biphasic therapy has gained acceptance and is now recognized as the standard of care. 

However, the various defibrillator manufacturers recommend a wide range of energy dosages. This is because defibrillator manufacturers have created distinct biphasic waveform “formulations.” So each manufacturer recommends energy doses appropriate for their shock formulation. 

While energy remains entrenched in defibrillator vocabulary as a descriptor of shock strength, current amps has been shown to be a better predictor. For meaningful shock strength comparisons of biphasic waveforms, it’s necessary to look beyond energy levels and compare the current delivered to the patient. All presently available Philips HeartStart defibrillators incorporate a proprietary biphasic truncated exponential (BTE) waveform formulation employing high current delivered in a low energy dosage. 

Further, Philips uses real-time impedance compensation to automatically adjust the waveform to deliver shock strength personalized to the needs of each patient, starting with the first shock. Philips therapy has been rigorously studied and is backed by a substantial body of peer-reviewed, published data demonstrating effectiveness across the full spectrum of patients, including those considered “difficult-to-treat.” 

While biphasic waveforms effectively terminate arrhythmias, meaningful clinical differences between defibrillators may lie in the amount of energy needed for successful defibrillation and its negative impact on post-resuscitation myocardial function. While high current defibrillates, high energy is associated with negative side effects. So the optimal waveform formulation delivers high current at lower energy doses to help reduce the total energy delivered. 

Meaningful clinical differences may also lie in how quickly a shock is delivered following the CPR pause, as this may substantially influence shock success. Only Philips AEDs and the Philips MRx Monitor/Defibrillator in AED mode offer Quick Shock technology, which helps shorten time-to-shock after CPR and increase the chance a shock will successfully return circulation, which may improve survival.

Source : 

http://laerdalcdn.blob.core.windows.net/downloads/f2375/SMART_Biphasic_Application_Note_(ENG).pdf