If VF is witnessed by EMS and the first shock is delivered at 2 minutes, what is the optimal initial joules for biphasic defibrillation?

The optimal initial joules for biphasic defibrillation, when ventricular fibrillation (VF) is witnessed by EMS and the first shock is delivered at 2 minutes, is between 150-200 joules. This range is endorsed by current clinical guidelines because studies have shown that higher energy levels in the biphasic waveform result in better defibrillation success rates.

Biphasic defibrillators are designed to deliver electrical shocks in two phases, with the first phase using a specific amount of energy followed by a second phase that may use less or equal energy. This reflects the evolving understanding of what is most effective in restoring a normal heart rhythm quickly while also minimizing potential damage to cardiac tissues.

Delivering shocks at the recommended initial energy levels within the 150-200 joules range follows these best practices, as it balances efficacy and safety. Adjusting the energy level based on specific patient conditions can further enhance outcomes; however, given the situation where VF is witnessed and immediate intervention occurs at the 2-minute mark, employing this initial joules range optimizes the likelihood of successful defibrillation.

Other options suggest either lower or higher joule settings that may not align with established guidelines for initial shocks in a defibrillation scenario