Method and apparatus for delivering an optimum shock duration in treating cardiac arrhythmias

A cardiac arrhythmia treatment method comprising:

• delivering a multiphasic waveform signal to a pair of electrodes applied externally to a patient;
• detecting a patient-dependent electrical characteristic during delivery of the multiphasic waveform signal;
• and
• calculating a duration of the multiphasic waveform signal based on the patient-dependent electrical characteristic.

A method for delivering a defibrillation pulse, the method comprising:

• delivering the defibrillation pulse to a pair of electrodes applied externally to a patient;
• determining a patient impedance as the defibrillation pulse is being delivered to the electrodes;
• determining a duration for the defibrillation pulse based on said patient impedance;
• and
• truncating the pulse when said duration is reached.

A method for delivering a defibrillation pulse comprising:

• delivering a multiphasic waveform signal to a patient until a condition for truncating the multiphasic waveform signal is met;
• monitoring an electrical parameter related to the multiphasic waveform signal while the multiphasic waveform signal is being delivered to the patient;
• and
• determining the condition for truncating the multiphasic waveform signal based on the electrical parameter.

An external defibrillator comprising:

• (a) an energy storage device;
• (b) electrodes in electrical communication with the energy storage device;
• and
• (c) a controller configured to cause the energy storage device to discharge energy in a defibrillation pulse through the electrodes, the controller further being configured to:
• (i) determine a patient impedance as the energy in the defibrillation pulse is being discharged through the electrodes;
• (ii) determine a duration for the discharge of energy in the defibrillation pulse based on said patient impedance;
• and
• (iii) cease the discharge of energy in the defibrillation pulse when said duration is reached.