Your patient is a 54-year-old male who is unresponsive and cyanotic and has agonal respirations. A "quick look" shows ventricular tachycardia. Which of the following is most important when determining the immediate treatment of this patient?

A) How long he has been "down"
B) Whether he has a pulse
C) Whether he is allergic to lidocaine
D) Whether he has an implanted cardioverter-defibrillator

B