Telemetry monitoring indicates asystole. The nurse finds the patient not breathing with no palpable carotid pulse. What is the nurse's initial action?

A. Begin cardiopulmonary resuscitation: Asystole indicates a complete absence of ventricular electrical activity, and the patient is pulseless and apneic. Immediate initiation of high-quality CPR is critical to maintain circulation and oxygen delivery to vital organs while advanced resuscitative measures are prepared. Early CPR improves the chance of return of spontaneous circulation. B. Prepare to defibrillate: Defibrillation is effective for shockable rhythms such as ventricular fibrillation or pulseless ventricular tachycardia. Asystole is a non-shockable rhythm, so defibrillation would not restore cardiac activity and would delay essential CPR. C. Begin rescue breathing with bag-valve-mask: While providing oxygenation is important, in a pulseless patient, chest compressions take priority over rescue breathing. CPR ensures perfusion of the brain and heart until advanced life support interventions can be applied. D. Prepare to cardiovert: Synchronized cardioversion is indicated for unstable tachyarrhythmias such as atrial fibrillation or supraventricular tachycardia. It is not appropriate for asystole, which requires immediate CPR and administration of medications such as epinephrine under advanced life support protocols.