Which rhythms are considered non-shockable?

Non-shockable rhythms refer to cardiac rhythms during a cardiac arrest that do not respond to defibrillation. The correct answer highlights pulseless electrical activity (PEA) and asystole as the two key non-shockable rhythms.

PEA is characterized by the presence of organized electrical activity on the ECG without a corresponding effective mechanical heartbeat, meaning that although there are electrical signals that could lead to heart contractions, the heart is not contracting effectively enough to generate a pulse. Asystole is the complete absence of any electrical activity in the heart; there are no contractions at all, which is often referred to as "flatline." Both of these rhythms require immediate advanced life support interventions focused on high-quality cardiopulmonary resuscitation (CPR), along with addressing reversible causes, rather than defibrillation.

In contrast, the other choices include rhythms that are typically shockable or mischaracterize the nature of non-shockable rhythms. For example, ventricular fibrillation (VF) and pulseless ventricular tachycardia (VT) are shockable rhythms, meaning that defibrillation is the recommended treatment for restoring a normal heart rhythm. Understanding the difference between shockable and non-shockable rhythms is crucial for effective CPR