Which is the most common cardiac arrest rhythm associated with the lowest survival rate?

The rhythm identified as having the lowest survival rate in cases of cardiac arrest is indeed Non-shockable rhythms, which include Pulseless Electrical Activity (PEA) and Asystole. These rhythms are characterized by the absence of effective cardiac output and may present with electrical activity on the ECG that does not result in effective heart contractions.

Survival rates associated with these rhythms are significantly lower compared to other rhythms, such as Ventricular Fibrillation. This is primarily due to the underlying causes of PEA and Asystole, which often include severe underlying pathology that has resulted in the patient’s critical state, such as hypoxia, hypovolemia, or severe metabolic disturbances. As a result, the chance of successfully reversing these conditions during a resuscitation attempt is often less favorable.

Effective interventions for achieving return of spontaneous circulation (ROSC) with non-shockable rhythms involve high-quality CPR and addressing reversible causes immediately, highlighting the complexity and challenges associated with resuscitating patients in these states. In contrast, rhythms like Ventricular Fibrillation, although also serious, can often be treated successfully with defibrillation, leading to higher survival rates in otherwise reversible scenarios.