What is the most critical indicator of successful CPR?

The most critical indicator of successful CPR is the return of spontaneous circulation. This refers to the reinstatement of an effective cardiac output and the ability of the heart to pump blood effectively without manual assistance. When CPR is performed correctly, the goal is not only to maintain some level of blood flow to vital organs but ultimately to restore the heart's ability to function independently.

Return of spontaneous circulation shows that the heart has resumed its normal pacemaker activity and is capable of generating a pulse, which is a crucial physiological sign that increases the patient’s chance of survival and reduces the risk of long-term neurological damage.

While the presence of a normal heart rhythm, restoration of conscious awareness, and improvement in blood pressure readings are important factors indicating recovery, they are typically outcomes that follow the return of spontaneous circulation. Only once the heart successfully resumes its natural rhythm and effective blood flow can these other indicators be assessed accurately in the evaluation of a patient's recovery after cardiac arrest.