The unified chain of survival is: early recognition, high-quality CPR, rapid defibrillation, advanced care, and post-arrest care, applying to all ages and settings. Focus on high-quality CPR, know your rhythm before administering epinephrine, match airway choice to your skill and resources, practice choking and opioid protocols, and always consider post-arrest stabilization and transfer.

Here is an excellent summary: Highlights of the 2025 American Heart Association Guidelines for CPR and ECC.

Epinephrine Timing: For non-shockable rhythms (asystole/PEA), give epinephrine as soon as feasible; for shockable rhythms (VF/pVT), give epinephrine after initial defibrillation attempts; high-dose epinephrine is not recommended. Note: Using vasopressin alone, or in combination with epinephrine, provides no benefit over epinephrine alone for adult patients in cardiac arrest. 

IV Access Is Preferred: IO is a fallback if IV cannot be established, and access should be prepared early in the code.

Airway Management: Use ETI if skilled; otherwise, a supraglottic airway is acceptable. Ventilate once every six seconds with an advanced airway and monitor ETCO₂ or arterial pressure when available.

Defibrillation: Deliver a single shock followed immediately by CPR; use biphasic energy per manufacturer recommendations or maximum if unknown; double-sequential or vector-change defibrillation is not routine.

Cardioversion: For synchronized cardioversion of atrial fibrillation, starting at an initial energy of at least 200 J is reasonable, with subsequent increases if the initial shock is unsuccessful, depending on the defibrillator type.

Bradycardia: Unstable bradycardia refractory to medical therapy, temporary transvenous pacing is reasonable to increase heart rate and improve symptoms.

Choking/Airway Obstruction: Alternate 5 back blows with 5 abdominal thrusts until the airway is cleared; for infants, alternate 5 back blows with 5 chest thrusts.

Opioid-Related Arrest: Administer naloxone when overdose is suspected, but do not delay CPR.

Post-Arrest Care: Monitor for ROSC, manage temperature, assess neurological status, stabilize the patient, and prepare for ICU transfer as indicated.