Cardiac Arrest and Protocols for Standard of Care

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Cardiac arrest: recognition thresholds and immediate lay response (Problem → Action)

Cardiac arrest means the heart stops pumping blood in a way that can sustain life. For practical, standard of care activation, cardiac arrest is when a person is unresponsive, not breathing normally, and shows no signs of circulation.

You do not need to “be sure” before you act because delays reduce survival, and the risk of harm from starting CPR on someone who is not in arrest is low compared with the risk of doing nothing for someone in cardiac arrest.

If you see a collapse or find someone unresponsive, call emergency services first, then start CPR. If an automated external defibrillator (AED) is available, turn it on and follow its prompts as soon as you can while CPR continues.

If you suspect opioid overdose, give naloxone if you have it and know how to use it, but keep CPR going and use the AED if it advises a shock.

These steps are most effective when dispatchers rapidly recognize cardiac arrest and provide real-time CPR instructions, which aligns with standard practice once trained responders arrive.

Adult resuscitation sequence and care-quality expectations (Explanation/Mechanism → Action)

During adult resuscitation, the core expectation is early, high-quality CPR with rapid defibrillation when the rhythm is shockable. CPR quality means you push hard and fast in the center of the chest, allow full chest rise between pushes, and minimize pauses so blood flow does not stop. End-tidal carbon dioxide and arterial blood pressure trends can help rescuers determine how effective their chest compressions are. 

Medication timing also matters, and epinephrine should be given early. Intravenous access is preferred, but intraosseous access is also acceptable when intravenous access is not feasible.

These actions work best when the system supports rescuers through training, coordination, and continuous improvement.

System-level protocols that define “standard of care” across prehospital and hospital settings (Implication)

The AHA describes cardiac arrest outcomes as a systems problem, not just an individual skill problem. A system of care links people, protocols, policies, resources, and quality improvement so that each step happens fast and reliably.

The Chain of Survival organizes the work from recognition through recovery. On the front end, dispatch matters. Telecommunicators should treat “unresponsive plus absent or abnormal breathing” as cardiac arrest and start telephone CPR instruction while sending help.

In most settings, EMS improves outcomes by initiating resuscitation on scene. Within hospitals and EMS systems, teams should train with clearly defined roles and conduct structured debriefings after events to identify and address performance gaps. Systems should also use registries and performance measures so improvements rely on data, not memory.

These system elements establish the foundation for post–return of spontaneous circulation care, which is addressed in the following section.

Post–cardiac arrest hospital protocol targets (Mechanism → Implication)

After return of spontaneous circulation (ROSC), standard care shifts from restarting the heart to preventing a second crash and limiting brain and organ injury. Blood pressure support is central. Clinicians should avoid hypotension and maintain a mean arterial pressure (MAP) of at least 65 mm Hg.

Oxygen and ventilation targets should avoid extremes. If a reliable oxygen saturation reading is not immediately available, it is appropriate to maintain 100% oxygen until accurate measurement can be obtained.

After that, it is reasonable to target an oxygen saturation (SpO2) range of 90% to 98%. For ventilation, clinicians generally target normal carbon dioxide levels, with PaCO2 about 35 to 45 mm Hg, because both low and high carbon dioxide can worsen brain injury.

In patients who do not follow commands after ROSC, temperature management is a core component of care. The AHA recommends maintaining temperature control for at least 36 hours, with clinicians selecting a protocol that effectively prevents fever.

Hospitals also need a diagnostic plan to find the cause of the arrest and identify any complications from CPR. It may be reasonable to use CT imaging and/or either formal or bedside cardiac ultrasound to look for major problems that need treatment.

If the patient has a specific type of heart attack called a STEMI, the usual treatment is to quickly perform coronary angiography to find the blocked artery, then percutaneous coronary intervention to open it. For cardiac arrest survivors where the underlying cause is suspected to be cardiac in origin, coronary angiography is recommended before hospital discharge.

Brain monitoring and seizure care also matter because seizures are common in comatose patients after arrest. EEG monitoring helps detect seizures, which require treatment. Conversely, the AHA cautions against treating myoclonus when it has no EEG correlation, because the harms can outweigh the benefits. 

Before discharge, teams should plan survivorship care, including screening and support for emotional distress in survivors and caregivers.

These targets and steps only help if everyone follows a clear workflow from scene to hospital, which I outline next.

Protocol decision workflow for responders and clinicians (Action)

A single decision pathway should be used throughout the event. The cardiac arrest pathway begins when a person is unresponsive and not breathing normally. At that point, emergency services are activated, CPR is started, and an AED is applied as soon as it becomes available. If an opioid overdose is possible, naloxone should be given if available while CPR and AED use is ongoing.

Dispatchers should identify cardiac arrest using the same trigger and provide immediate CPR instructions. EMS and hospital teams should prioritize high-quality CPR, perform rapid defibrillation for shockable rhythms, obtain vascular access based on speed (with IV preferred and IO acceptable), and administer epinephrine according to the presenting rhythm.

After ROSC (return of spontaneous circulation), the receiving team should continue care with MAP at least 65 mm Hg, SpO2 92% to 98% once reliable measurement is available, PaCO2 in 35-45, temperature control for at least 36 hours in unresponsive patients, and prompt diagnostics and cardiac catheterization pathways when indicated.

After a cardiac arrest event, teams should engage in structured debriefings and submit data to registries or tracking systems to identify deficiencies and drive continuous improvement in subsequent responses.

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