Adult Cardiac Arrest Algorithm Guide for Clinical Teams

A cardiac arrest team does not need more noise in the room. It needs a shared sequence: recognize arrest, start excellent CPR, identify the rhythm, deliver the right intervention, and search for the cause without losing track of the basics. This adult cardiac arrest algorithm guide is designed to help healthcare professionals connect those actions under pressure.

For clinicians, ACLS learners, and team members who support resuscitation, the algorithm is more than a flowchart. It is a structure for making time-sensitive decisions while preserving high-quality chest compressions. Local policies, current certifying-body guidance, available equipment, and the patient’s clinical context always apply.

Applying the adult cardiac arrest algorithm guide

Begin with rapid recognition. If an adult is unresponsive, is not breathing normally or is only gasping, and has no definite pulse within 10 seconds, treat the situation as cardiac arrest. Activate the emergency response system, call for a defibrillator or monitor, and start CPR immediately.

The first priorities are deliberately simple. Compressions and defibrillation, when indicated, have the greatest immediate effect on survival. Procedures, medications, airway placement, and documentation all matter, but none should create unnecessary pauses in compressions.

A capable team works in parallel. One clinician provides compressions, another manages the monitor or defibrillator, another establishes vascular access and prepares medications, and a team leader maintains the rhythm of the resuscitation. In smaller teams, roles may overlap. The principle remains the same: every action should support continuous, effective CPR and rapid treatment of a shockable rhythm.

Deliver high-performance CPR

For an adult, aim for a compression rate of 100 to 120 per minute and a depth of at least 2 inches, while avoiding excessive depth. Allow complete chest recoil, minimize interruptions, and switch compressors about every two minutes or sooner if quality is declining.

Before an advanced airway is in place, use a 30:2 compression-to-ventilation ratio. Provide each breath over about one second with visible chest rise. Overventilation can reduce venous return and compromise perfusion, so more air is not better.

After an advanced airway is placed, provide continuous compressions and ventilate at one breath every six seconds, or 10 breaths per minute. Waveform capnography, when available, supports confirmation of airway placement and provides useful feedback during the arrest. A sudden and sustained rise in end-tidal carbon dioxide may indicate return of spontaneous circulation, or ROSC.

CPR quality requires active coaching. The compressor may not recognize shallow compressions, incomplete recoil, or fatigue. The team leader should use direct prompts such as, “Compress deeper,” “Allow recoil,” “Switch at the next rhythm check,” and “Resume compressions.” This is not criticism. It is closed-loop performance management for a patient who cannot wait.

Determine whether the rhythm is shockable

Rhythm analysis should occur in brief, organized pauses, generally every two minutes. The key branch point in the adult cardiac arrest algorithm is whether the patient has ventricular fibrillation, or VF, or pulseless ventricular tachycardia, or pVT.

Shockable rhythms: VF and pulseless VT

VF and pVT require rapid defibrillation. Charge the defibrillator during ongoing CPR when possible, clear the patient efficiently, deliver the shock, and restart compressions immediately. Do not pause to check a pulse after a shock unless there is an organized rhythm and a clinical reason to suspect ROSC.

Use the device manufacturer’s recommended energy setting. If the initial shock is unsuccessful and the energy range is known, escalating energy for subsequent shocks may be appropriate. What matters operationally is reducing the interval between the last compression and the shock, then returning to compressions without delay.

After the second shock, epinephrine is generally administered at 1 mg IV or IO every three to five minutes during continued CPR. After the third shock, an antiarrhythmic such as amiodarone or lidocaine may be considered according to the current ACLS algorithm and local protocol. Medication preparation should happen during compressions, not instead of compressions.

A shockable rhythm can become nonshockable, and a nonshockable rhythm can become shockable. Reassess the displayed rhythm at each planned check. Avoid treating the monitor rather than the patient: confirm lead placement, ensure adequate pad contact, and quickly consider whether artifact is mimicking a rhythm.

Nonshockable rhythms: PEA and asystole

Pulseless electrical activity, or PEA, and asystole are managed with high-quality CPR, epinephrine as soon as feasible, and a focused search for reversible causes. Defibrillation is not indicated for true asystole or PEA.

Asystole should prompt a quick check of leads, gain, and connections before the team commits to that interpretation. This check must be fast. A prolonged search for a hidden rhythm only steals time from CPR.

In PEA, electrical activity is present but there is no effective mechanical output. The rhythm is a clue, not a diagnosis. A slow, wide-complex PEA rhythm may suggest a different problem than narrow-complex PEA, but the immediate response remains organized CPR, early epinephrine, and cause-directed treatment.

Search for reversible causes without losing the rhythm of care

The H’s and T’s help teams avoid missing a treatable cause. They are most useful when discussed out loud and tied to the clinical setting, monitor findings, history, physical assessment, and point-of-care resources.

Common reversible causes include:

• Hypovolemia

• Hypoxia

• Hydrogen ion excess, or acidosis

• Hypo- or hyperkalemia and other metabolic abnormalities

• Hypothermia

• Tension pneumothorax

• Cardiac tamponade

• Toxins

• Pulmonary thrombosis

• Coronary thrombosis

The list is not a requirement to perform every intervention in every arrest. It is a prompt to think clinically. For example, a patient who arrests after severe bleeding needs hemorrhage control and volume or blood-product resuscitation alongside CPR. Sudden collapse with obstructive shock features may raise concern for pulmonary embolism. A dialysis patient with a wide-complex rhythm may require immediate attention to hyperkalemia.

This is where team communication makes a measurable difference. The leader can ask, “What is our leading reversible cause?” A team member can state, “Possible hyperkalemia, calcium is being prepared,” or “Breath sounds are absent on the left, concern for tension pneumothorax.” Clear statements align treatment with the likely problem and prevent duplicated work.

Airway, access, and monitoring: useful, but not at the expense of CPR

Bag-mask ventilation is often effective early in resuscitation when performed by trained clinicians. An advanced airway can improve ventilation control and allow uninterrupted compressions, but placement should not become a prolonged interruption. The best airway choice depends on provider skill, patient factors, equipment, and the ability to maintain oxygenation and ventilation.

IV access is preferred when readily obtainable, with IO access providing a rapid alternative when IV access is delayed or difficult. Medication timing matters, particularly for epinephrine in nonshockable rhythms, but teams should not allow repeated attempts at access to distract from compressions and defibrillation.

Use waveform capnography whenever feasible after advanced airway placement. In addition to confirming tube placement, it can help assess CPR quality. Persistently low values may prompt the team to reassess compression depth, rate, recoil, ventilation rate, and the possibility of reversible causes. Values must be interpreted in context, not as a standalone measure of prognosis.

Recognize ROSC and transition to post-arrest care

ROSC may be signaled by an organized rhythm with a palpable pulse, a sudden rise in end-tidal carbon dioxide, spontaneous movement, or an abrupt improvement in arterial pressure. When ROSC is suspected during a scheduled rhythm check, confirm the pulse promptly. If there is no pulse, resume CPR immediately.

After ROSC, the clinical task changes from restarting circulation to protecting the brain, heart, and other organs. Support oxygenation and ventilation, then titrate oxygen to avoid both hypoxemia and unnecessary hyperoxia. Many protocols target an oxygen saturation of 92% to 98% once reliable monitoring is available. Manage hypotension with fluids and vasoactive support as indicated, obtain a 12-lead ECG, and assess for coronary occlusion or other causes of arrest.

Temperature management, glucose assessment, seizure recognition, and frequent neurologic evaluation are also part of post-cardiac arrest care. Avoid fever and follow the receiving facility’s protocol for targeted temperature management when appropriate. A patient with ROSC still needs disciplined, time-sensitive care.

Build algorithm confidence before the emergency

The algorithm is easiest to follow when the team has practiced the parts that usually fail under stress: assigning roles, changing compressors, charging during CPR, giving concise rhythm reports, and resuming compressions after a shock. Scenario practice should include both VF/pVT and PEA or asystole, because the cognitive work is different in each pathway.

For ACLS learners and renewing clinicians, focus less on memorizing isolated medication details and more on the sequence that protects CPR quality. Know what happens during a two-minute cycle, what changes at a rhythm check, who verbalizes the rhythm, and how the team identifies a reversible cause.

At Beats and Breaths Academy, hands-on resuscitation training is built to strengthen that clinical rhythm: assess, act, communicate, reassess. The goal is not simply to complete an algorithm on paper. It is to help every team member bring calm, accurate action to the bedside when seconds matter.