Start CPR & Attach Monitor/Defibrillator

The first step in the Adult Cardiac Arrest Circular Algorithm is to act fast. Every second matters.

First, give oxygen and begin chest compressions right away.
Then check the rhythm quickly. For example, if VF or pVT is present, shock. In contrast, if asystole or PEA is found, resume CPR and give epinephrine.

Tip: Rotate compressors every 2 minutes to reduce fatigue. In addition, minimize all pauses to keep blood flowing.

The 2-Minute Circular Loop

Core Actions (every cycle)

First, check the rhythm. Then shock if VF/pVT is present; otherwise, continue CPR.
Next, give drug therapy: epinephrine every 3–5 min. Also add amiodarone or lidocaine for refractory VF/pVT.
Furthermore, consider an advanced airway with waveform capnography.
Meanwhile, treat reversible causes (Hs & Ts) every cycle.
Finally, monitor and improve CPR quality throughout the arrest.

Goal

Cycle with discipline until return of spontaneous circulation (ROSC) occurs. However, be ready to change the strategy when needed. According to the AHA CPR & ECC Guidelines, staying organized during each loop is key to better outcomes.

CPR Quality: What to Aim For

First, push at least 5 cm (2 in) deep. Also keep the rate at 100–120/min and allow full chest recoil after each compression.
In addition, minimize interruptions and avoid hyperventilation at all times.
Moreover, change the compressor every 2 min or sooner if the provider is tired.
Finally, use waveform capnography. As a result, a falling ETCO₂ will prompt a quality check and a search for causes. For more detail, see the Resuscitation Journal.

Shock Energy

Biphasic: First, use the dose the manufacturer recommends (often around 120–200 J). Then escalate if needed. Subsequent doses should be equal or higher.
Monophasic: In contrast, use 360 J for all subsequent shocks.

Technique tip: Charge the defibrillator during compressions. Then shock within seconds of the rhythm check to reduce the pause.

Drug Therapy

Epinephrine (IV/IO)

Give 1 mg every 3–5 minutes throughout the arrest. This applies to both shockable and non-shockable rhythms.

Antiarrhythmics (for VF/pVT)

Amiodarone: First dose is 300 mg bolus. Then give 150 mg as a second dose if needed.
Or Lidocaine: First dose is ~1–1.5 mg/kg. Then follow with ~0.5–0.75 mg/kg as the second dose.

Therefore, always use your local formulary and protocols for exact dosing rules and contraindications.

Advanced Airway & Ventilation

When indicated, place an endotracheal tube or a supraglottic airway. Then confirm placement with waveform capnography.
After you secure the airway, ventilate at ~1 breath every 6 sec while keeping compressions continuous.

Return of Spontaneous Circulation (ROSC)

First, check for a pulse and blood pressure. In addition, an abrupt rise in ETCO₂ can signal ROSC before you feel a pulse.
After ROSC, optimize oxygen and ventilation. Then treat hypotension, get a 12-lead ECG, and start post–cardiac arrest care right away.

Reversible Causes (Hs & Ts)

Hs

Hypovolemia
Hypoxia
Hydrogen ion (acidosis)
Hypo- or Hyperkalemia
Hypothermia
Hypoglycemia (consider)

Ts

Tension pneumothorax
Cardiac tamponade
Toxins
Thrombosis (pulmonary)
Thrombosis (coronary)

Why it matters: Fixing an H or a T can be the turning point for ROSC. Therefore, keep checking every cycle. For instance, treating tension pneumothorax can restore circulation immediately. As a result, never skip this step.

Cited Keywords & Referral Links

Each keyword links to the main website or a related post on gyathshammha.com.

ACLS Cardiac arrest CPR Defibrillation Epinephrine Amiodarone Lidocaine Advanced airway Capnography ROSC Hs & Ts Related education post AHA Guidelines Resuscitation Journal

Bottom line

The Adult Cardiac Arrest Circular Algorithm (ACLS) works best when the team is disciplined and prepared. First, run the circular loop with discipline. This means high-quality CPR and quick rhythm checks. Then shock right away for VF/pVT. Next, give epinephrine and antiarrhythmics on time. Furthermore, secure the airway when it is needed. Finally, search for Hs & Ts every single cycle—until ROSC is achieved or the plan must change.

This guide summarizes common teaching points. Therefore, it is not a substitute for up-to-date guidelines or clinical judgment.