ACLS Algorithms
The ACLS algorithms are the American Heart Association’s step-by-step pathways for the adult emergencies a resuscitation team meets most often. They are not a substitute for clinical judgement, but in a cardiac arrest they give every member of the team the same map. This guide explains the logic of each one; the course teaches them hands-on, and the published AHA guidelines are the authoritative version.
The core pathways
Adult cardiac arrest (shockable VF/pVT and non-shockable asystole/PEA), bradycardia with a pulse, tachycardia with a pulse, and post-cardiac arrest care — all built on continuous high-quality CPR and a search for reversible causes (the H’s and T’s).
Everything starts with high-quality CPR: compressions at 100 to 120 a minute, at least 5 cm deep in an adult, full recoil, minimal interruptions, and no excessive ventilation. Attach the monitor or defibrillator as soon as it arrives. The first rhythm check splits the algorithm in two.
Shockable — ventricular fibrillation or pulseless ventricular tachycardia. Shock, then resume compressions immediately for two minutes before the next rhythm check. Vascular access and adrenaline (epinephrine) follow, and an antiarrhythmic such as amiodarone or lidocaine is considered for rhythms that persist after shocks.
Non-shockable — asystole or pulseless electrical activity. No shock. Continue CPR, give adrenaline as soon as it is feasible, and put the effort into finding and treating a reversible cause.
In both pathways, the team works in two-minute cycles, swaps compressors to prevent fatigue, considers an advanced airway and uses waveform capnography to monitor CPR quality and to help detect return of spontaneous circulation.
The reversible causes are usually remembered as the H’s — hypovolaemia, hypoxia, hydrogen ion (acidosis), hypo- or hyperkalaemia and hypothermia — and the T’s — tension pneumothorax, tamponade, toxins, and thrombosis (pulmonary or coronary). In a PEA arrest especially, finding one of these is often the only route to survival.
The question is whether the slow rate is causing the patient harm: low blood pressure, altered consciousness, signs of shock, chest pain or heart failure. If not, monitor and look for the cause. If it is, atropine is the first drug, and if that does not work the team moves to transcutaneous pacing or an infusion of a drug such as dopamine or adrenaline while specialist help is arranged.
Again the first question is stability. An unstable patient with a tachyarrhythmia needs synchronised cardioversion. If the patient is stable, the rhythm is assessed on a 12-lead ECG: a narrow regular complex tachycardia such as SVT may respond to vagal manoeuvres and adenosine, while a wide complex tachycardia needs expert input and specific antiarrhythmic treatment.
Return of circulation is the start of a new phase, not the end. The team optimises oxygenation and ventilation, treats low blood pressure, obtains a 12-lead ECG to look for a coronary cause, and considers temperature control and the other elements of post-arrest care set out in the current guidelines.
ACLS also teaches the early recognition and first steps for suspected acute coronary syndromes and acute stroke, where the priority is getting the patient to reperfusion — a cath lab or a stroke team — as fast as possible.
Draw each one from memory, then talk through it as if you were leading a team. On the course you practise them on a manikin with a rhythm simulator, which is far more effective than reading. The Megacode guide explains how they are tested, and the ACLS course page has live dates.
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The course centres on the adult cardiac arrest algorithm, the bradycardia and tachycardia algorithms with a pulse, and post-cardiac arrest care, alongside the systematic approach, ACS and stroke pathways.
The reversible causes of cardiac arrest: hypovolaemia, hypoxia, hydrogen ion (acidosis), hypo- or hyperkalaemia and hypothermia; tension pneumothorax, tamponade, toxins and thrombosis (pulmonary or coronary).
Ventricular fibrillation and pulseless ventricular tachycardia. Asystole and pulseless electrical activity are not shockable.
The American Heart Association publishes them with its CPR and ECC Guidelines, linked in the sources below. The ACLS provider manual used on the course contains them in full.
They are updated when the AHA publishes new guidelines based on the international evidence review. The course always teaches the current version.
Safety First Medical Services is an American Heart Association training centre on Al Reem Island. HeartCode blended ACLS, classroom ACLS and on-site group sessions for hospitals and clinics, with a two-year AHA ACLS Provider eCard on completion.
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What we teach follows the awarding body and the UAE health authorities. For the definitive position on a course or licensing question, these are the places to check.
Last reviewed by the training team at Safety First Medical Services, an American Heart Association training centre at Addax Office Tower, Al Reem Island, Abu Dhabi. Call +971 55 761 9841 or email training@safetyfirstmed.ae.