The AHA ACLS adult cardiac arrest algorithm 2020 PDF is the single most-tested document in Advanced Cardiovascular Life Support certification. Issued by the American Heart Association and updated in the 2020 Guidelines for CPR and Emergency Cardiovascular Care, it maps every decision point a resuscitation team must navigate from the moment a patient loses a pulse through post-resuscitation care. Whether you are preparing for your initial certification or renewing after two years, understanding the structure of this algorithm is the fastest path to a passing score and — more importantly — to confident clinical performance.
The AHA ACLS adult cardiac arrest algorithm 2020 PDF is the single most-tested document in Advanced Cardiovascular Life Support certification. Issued by the American Heart Association and updated in the 2020 Guidelines for CPR and Emergency Cardiovascular Care, it maps every decision point a resuscitation team must navigate from the moment a patient loses a pulse through post-resuscitation care. Whether you are preparing for your initial certification or renewing after two years, understanding the structure of this algorithm is the fastest path to a passing score and — more importantly — to confident clinical performance.
ACLS algorithms are not arbitrary checklists. Each box, diamond, and arrow reflects decades of resuscitation research compressed into a format designed for high-stress, time-critical decision-making. The 2020 update refined drug timing, compressed chest-compression fraction targets, and clarified the role of advanced airway placement in a way that directly affects multiple exam questions. Candidates who treat the algorithms as static memorization targets routinely miss the nuanced judgment questions that distinguish an 80% score from a 95% score.
Across all AHA ACLS algorithms — cardiac arrest, post-cardiac arrest care, bradycardia, tachycardia, acute coronary syndrome, and stroke — the PDF package you download from the AHA or study through preparation resources covers roughly 40 discrete clinical decision nodes. The adult cardiac arrest algorithm alone contains seven major branch points that hinge on rhythm interpretation, pulse assessment, and drug selection. Mastering each branch point is the core study task for most candidates in the two to four weeks before their provider course.
This guide breaks down every major AHA ACLS algorithm from the 2020 guidelines, explains the clinical reasoning behind each step, and connects you to free practice quizzes that mirror the question style used in actual provider course written exams and HeartCode online modules. You will find coverage of the shockable versus non-shockable pathway split, the two-minute CPR cycles, vasopressor timing, amiodarone versus lidocaine decisions, and the reversible causes framework known as the Hs and Ts — all in enough depth to build genuine mastery rather than surface-level familiarity.
For those who have already reviewed the raw aha acls algorithms pdf but want to understand how the 2020 update changed clinical practice, this article provides a structured comparison of the key modifications and explains why each change was made based on the underlying evidence. Understanding the rationale behind a guideline change makes it dramatically easier to retain and apply under exam conditions and at the bedside.
The AHA organizes its ACLS algorithms in a circular systematic approach: recognize the emergency, activate the team, perform high-quality CPR, defibrillate if indicated, establish IV or IO access, administer appropriate medications, identify and treat reversible causes, and reassess continuously. Every algorithm you encounter in the 2020 PDF threads through this same backbone, which means learning the shared framework first pays dividends across all six core algorithms rather than requiring you to memorize each one in complete isolation.
By the end of this guide, you will know exactly which algorithms appear on the written exam, how many questions the AHA typically devotes to each one, which drug doses are most commonly tested, and how to use timed practice quizzes to identify and close your remaining knowledge gaps before your certification date. Let's start with the numbers that frame what you are preparing for.
The flagship algorithm covering VF/pVT shockable pathway and asystole/PEA non-shockable pathway. Includes CPR cycles, defibrillation energy levels, epinephrine timing, amiodarone versus lidocaine decisions, and the H's and T's framework for reversible causes.
Guides management after return of spontaneous circulation (ROSC). Covers targeted temperature management at 32–36°C, hemodynamic optimization with MAP ≥65 mmHg, 12-lead ECG for STEMI, and neuroprognostication timing after at least 72 hours.
Branches on patient stability and QRS width. Unstable patients require immediate synchronized cardioversion regardless of rhythm. Stable patients follow separate narrow-complex and wide-complex pathways with adenosine, beta-blockers, or antiarrhythmics.
Identifies symptomatic bradycardia as HR below 50 with hemodynamic compromise. First-line treatment is atropine 0.5 mg IV; transcutaneous pacing and dopamine or epinephrine infusions are used when atropine fails to restore adequate rate and perfusion.
Covers STEMI and NSTEMI/UA pathways from initial aspirin administration through reperfusion decision-making. Key time targets are door-to-balloon under 90 minutes for STEMI and fibrinolysis within 30 minutes when PCI is not available.
Time-critical pathway from symptom onset through CT imaging, tPA eligibility assessment, and thrombectomy candidacy. The 2020 update extended thrombectomy eligibility to 24 hours from symptom onset in selected patients, a major change from prior guidelines.
The adult cardiac arrest algorithm sits at the center of every ACLS provider course because cardiac arrest is both the most time-sensitive emergency and the scenario most likely to be tested across multiple question formats. The 2020 version of the algorithm simplified the entry point: when you identify an unresponsive patient without normal breathing, you simultaneously activate the emergency response system and begin high-quality CPR. The algorithm does not wait for a defibrillator to arrive before starting compressions, and it explicitly deprioritizes anything that interrupts chest compression fraction below 60%.
The first major branch point in the algorithm occurs when the defibrillator or AED arrives and a rhythm check is performed. If the rhythm is ventricular fibrillation or pulseless ventricular tachycardia — the shockable pathway — the team delivers one shock, immediately resumes CPR for two minutes, then rechecks.
If the rhythm is asystole or pulseless electrical activity — the non-shockable pathway — CPR continues without a shock and the team focuses on identifying and treating the underlying reversible cause. This binary split is the single most important concept in the entire algorithm and appears directly or indirectly on the majority of written exam questions.
Epinephrine 1 mg IV or IO every 3 to 5 minutes is administered regardless of which pathway the patient is on, but the timing relative to shocks differs. On the shockable pathway, epinephrine is given after the second shock, meaning CPR plus the first shock cycle runs before the first drug dose. On the non-shockable pathway, epinephrine should be given as soon as IV or IO access is established, ideally within the first two-minute CPR cycle. This timing distinction is a frequent source of exam errors and is worth drilling with practice questions before your certification date.
Antiarrhythmic drugs — amiodarone 300 mg IV/IO or lidocaine 1 to 1.5 mg/kg IV/IO — are considered on the shockable pathway after the third shock if VF or pVT persists. The 2020 guidelines acknowledge that neither drug has been shown to improve survival to hospital discharge, but both reduce the defibrillation threshold and may improve return of spontaneous circulation rates in shock-refractory rhythms.
A second dose of amiodarone 150 mg or lidocaine 0.5 to 0.75 mg/kg can be given after the fifth shock if needed. Understanding this drug hierarchy — epinephrine first, antiarrhythmic after third shock — is critical for answering sequencing questions correctly.
The reversible causes framework, universally known as the H's and T's, applies to both pathways but is especially emphasized on the non-shockable pathway where rhythm correction alone cannot restore circulation. The six H's are hypovolemia, hypoxia, hydrogen ion excess (acidosis), hypo- or hyperkalemia, hypothermia, and hypoglycemia. The five T's are tension pneumothorax, tamponade (cardiac), toxins, thrombosis pulmonary, and thrombosis coronary.
Providers are expected to run through this mental checklist during each two-minute CPR cycle and to treat any identified cause aggressively. Ultrasound has become a valuable bedside tool for rapidly identifying tamponade or pneumothorax during CPR pauses, though it is not formally integrated into the 2020 algorithm flowchart itself.
Advanced airway management received nuanced guidance in the 2020 update. Unlike previous versions that encouraged early intubation, the 2020 guidelines state that either an advanced airway or bag-mask ventilation is reasonable during CPR, and that placement of an advanced airway should not interrupt chest compressions. When an advanced airway is in place, the compression-to-ventilation ratio changes from 30:2 to continuous compressions at 100 to 120 per minute with one breath every 6 seconds. This shift eliminates compression pauses for ventilation and substantially increases chest compression fraction, particularly important in prolonged resuscitations.
Post-resuscitation care begins the moment ROSC is achieved, defined by sustained organized rhythm with a palpable pulse. The transition from the cardiac arrest algorithm to the post-cardiac arrest care algorithm should be seamless — the team immediately targets an SpO₂ of 92 to 98%, avoids hyperoxia, targets normocapnia with ETCO₂ of 35 to 45 mmHg, and initiates targeted temperature management in comatose survivors.
The 2020 guidelines continue to support TTM at 32 to 36°C maintained for at least 24 hours as the standard of care for comatose post-arrest patients, though subsequent trials have generated ongoing debate about the optimal target temperature within that range.
Epinephrine 1 mg IV/IO every 3 to 5 minutes is the primary vasopressor for all cardiac arrest rhythms. Amiodarone 300 mg IV/IO is the first-line antiarrhythmic for shock-refractory VF or pVT, with a second dose of 150 mg available. Lidocaine 1 to 1.5 mg/kg IV/IO is the acceptable alternative, with a second dose of 0.5 to 0.75 mg/kg. Atropine 0.5 mg IV every 3 to 5 minutes (maximum 3 mg) is the first drug for symptomatic bradycardia. Adenosine 6 mg rapid IV push treats stable narrow-complex SVT, with 12 mg for subsequent doses.
Magnesium sulfate 1 to 2 g IV is specifically indicated for Torsades de Pointes, a polymorphic VT associated with prolonged QT interval. Sodium bicarbonate 1 mEq/kg IV is considered for severe metabolic acidosis, hyperkalemia, or tricyclic antidepressant overdose — not routinely during cardiac arrest. Calcium chloride 500 to 1000 mg IV treats hyperkalemia, hypocalcemia, and calcium channel blocker toxicity. Dopamine infusion at 2 to 20 mcg/kg/min and epinephrine infusion at 2 to 10 mcg/min are second-line options when atropine and pacing fail in bradycardia. Memorizing doses with their indications — not just the numbers — is the most efficient way to answer pharmacology questions correctly.
Ventricular fibrillation appears as chaotic, irregular waveforms with no identifiable P waves, QRS complexes, or T waves — the rhythm has no organized electrical activity. Pulseless ventricular tachycardia shows wide, bizarre QRS complexes at rates above 150 bpm without a palpable pulse. Both are shockable rhythms requiring immediate defibrillation. Asystole is a flat or nearly flat line with no discernible electrical activity; confirm in two leads before treating. PEA is any organized rhythm — sinus, junctional, or otherwise — occurring without a palpable pulse, always demanding a systematic search for reversible causes.
Distinguishing fine VF from asystole is a classic trap on written exams. The AHA recommends checking a second lead or increasing the gain on the monitor before declaring asystole, because fine VF is shockable while asystole is not. Torsades de Pointes is recognized by its twisting-around-the-axis morphology and prolonged QT on the preceding rhythm strip; it is treated with magnesium sulfate rather than standard antiarrhythmics. SVT appears as a narrow-complex rapid rhythm, typically regular at 150 to 250 bpm with no visible P waves, and responds to vagal maneuvers or adenosine in stable patients. Wide-complex tachycardia should be presumed VT until proven otherwise, especially in patients with structural heart disease.
The H's and T's is the systematic framework ACLS providers use to identify and correct the underlying cause of cardiac arrest or hemodynamic instability. Hypovolemia — the most common reversible cause of PEA — is treated with aggressive IV fluid resuscitation. Hypoxia is addressed by optimizing oxygenation and ventilation; an SpO₂ below 94% during resuscitation is a red flag. Hydrogen ion excess (acidosis) from prolonged arrest may warrant sodium bicarbonate. Hypo- or hyperkalemia can precipitate fatal arrhythmias and requires electrolyte replacement or correction. Hypothermia below 30°C can cause cardiac arrest resistant to defibrillation until core temperature is raised. Hypoglycemia should be checked and corrected rapidly in any altered patient.
The T's begin with tension pneumothorax, which presents with absent unilateral breath sounds, tracheal deviation, and hypotension — treated by immediate needle decompression at the second intercostal space midclavicular line. Cardiac tamponade causes the Beck's triad of hypotension, distended neck veins, and muffled heart sounds and is relieved by pericardiocentesis. Toxins from medication overdose, particularly tricyclics, beta-blockers, or calcium channel blockers, require specific antidotes. Pulmonary thromboembolism causing obstructive shock may require empiric thrombolytics during CPR. Coronary thrombosis — acute MI — is treated with emergent reperfusion; STEMI identified on a 12-lead ECG after ROSC triggers immediate cath lab activation. Working through all ten systematically during each two-minute CPR cycle prevents tunnel vision on any single cause.
Every action in the cardiac arrest algorithm — rhythm checks, shocks, drug administration, and reversible cause assessment — is organized around two-minute CPR cycles. On exam questions that ask about sequencing, timing, or what happens next, the answer almost always returns to: continue high-quality CPR, minimize interruptions, and reassess at the end of the two-minute cycle. Candidates who internalize this rhythm answer sequencing questions 30% faster and with significantly higher accuracy than those who memorize isolated steps without the underlying cycle structure.
Studying the AHA ACLS algorithms PDF effectively requires a deliberate strategy that goes beyond passive reading. The most common mistake candidates make is spending the majority of their preparation time re-reading the algorithm document without ever testing their recall under conditions that resemble the actual written exam. Research on medical education consistently shows that retrieval practice — recalling information from memory rather than recognizing it on a page — produces two to three times better long-term retention than equivalent time spent re-reading or highlighting. For ACLS candidates, this means practice questions should constitute at least 50% of total study time.
Start your study plan by reading each of the six algorithms once in full while actively narrating the clinical reasoning behind each step. Do not just follow the arrows; ask yourself why the algorithm branches at each decision point and what would happen if you took the wrong branch.
For example, when you reach the rhythm check box in the cardiac arrest algorithm, ask: what would I see on the monitor for each of the four possible rhythms, and what does each rhythm tell me about the underlying physiology? This active engagement transforms passive reading into meaningful schema-building that persists under the stress of the exam environment.
After the initial read-through, use spaced repetition to revisit the algorithms at increasing intervals. Study sessions on day one, day three, day seven, and day fourteen before your course exploit the spacing effect and dramatically reduce the forgetting that occurs with massed practice. During each spaced session, cover the algorithm and attempt to reconstruct it from memory before checking.
Note which branch points you hesitate on or reconstruct incorrectly — these are your highest-priority areas for focused practice in the following session. Drug doses and timing tend to be the most vulnerable to forgetting and warrant the most frequent retrieval practice.
Rhythm strip interpretation deserves its own dedicated practice stream running parallel to algorithm study. The written exam typically includes four to eight rhythm strip questions, and rhythm identification is the gateway to every algorithm branch decision. Use free online rhythm strip libraries and timed quizzes to build speed and accuracy to the point where you can confidently identify the eight most common ACLS rhythms within ten seconds.
VF, pVT, asystole, and PEA are the four cardiac arrest rhythms; SVT, atrial fibrillation, third-degree heart block, and wide-complex VT/Torsades round out the set most likely to appear. Practice until identification feels automatic rather than deliberate.
Pharmacology is the second-highest-yield area after rhythm interpretation. Create a one-page drug reference card with the drug name, dose, route, indication, and one key clinical pearl for each ACLS medication. Carry this card and review it during breaks in your workday.
Common exam traps include confusing amiodarone versus lidocaine timing, forgetting that atropine is not recommended for high-degree AV blocks (it may paradoxically worsen them), and mixing up adenosine doses for SVT versus the doses used in specific diagnostic situations. Understanding why each drug is used — not just the dose — allows you to reason through novel question scenarios that do not match any memorized pattern exactly.
Simulation and team scenarios, even informal ones, build the procedural fluency that written practice alone cannot develop. If your workplace allows it, run through the cardiac arrest algorithm verbally with a colleague, taking turns as team leader and assigning roles.
If not, use mental simulation — close your eyes and walk through the algorithm from the moment you find an unresponsive patient, narrating every action aloud including who you are directing, what you are asking them to do, and what you expect to see next. Mental rehearsal activates many of the same neural pathways as physical practice and has been shown to improve both speed and accuracy in procedural task performance.
In the week before your provider course, shift from comprehensive study to focused gap-closing. Identify your three to five weakest algorithm areas using your practice test performance data and devote the majority of your final study sessions to those specific topics. Do not try to re-learn everything from scratch — trust the retrieval practice you have already done and use the final week to sharpen your weakest points.
The night before the course, review your one-page drug card and the H's and T's list one final time, then prioritize rest. Sleep consolidates memory, and arriving well-rested will serve you far better than a late-night cram session that leaves you fatigued during the skills stations.
Practice tests are the single most effective tool for converting algorithm knowledge into exam-ready performance, but only when you use them strategically rather than as a passive score-tracking exercise.
The most productive approach to ACLS practice questions involves four phases for each session: attempt the questions under timed conditions without referring to notes, review every answer in detail regardless of whether you got it right, identify the underlying algorithm concept each question is testing, and update your personal gap list based on the review. Candidates who complete this four-phase cycle consistently outperform those who simply retake tests until the score improves.
Question difficulty in ACLS written exams ranges from direct recall — what is the dose of epinephrine in cardiac arrest? — to complex application questions that present a multi-step scenario and ask which intervention is most appropriate next. The higher-difficulty application questions are where most certification failures occur, and they are precisely the questions that practice testing prepares you for.
When you encounter a scenario question, practice explicitly identifying the algorithm the scenario falls under, the branch point the question is testing, and the relevant drug or timing guideline before looking at the answer choices. This structured approach dramatically reduces the impact of distractors and partial-credit temptation.
Timed conditions matter more than most candidates realize. The AHA written exam has a time limit that averages approximately one minute per question for the written portion of provider courses. Candidates who practice exclusively without a timer often discover in the actual exam that their correct reasoning process takes longer than the allotted time, particularly for rhythm strip interpretation and multi-step scenario questions. Set a one-minute timer per question during at least two of your full-length practice sessions to calibrate your pace and identify which question types consistently take you over time.
Use your practice test performance to prioritize, not to predict. A 75% score on a practice test does not mean you will pass with 75% on the actual exam — the actual question distribution, difficulty calibration, and scenario framing will differ. What the score does tell you is which categories need more work. If you are consistently missing pharmacology questions, that is where to invest the next study session. If your rhythm strip questions are strong but post-resuscitation care questions are weak, allocate time accordingly. Treat each practice test as diagnostic data, not as a final judgment on your readiness.
Peer discussion and teaching are underutilized study strategies for ACLS preparation. Explaining the adult cardiac arrest algorithm to a colleague — even one who is not in a clinical field — forces you to articulate your reasoning in precise terms and exposes logical gaps you did not know existed.
If you cannot explain why epinephrine is given after the second shock on the shockable pathway rather than before the first shock, your understanding of the algorithm's structure is incomplete in a way that will likely manifest as errors on application questions. Teaching consolidates your own knowledge while giving you immediate feedback on which concepts you understand deeply versus superficially.
The relationship between the written exam and the skills stations at the AHA provider course is tighter than many candidates expect. Skills scenarios often begin with the same patient presentations that appear on written exam questions, and strong algorithm knowledge directly accelerates your performance in the simulated resuscitation scenarios.
Candidates who enter the skills station with a confident mental map of the cardiac arrest algorithm can devote their cognitive bandwidth to team leadership and communication rather than trying to recall the next step under pressure. This is why written exam preparation and skills preparation are not separate tracks — they reinforce each other and should be studied in an integrated way throughout your preparation period.
For renewal candidates who completed their initial ACLS certification two years ago, the 2020 update introduced changes that may differ from what they learned previously. The most significant practical changes are the de-emphasis of early advanced airway placement, the clarified timing of epinephrine on non-shockable pathways, and the post-cardiac arrest care refinements around TTM and prognostication timing.
Renewal candidates should not assume their previous algorithm knowledge is current — reviewing the specific 2020 changes before the renewal course will prevent the common error of applying outdated protocols on the written exam and in the skills stations. The aha acls algorithms pdf updates are substantial enough to warrant a complete review rather than a cursory skim.
In the final 72 hours before your ACLS provider course, your preparation strategy should shift from learning new material to optimizing retrieval of what you have already studied. Begin with a single timed practice test to establish your current baseline and identify any remaining weak areas.
Resist the temptation to study any topic you have not covered yet — introducing new information in the final days increases cognitive load without providing sufficient time for consolidation and is more likely to create confusion than clarity. Focused review of your established weak areas is consistently more productive than broad coverage at this stage.
Create a two-sided quick reference card the night before your course. Side one should contain the adult cardiac arrest algorithm condensed to its key branch points, drug doses, and timing rules. Side two should list the H's and T's with one treatment note for each and the post-cardiac arrest care targets.
Review this card on the morning of your course but put it away before the written exam begins — the goal of creating the card is not to smuggle notes into the exam but to drive one final high-intensity retrieval session that activates your long-term memory of these critical facts.
During the written exam itself, read each question stem carefully and identify the algorithm scenario before looking at the answer choices. Most exam failures on ACLS written tests are not due to knowledge gaps but to misidentifying which algorithm or branch point is being tested.
A question about a patient with a heart rate of 40 and hypotension is a bradycardia algorithm question, not a cardiac arrest question — the distinction changes the correct answer entirely. Taking three to five seconds to categorize the scenario before evaluating answer choices dramatically reduces these categorization errors and pays dividends across multiple questions per exam.
For the skills stations, remember that the AHA evaluates your performance as a team leader on specific critical actions rather than on the overall outcome of the simulated resuscitation. Critical actions include calling for a rhythm check at the appropriate time, directing compressions to resume immediately after the shock, stating the correct drug and dose before it is administered, and identifying and verbalizing the H's and T's during the scenario.
Practicing these verbal prompts explicitly — not just thinking them but saying them out loud — during your preparation will make them feel natural rather than forced during the actual skills evaluation.
Post-certification, your ACLS algorithms become a practical clinical reference rather than a study document. Most hospitals and health systems post laminated algorithm cards in emergency areas, and many practitioners keep a digital copy on their phone for quick reference during real resuscitations.
The two-year renewal cycle is designed to ensure that your algorithm knowledge stays current and your hands-on skills remain sharp, particularly as guidelines continue to evolve with new resuscitation research. ACLS providers who treat their certification as a minimum floor rather than a maximum ceiling — who continue reading resuscitation literature and debriefing real cardiac arrest cases — consistently perform at a higher level than those who study only at renewal time.
The connection between algorithm mastery and patient outcomes is not theoretical. Hospitals with higher code team compliance with AHA algorithms consistently show better survival-to-discharge rates for in-hospital cardiac arrest than those with variable or protocol-deviant teams.
The AHA's Get With The Guidelines-Resuscitation registry, which tracks in-hospital cardiac arrest outcomes across hundreds of US hospitals, demonstrates that each percentage point increase in chest compression fraction is associated with measurable improvement in survival outcomes. Your investment in truly understanding these algorithms — not just passing the exam — directly translates to better outcomes for the patients you will resuscitate over the course of your career.
Whether you are a physician, nurse, paramedic, respiratory therapist, or other healthcare professional preparing for ACLS certification for the first time or the fifth time, the most important thing to remember is that algorithm knowledge and clinical judgment are not opposites — they are partners. The algorithm provides the framework; your clinical judgment fills in the patient-specific details that no algorithm can fully anticipate.
The best ACLS providers use the 2020 AHA algorithms as a cognitive scaffold that frees them to focus on team coordination, patient-specific adjustments, and real-time reassessment rather than trying to recall basic protocol steps under pressure. Start your free practice quizzes today, identify your gaps, and enter your provider course with the confidence that comes from genuine preparation.