When cardiac arrest strikes, you have minutes to act. Healthcare professionals need instant access to the correct resuscitation sequence, such as the basic life support algorithm, but searching through lengthy guidelines or outdated materials wastes precious seconds. You need the current protocol at your fingertips, ready to follow without hesitation.
The Australian and New Zealand Committee on Resuscitation (ANZCOR) provides the definitive basic life support algorithm for adult CPR and AED use. This flowchart gives you a clear, evidence based sequence that meets national standards and aligns with your credentialing requirements. Following this algorithm ensures you deliver consistent, effective resuscitation care.
This guide breaks down each step of the ANZCOR basic life support algorithm. You’ll learn when to use the algorithm, how to assess for danger and responsiveness, the correct technique for chest compressions and rescue breaths, and how to deploy an AED. Whether you’re refreshing your skills or preparing for recertification, you’ll have a practical reference that walks through the complete resuscitation sequence.
When to use the ANZCOR basic life support algorithm
You activate the basic life support algorithm when you encounter an unresponsive person who shows no signs of normal breathing. This critical decision point occurs within seconds of your initial assessment, and getting it right determines whether you begin life-saving interventions or pursue a different care pathway. The algorithm applies specifically to adults (anyone over the age of 8 years or who has reached puberty).
Clinical scenarios requiring the algorithm
Several situations demand immediate activation of the basic life support protocol. You’ll use this algorithm when responding to suspected cardiac arrest in any healthcare or community setting, whether you’re working in a hospital ward, GP clinic, aged care facility, or public space. The algorithm covers scenarios where the person has collapsed suddenly, where you discover someone unconscious, or where a patient deteriorates rapidly despite medical intervention.
Apply the algorithm when you observe:
- Sudden collapse with loss of consciousness
- Unresponsiveness during routine patient checks
- Witnessed cardiac arrest in clinical or public settings
- Patient found unconscious with unknown downtime
- Deterioration following a medical emergency (such as myocardial infarction, stroke, or respiratory failure)
Recognition of cardiac arrest
You confirm cardiac arrest by checking for two critical signs: lack of response and absent or abnormal breathing. Your initial assessment takes no more than 10 seconds. An unresponsive person who gasps, makes occasional slow breaths, or doesn’t breathe at all requires immediate resuscitation. These agonal breaths often confuse rescuers, but you must treat them as a sign of cardiac arrest, not adequate breathing.
Do not waste time checking for a pulse unless you have advanced training, as pulse checks delay compressions and prove unreliable in emergency situations.
Step 1. Check for danger, response and send for help
Your safety determines whether you can deliver effective resuscitation, so you assess the environment before touching any patient. This first step of the basic life support algorithm establishes scene safety, confirms unresponsiveness, and activates the emergency response system. You complete these actions within the first 30 seconds of encountering a potential cardiac arrest, as delays compromise patient outcomes.
Assess the scene for hazards
Survey the immediate area for threats to yourself, the patient, and bystanders before approaching. You identify environmental dangers such as traffic, electrical hazards, fire, smoke, toxic substances, unstable structures, or potential violence. Healthcare settings present specific risks including bodily fluids, sharps, aggressive family members, or equipment malfunction.
Only move the patient if the current location poses immediate danger or prevents you from delivering effective resuscitation. Most situations allow you to provide care where you find the patient. When you must relocate someone, use proper manual handling techniques and move them the minimum distance necessary to ensure safety. Consider whether moving the patient from difficult terrain, extreme weather, or a confined space outweighs the risks of relocation.
Check for responsiveness
Apply the “talk and touch” method to assess consciousness. Speak loudly and clearly, giving direct commands such as “Open your eyes” or “Squeeze my hand.” Simultaneously, grasp the patient’s shoulders firmly and shake them. You observe for any response, including eye opening, verbal sounds, or purposeful movement.
Treat minimal responses (such as groaning without opening eyes) as unconscious states requiring full resuscitation protocols. An unconscious patient cannot maintain their own airway, breathe adequately, or protect themselves from aspiration. Your assessment takes no more than 10 seconds, as prolonged assessment delays critical interventions.
Activate emergency response immediately
Call for help the moment you confirm unresponsiveness, before checking breathing. Delegate this task by pointing to a specific person and stating “You, call 000 now and bring the AED.” Provide clear, direct instructions rather than general requests, as specific delegation ensures action. If you’re alone, activate emergency services yourself before proceeding, placing your mobile on speaker if possible.
Never leave an unconscious patient face up to call for help, as they risk airway obstruction. Position them on their side before leaving.
Communicate three essential details to emergency services: the location (with specific building, floor, and room numbers in healthcare facilities), the number of patients, and the nature of the emergency. Request an AED immediately, as early defibrillation provides the greatest chance of survival in cardiac arrest.
Step 2. Open the airway and assess breathing
You position the patient and manage their airway once you confirm unresponsiveness and activate emergency help. This step of the basic life support algorithm requires you to physically open the airway, assess breathing quality, and decide within 10 seconds whether to begin chest compressions. Your actions here directly determine whether you proceed to resuscitation or place the patient in recovery position.
Perform the head tilt/chin lift maneuver
Place one hand on the patient’s forehead and your other hand under the bony part of their chin. Push down on the forehead while lifting the chin upward, tilting the head backward to extend the neck. This maneuver pulls the tongue away from the back of the throat, opening the airway passage. Your chin lift should raise the jaw without applying pressure to the soft tissues under the chin, as this pressure can obstruct rather than open the airway.
Keep the patient’s mouth slightly open during this procedure. You maintain this airway position throughout your breathing assessment, as allowing the head to return to a neutral position closes the airway again. The head tilt/chin lift remains the standard technique for all unconscious adults unless you have specific training in alternative airway management methods.
Assess for normal breathing (10-second check)
Position your face close to the patient’s mouth and nose while maintaining the open airway. You simultaneously look for chest movement, listen for breath sounds, and feel for air movement against your cheek. Spend no more than 10 seconds on this assessment, as delays in starting compressions reduce survival rates.
Watch the chest and upper abdomen for regular rise and fall. Normal breathing produces obvious, rhythmic chest expansion. Listen carefully at the patient’s mouth and nose for the sound of air moving in and out. Feel for exhaled air on your cheek, which confirms air movement through the airway.
Recognize breathing patterns that require CPR
Identify absent breathing or abnormal breathing as your triggers to begin resuscitation immediately. Abnormal breathing includes gasping, occasional slow breaths, or irregular patterns that fail to provide adequate ventilation. Many rescuers mistake agonal gasps for normal breathing, but these gasps represent a brainstem reflex during cardiac arrest, not effective respiration.
Agonal breathing appears as infrequent, irregular gasps or snoring sounds. Treat any gasping patient as requiring immediate CPR.
You must also clear the airway if you see vomit, blood, or foreign material during your assessment. Turn the patient’s head to the side, allowing fluids to drain. Use a finger sweep to remove solid objects from the mouth. Once you clear the airway, reassess breathing before deciding your next action. Patients who breathe normally after airway opening should be placed on their side in the recovery position. Any patient who remains unresponsive with absent or abnormal breathing requires immediate chest compressions.
Step 3. Start chest compressions and rescue breaths
You begin chest compressions immediately after confirming the patient is unresponsive with absent or abnormal breathing. This step of the basic life support algorithm requires you to deliver high-quality compressions combined with rescue breaths in a specific ratio. Your compressions maintain minimal blood flow to the brain and vital organs, while rescue breaths provide oxygen. Both actions work together to sustain life until advanced help arrives.
Compress first, breathe second. You prioritise chest compressions over rescue breaths because compressions generate the critical blood flow that keeps organs viable. Research shows that continuous compressions without rescue breaths still provide better outcomes than no CPR at all. However, trained healthcare professionals should deliver both compressions and breaths, as the combination provides optimal resuscitation.
Position yourself and locate the compression point
Kneel beside the patient’s chest, positioning yourself close enough to deliver vertical compressions without reaching. Place the heel of one hand on the centre of the patient’s lower sternum (the lower half of the breastbone). You find this landmark by locating where the ribs meet at the bottom of the sternum, then measuring two finger widths up from this point.
Stack your second hand on top of the first hand, interlocking your fingers to keep them off the ribs. Your shoulders should sit directly above your hands, creating a straight line from shoulders through arms to hands. This alignment allows you to use your body weight rather than arm strength, preventing fatigue and maintaining compression quality throughout the resuscitation.
Deliver high-quality chest compressions
Push straight down on the sternum, depressing it at least 5 centimetres but not exceeding 6 centimetres in adults. Your compressions must be forceful enough to generate blood flow, but excessive depth risks rib fractures and internal injuries. Allow the chest to recoil completely between compressions, lifting your hands slightly without losing contact with the sternum.
Maintain a compression rate of 100 to 120 per minute, roughly matching the tempo of familiar songs at this pace. Count compressions out loud to maintain rhythm and track your progress toward the 30-compression target. Your compression rhythm should remain regular and consistent, avoiding erratic patterns or variable depths.
Deliver 30 compressions followed by 2 rescue breaths, repeating this 30:2 cycle continuously until the AED arrives or the patient shows signs of life.
Key compression parameters include:
| Parameter | Target | Critical Points |
|---|---|---|
| Depth | 5-6 cm | At least 5 cm, not more than 6 cm |
| Rate | 100-120/min | About 2 compressions per second |
| Recoil | Complete | Chest fully expands between compressions |
| Interruptions | Minimal | Pause only for breaths and AED analysis |
| Hand position | Lower sternum centre | Two finger widths above xiphoid process |
Provide rescue breaths between compressions
Open the airway using the head tilt/chin lift after delivering 30 compressions. Take a normal breath, then seal your mouth completely over the patient’s mouth while pinching their nostrils closed. Blow steadily for about 1 second, watching for visible chest rise. If the chest doesn’t rise, reposition the head and try again, as poor airway opening causes most breath delivery failures.
Deliver the second rescue breath using the same technique, allowing the chest to fall between breaths. Each breath should achieve visible chest movement without overinflation, which risks gastric distension and reduces the effectiveness of subsequent compressions. Your breath volume should match what you’d use for a normal breath, not a deep or forceful exhalation.
Return immediately to chest compressions after delivering both breaths, minimising the pause to less than 10 seconds. Continue the 30:2 cycle without stopping to check for response or breathing unless the patient shows obvious signs of life such as normal breathing, coughing, or movement. If you’re unwilling or unable to give rescue breaths, provide continuous chest compressions without pausing, as compression-only CPR still saves lives.
Step 4. Attach AED, follow prompts and hand over care
You retrieve and deploy the automated external defibrillator (AED) as soon as it arrives at the scene, as this step of the basic life support algorithm delivers the definitive treatment for cardiac arrest caused by shockable rhythms. The AED analyses the patient’s heart rhythm and determines whether an electrical shock will restore normal cardiac function. Your role shifts from manual resuscitation to supporting the AED’s operation, following voice and visual prompts while maintaining high-quality CPR between rhythm analyses.
Apply AED pads correctly to bare skin
Turn on the AED immediately after opening the case, as most devices activate automatically when opened or require a single button press. Expose the patient’s bare chest completely, removing all clothing and wiping away moisture, sweat, or medication patches that interfere with pad contact. You cut through clothing with scissors if removal proves difficult, prioritising speed over preserving garments.
Place the first pad on the patient’s upper right chest just below the collarbone, positioning it to the right of the sternum. Apply the second pad on the left side of the chest below and to the left of the nipple, in the mid-axillary line. Press each pad firmly onto the skin, smoothing from the centre outward to eliminate air pockets that reduce electrical conductivity.
Remove excessive chest hair only if it prevents proper pad adhesion. Quickly shave or use a second set of pads to remove hair by pressing and ripping off.
Alternative pad placements include anterior-posterior positioning (one pad on the front of the chest over the heart, one pad on the back between the shoulder blades) when standard placement isn’t possible. You maintain at least 8 centimetres distance from implanted medical devices such as pacemakers or defibrillators, repositioning pads if necessary to avoid direct contact with these devices.
Follow AED voice prompts without interruption
Stand clear of the patient when the AED instructs “Analysing rhythm, do not touch the patient.” The device cannot accurately assess the heart rhythm if anyone touches the patient during analysis. Ensure all rescuers and bystanders step back, visually confirming that nobody maintains contact with the patient or the surface they’re lying on.
Listen for the AED’s instruction after analysis completes. When the device advises “Shock advised,” you press the flashing shock button only after confirming everyone is clear. Announce “Stand clear” loudly before delivering the shock. The device delivers a controlled electrical current through the chest, causing the patient’s muscles to contract briefly.
Resume chest compressions immediately after shock delivery, continuing for two minutes before the AED analyses the rhythm again. If the AED advises “No shock advised,” restart compressions without delay and continue for two complete minutes. You never remove the AED pads or turn off the device, as the patient may develop a shockable rhythm later in the resuscitation.
Hand over to paramedics and document events
Continue the CPR and AED cycle until ambulance paramedics arrive or the patient shows signs of recovery such as normal breathing, coughing, or purposeful movement. When advanced life support personnel take over, provide a brief handover covering the time of collapse, interventions performed, number of shocks delivered, and any witnessed changes in the patient’s condition.
Prepare a concise summary using this structure:
| Information Type | Details to Report |
|---|---|
| Event timeline | Time found, time CPR started, time of first shock |
| Patient details | Name, age, known medical conditions |
| Interventions | Number of CPR cycles, number of shocks delivered |
| Observations | Witnessed collapse, initial rhythm, response to treatment |
Record the AED serial number and note any special circumstances for quality assurance purposes after the emergency resolves.
Bringing it all together
You now have the complete ANZCOR basic life support algorithm mapped out in practical steps you can apply immediately. Each phase builds on the previous one, from your initial danger assessment through to AED deployment and handover. This systematic approach removes guesswork and ensures you deliver evidence-based resuscitation care that meets national standards.
Knowing the algorithm and applying it under pressure require different skill levels. You build confidence through regular practice, hands-on training, and scenario-based learning that simulates real cardiac arrest situations. Your muscle memory for compression depth, hand placement, and AED operation develops through repetition, not reading alone.
Book an ALS course to refresh your practical skills and maintain your professional credentials. Accredited training ensures you stay current with the latest resuscitation guidelines while earning the CPD points your registration requires.
