Does the patient look unconscious? If so, perform the BLS Survey. Does the patient look conscious? If so, perform the ACLS Survey. The BLS Survey The BLS Survey includes four steps:
The ACLS Survey
When the BLS survey is complete or if the patient is conscious and responsive, the responder should conduct the ACLS survey with a focus on identifying and treating the underlying cause(s) of the patient’s problem.
The ACLS Survey follows A, B, C, and D: Airway, Breathing, Circulation, and Differential Diagnosis.
- Assess Airway – Use the least advanced airway possible to maintain the airway and oxygenation (laryngeal mask, laryngeal tube, or esophageal tracheal tube).
- Assess Breathing – Monitor tube placement and oxygenation using waveform capnography if available; avoid excessive ventilation.
- Assess Circulation – Medications, CPR, fluids and defibrillation when needed according to the ACLS cases.
- Determine Differential Diagnosis – Use an AED or defibrillator to identify the arrhythmia or symptoms and treat reversible causes.
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Last updated: March 15, 2022
Version control: Our ACLS, PALS & BLS courses follow 2020 American Heart Association Guidelines for CPR and ECC. American Heart Association guidelines are updated every five years. If you are reading this page after December 2025, please contact for an update. Version 2021.01.c
The main focus of the BLS Primary Survey is early CPR and early defibrillation, if needed. For a patient in respiratory arrest, however, the focus is on breathing and airway issues. The process starts with assessing the patient and then perform an appropriate action. Each step in the survey has an assessment and actions to follow.
Is the patient breathing? | Look for the rise and fall of the patient's chest. |
Does the patient have a pulse? | The healthcare provider can take 5–10 seconds to check for a pulse. |
AED | When the AED arrives, turn it on and follow the prompts |
Is the patient breathing NORMALLY? (small gasping breaths are not considered normal.
If no pulse – BEGIN COMPRESSIONS at a rate of 100/min to 120/min.
If not sure if a pulse is present, BEGIN COMPRESSIONS at a rate of 100/min to 120/min.
If pulse is present and breathing absent, begin ventilation at a rate of 10 per minute or once every 6 seconds using mouth to mouth or bag valve mask.
The last step, defibrillation, is part of the primary survey, but is not required for respiratory arrest as the patient has a pulse for this case. Therefore the AED will advise the user "no shock advised, continue CPR if necessary."