Apr 17

ABC stands for Airway, Breathing, and Circulation. It's a foundational approach used in patient assessment used to identify actual or potential life threats. Here's when and how each component of ABC is typically applied: 

  1. Airway: Assessing and maintaining a clear airway is the first priority in EMS. This involves checking if the patient's airway is open and unobstructed. If necessary, interventions such as head-tilt chin-lift or jaw thrust maneuvers can be used to open the airway. In some cases, adjuncts like oropharyngeal or nasopharyngeal airways may be inserted to maintain airway patency. 
  1. Breathing: Once the airway is secured, the focus shifts to assessing the patient's breathing. This includes checking for adequate respiratory rate and depth, signs of respiratory distress or difficulty, and the presence of abnormal breath sounds. Patients with compromised breathing may require interventions such as supplemental oxygen administration, assisted ventilation (e.g., bag-valve-mask ventilation), or advanced airway management (e.g., endotracheal intubation). 
  1. Circulation: After addressing the airway and breathing, the next step is to evaluate circulation. This involves assessing the patient's pulse, skin color, temperature, and capillary refill time to determine perfusion status. It also includes identifying uncontrolled bleeding. Patients with compromised circulation may receive treatment for shock and treatments for uncontrolled bleeding (e.g., pressure dressing, tourniquet, fluid resuscitation). 

The ABC approach serves as a systematic method to quickly identify and address life-threatening issues in a patient. However, if you at any point identify that one life threat will kill a patient before another life threat, you must treat the deadliest life threat first. For example, an arterial bleed will kill someone much faster than snoring respirations (partial airway obstruction) will. In this example, even though they have a compromised airway, we would control the bleeding first and then address the airway concern.

In patients who have gone into cardiac arrest, you will use CAB instead of ABC. This means that you will start compressions first and then manage your airway and breathing.

The use of CAB (Circulation, Airway, Breathing) instead of ABC (Airway, Breathing, Circulation) in EMS reflects a shift in emphasis based on evolving best practices in emergency care. The CAB sequence is primarily used in situations where cardiac arrest is suspected or confirmed. Here's when and why CAB is used instead of ABC: 

  1. Cardiac Arrest Management: In cases of cardiac arrest, the primary concern is restoring circulation and perfusion as quickly as possible to maximize the chances of survival. Therefore, the CAB sequence prioritizes circulation (C) first, followed by airway (A) and breathing (B).
  1. Rationale for CAB:  
  • Circulation (C): The first step is to assess the patient's circulation by checking for the presence or absence of a pulse. If no pulse is detected, immediate cardiopulmonary resuscitation (CPR) should be initiated to maintain blood flow and vital organ perfusion.
  • Airway (A): Once CPR has been started, attention is then directed to securing the airway to ensure it is patent. This may involve basic maneuvers like head-tilt chin-lift or more advanced airway interventions such as insertion of an advanced airway device (e.g., endotracheal tube).
  • Breathing (B): After the airway is managed, the focus shifts to assessing breathing and providing appropriate ventilation if needed. This could involve bag-valve-mask ventilation or deployment of advanced airway devices for controlled ventilation. 
  1. Simplicity and Efficiency: The CAB approach is designed to simplify and expedite the initial management of cardiac arrest patients, emphasizing the critical importance of early and effective chest compressions to maintain vital blood flow to the heart and brain. 
  1. Integration with CPR Guidelines: The CAB sequence aligns with current guidelines for cardiopulmonary resuscitation (CPR) recommended by organizations like the American Heart Association (AHA), which emphasize the importance of high-quality chest compressions as the cornerstone of resuscitation efforts. 

In summary, the CAB sequence is specifically used in cases of suspected or confirmed cardiac arrest.