Airway, Breathing, and Circulation Support
Airway, breathing, and circulation (ABC) is the organizing framework of acute and critical care, prioritizing the physiologic functions on which life most immediately depends: a patent airway, adequate gas exchange, and effective tissue perfusion. This area groups the nursing knowledge needed to assess and support these functions in critically ill and emergency patients, from airway protection and mechanical ventilation to resuscitation and circulatory support.
Definition
Airway, breathing, and circulation support is the prioritized assessment and maintenance of airway patency, ventilation and oxygenation, and circulatory perfusion in patients with actual or threatened failure of these functions.
Scope
The area orients the reader to the ABC priorities and the interventions that support each: airway management and intubation, mechanical ventilation, oxygen delivery, cardiopulmonary resuscitation, and circulatory support with vasoactive agents. It frames these as a coherent system of physiologic support within critical and emergency nursing rather than as procedure-by-procedure instructions.
Sub-topics
Core questions
- Is the airway patent and protected, and what threatens it?
- Is gas exchange adequate, and does it require supplemental oxygen or mechanical support?
- Is tissue perfusion sufficient, and what circulatory support does it require?
- How are these priorities sequenced and reassessed during resuscitation?
Key concepts
- ABC prioritization and the primary survey
- Airway patency and protection
- Oxygenation versus ventilation
- Tissue perfusion and shock
- Resuscitation as a time-critical sequence
- Continuous reassessment
Mechanisms
The ABC sequence reflects the order in which failure of vital functions causes death: airway obstruction kills within minutes, inadequate breathing within minutes more, and circulatory failure over a slightly longer but still short interval. Supporting each function in turn restores the substrate for the next: a patent airway permits ventilation, ventilation and oxygen delivery support gas exchange, and restored circulation distributes oxygenated blood to tissues. Critical-care nursing applies continuous monitoring to detect deterioration in any of these and to titrate support, recognizing that the three functions are physiologically coupled.
Clinical relevance
The ABC framework structures bedside assessment and the response to deterioration across emergency and intensive-care settings, and it underlies resuscitation algorithms and rapid-response systems. This area describes how these priorities and supports are organized as reference knowledge; it is not a protocol for managing an individual patient.
Epidemiology
Failure of airway, breathing, or circulation underlies the major causes of preventable death in acute care, including cardiac arrest, respiratory failure, and shock, which together account for a large share of intensive-care admissions and in-hospital mortality.
History
The explicit ABC mnemonic emerged from mid-twentieth-century advances in resuscitation, as closed-chest cardiac massage and mouth-to-mouth ventilation were combined into modern cardiopulmonary resuscitation and codified by professional bodies. The framework was subsequently extended from cardiac arrest into a general primary-survey approach used throughout emergency and critical care.
Related topics
Seminal works
- panchal-2020
Frequently asked questions
- Why is airway assessed before breathing and circulation?
- Because the functions are sequenced by how quickly their failure becomes fatal: an obstructed airway prevents any effective ventilation, so it must be secured before breathing and circulation can be meaningfully supported.
- Does the ABC order ever change?
- Some resuscitation guidance reorders the steps in specific situations, such as prioritizing chest compressions in adult cardiac arrest, but airway, breathing, and circulation remain the core functions that any acute assessment must address.