Basic Life Support (BLS) is not the same as Cardiopulmonary Resuscitation (CPR), though they are closely related in emergency medicine. CPR is a specific, manual skill set used to maintain circulation and oxygenation when a person’s heart has stopped. BLS is a comprehensive, systematic protocol of care that recognizes life-threatening emergencies, activates the emergency medical services (EMS) system, and provides immediate interventions, including CPR. BLS functions as the umbrella framework, integrating several life-saving techniques until advanced medical help arrives.
What is Cardiopulmonary Resuscitation (CPR)?
Cardiopulmonary Resuscitation is a physical intervention designed to manually pump blood to the brain and other vital organs when the heart is ineffective. This technique involves chest compressions and rescue breathing, following the “C-A-B” sequence: compressions, airway, and breathing. The goal is to sustain life until the heart’s normal rhythm can be restored.
High-quality chest compressions are the most important part of modern CPR, circulating oxygenated blood. Rescuers push hard and fast on the center of the chest, aiming for 100 to 120 compressions per minute. For adults, the depth should be at least 2 inches (5 cm), but no more than 2.4 inches (6 cm). Minimizing interruptions is a primary focus, as pauses significantly reduce the blood pressure needed to perfuse the brain.
Conventional CPR for trained rescuers involves alternating 30 compressions with two rescue breaths. Rescue breathing is delivered after compressions to ensure the airway is open. For lay rescuers, compression-only CPR is often recommended, as it provides the most critical element—blood flow—without the hesitation associated with rescue breathing.
The Comprehensive Scope of Basic Life Support (BLS)
Basic Life Support represents the systematic process of responding to a sudden cardiac or respiratory emergency, extending beyond the isolated skill of CPR. The BLS protocol begins with an initial assessment, where the rescuer must first ensure scene safety. This is followed by checking for responsiveness and signs of life, which informs subsequent steps.
A core component of BLS is the immediate activation of the emergency response system (e.g., calling 911) and retrieving an automated external defibrillator (AED). This step sets the entire Chain of Survival in motion, recognizing that time is a factor for survival. BLS training also encompasses recognizing and treating a foreign body airway obstruction, such as choking, using techniques like the Heimlich maneuver.
This systematic approach is guided by the Chain of Survival, which outlines actions that increase the likelihood of survival from cardiac arrest. The BLS provider is responsible for the first three links: immediate recognition and activation of EMS, early high-quality CPR, and rapid defibrillation. BLS transforms CPR from a singular action into an integrated, coordinated response for effective emergency care.
The Critical Role of Early Defibrillation
Early defibrillation is a distinct, life-saving intervention taught within the BLS curriculum, separate from the physical actions of CPR. Most sudden cardiac arrests in adults are caused by ventricular fibrillation, a chaotic electrical rhythm. An Automated External Defibrillator (AED) delivers a controlled electrical shock to interrupt this abnormal rhythm, allowing the heart’s natural pacemaker to reset.
The time elapsed until defibrillation is the most important factor determining survival from cardiac arrest. For every minute defibrillation is delayed, the chance of survival decreases significantly. BLS providers are trained to integrate AED use seamlessly with chest compressions, minimizing the pause in blood flow.
The AED is an easy-to-use device that analyzes the patient’s heart rhythm and provides voice prompts. Once the pads are applied, the machine determines if a shockable rhythm is present. If a shock is advised, the rescuer delivers the electrical charge, followed immediately by resuming chest compressions.