Introduction to Basic Life Support

Basic Life Support: A Complete Guide What Is Basic Life Support? Basic Life Support (BLS) is an emergency procedure designed to maintain circulation and oxygen delivery to vital organs—particularly the brain and heart—in a person who is unresponsive and not breathing. It serves as a critical bridge between the moment someone collapses and when professional medical personnel arrive to provide definitive care. The core idea behind BLS is simple: when a person's heart stops beating effectively, blood no longer flows through the body. Without oxygenated blood reaching the brain and other vital organs, permanent damage or death can occur within minutes. BLS keeps blood flowing through physical chest compressions, and if trained providers have a barrier device, through rescue breathing as well. The Initial Assessment: Checking for Life-Threatening Conditions Before you can help someone, you need to quickly evaluate the situation. This process has several critical steps. Step 1: Ensure Your Safety Always assess the scene first. Look for hazards that could harm you—traffic, downed power lines, chemical spills, or violence. You cannot help if you become a victim yourself. Only approach the person if it's safe to do so. Step 2: Check Responsiveness Tap the person's shoulder firmly and shout, "Are you okay?" This tells you immediately whether the person is conscious. If they respond, they don't need BLS—instead, you'd provide care appropriate to their condition and call emergency services if needed. Step 3: Assess Breathing If the person is unresponsive, determine their breathing status. Look for normal chest rise and fall. Be aware of a critical distinction: gasping is not normal breathing. A person in cardiac arrest may gasp irregularly—this is a reflex, not effective breathing. If the person is not breathing normally or is only gasping, they need immediate BLS and emergency services activation. Step 4: Call Emergency Services If the person is unresponsive and not breathing (or only gasping), call 911 immediately. If you're alone, use the speakerphone feature on your phone so you can continue assessment and intervention while staying on the line with dispatch. This step is critical because professional help is needed urgently. Chest Compressions: The Heart of BLS Chest compressions manually pump blood throughout the body by compressing the heart against the backbone. This is the most important part of BLS. Location and Depth Place the heel of one hand on the center of the sternum (breastbone), just above the nipple line. Place your other hand on top, interlacing the fingers. Now push down hard and fast. Compressions must be at least 2 inches (5 centimeters) deep—this depth is necessary to generate enough pressure to move blood forward. Rate Perform compressions at a rate of 100 to 120 compressions per minute. Many rescuers find it helpful to match compressions to a beat—the Bee Gees song "Stayin' Alive" has the right tempo, as do many pop songs. The rhythm matters because compressions that are too slow or too fast reduce their effectiveness. Full Recoil Between each compression, allow your hands to come completely off the chest so it fully recoils. This full recoil is essential for allowing blood to flow back into the heart chambers, which maximizes the forward flow on the next compression. Continuous Compressions Once you begin compressions, continue them without pause. Do not stop to check for a pulse, assess breathing, or reassess the person. Compressions should continue until an automated external defibrillator (AED) arrives, professional help takes over, or the person shows clear signs of life (normal breathing or purposeful movement). Even brief pauses in compressions reduce survival chances. Adding Breathing: Ventilation for Trained Rescuers If you are trained and have a barrier device (such as a face shield or bag-valve-mask), you should combine compressions with ventilation. The Compression-to-Ventilation Ratio After every 30 chest compressions, deliver 2 rescue breaths. This 30:2 ratio balances the oxygen delivery benefits of breathing for the victim with the critical importance of keeping blood flowing through compressions. To deliver rescue breaths safely with a barrier device, create an airtight seal over the person's mouth and nose, then blow steadily for 1 second, watching for chest rise. Effective breaths should make the chest visibly rise. Important Note on Hands-Only CPR If you are untrained or do not have a barrier device, provide hands-only compressions only. Do not attempt mouth-to-mouth ventilation without training or a barrier. Research shows that hands-only compressions are highly effective, especially in adults, and they eliminate the reluctance some rescuers feel about mouth-to-mouth contact. Continuous chest compressions alone provide significant survival benefit compared with no intervention. Using an Automated External Defibrillator An AED is a portable device that analyzes a person's heart rhythm and can deliver an electrical shock to restore normal heartbeat in certain cardiac arrest rhythms. Getting the AED As soon as an AED becomes available—whether from your facility, a nearby public location, or emergency responders—attach it to the victim. If you're alone, call 911 first, then retrieve the nearest AED. If others are present, send someone to fetch the AED immediately while you start compressions. Operation Turn on the AED and follow its voice prompts. The device will expose the person's chest, place adhesive pads on the skin (typically one below the right collarbone and one on the left mid-axillary line), and analyze the heart rhythm. The AED determines whether a shock is needed. If a Shock Is Advised Ensure no one is touching the person, then press the shock button when prompted. After shock delivery, immediately resume chest compressions at the 30:2 ratio (or hands-only compressions if trained providers are not present). Continue following the AED's prompts, which typically ask you to resume compressions after each analysis interval. Monitoring for Recovery As you perform BLS, continuously watch for signs that the person's heart has begun beating effectively again—a state called Return of Spontaneous Circulation (ROSC). Signs of ROSC Normal breathing (not gasping) Purposeful movement (the person moves intentionally or responds to stimuli) A palpable pulse (if you're trained to check) If you notice any of these signs, stop chest compressions and reassess the person's breathing and responsiveness. If breathing is normal and the person is responsive, place them in the recovery position (on their side) and monitor them carefully until professional help arrives. Important: Even after ROSC, keep the airway open and stay alert for another collapse. The person's condition can change rapidly. Professional medical personnel need to take over as soon as they arrive to provide ongoing monitoring and definitive care. From Emergency Response to Professional Care Your role as a BLS rescuer is to maintain life support until professional paramedics or emergency medical technicians arrive. Once they take over, provide them with a brief summary of what happened: when the person collapsed, how long you performed CPR, whether an AED was used, and whether the person showed any signs of recovery. Throughout this entire process, remember that you are performing a life-saving intervention. Every compression counts, and even if the outcome is uncertain, performing BLS gives the person the best chance of survival.