Basic Life Support (BLS): What You Need to Know

Basic Life Support (BLS)

BLS is a set of fundamental skills used to preserve life in individuals experiencing cardiac arrest, respiratory failure, or choking. By promptly intervening with BLS techniques, you can significantly increase a person’s chances of survival until advanced medical care arrives.

This comprehensive guide will equip you with the knowledge and understanding of essential BLS components. We’ll delve into recognizing emergencies, performing CPR (Cardiopulmonary Resuscitation), using an AED (Automated External Defibrillator), and maintaining a safe environment for both the patient and yourself.

Recognizing a Life-Threatening Emergency

The first crucial step in BLS is recognizing a situation where immediate action is necessary. Here are some key signs to watch for:

  • Unconsciousness: The person is unresponsive and doesn’t awaken even with strong stimulation (shaking or shouting).
  • Absence of Breathing: There’s no observable chest rise and fall, and you cannot feel or hear breath sounds when placing your ear close to the mouth and nose.
  • Abnormal Breathing: The person is gasping, wheezing, or experiencing difficulty breathing.
  • No Pulse: No detectable pulse at the carotid artery (located on the neck, just below the jawbone).

If you encounter any of these signs, it’s imperative to act swiftly and initiate BLS procedures. Remember, early intervention is critical in improving the chances of survival.

The Chain of Survival: A Framework for BLS Intervention

The American Heart Association outlines the Chain of Survival, a four-link model that emphasizes the importance of each step in a successful resuscitation attempt.

  • Early Access: This involves recognizing an emergency and immediately calling for help by dialing emergency medical services (EMS).
  • Early CPR: Promptly initiating CPR with high-quality chest compressions to maintain blood circulation.
  • Early Defibrillation: Utilizing an AED as soon as possible to shock the heart back into a normal rhythm.
  • Early Post-Resuscitation Care: Providing continued care and support to the person until advanced medical professionals arrive.

Each link in the Chain of Survival is equally important. By effectively performing BLS techniques and ensuring a smooth transition to advanced medical care, you can significantly improve the person’s outcome.

Performing CPR: Chest Compressions and Rescue Breaths

Cardiopulmonary Resuscitation (CPR) is a core BLS technique that combines chest compressions with rescue breaths (if trained) to artificially maintain blood circulation and oxygen delivery to the body. Here’s a breakdown of the steps involved in performing CPR for adults:

  1. Scene Safety: Before approaching the person, ensure it’s safe for you to intervene. Look for potential hazards like traffic, electrical dangers, or unstable environments.
  2. Check for Unconsciousness: Gently tap the person on the shoulder and ask loudly, “Are you okay?” If they don’t respond, proceed to the next step.
  3. Call for Help: Activate the emergency medical services (EMS) immediately. Put the phone on speakerphone if possible, so you can continue with CPR.
  4. Position Yourself: Kneel next to the person on a firm surface.
  5. Locate the Compression Point: Place the heel of your dominant hand on the center of the chest, between the nipples.
  6. Interlock Fingers: Place your other hand on top of the first hand, with fingers interlaced.
  7. Push Hard and Fast: Deliver chest compressions with a depth of at least 2 inches (5 cm) at a rate of 100-120 compressions per minute. Aim for a smooth and complete recoil of the chest after each compression.
  8. Minimize Interruptions: Minimize pauses between compressions to maintain blood flow.
  9. Rescue Breaths (Optional): If you are trained in rescue breathing, you can provide breaths after every 30 compressions. Tilt the head back and lift the chin to open the airway. Pinch the nose closed and create a seal with your mouth over the person’s mouth. Deliver one breath that takes about 1 second, ensuring the chest rises.
  10. Continue CPR: Repeat cycles of 30 chest compressions (if performing rescue breaths) or uninterrupted compressions (if not trained in breaths) until help arrives or the person shows signs of recovery (regains consciousness, starts breathing normally).

Remember: Even if you are not trained in rescue breaths, performing hands-only CPR with high-quality chest compressions can be lifesaving.

Using an Automated External Defibrillator (AED)

An Automated External Defibrillator (AED) is a portable electronic device that analyzes the heart rhythm and delivers an electrical shock, if necessary, to restore a normal heart rhythm in individuals experiencing sudden cardiac arrest. Here’s how to use an AED effectively:

  1. Retrieve the AED: If an AED is available nearby, retrieve it immediately. Most public buildings, workplaces, and even some airplanes are equipped with AEDs.
  2. Turn on the AED: Once you have the AED, power it on. The device will provide clear voice instructions guiding you through the process.
  3. Prepare the Person: Carefully remove any wet clothing from the person’s chest.
  4. Attach the AED Pads: The AED will have adhesive pads with clear instructions for placement. Typically, one pad goes on the bare chest, on the upper right side, and the other pad goes on the left side, below the collarbone.
  5. Analyze the Rhythm: The AED will analyze the person’s heart rhythm. Do not touch the person while the AED is analyzing.
  6. Follow the Instructions: The AED will instruct you on the next steps. If a shock is advised, the AED will automatically deliver the shock.
  7. Continue CPR: After a shock is delivered (if recommended), or if no shock is advised, resume CPR with chest compressions at a rate of 100-120 compressions per minute.
  8. Repeat Steps: Continue following the AED’s instructions, which may involve repeating rhythm analysis and potentially delivering additional shocks.
  9. Continue CPR Until Help Arrives: Keep performing CPR cycles (compressions only or with breaths if trained) until the person regains consciousness, starts breathing normally, or help arrives from emergency medical services.

Using an AED is a straightforward process. The device is designed to be user-friendly, even for those with no prior medical training. By following the clear voice instructions, you can significantly increase the chances of survival for someone experiencing sudden cardiac arrest.

Maintaining a Safe Environment for BLS Care

While providing BLS care, it’s crucial to ensure a safe environment for both yourself and the person in need. Here are some key points to remember:

  • Universal Precautions: Practice universal precautions to protect yourself from potential bloodborne pathogens. Wear gloves if available and avoid contact with bodily fluids.
  • Scene Safety: Always assess the scene for potential hazards before approaching the person. This includes dangers like traffic, unstable structures, electrical wires, or hostile environments.
  • Body Mechanics: Maintain proper body mechanics while performing CPR to avoid injury to yourself. Keep your back straight and knees bent when delivering chest compressions.
  • Stay Calm: Emergency situations can be stressful, but remaining calm is essential. Taking deep breaths and focusing on each step of the BLS procedure will ensure you can provide effective care.

The Importance of BLS Training

While this article provides a general overview of BLS techniques, it is highly recommended to take a formal BLS training course. BLS courses offered by organizations like the American Heart Association (AHA) or the American Red Cross provide hands-on training and certification in performing CPR and using an AED.

A certified BLS provider will have the knowledge, skills, and confidence to effectively intervene in a life-threatening emergency. The training also covers important aspects like choking management and proper communication with emergency services.


Basic Life Support (BLS) equips you with the fundamental skills to potentially save a life in a critical situation. By recognizing the signs of a life-threatening emergency, performing CPR, using an AED, and maintaining a safe environment, you can significantly improve the person’s chances of survival until advanced medical care arrives.

Remember, every second counts in an emergency. Even if you are not formally trained in BLS, performing hands-only CPR with high-quality chest compressions can make a crucial difference. Taking a BLS training course is an invaluable investment in learning potentially lifesaving skills.

Empower yourself with the knowledge of BLS and be prepared to act when faced with a medical emergency.