Adult BLS: Importance, Algorithm, and Techniques

Last updated:
June 3, 2023

When it comes to providing emergency care to adult patients in critical situations, the Adult BLS Algorithm is an indispensable tool. This sequence of techniques and interventions serves as a guiding light for healthcare professionals, enabling them to deliver timely and effective care that can ultimately make the difference between life and death. Understanding the BLS algorithm's sequence and techniques is crucial for healthcare providers, as it empowers them to optimize patient outcomes in emergency scenarios. 


What is Adult Basic Life Support?

The Adult BLS Algorithm is a structured sequence of techniques and interventions designed to provide immediate life support to adult patients experiencing cardiac arrest or other life-threatening emergencies. BLS for adults refers specifically to the set of procedures used for adults who are experiencing these types of emergencies.

The rationale behind the design of the BLS Algorithm is based on scientific evidence and extensive research on resuscitation techniques. The algorithm is continuously updated and refined by organizations such as the American Heart Association (AHA) and the European Resuscitation Council (ERC) to incorporate the latest advancements and best practices in resuscitation.


One Rescuer BLS for Adults

One rescuer BLS for adults is a technique that involves a single rescuer providing chest compressions and rescue breaths to an adult in cardiac arrest. This approach requires the rescuer to perform all of the necessary tasks, including checking for a pulse, starting compressions, and providing rescue breaths. It is essential to know the appropriate steps for this technique to provide effective and efficient care to the patient.


Recognition of Cardiac Arrest and Emergency Response Activation

Recognition of cardiac arrest and activation of the emergency response system are crucial steps in the Adult Basic Life Support (BLS) Algorithm. Prompt recognition allows you to initiate a rapid and coordinated response, leading to timely interventions and improved patient outcomes.

Related Article:
Understanding Cardiac Arrest: Causes, Symptoms, Treatment, and Prevention

Check Responsiveness

To check for responsiveness, shake the cardiac arrest victim's shoulder and ask if they are okay. Simultaneously, look at the chest and torso for movement and normal breathing.

  • If you witnessed the adult victim collapse, assume cardiac arrest with a shockable rhythm. If you can get an Automated External Defibrillator quickly, you may leave the victim to call 911, get an AED, and do CPR for 2 minutes.
  • Clearly communicate the situation: "I suspect cardiac arrest. Activate the emergency response system immediately."
  • If you find an unresponsive adult, tailor your response to the presumed cause of injury.
  • If you suspect cardiac arrest: Call 911, get an AED, perform 2 minutes of CPR, and use the AED once available.
  • If you suspect asphyxia: Perform 2 minutes of CPR, Activate Emergency Medical Services, get AED, use AED


Assess the Patient and Check Pulse

Assess the patient's condition and check for the presence of a pulse. Place your fingers on the side of the patient's neck, feeling for a pulse. If a pulse is absent or difficult to determine within a few seconds, assume cardiac arrest and proceed to CPR immediately.


If the adult victim has a pulse but not breathing, provide adequate rescue breathing:

  • Provide ten rescue breaths per minute or 1 breath every 6 seconds.
  • Recheck the victim's pulse and breathing every 2 minutes.


If the adult victim doesn't have a pulse: Begin CPR starting with chest compressions


Cardiopulmonary Resuscitation

If the adult victim does not have a pulse, or you are not sure whether it is present, begin 5 cycles of CPR, starting with chest compressions: 1 cycle of CPR is 30 compressions to 2 rescue breaths (30:2). You should provide compressions at a rate of 100–120 compressions per minute.


cpr steps for adults


  • Standard CPR without an advanced airway: 6-8 rescue breaths per minute
  • Standard CPR with an advanced airway: 10 rescue breaths per minute
  • If the patient has a pulse and CPR is not required: Provide 10 rescue breaths per minute (1 breath every 6 seconds).


The healthcare provider should continue CPR until the return of spontaneous circulation (ROSC) or until the termination of efforts.


High-Quality CPR includes

  • Minimal interruptions for ventilation
  • Compression rate: 100-120 per minute
  • Compression Depth: 2–2.4 inches
  • 18 seconds per cycle
  • Allow for full chest recoil with each compression.
  • Do not over-ventilate.


Arrival of AED

Prompt defibration is crucial for increasing the chances of survival in cases of cardiac arrest and should be administered upon arrival.

Power: Turn AED ON and follow the voice prompts.

Attachment: Firmly place the adult pads on the patient's chest to the indicated locations, as seen on the pad image.

Analyze: Allow the Automated External Defibrillator to analyze the rhythm.


If the rhythm is not shockable: Administer CPR for 2 minutes and recheck the rhythm every 2 minutes. Then, continue CPR until Advanced Life Support is available.

If the shock is indicated:

  • Ensure no one touches the patient. Shout "Clear, I'm Clear, you're Clear!" before delivering a shock.
  • Press the "shock" button when the rescuers and the crowd are clear of the patient.
  • Resume 5 cycles of CPR.


Recovery Position

If the adult patient starts showing signs of life or breathing normally, place them in the recovery position. This helps maintain an open airway and prevents choking on fluids or vomit. To put the adult victim in a recovery position:

  1. Position the patient in a lateral position with the head dependent to allow drainage of fluids.
  2. Assure the position is stable.
  3. Avoid pressure on the chest that could impair normal breathing.
  4. Position the patient in such a way that will quickly turn them onto their back.
  5. Be careful to stabilize the neck in case of cervical spine injury.
  6. Continue to assess and maintain access to the airway.
  7. Avoid the recovery position if it will sustain harm to the patient.

Related Article:
Recovery Position: Proper Technique and Importance for First Aid

Two-Rescuer BLS for Adults

Two-rescuer BLS for adults is a technique that involves two rescuers working together to provide chest compressions and rescue breaths to an adult in cardiac arrest. This approach allows for more efficient care, as one rescuer can focus on compressions while the other provides rescue breaths. It is essential to know the appropriate steps for this technique to provide effective and efficient care to the patient.


Checking For Responsiveness

Check to see if the adult victim is responsive by shaking the shoulder and asking, "Are you okay?" loudly.

  • Rescuer 1 will stay with the victim.
  • Rescuer 2 will activate the Emergency Medical Services and retrieve an AED.

Assess the Patient and Check Pulse

While the other rescues are calling 911 and looking for an Automated External Defibrillator, the rescuer who stayed with the patient will check for a carotid pulse for 5-10 seconds.


If the adult victim has a pulse, one rescuer will proceed with rescue breathing:

  • Provide ten rescue breaths per minute or 1 breath every 6 seconds.
  • Watch for chest rise.
  • Recheck the victim's pulse every 2 minutes.


If the adult victim doesn't have a pulse: Begin CPR starting with chest compressions.


Begin CPR

If the adult victim does not have a pulse, or there is a question as to whether the pulse is present, begin 5 cycles of CPR, starting with chest compressions:

  • One rescuer will do the chest compressions, and another will do the rescue breathing.
  • Rescuers should switch places every 2 minutes.
  • You should continue cardiopulmonary Resuscitation until the return of spontaneous circulation (ROSC) or until the termination of efforts.


AED Arrival

The rescuer who retrieved the Automated External Defibrillator applies the AED and follows directions given by the device. The rescuers who stayed with the victim will continue CPR until the defibrillator is ready.

  • If a shock is indicated on the device; clear everyone and press the shock button. After providing a shock, other rescuers will resume CPR.
  • Check the victim's pulse and cardiac rhythm every two minutes.
  • Keep going until the EMS arrives or the victim regains spontaneous circulation.

Recovery position

The recovery position maintains a patent airway in the unconscious person.

  1. Place the patient close to a proper lateral position with the head dependent to allow fluid to drain.
  2. Assure the position is stable and avoid pressure on the chest that could impair breathing.
  3. Position patients in such a way that will quickly turn them onto their back.
  4. Take precautions to stabilize the neck in case of cervical spine injury.
  5. Continue to assess the patient and maintain access to the airway.
  6. Avoid the recovery position if it will sustain harm to the patient.


Adult Mouth-to-Mask Ventilation

Adult Mouth-to-Mask Ventilation is a technique used to provide rescue breaths to an adult in cardiac arrest. It is an important skill in two-rescuer BLS/CPR and should be used if the patient does not have a pulse or if rescue breathing cannot be provided with mouth-to-mouth.


If a pocket mask is available, it should be used to supply breaths during one-rescuer CPR. The technique involves:

  • Sealing the mask against the person's face with four fingers on top and the thumb on the bottom edge of the mask.
  • Make sure the mask is sealed tightly to avoid leaks.
  • The airway should then be opened using the head-tilt/chin-lift maneuver, but this should not be done if a neck injury is suspected.
  • After the airway is open, the edges of the mask should be pressed firmly, and deliver two rescue breaths with 1 second of inflation for each breath.
  • Assess for chest rise and fall.
  • Continue providing 10 rescue breaths per minute or 1 breath every 6 seconds.


Bag-Mask Ventilation

Bag-Mask Ventilation is a technique of providing artificial respiration to an adult in cardiac arrest. It involves the use of a face mask connected to a bag that is filled with oxygen. The rescuer compresses the bag, creating pressure within the lungs and forcing oxygen into them. This technique can be used in one-man CPR or as part of two-person CPR.

mouth to mask ventilation guide using bag mask


When two rescuers are present, and a bag-mask device is available:

  • The second rescuer should position themselves at the victim's head while the first rescuer performs chest compressions.
  • The first rescuer should deliver 30 high-quality chest compressions while counting out loud.
  • The second rescuer should hold the bag mask with one hand using the thumb and index finger in a "C" shape on one side of the mask to form a seal between the mask and the victim's face.
  • The other fingers should be used to open the victim's airway by lifting their lower jaw.
  • The second rescuer should then deliver two breaths over one second each while watching the victim's chest rise.
  • Practicing using the bag valve mask is important to ensure a tight seal and effective breath delivery.


Related Article
Bag Valve Mask

Adult Basic Life Support (BLS) Algorithm

This Adult BLS algorithm includes a series of steps that should be followed in a specific order to maximize the chances of survival for the patient. It is important to know the algorithm's appropriate steps and practice them regularly to provide effective and efficient care to the patient.

bls algorithm for adult
bls algorithm for adult

Special Considerations for Pregnancy, Trauma, and Drowning

Adapting the Adult Basic Life Support (BLS) Algorithm to specific situations such as pregnant individuals, trauma victims, or drowning cases requires certain adjustments to address the unique physiological considerations and potential complications associated with these conditions. Here's a discussion of the adaptations and adjustments needed for each scenario:


Pregnant Individuals

When applying the Adult BLS Algorithm to pregnant individuals, certain adaptations are necessary due to the physiological changes and potential impact on both the mother and fetus. Key considerations include:

  • Modifications in Chest Compressions: The rescuer should displace the uterus manually to the left side to prevent aortocaval compression during chest compressions. This displacement allows for better blood flow and oxygen delivery to the heart and brain.
  • Airway Management: It is essential to maintain a clear and open airway. Rescuers should consider the potential for airway obstruction caused by physiological changes and the possibility of regurgitation or aspiration due to pressure on the stomach. Positioning the pregnant individual on their left side can help prevent these complications.
  • External Chest Compressions: Rescuers may need to exert slightly more force during chest compressions due to the increased size of the chest and uterus. Maintaining the appropriate depth and rate of compressions remains crucial for effective resuscitation.


Trauma Victims

The BLS Algorithm for trauma victims includes specific adaptations to address potential injuries and associated complications. Here are some key considerations:

  • Manual Cervical Spine Stabilization: Rescuers should take additional precautions to stabilize the cervical spine when initiating CPR on a trauma victim. Proper immobilization helps minimize the risk of exacerbating spinal cord injuries.
  • Control of Bleeding: If there is significant external bleeding, direct pressure should be applied to control the bleeding before initiating CPR. Hemorrhage control takes precedence to optimize the chances of survival.
  • Airway Management: Airway patency should be ensured while considering potential trauma to the neck or face. Jaw-thrust maneuver without head tilt is preferred to maintain alignment of the cervical spine.
  • Avoiding Aggravation of Injuries: Care should be taken to avoid unnecessary movements or compressions over obvious fractures or areas of injury to minimize further harm.


Drowning Cases

Applying the BLS Algorithm to drowning cases requires specific considerations due to the potential for respiratory compromise and hypoxia. The following adaptations should be kept in mind:

  • Rapid Assessment: Promptly evaluate the patient's responsiveness and breathing status. Patients who are unresponsive or not breathing normally should be assumed to be in cardiac arrest and CPR should be initiated.
  • Airway Management: Clear any airway obstruction such as water, debris, or vomit to facilitate effective ventilation. The head-tilt, chin-lift maneuver can be used to open the airway.
  • Early Ventilation: Early rescue breathing is crucial in drowning cases to oxygenate the body and improve outcomes. Ensure proper ventilation with rescue breaths, maintaining an adequate rate and volume.
  • Hypothermia Management: Hypothermia is common in drowning cases. Rescuers should initiate rewarming measures while providing CPR to prevent further deterioration and optimize the chances of survival.
  • Consideration for Aspiration: Due to the potential for aspiration of water, lung damage, and pneumonia, healthcare providers may need to monitor for signs of respiratory distress or infection and provide appropriate interventions.

How does the Adult BLS algorithm differ for drowning or drug overdose victims?

For drowning or drug overdose victims, the Adult BLS algorithm may differ slightly because of the need for additional steps. If a patient presents with symptoms of a possible drowning, rescue breathing should be performed first before chest compressions are attempted. This is because the water in their lungs needs to be cleared first in order to allow oxygen to reach the body’s organs and tissues.

In cases of a drug overdose, rescue breathing should be performed while administering an opioid antagonist such as naloxone. This is because the opioid antagonist must be administered through the lungs in order to take effect quickly.


How should rescuers monitor the effectiveness of their BLS interventions during adult resuscitation efforts?

When performing BLS on an adult patient, it is important to monitor the effectiveness of interventions to ensure that the patient receives optimal care. Rescuers should check for signs of a pulse and signs of adequate chest rise and fall with each breath delivered. In addition, rescuers should observe chest compression depth and rate and assess for any changes in the patient's color. If these signs are not present, rescuers should re-evaluate and adjust their interventions as necessary.


Application in Different Settings: Pre-hospital and In-hospital

Implementing the Adult Basic Life Support (BLS) Algorithm can vary in pre-hospital and in-hospital environments due to the different settings, available resources, and level of expertise of healthcare providers. Here is a comparison and contrast of the implementation of the Adult BLS Algorithm in these two contexts:

Pre-Hospital Environment:

  1. The pre-hospital environment includes emergency medical services (EMS), where BLS is often initiated by first responders or paramedics at the scene of an emergency before transporting the patient to a medical facility.
  2. Pre-hospital settings may have limited resources compared to a hospital. EMS providers typically carry portable equipment such as automated external defibrillators (AEDs), basic airway adjuncts, and limited medication options.
  3. In the pre-hospital setting, time is of the essence. EMS providers need to quickly assess the situation, recognize cardiac arrest, initiate CPR, and, if available, use an AED to deliver a shock when indicated. Their goal is to stabilize the patient's condition and transport them to a hospital for further advanced care.
  4. Pre-hospital providers must communicate effectively with each other, the patient, and the hospital. They relay vital information about the patient's condition, initiate the emergency response system, and provide updates to the receiving hospital to ensure continuity of care.


In-Hospital Environment:

  1. In-hospital environments refer to medical facilities where BLS is performed by healthcare providers within the hospital setting, such as nurses, doctors, or other trained personnel.
  2. In hospitals, there is a broader range of resources available compared to pre-hospital settings. This includes a wide array of medical equipment, advanced airway management tools, intravenous access, and a larger selection of medications for resuscitation.
  3. In-hospital BLS involves the collaboration of various healthcare professionals, including nurses, physicians, respiratory therapists, and others. The coordinated efforts of this multidisciplinary team enhance the quality of care provided during resuscitation efforts.
  4. In-hospital environments have immediate access to specialized medical interventions and facilities such as cardiac catheterization labs, operating rooms, and intensive care units. This allows for a rapid transition to advanced interventions or procedures if required.
  5. Healthcare providers in the hospital setting often receive more extensive training and have greater experience in managing cardiac arrest cases. They are familiar with the facility's protocols and have a deeper understanding of advanced interventions, such as intubation, medication administration, and invasive procedures.

Despite these differences, the fundamental principles of the Adult BLS Algorithm remain the same in both pre-hospital and in-hospital environments. The primary goals include recognizing cardiac arrest, initiating CPR, early defibrillation when appropriate, maintaining effective ventilation, and coordinating efforts to optimize patient outcomes.

Ultimately, successful implementation of the Adult BLS Algorithm in both settings relies on effective teamwork, clear communication, ongoing training, and a commitment to providing timely and high-quality care to patients experiencing cardiac arrest.

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