The steps of BLS consist of a series of sequential assessments and actions, which are illustrated in a simplified BLS algorithm (see Figure 1).
Trained rescuers are encouraged to perform some steps simultaneously (eg. checking for breathing and pulse at the same time) in an effort to reduce the time to first compressions.
Integrated teams of highly trained rescuers may use a choreographed approach that accomplishes multiple steps and assessments simultaneously rather than in the sequential manner used by individual rescuers.
BLS assessments and actions for specific types of rescuers are summarized in (Table 1).
We recommend that emergency dispatchers determine if a person is unresponsive with abnormal breathing after acquiring the requisite information to determine the location of the event.
(Class I, Level of Evidence [LOE] C-LD) (2015 Part 5)
We recommend that emergency dispatch centers offer CPR instructions and empower
dispatchers to provide such instructions for adult patients in cardiac arrest. (Class 1, LOE C-LD) (2019 Systems of Care Update)
We recommend that when dispatchers’ instructions are needed, dispatchers should provide chest compression–only CPR instructions to callers for adults with suspected out-of-hospital cardiac arrest. (Class I, LOE C-LD) (2017 Update)
The EMS system quality improvement process, including review of the quality of dispatcher CPR instructions provided to specific callers, is considered an important component of a high-quality lifesaving program. (Class IIa, LOE B) (2010 Part 5)
Note: Further information regarding Dispatch-Assisted CPR can be found in Part 4, Systems of Care.
The healthcare provider should take no more than 10 seconds to check for a pulse and, if the rescuer does not definitely feel a pulse within that time period, the rescuer should start CPR beginning with chest compressions. (Class IIa, LOE C) (2010 Part 5)
Ideally, the healthcare provider performs a pulse check at the same time as the check for no breathing or only gasping, to minimize delay in detection of cardiac arrest and initiation of CPR.
Begin chest compressions as quickly as possible after recognition of cardiac arrest.
After activating the emergency response system, retrieve an AED (if nearby and easily accessible) and then return to the victim to attach and use the Automated External Defibrillator (AED) and provide CPR.
Two or more trained rescuers:
See, also, Defibrillation with an AED, below.
The specific steps for rescuers and healthcare providers (compression-only [Hands-Only™] CPR, conventional CPR with rescue breaths, and CPR with AED use) are determined by the rescuer’s level of training.
For lay rescuers trained in CPR using chest compressions and ventilation (rescue breaths), it is reasonable to provide ventilation (rescue breaths) in addition to chest compressions for the adult in out-of-hospital cardiac arrest. (Class IIa, LOE C-LD) (2017 Adult BLS)
For lay rescuers trained in CPR using chest compressions and ventilation (rescue breaths), it is reasonable to provide ventilation (rescue breaths) in addition to chest compressions for the adult in out-of-hospital cardiac arrest. (Class IIa, LOE C-LD) (2017 Update)
The rescuer should add rescue breaths in a ratio of 30 compressions to 2 breaths. The rescuer should continue CPR until an AED arrives and is ready for use or EMS providers take over care of the victim. (Class I, LOE C-LD) (2015 Part 5)
All healthcare providers should be trained in BLS.
It is realistic for healthcare providers to tailor the sequence of rescue actions to the most likely cause of arrest.
For example, if a lone healthcare provider sees an adolescent suddenly collapse, the provider may assume that the victim has had a sudden arrhythmic arrest and call for help, get a nearby AED, return to the victim to use the AED, and provide CPR.
It is reasonable for healthcare providers to provide chest compressions and ventilation for all adult patients in cardiac arrest, from either a cardiac or noncardiac cause. (Class IIa, LOE C-LD) (2015 Part 5)
If a lone healthcare provider aids an adult drowning victim or a victim of foreign body airway obstruction who becomes unconscious, the healthcare provider may give about 5 cycles (approximately 2 minutes) of CPR before activating the emergency response system. (Class IIa, LOE C) (2010 Part 5)
Rescuers arriving on the scene of an emergency should verify that the environment in which they are approaching a patient is safe for the provider.
Because of the difficulty in providing effective chest compressions while moving the person during CPR, the resuscitation should generally be conducted where the patient is found. (Class IIa, LOE C) (2010 Part 5)
If the environment is dangerous, it may be necessary to move the victim.
The first step in the treatment of cardiac arrest is recognition.
When a bystander witnesses the sudden collapse of a victim or finds someone who appears lifeless, the bystander should:
When phoning 911, the bystander should be prepared to provide:
The bystander should:
After activation of the emergency response system, the rescuer immediately begins CPR for adult victims who are unresponsive with no breathing or no normal breathing (only gasping).
If a lone rescuer finds an unresponsive adult (ie, no movement or response to stimulation) or witnesses an adult who suddenly collapses, after ensuring the scene is safe, the rescuer should check for a response by tapping the victim on the shoulder and shouting at the victim. The trained or untrained bystander should—at a minimum—activate the community emergency response system…If the victim also has absent or abnormal breathing (ie, only gasping), the rescuer should assume the victim is in cardiac arrest. (Class I, LOE C-LD) (2010 Part 5)
The health care provider should also check for no breathing or no normal breathing (eg. only gasping) while checking for responsiveness; if the healthcare provider finds the victim is unresponsive with no breathing or no normal breathing (ie, only gasping), the rescuer should assume the victim is in cardiac arrest and immediately activate the emergency response system. (Class I, LOE C) (2010 Part 5)
Because delays in chest compressions should be minimized, the healthcare provider should take no more than 10 seconds to check for a pulse; and if the rescuer does not definitely feel a pulse within that time period the rescuer should start chest compressions. (Class IIa, LOE C) (2010 Part 5)
Closely monitor the patient, and activate the emergency response system as indicated by location and patient condition.
For a patient with known or suspected opioid overdose who has a definite pulse but no normal breathing or only gasping (ie, a respiratory arrest), in addition to providing standard BLS care, it is reasonable for appropriately trained BLS healthcare providers to administer intramuscular or intranasal naloxone. (Class IIa, LOE C-LD) (2015 Part 5)
For patients in cardiac arrest, medication administration is ineffective without concomitant chest compressions for drug delivery to the tissues, so naloxone administration may be considered after initiation of CPR if there is high suspicion for opiate overdose. (Class IIb, LOE C-EO) (2015 Part 5)
It is reasonable to provide opioid overdose response education with or without naloxone distribution to persons at risk for opioid overdose (or those living with or in frequent contact with such persons). (Class IIa, LOE C-LD) (2015 Part 5)
See Ventilation with Bag-Mask Device Before Placement of an Advanced Airway, below.
Chest compressions are
Characteristics of effective chest compressions:
The rescuer should place the heel of one hand on the center (middle) of the victim’s chest (which is the lower half of the sternum) and the heel of the other hand on top of the first so that the hands are overlapped and parallel. (Class IIa, LOE B) (2010 Part 5)
Compression rate is defined as the actual rate (compressions per minute) used during each continuous period of chest compressions.
The depth of chest compressions can affect the relative increase in intrathoracic pressure and, in turn, influence forward blood flow from the heart and great vessels to and through the systemic and pulmonary circulations.
During manual CPR, rescuers should perform chest compressions to a depth of at least 2 inches or 5 cm for an average adult, while avoiding excessive chest compression depths (greater than 2.4 inches or 6 cm). (Class I, LOE C-LD) (2015 Part 5)
Full chest wall recoil occurs when the sternum returns to its natural or neutral position during the decompression phase of compressions. When the chest recoils, the heart fills with blood. If rescuers “lean” on the chest between compressions and do not allow complete chest recoil, blood return to the heart is reduced and the heart does not fill with as much blood. This reduces the output of the next compression.
Interruptions in chest compressions, whether intended (eg. for required care such as rhythm analysis) or unintended, will stop blood flow.
Expert consensus is that a goal of 80% chest compression fraction (proportion of resuscitation time that chest compressions are performed) is achievable if the team trains well and works together.This requires minimizing both the number and duration of interruptions in chest compressions. The Guidelines recommendations (see below) note that the chest compression fraction should be at least 60%, but CPR Quality experts note that a goal of 80% is very achievable.
Interruptions in chest compressions for attempted defibrillation requires team coordination and practice to minimize the pause between the last compression and shock delivery, and to ensure that compressions are resumed immediately after shock delivery.
Shorter interruptions for shock delivery are associated with greater likelihood of shock success, greater likelihood of return of spontaneous circulation, and greater survival to hospital discharge.
In adult cardiac arrest without an advanced airway, it may be reasonable to perform CPR with the goal of a chest compression fraction (ie, the proportion of time that compressions are performed) as high as possible, with a target of at least 60%. (Class IIb, LOE C-LD) (2015 Part 5)
When 2 or more rescuers are available it is reasonable to switch chest compressors approximately every 2 minutes (or after about 5 cycles of compressions and ventilation at a ratio of 30:2) to prevent decreases in the quality of compressions. (Class IIa, LOE B) (2010 Part 5)
Consider switching compressors during interventions associated with appropriate interruptions in chest compressions (eg. when an AED is delivering a shock).
Every effort should be made to switch compressors in <5 seconds.
If the 2 rescuers are present, they can be positioned on either side of the patient, so 1 rescuer will be ready and waiting to relieve the “working compressor” every 2 minutes.
It is reasonable for rescuers trained in CPR using chest compressions and ventilation (rescue breaths) to provide a compression-to-ventilation ratio of 30:2 for adults in cardiac arrest. (Class IIa; LOE C-LD) (2017 Update)
It is reasonable that before placement of an advanced airway (supraglottic airway or tracheal tube), EMS providers perform CPR with cycles of 30 compressions and 2 breaths. (Class IIa, LOE B-R) It may be reasonable for EMS providers to use a rate of 10 breaths per minute (1 breath every 6 seconds) to provide asynchronous ventilation during continuous chest compressions before placement of an advanced airway. (Class IIb, LOE B-R) (2017 Update)
For victims with suspected spinal injury, rescuers should initially use manual spinal motion restriction (eg. placing 1 hand on either side of the patient’s head to hold it still) rather than immobilization devices, because use of immobilization devices by lay rescuers may be harmful. (Class III: Harm, LOE C-LD) (2015 Part 5)
Although the head tilt–chin lift technique was developed using unconscious, paralyzed adult volunteers and has not been studied in victims with cardiac arrest, clinical and radiographic evidence and a case series have shown it to be effective.
Because maintaining a patent airway and providing adequate ventilation are priorities in CPR (Class I, LOE C), use the head tilt–chin lift maneuver if the jaw thrust does not adequately open the airway. (2010 Part 5)
During CPR, cardiac output is about 25% to 33% of normal, so oxygen uptake from the lungs and CO2 delivery to the lungs are also reduced. As a result, a low minute ventilation (tidal volume lower than normal and respiratory rate slower than normal) can maintain effective oxygenation and ventilation.
Excessive ventilation is not necessary and can be harmful because it increases intrathoracic pressure, decreases venous return to the heart, and decreases cardiac output and survival. It can also cause gastric inflation and resultant complications such as regurgitation and aspiration.
If an adult victim with spontaneous circulation (eg. strong and easily palpable pulses) requires support of ventilation, the healthcare provider should give rescue breaths at a rate of about 1 breath every 5 to 6 seconds, or about 10 to 12 breaths per minute. (Class IIb, LOE C) (2010 Part 5) Note: When a perfusing rhythm is present, pulmonary blood flow and carbon dioxide delivery to the lungs may be normal or near-normal, so a slightly higher ventilation rate will likely be required to match ventilation to perfusion. See Ventilation During CPR with an Advanced Airway.
Mouth-to-mouth rescue breathing provides oxygen and ventilation to the victim.
Mouth-to-nose ventilation is recommended if ventilation through the victim’s mouth is impossible (eg, the mouth is seriously injured), the mouth cannot be opened, the victim is in water, or a mouth-to-mouth seal is difficult to achieve. (Class IIa, LOE C) (2010 Part 5)
Give mouth-to-stoma rescue breaths to a victim with a tracheal stoma who requires rescue breathing. A reasonable alternative is to create a tight seal over the stoma with a round, pediatric face mask. (Class IIb, LOE C) (2010 Part 5)
The elements of a bag-mask device include:
Masks should be:
It is reasonable for rescuers to use an adult (1 to 2 L) bag to deliver approximately 600 mL tidal volume for adult victims. This amount is usually sufficient to produce visible chest rise and maintain oxygenation and normocarbia in apneic patients. (Class IIa, LOE C) (2010 Part 5)
It is reasonable that before placement of an advanced airway (supraglottic airway or tracheal tube), EMS providers perform CPR with cycles of 30 compressions and 2 breaths. (Class IIa, LOE B-R) (2017 BLS)
It may reasonable for EMS providers to use a rate of 10 breaths per min (1 breath every 6 seconds) to provide asynchronous ventilation during continuous chest compressions before placement of an advanced airway. (Class IIb; LOE C-LD) (2017 BLS)
Either bag-mask-ventilation or an advanced airway strategy may be considered during CPR for adult cardiac arrest in any setting. (Class IIb, LOE B-R) (2019 ACLS)
For further information about choice of advanced airway strategy, see Advanced Cardiovascular Life Support Section (Part 7).
If an advanced airway is used, the supraglottic airway can be used for adults with OHCA in settings with low tracheal intubation success rate or minimal training opportunities for endotracheal tube placement. (Class IIa, LOE B-R)
If an advanced airway is used, either the supraglottic airway or endotracheal tube can be used for adults with OHCA in settings with high tracheal intubation success rates or optimal training opportunities for endotracheal tube placement. (Class IIa, LOE B-R) (2019 ACLS)
Emergency medical services systems that perform prehospital intubation should provide a program of ongoing quality improvement to minimize complications and to track overall supraglottic airway and endotracheal tube placement success rates. (Class I, LOE C-EO) (2019 ACLS)
When the victim has an advanced airway in place during CPR, rescuers no longer deliver cycles of 30 compressions and 2 breaths (ie, they no longer interrupt compressions to deliver 2 breaths). Instead, it may be reasonable for the provider to deliver 1 breath every 6 seconds (10 breaths per minute) while continuous chest compression are being performed. (Class IIb, LOE C-D) (2015 Part 5)
Whenever an advanced airway (endotracheal tube or supraglottic device) is inserted during CPR, it may be reasonable for providers to perform continuous compressions with positive-pressure ventilation delivered without pausing chest compressions. (Class IIb, LOE C-LD) (2017 BLS)
For witnessed OHCA with a shockable rhythm, it may be reasonable for EMS systems with priority-based, multitiered response to delay positive-pressure ventilation by using a strategy of up to 3 cycles of 200 continuous compressions with passive oxygen insufflation and airway adjuncts. (Class IIb, LOE C-LD) (2015 Part 5)
A reasonable alternative for EMS systems that have adopted bundles of care is the initial use of minimally interrupted chest compressions (ie, delayed ventilation) for witnessed shockable OHCA. (Class IIb, LOE C-LD) (2017 Adult BLS)
Cricoid pressure — pros:
Cricoid pressure — cons:
Cricoid pressure might be used in a few special circumstances (eg. to aid in viewing the vocal cords during tracheal intubation). However, the routine use of cricoid pressure in adult cardiac arrest is not recommended. (Class III, LOE B) (2010 Part 5)
Rapid defibrillation is the treatment of choice for ventricular fibrillation of short duration, such as for victims of witnessed out-of-hospital cardiac arrest or for hospitalized patients whose heart rhythm is monitored. (Class I, LOE A) (2010 Part 5)
For adults with unmonitored cardiac arrest or for whom an AED is not immediately available, it is reasonable that CPR be initiated while the defibrillator equipment is being retrieved and applied and that defibrillation, if indicated, be attempted as soon as the device is ready for use. (Class IIa, LOE B-R) (2015 Part 5)
After activating the emergency response system the lone rescuer should next retrieve an AED (if nearby and easilt accessible) and then return to the victim to attach and use the AED. The rescuer should then provide high-quality CPR. When 2 or more rescuers are present, one rescuer should begin chest compressions while a second rescuer activates the emergency response system and gets the AED (or a manual defibrillator in most hospitals). (Class IIa, LOE C) (2010 Part 5)
There is insufficient evidence to recommend the use of artifact-filtering algorithms for analysis of ECG rhythm during CPR. Their use may be considered as part of a research protocol or if an EMS system, hospital, or other entity has already incorporated ECG artifact-filtering algorithms in its resuscitation protocols. (Class IIb, LOE C-EO) (2015 Part 5)
Pausing to assess the rhythm after shock delivery increases the time that chest compressions are interrupted.
Compressions are needed immediately after shock delivery to provide blood flow and coronary perfusion: Even if a shock eliminates VF, it takes time for the heart to resume a perfusing rhythm.
Shorter “perishock pauses” (ie, total time compressions are interrupted for shock delivery) are associated with greater likelihood of shock success, greater likelihood of return of spontaneous circulation, and greater survival to hospital discharge.
For these reasons, immediate resumption of chest compressions, with a rhythm check after about 2 minutes of CPR, is preferred.
Resuscitation from cardiac arrest most often involves a team of caregivers with varied experience and composition.
A designated team leader directs team activities with the aim to minimize interruptions in CPR, ensure delivery of adequate compression rate and depth, minimization of leaning and avoidance of excessive ventilation.
We have not yet determined an optimal duration of resuscitation before the termination of efforts nor identified which patients may benefit from prolonged efforts at resuscitation. However, limited evidence suggests that extending the duration of resuscitation may be a means of improving survival in selected hospitalized patients.
Observational data from registries can be a valuable resource for studying and reporting resuscitation processes and outcomes.
The AHA’s Get-With-The-Guidelines-Resuscitation registry is the largest prospective, multicenter, observational registry of in-hospital cardiac arrest.
The Resuscitation Outcomes Consortium (ROC) is a clinical research network that evaluated the effectiveness of prehospital emergency care for patients with OHCA or life-threatening injury.
The Cardiac Arrest Registry to Enhance Survival (CARES) is a central US repository of data from OHCA events of presumed cardiac etiology treated with CPR and/or defibrillation.
With some evidence for improved psychological benefits for families present during out-of-hospital resuscitation and without an apparent negative effect on outcomes at hospitals that allow families to be present, family presence represents an important dimension in the paradigm of resuscitation quality.
There are several variations of the recovery position. The position used should be stable, near a true lateral position, with the head dependent and with no pressure on the chest to impair breathing. (Class IIa, LOE C) (2010 Part 5)
Note: This topic was last reviewed in 2010. Refer to the current American College of Cardiology/AHA published clinical practice guidelines for full details on the management of ACS, including recommendations for treatment of ST-Elevation Myocardial Infarction and treatment for Unstable Angina/Non-ST-elevation Myocardial Infarction. (2014 NSTEMI Guidelines) (2015 Update PCI STEMI) (2013 STEMI Guideline)
Note: These recommendations were last reviewed in 2019. Refer to 2018 Guidelines for the Early Management of Patients With Acute Ischemic Stroke and 2019 Stroke Update for complete current recommendations.
Refer to the most recent ILCOR statement regarding drowning. (Drowning-Related Resuscitation: An ILCOR Advisory Statement)
Although chest thrusts, back slaps, and abdominal thrusts are feasible and effective for relieving severe foreign body airway obstruction in conscious (responsive) adults and children >1 year of age, for simplicity in training it is recommended that abdominal thrusts be applied in rapid sequence until the obstruction is relieved. (Class IIb, LOE B) (2010 Part 5)
Monica E. Kleinman, MD, Chair; Zachary D. Goldberger, MD, MSc, FAHA; Thomas Rea, MD, MPH; Robert A. Swor, DO; Bentley J. Bobrow, MD, FAHA; Erin E. Brennan, MD, MMEd; Mark Terry, MPA, NRP; Robin Hemphill, MD, MPH; Raúl J. Gazmuri, MD, PhD; Mary Fran Hazinski, MSN, RN, FAHA; Andrew H. Travers, MD, MSc
Lorrel E. Brown; Tomas Drabek; Judith Finn; Fredrik Folke; Guillaume Geri; James T. Niemann
Monica E. Kleinman, Chair; Erin E. Brennan; Zachary D. Goldberger; Robert A. Swor; Mark Terry; Bentley J. Bobrow; Raúl J. Gazmuri; Andrew H. Travers; Thomas Rea
Robert A. Berg, Chair; Robin Hemphill; Benjamin S. Abella; Tom P. Aufderheide; Diana M. Cave; Mary Fran Hazinski; E. Brooke Lerner; Thomas D. Rea; Michael R. Sayre; Robert A. Swor
The American Heart Association requests that this document be cited as follows:
American Heart Association. Web-based Integrated Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care – Part 5: Adult Basic Life Support and Cardiopulmonary Resuscitation Quality. ECCguidelines.heart.org.
© Copyright 2015, 2017 American Heart Association, Inc.