Basic life support

For techniques and equipment for keeping a patient alive longer term, see life support.

Basic life support (BLS) is a level of medical care which is used for victims of life-threatening illnesses or injuries until they can be given full medical care at a hospital. It can be provided by trained medical personnel, including emergency medical technicians, paramedics, and by qualified bystanders.


Many countries have guidelines on how to provide basic life support (BLS) which are formulated by professional medical bodies in those countries. The guidelines outline algorithms for the management of a number of conditions, such as cardiac arrest, choking and drowning. BLS does not include the use of drugs or invasive skills, and can be contrasted with the provision of Advanced Life Support (ALS). Firefighter, lifeguards, and police officers are often required to be BLS certified. BLS skills are also appropriate for many other professions, such as daycare providers, teachers and security personnel and social workers especially working in the hospitals and ambulance drivers.

CPR provided in the field increases the time available for higher medical responders to arrive and provide ALS care. An important advance in providing BLS is the availability of the automated external defibrillator or AED. This improves survival outcomes in cardiac arrest cases.[1]

Basic life support promotes adequate blood circulation in addition to breathing through a clear airway:

These goals are codified in mnemonics such as ABC and CAB. The American Heart Association (AHA) endorses CAB in order to emphasize the primary importance of chest compressions in cardiopulmonary resuscitation.[2]

Healthy people maintain the CABs by themselves. In an emergency situation, due to illness (medical emergency) or trauma, BLS helps the patient ensure his or her own CABs, or assists in maintaining for the patient who is unable to do so. For airways, this will include manually opening the patients airway (Head tilt/Chin lift or jaw thrust) or possible insertion of oral (Oropharyngeal airway) or nasal (Nasopharyngeal airway) adjuncts, to keep the airway unblocked (patent). For breathing, this may include artificial respiration, often assisted by emergency oxygen. For circulation, this may include bleeding control or cardiopulmonary resuscitation (CPR) techniques to manually stimulate the heart and assist its pumping action.

United States

BLS in the United States is generally identified with Emergency Medical Technicians-Basic (EMT-B). However, the American Heart Association's BLS protocol is designed for use by laypeople, as well as students and others certified first responder, and to some extent, higher medical function personnel. It includes cardiac arrest, respiratory arrest, drowning, and foreign body airway obstruction (FBAO, or choking). EMT-B is the highest level of healthcare provider that is limited to the BLS protocol; higher medical functions use some or all of the Advanced Cardiac Life Support (ACLS) protocols, in addition to BLS protocols.

Chain of survival

The medical algorithm for providing basic life support to adults in the USA was published in 2005 in the journal Circulation by the American Heart Association.[3]

The AHA uses a four-link "chain of survival" to illustrate the steps needed to resuscitate a collapsed victim:

  1. Early recognition of the emergency and activation of emergency medical services
  2. Early bystander CPR, so as not to delay treatment until arrival of EMS
  3. Early use of a defibrillator
  4. Early advanced life support and post-resuscitation care

Bystanders with training in BLS can perform the first three of the four steps.[4]

The AHA-recommended steps for resuscitation are known as DRS CAB:

  1. Check for Danger
  2. Check for a Response
  3. Send for help
  4. C directs rescuers to perform 30 Compressions to patients who are unresponsive and not breathing normally, followed by 2 rescue breaths
  5. A directs rescuers to open the Airway
  6. B directs rescuers to check Breathing but no need to deliver rescue breaths
  7. D directs rescuers to attach an AED as soon as it is available and follow prompts

If the patient is unresponsive and not breathing, the responder begins CPR with chest compressions. Previously, the AHA recommended beginning CPR with rescue breaths. If responders are unwilling or unable to perform rescue breathing, they are to perform compression-only CPR, because any attempt at resuscitation is better than no attempt.

BLS course

According to the American Heart Association, in order to be certified in BLS, a student take an online or in-person course. However, an online BLS course must be followed with an in-person skills session in order to obtain a certification issued by The American Heart Association.[5]

Adult BLS sequence

Assess:* If the patient is breathing normally, and pulse is present then the patient should be placed in the recovery position and monitored. Transport if required, or wait for the EMS to arrive and take over.

If the victim has no suspected cervical spine trauma, open the airway using the head-tilt/chin-lift maneuver; if the victim has suspected neck trauma, the airway should be opened with the jaw-thrust technique. If the jaw-thrust is ineffective at opening/maintaining the airway, a very careful head-tilt/chin-lift should be performed.


Rescuers should provide CPR as soon as an unresponsive victim is removed from the water. In particular, rescue breathing is important in this situation.

A lone rescuer is typically advised to give CPR for a short time before leaving the victim to call emergency medical services.

Since the primary cause of cardiac arrest and death in drowning and choking victims is hypoxia, it is more important to provide rescue breathing as quickly as possible in these situations, whereas for victims of VF cardiac arrest chest compressions and defibrillation are more important.



Choking can occur from foreign body airway obstruction.

United Kingdom

Adult BLS guidelines in the United Kingdom were also published in 2005 by the Resuscitation Council (UK),[6] based on the 2005 International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science with Treatment Recommendations (CoSTR) published in November 2005.[7]


These guidelines differ from previous versions in a number of ways:

These changes were introduced to simplify the algorithm, to allow for faster decision making and to maximize the time spent giving chest compressions; this is because interruptions in chest compressions have been shown to reduce the chance of survival.[8] It is also acknowledged that rescuers may either be unable, or unwilling, to give effective rescue breaths; in this situation, continuing chest compressions alone is advised, although this is only effective for about 5 minutes.[9]

Adult choking

Other countries

The term BLS is also used in some non-English speaking countries (e.g. in Italy[10]) for the education of first responders.

See also


  1. "Public-access defibrillation and survival after out-of-hospital cardiac arrest". The New England Journal of Medicine. 351 (7): 637–46. 2004. doi:10.1056/NEJMoa040566. PMID 15306665.
  2. Khalid, U.; Juma, A A. (2010). "Paradigm shift: 'ABC' to 'CAB' for cardiac arrests". Scandinavian Journal of Trauma, Resuscitation and Emergency Medicine. 18: 59. doi:10.1186/1757-7241-18-59. PMC 2992496Freely accessible. PMID 21078163.
  3. 1 2 "2005 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care". Circulation. 112 (24 Suppl): IV–19–34. December 2005. doi:10.1161/CIRCULATIONAHA.105.166553. PMID 16314375. |chapter= ignored (help)
  4. 2010 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science, Part 5: Adult Basic Life Support
  6. Resuscitation Council (UK) Adult Basic Life Support (2005)
  7. European Resuscitation Council guidelines and CoSTR documents
  8. Eftestøl T, Sunde K, Steen PA (May 2002). "Effects of interrupting precordial compressions on the calculated probability of defibrillation success during out-of-hospital cardiac arrest". Circulation. 105 (19): 2270–3. doi:10.1161/01.cir.0000016362.42586.fe. PMID 12010909.
  9. Hallstrom A, Cobb L, Johnson E, Copass M (May 2000). "Cardiopulmonary resuscitation by chest compression alone or with mouth-to-mouth ventilation". N. Engl. J. Med. 342 (21): 1546–53. doi:10.1056/NEJM200005253422101. PMID 10824072.
  10. Nozioni primo soccorso BLS Archived October 28, 2005, at the Wayback Machine. (Italian), PDF document (12p, 912 Kb)
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