Basic life support
Synonyms and keywords: BLS.

# Overview
Basic Life Support is a specific level of prehospital medical care provided by trained responders, including emergency medical technicians, in the absence of advanced medical care. Earlier guidelines used to focus on an 'ABCD' sequence in which the BLS providers followed the sequence of airway protection, followed by breathing and cardiac compression. However, recent 2010 revised guidelines recommend certain changes based on the results of the randomized trials. The current guidelines support a CABD sequence (cardiac compression followed by airway protection, breathing, and defibrillator). Additionally, these guidelines de-emphasize continuous pulse checks, placement of cricoid pressure, and following the sequence of 'look, listen, and feel during breathing assessment.

# Goals of Resuscitation
- The aim of resuscitation team is to restore effective oxygenation, ventilation, and circulation in a cardiac or respiratory arrest patients. The intermediate goal is return of spontaneous circulation (ROSC) and return of intact neurological function.

# Approach to Suspected Patient of Cardiac or Respiratory Arrest
- Unconscious patient - Do BLS (basic life support) survey followed by ACLS (Advanced cardiac life support) survey
- Conscious patient - Start with ACLS (Advanced cardiac life support) survey directly

# Basic Life Support Guidelines (Revised American Heart Association 2010 Guidelines) 

## Steps of Basic life support Survey (Revised AHA 2010 Guidelines)
- Check for the safety of scene (both your and the patient safety)
- Try to place the patient supine on a firm surface.
- Check for responsiveness
"Are you all right"
Observe for absent breathing or abnormal breathing (gasping only) by looking at the chest movements (not more than 5-10 seconds).
- "Are you all right"
- Observe for absent breathing or abnormal breathing (gasping only) by looking at the chest movements (not more than 5-10 seconds).
- Activate the emergency response system and get an AED (Automated External Defibrillator) if a single rescuer is there. In case of two rescuers send the other person to do so.
- Check for circulation by palpating the carotid pulse. Don't spend more than 10 seconds for palpating the pulse. If a pulse is present give the patient 1 rescue breath (10-12 breath/min) once every 5-6 seconds. If no pulse is palpated within 10 seconds, start giving 30 chest compressions followed by two rescue breaths (ventilation)
- Connect an Automated External Defibrillator as soon as it becomes available and if indicated give a shock. Follow the shocks with cardiac compression. If no shock is indicated, continue CPR for 2 minutes. Check rhythm every two minutes. Continue CPR until ACLS help arrives or the patient starts to move.
- Depending on the suspected cause, a lone provider can have different responses. For instance, in cases of sudden cardiac arrest a lone provider should activate the emergency response services and get an AED (if available first) followed by cardiac compression. However, in suspected cases of drowning they should first give 5 cycles of cardiac compression (2 minutes) followed by activation of the emergency response system.

## Similarities Between Basic life support Guidelines 2005 and 2010
- The revised AHA basic life support guidelines 2010 have emphasized on high quality CPR (cardiopulmonary resuscitation) similar to the 2005 guidelines. A high quality CPR should be hard and fast and include:
Cardiac compression at a rate of at least 100 chest compression/minutes (fast).
Compression depth of at least 2 inches in adults (hard)
Complete chest recoil between two compressions
Minimizing interruptions in compression
Changing rescuers every two minutes
Avoiding excessive ventilation
- Cardiac compression at a rate of at least 100 chest compression/minutes (fast).
- Compression depth of at least 2 inches in adults (hard)
- Complete chest recoil between two compressions
- Minimizing interruptions in compression
- Changing rescuers every two minutes
- Avoiding excessive ventilation

## Differences Between Basic life support Guidelines 2005 and 2010
- Change of the sequence from ABCD (clearing airway, breathing, chest compression, and defibrillator) to CABD (chest compression, clearing airway, breathing, and defibrillator) in all age groups i.e. adults, children, and infants. Although no studies are available to show increased survival benefits with the change of sequence from ABCD to CABD, then again since blood flow depends on chest compression so delay of chest compression due to providing rescue breathing is not advised. The reason being that most adults have a sudden cardiac arrest due to ventricular fibrillation or pulseless ventricular tachycardia and have a better survival benefits if they received immediate chest compression or defibrillation. However, the health care provider should also take into consideration for the cause of unresponsiveness. For e.g. in cases of drowning hypoxia may be the primary cause for unresponsiveness so rescue breathing should be given before the chest compressions.
- Removal of 'Look, listen, and feel' for breathing and the two initial rescue breaths- The new guidelines removed this step from assessment as sometimes the BLS providers delayed giving chest compression if they see agonal breathing (abnormal breathing, only gasping)
- The steps of BLS survey are now represented by 1, 2, 3, 4 instead of the previous A, B, C, and D. The ACLS steps are represented by A, B, C, and D
- De-emphasis on the continued pulse check
- The routine use of cricoid compression in cardiac arrest is not recommended. This was done as randomized studies found the following findings:
Though it was thought to prevent regurgitation and aspiration, it made it difficult to put an advanced airway and block ventilation.
Some degree of aspiration does occur even after placement of cricoid pressure.
It was a difficult technique to train and lacked uniformity among BLS providers.
- Though it was thought to prevent regurgitation and aspiration, it made it difficult to put an advanced airway and block ventilation.
- Some degree of aspiration does occur even after placement of cricoid pressure.
- It was a difficult technique to train and lacked uniformity among BLS providers.

## Automated External Defibrillator

### Indications
- Unresponsive patient
- No breathing
- Abnormal breathing (agonal gasping only)
- Absent pulse

### Principle of Early Defibrillation  
Ventricular fibrillation and pulseless ventricular tachycardia are one of the most common causes of a cardiac arrest. A defibrillator gives a shock to the heart that stops these rhythms. If the heart is still alive its natural pacemakers start producing spontaneous (weak and slow initially) rhythms. Defibrillation should then be followed by cardiac compression, which helps the heart to return to adequate heart functioning.

### Advantages of Early Defibrillation  
- CPR can only  provide small amounts of blood to the brain and the heart. It can't restore the spontaneous normal rhythm. An early defibrillation shocks the heart, terminate the abnormal rhythm cycle, and helps in restoration of a normal rhythm. This doesn't mean that cardiac compressions are not important. Studies have shown that in the absence of any cardiac compression, the chances of survival post ventricular fibrillation decreases by 7-10% / minute between collapse and availability of defibrillation. However, with CPR the decline in survival slows down and occurs at a rate of 3-4% / minute. Thus, application of both an early cardiac compression and AED are of utmost importance to the survival of the patient.

### Special Situations
- Water - Remove the patient from water, wipe water and then attach AED
- Snow or Ice - Use AED directly
- Implanted pacemaker - Don't apply AED directly on implanted pacemakers, but apply them to sides.
- Transdermal medications patches - Don't apply AED directly on implanted pacemakers, but apply them to sides or remove the patches wipe the area and apply AED.

# General Consideration
Basic Life Support consists of a number of life-saving techniques. It earlier focused on the "ABC"s sequence of prehospital emergency care which has been changed to CAB sequence in the recent 2010 guidelines. The key steps in BLS are:
- Airway: The protection and maintenance of patient airway including the use of airway adjuncts such as an oral or nasal airway
- Breathing: The actual flow of air through respiration, natural or artificial respiration, often assisted by emergency oxygen
- Circulation: The movement of blood through the beating of the heart or the emergency measure of CPR
- BLS may also include considerations of patient transport such as the protection of the cervical spine and avoiding additional injuries through splinting and immobilization.
- BLS generally does not include the use of drugs or invasive skills, and can be contrasted with the provision of advanced cardiac life support (ACLS). Most laypersons can master BLS skill after attending a short course. Firefighters and police officers are often required to be BLS certified. BLS is also immensely useful for many other professions, such as daycare providers, teachers and security personnel.
- CPR provided in the field buys time for higher medical responders to arrive and provide ACLS.  For this reason it is essential that any person starting CPR also obtains ACLS support by calling for help via radio using agency policies and procedures and/or using an appropriate emergency telephone number.
- An important advance in providing BLS is the availability of the automated external defibrillator or AED, which can be used to deliver defibrillation.  This improves survival outcomes in cardiac arrest cases, sometimes dramatically.

# In Other Countries
The term BLS is also used in some non-English speaking countries (e.g. in Italy) for the education of first responders.
- Belgium: Aide medicale urgente ("emergency medical assistance")
- France: CFAPSE (certificat de formation aux activites des premiers secours en equipe, "education certificate for the team first responder activity")
- Germany: Erste Hilfe Schein (first aid certificate).
- Netherlands: EHBO (Eerste Hulp Bij Ongelukken, "first aid")
- Turkey: Ilk Yardm Kursu
These courses do not include the use of drugs or of invasive techniques, but include the management of various traumas and casualty lifting and movement.

# Related Chapters
- Advanced Life Support
- Emergency Medical Technician
- EMT Basic Skills
- Artificial respiration
- CPR
- Advanced cardiac life support