ABC and its variations are initialism mnemonics for essential steps used by
both medical professionals and lay persons when dealing with a patient. In
its original form it stands for Airway, Breathing and Circulation. The protocol
was originally developed as a memory aid for rescuers performing cardiopulmonary
resuscitation, and the most widely known use of the initialism is in the care of
the unconscious or unresponsive patient, although it is also used as a reminder
of the priorities for assessment and treatment of patients in many acute
medical and trauma situations, from first-aid to hospital medical treatment.
Airway, breathing, and circulation are vital for life, and each is required, in
that order, for the next to be effective. Since its development, the
mnemonic has been extended and modified to fit the different areas in which it
is used, with different versions changing the meaning of letters or
adding other letters. In 2010, the American Heart Association
and International Liaison Committee on Resuscitation changed the recommended
order of CPR interventions for most cases of cardiac arrest to chest
compressions, airway, breathing or CAB. History
The 'ABC' method of remembering the correct protocol for CPR is almost as
old as the procedure itself, and is an important part of the history of
cardiopulmonary resuscitation. Throughout history, a variety of
differing methods of resuscitation had been attempted and documented, although
most yielded very poor outcomes. In 1957, Peter Safar wrote the book ABC of
Resuscitation, which established the basis for mass training of CPR. This new
concept was distributed in a 1962 training video called "The Pulse of
Life" created by James Jude, Guy Knickerbocker and Peter Safar. Jude and
Knickerbocker, along with William Kouwenhouen developed the method of
external chest compressions, while Safar worked with James Elam to prove the
effectiveness of artificial respiration. Their combined findings were presented
at annual Maryland Medical Society meeting on September 16, 1960 in Ocean
City, and gained rapid and widespread acceptance over the following decade,
helped by the video and speaking tour the men undertook. The ABC system for
CPR training was later adopted by the American Heart Association, which
promulgated standards for CPR in 1973. As of 2010, the American Heart
Association chose to focus CPR on reducing interruptions to compressions,
and has changed the order in its guidelines to Circulation, Airway,
Breathing. Importance
At all levels of care, the ABC protocol exists to remind the person delivering
treatment of the importance of airway, breathing, and circulation to the
maintenance of a patient's life. These three issues are paramount in any
treatment, in that the loss any one of these items will rapidly lead to the
patient's death. The three objectives are so important to successful patient
care that they form the foundation of training for not only first aid
providers, but also participants in many advanced medical training programs.
Hypoxia, the result of insufficient oxygen in the blood, is a potentially
deadly condition and one of the leading causes of cardiac arrest. Cardiac arrest
is the ultimate cause of clinical death for all animals, and it is linked to an
absence of circulation in the body, for any one of a number of reasons. For this
reason, maintaining circulation is vital to moving oxygen to the tissues and
carbon dioxide out of the body. Airway, breathing, and circulation
therefore work in a cascade; if the patient's airway is blocked, breathing
will not be possible, and oxygen cannot reach the lungs and be transported
around the body in the blood, which will result in hypoxia and cardiac arrest.
Ensuring a clear airway is therefore the first step in treating any patient; once
it is established that a patient's airway is clear, rescuers must evaluate
a patient's breathing, as many other things besides a blockage of the airway
could lead to an absence of breathing. Simple application for CPR
The basic application of the ABC principle is in first aid, and is used
in cases of unconscious patients to start treatment and assess the need for,
and then potentially deliver, cardiopulmonary resuscitation.
In this simple usage, the rescuer is required to open the airway, then check
for normal breathing. These two steps should provide the initial assessment of
whether the patient will require CPR or not.
In the event that the patient is not breathing normally, the current
international guidelines indicate that chest compressions should be started.
Previously, the guidelines indicated that a pulse check should be performed
after the breathing was assessed, and this made up the 'circulation' part of
the initialism, but this pulse check is no longer recommended for lay rescuers.
Some trainers continue to use 'circulation' as the label for the third
step in the process, since performing chest compressions is effectively
artificial circulation, and when assessing patients who are breathing,
assessing 'circulation' is still important. However, some trainers now
use the C to mean 'Compressions' in their basic first aid training.
Airway = Unconscious patients =
In the unconscious patient, the priority is airway management, to avoid a
preventable cause of hypoxia. Common problems with the airway of patient with
a seriously reduced level of consciousness involve blockage of the
pharynx by the tongue, a foreign body, or vomit.
At a basic level, opening of the airway is achieved through manual movement of
the head using various techniques, with the most widely taught and used being
the "head tilt — chin lift", although other methods such as the "modified jaw
thrust" can be used, especially where spinal injury is suspected, although in
some countries, its use is not recommended for lay rescuers for safety
reasons. Higher level practitioners such as
emergency medical service personnel may use more advanced techniques, from
oropharyngeal airways to intubation, as deemed necessary.
= Conscious patients = In the conscious patient, other signs of
airway obstruction that may be considered by the rescuer include
paradoxical chest movements, use of accessory muscles for breathing,
tracheal deviation, noisy air entry or exit, and cyanosis.
Breathing = Unconscious patients =
In the unconscious patient, after the airway is opened the next area to assess
is the patient's breathing, primarily to find if the patient is making normal
respiratory efforts. Normal breathing rates are between 12 and 20 breaths per
minute, and if a patient is breathing below the minimum rate, then in current
ILCOR basic life support protocols, CPR should be considered, although
professional rescuers may have their own protocols to follow, such as artificial
respiration. Rescuers are often warned against
mistaking agonal breathing, which is a series of noisy gasps occurring in
around 40% of cardiac arrest victims, for normal breathing.
If a patient is breathing, then the rescuer will continue with the treatment
indicated for an unconscious but breathing patient, which may include
interventions such as the recovery position and summoning an ambulance.
= Conscious or breathing patients = In a conscious patient, or where a pulse
and breathing are clearly present, the care provider will initially be looking
to diagnose immediately life-threatening conditions such as severe asthma,
pulmonary oedema or haemothorax. Depending on skill level of the rescuer,
this may involve steps such as: Checking for general respiratory
distress, such as use of accessory muscles to breathe, abdominal breathing,
position of the patient, sweating, or cyanosis
Checking the respiratory rate, depth and rhythm - Normal breathing is between 12
and 20 in a healthy patient, with a regular pattern and depth. If any of
these deviate from normal, this may indicate an underlying problem
Chest deformity and movement - The chest should rise and fall equally on both
sides, and should be free of deformity. Clinicians may be able to get a working
diagnosis from abnormal movement or shape of the chest in cases such as
pneumothorax or haemothorax Listening to external breath sounds a
short distance from the patient can reveal dysfunction such as a rattling
noise or stridor Checking for surgical emphysema which is
air in the subcutaneous layer which is suggestive of a pneumothorax
Auscultation and percussion of the chest by using a stethoscope to listen for
normal chest sounds or any abnormalities Pulse oximetry may be useful in
assessing the amount of oxygen present in the blood, and by inference the
effectiveness of the breathing Circulation
Once oxygen can be delivered to the lungs by a clear airway and efficient
breathing, there needs to be a circulation to deliver it to the rest of
the body. = Non-breathing patients =
Circulation is the original meaning of the "C" as laid down by Jude,
Knickerbocker & Safar, and was intended to suggest assessing the presence or
absence of circulation, usually by taking a carotid pulse, before taking
any further treatment steps. In modern protocols for lay persons,
this step is omitted as it has been proven that lay rescuers may have
difficulty in accurately determining the presence or absence of a pulse, and
that, in any case, there is less risk of harm by performing chest compressions on
a beating heart than failing to perform them when the heart is not beating. For
this reason, lay rescuers proceed directly to cardiopulmonary
resuscitation, starting with chest compressions, which is effectively
artificial circulation. In order to simplify the teaching of this to some
groups, especially at a basic first aid level, the C for Circulation is changed
for meaning CPR or Compressions. It should be remembered, however, that
health care professionals will often still include a pulse check in their ABC
check, and may involve additional steps such as an immediate ECG when cardiac
arrest is suspected, in order to assess heart rhythm.
= Breathing patients = In patients who are breathing, there is
the opportunity to undertake further diagnosis and, depending on the skill
level of the attending rescuer, a number of assessment options are available,
including: Observation of colour and temperature of
hands and fingers where cold, blue, pink, pale, or mottled extremities can
be indicative of poor circulation Capillary refill is an assessment of the
effective working of the capillaries, and involves applying cutaneous pressure
to an area of skin to force blood from the area, and counting the time until
return of blood. This can be performed peripherally, usually on a fingernail
bed, or centrally, usually on the sternum or forehead
Pulse checks, both centrally and peripherally, assessing rate,
regularity, strength, and equality between different pulses
Blood pressure measurements can be taken to assess for signs of shock
Auscultation of the heart can be undertaken by medical professionals
Observation for secondary signs of circulatory failure such as oedema or
frothing from the mouth ECG monitoring will allow the healthcare
professional to help diagnose underlying heart conditions, including myocardial
infarctions Variations
Nearly all first aid organisations use "ABC" in some form, but some incorporate
it as part of a larger initialism, ranging from the simple 'ABCD' to
'AcBCDEEEFG'. = DR ABC =
One of the most widely used adaptations is the addition of "DR" in front of
"ABC", which stands for Danger and Response. This refers to the guiding
principle in first aid to protect yourself before attempting to help
others, and then ascertaining that the patient is unresponsive before
attempting to treat them, using systems such as AVPU or the Glasgow Coma Score.
As the original initialism was devised for in-hospital use, this was not part
of the original protocol. In some areas, the related SR ABC is
used, with the S to mean Safety. = DRsABC =
A modification to DRABC is that when there is no response from the patient,
the rescuer is told to send for help' = ABCD =
There are several protocols taught which add a D to the end of the simpler ABC.
This may stand for different things, depending on what the trainer is trying
to teach, and at what level. It can stand for:
Defibrillation — The definitive treatment step for cardiac arrest
Disability or Dysfunction — Disabilities caused by the injury, not pre-existing
conditions Deadly Bleeding
(Differential) Diagnosis Decompression
= ABCDE = Additionally, some protocols call for an
'E' step to patient assessment. All protocols that use 'E' steps diverge
from looking after basic life support at that point, and begin looking for
underlying causes. In some protocols, there can be up to 3 E's used. E can
stand for: Expose and Examine — Predominantly for
ambulance-level practitioners, where it is important to remove clothing and
other obstructions in order to assess wounds.
Environment — only after assessing ABCD does the responder deal with
environmentally related symptoms or conditions, such as cold and lightning.
Escaping Air — Checking for air escaping, such as through a sucking
chest wound, which could lead to a collapsed lung.
Elimination Evaluate — Is the patient
"time-critical" and/or does the rescuer need further assistance.
= ABCDEF = An 'F' in the protocol can stand for:
Fundus — relating to pregnancy, it is a reminder for crews to check if a female
is pregnant, and if she is, how far progressed she is.
Family — indicates that rescuers must also deal with the witnesses and the
family, who may be able to give precious information about the accident or the
health of the patient, or may present a problem for the rescuer.
Fluids — A check for obvious fluids etc.)
Fluid resuscitation Final Steps — Consulting the nearest
definitive care facility = ABCDEFG =
A 'G' in the protocol can stand for Go Quickly! — A reminder to ensure all
assessments and on-scene treatments are completed with speed, in order to get
the patient to hospital within the Golden Hour
Glucose — The professional rescuer may choose to perform a blood glucose test,
and this can form the 'G' or alternately, the 'DEFG' can stand for
"Don't Ever Forget Glucose" = AcBC =
Some trainers and protocols use an additional 'c' in between the A and B,
standing for 'cervical spine' or 'consider C-spine'. This is a reminder
to be aware of potential neck injuries to a patient, as opening the airway may
cause further damage unless a special technique is used.
= CABC = The military frequently use CABC. With
the first C standing for catastrophic haemorrhage. It is hypothesised that
major bleeding will kill a casualty before an airway obstruction and with
the development of quick and easy to apply haemostatic agents controlling
blood loss should occur first. = MARCH =
Massive Haemorrhage Airway
Respiratory Circulation
Hypothermia See also
Cardiopulmonary resuscitation Artificial respiration
Recovery position First aid
References External links