Human Cardiovascular system - Basic-life-support

Basic life support

Basic life support (BLS) is a level of medical care which is used for patients with life-threatening illness or injury until the patient can be given full medical care. It can be provided by trained medical personnel, including emergency medical technicians, and by laypersons who have received BLS training. BLS is generally used in the pre-hospital setting, and can be provided without medical equipment.


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 generally does not include the use of drugs or invasive skills, and can be contrasted with the provision of Advanced Life Support (ALS). Most laypersons can master BLS skills 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 ALS care. For this reason it is essential that any person starting CPR also obtains ALS 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 defibrillation or delivery. This improves survival outcomes in cardiac arrest cases. Basic life support consists of a number of life-saving techniques focused on the medicine ABCs of pre-hospital emergency care:

  1. Airway: the protection and maintenance of a clear passageway for gases (principally oxygen and carbon dioxide) to pass between the lungs and the outside of the body
  2. Breathing: inflation and deflation of the lungs (respiration) via the airway
  3. Circulation: providing an adequate blood supply to the body, especially critical organs, so as to deliver oxygen to all cells and remove carbon dioxide, via the perfusion of blood throughout the body,

Healthy people maintain the ABCs by themselves. In an emergency situation, due to illness (medical condition) or trauma, BLS helps the patient ensure his or her own ABCs, or assists in maintaining fir the patient who is unable to do so. For airways, this will include maintaining optimal angles or possible insertion of oral or nasal adjuncts, to keep the airway unblocked. 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. In each case, the BLS provider is trained to detect ABC problems and attempt to correct them. BLS also typically includes considerations of patient transport such as various forms immobilization to prevent additional injury, including cervical collars, splinting limbs, and full body splints (backboards).

BLS in the United States of America

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, first responders, EMT-B, and to some extent, higher medical functions. It covers cardiac arrest, respiratory arrest, drowning, and foreign body airway obstruction(FBAO, or choking). EMT-B is t he highest level of healthcare provider that is limited to the BLS protocol; higher medical functions use some or all of the Advanced Life Support (ALS) protocols, in addition to BLS protocols. The algorithm for providing basic life support to adults in the USA was published in 2005 in the journal Circulation by the American Heart Association (AHA). The AHA uses 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 3 of the 4 steps.

Adult BLS sequence

  1. Ensure that the scene is safe.

  2. Assess the victim!!!s level of consciousness by asking loudly are you okay? and by checking for the victim!!!s responsiveness to pain.

  3. Activate the local EMS system by instructing someone to call 911. If an AED is available, it should be retrieved and prepared.

  4. If the victim has no suspected cervical spine trauma, open the airway using the head-tilt/chin-lift maneuver; if the victim has suspected 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.

  5. Assess the airway for foreign object obstructions, and if any are visible, remove them using the finger-sweep technique. Blind finger-sweeps should not be performed, as they may push foreign objects deeper into the airway.

  6. Look, listen, and feel for breathing for at least 5 seconds and no more than 15 seconds.

  7. If the patient is breathing normally, then the patient should be placed in the recovery position and monitored and transported; do not continue the BLS sequence.

  8. If patient is not breathing normally, and the arrest was witnessed immediately before assessment, then immediate defibrillation is the treatment of choice

  9. Attempt to administer two artificial ventilations using the mouth-to-mouth technique, the mouth-to-mask technique, or a bag-valve-mask. Verify that the chest rises and falls; if it does not, reposition (i.e. re-open) the airway using the appropriate technique and try again. If ventilation is still unsuccessful, and the victim is unconscious, it is possible that they have a foreign body in their airway. Begin chest compressions, stopping every 30 compressions, re-checking the airway for obstructions, removing any found, and re-attempting ventilation.

  10. If the ventilations are successful, assess for the presence of a pulse at the carotid artery. If a pulse is detected, then the patient should continue to receive artificial ventilations at an appropriate rate and transported immediately. Otherwise, begin CPR at a ratio of 30:2 compressions to ventilations at 100 compressions/minute for 5 cycles.

  11. After 5 cycles of CPR, the BLS protocol should be repeated from the beginning, assessing the patient!!!s airway, checking for spontaneous breathing, and checking for a spontaneous pulse. Laypersons are commonly instructed not to perform re-assessment, but this step is always performed by healthcare professionals (HCPs). If an AED is available after 5 cycles of CPR, it should be attached, activated, and (if indicated) defibrillation should be performed. If defibrillation is performed, 5 more cycles of CPR should be immediately repeated before re-assessment.

  12. BLS protocols continue until (1) the patient regains a pulse, (2) the rescuer is relieved by another rescuer of equivalent or higher training, (3) the rescuer is too physically tired to continue CPR, or (4) the patient is pronounced dead by a medical doctor.

  13. At the end of five cycles of CPR, always perform defibrillation (AED), and repeat assessment before doing another five cycles.

  14. CPR continues indefinitely, until the patient is revived, or until the caregiver is relieved, or discharged by a higher medical authority

  15. The CPR cycle is often abbreviated as 30:2 (30 compressions, 2 ventilations or breaths). Note CPR for infants and children uses a 15:2 cycle when two rescuers are performing CPR (but still uses a 30:2 if there is only one rescuer)


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

  2. A lone rescuer should give 3 cycles of CPR before leaving the victim to call emergency medical services. A cycle of CPR consists of giving 30 chest compressions and 2 breaths to the victim.

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.


In unresponsive victims with hypothermia, the breathing and pulse should be checked for 30 to 45 seconds as both breathing and heart rate can be very slow in this condition.

  1. If cardiac arrest is confirmed, CPR should be started immediately. Wet clothes should be removed, and the victim should be insulated from wind. CPR should be continued until the victim is assessed by advanced care providers.

Foreign body airway obstruction (choking)

  1. Rescuers should intervene in victims who show signs of severe airway obstruction, such as a silent cough, cyanosis, or inability to speak or breathe.

  2. If a victim is coughing forcefully, rescuers should not interfere with this process.

  3. If a victim shows signs of severe airway obstruction, abdominal thrusts should be applied in rapid sequence until the obstruction is relieved. If this is not effective, chest thrusts can also be used. Chest thrusts can also be used in obese victims or victims in late pregnancy. Abdominal thrusts should not be used in infants under 1 year of age due to risk of causing injury.

  4. If a victim becomes unresponsive he should be lowered to the ground, and the rescuer should call emergency medical services and initiate CPR. When the airway is opened during CPR, the rescuer should look into the mouth for an object causing obstruction, and remove it if it is evident.

BLS in the United Kingdom

Adult BLS sequence

  1. Ensure the safety of the victim, the rescuer, and any bystanders.

  2. Check the victim for a response by gently shaking the victim!!!s shoulders and asking loudly Are you all right?

  3. If the victim responds, leave him in the position in which he was found provided there is no further danger, try to find out what is wrong with him and get help if needed, and reassess him regularly.

  4. If the victim does not respond, turn him on to his back and open the airway using the head tilt and chin lift. Shout for help.

  5. Look, listen and feel for normal breathing for no more than 10 seconds. If the victim is breathing normally, turn him into the recovery position and get help. Continue to check for breathing.

  6. If the victim is not breathing normally, call for an ambulance, then give 30 chest comnpressions at a rate of 100 per minute.

  7. After 30 chest compressions, give 2 rescue breaths, and continue to alternate between 30 chest compressions and 2 breaths.

  8. Continue resuscitation until qualified help arrives, the victim starts breathing normally, or you become exhausted.

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

  1. They allow the rescuer to diagnose cardiac arrest if the victim is unresponsive and not breathing normally.
  2. Rescuers are taught to give chest compressions in the centre of the chest, rather than measuring from the lower border of the sternum.
  3. Rescue breaths should be given over 1 second rather than 2 seconds.
  4. Rescuers should use the ratio of 30:2 for compressions to breaths, rather than the previous 15:2 or 5:1 ratios.
  5. For an adult victim, the initial 2 rescue breaths should be omitted, so that 30 chest compressions are given immediately a cardiac arrest has been diagnosed.

These changes were introduced to simplify the algorithm, to allow for faster decision making and to maximise the time spent giving chest compressions; this is because interruptions in chest compressions have been shown to reduce the chance of survival.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.

Adult choking sequence

  1. Assess the severity of airway obstruction. If the victim is able to speak and cough effectively, the obstruction is mild. If the victim is unable to speak or cough effectively, or is unable to breathe or is breathing with a wheezy sound, the airway obstruction is severe.

  2. If the victim has signs of mild airway obstruction, encourage him to continue coughing; do nothing else.

  3. If the victim has signs of severe airway obstruction, and is conscious, give up to 5 back blows (sharp blows between the shoulder blades with the victim leaning well forwards). Check to see if the obstruction has cleared after each blow. If 5 back blows fail to relieve the obstruction, give up to 5 abdominal thrusts, again checking if each attempt has relieved the obstruction.

  4. If the obstruction is still present, and the victim still conscious, continue alternating 5 back blows and 5 abdominal thrusts.

  5. If the victim becomes unconscious, lower him to the ground, call an ambulance, and begin CPR.

Advanced life support

Advanced life support (ALS) implies that an emergency medical technician (EMT) is capable of performing advanced life support skills as either an EMT-A (Advanced), EMT-I (Intermediate) or an EMT-P (Paramedic), commonly referred to simply as a paramedic or medic. Canadian paramedics may be certified in either ALS or in only basic life support (see paramedics in canada). ALS (in most cases) refers to the skills and knowledge that a practitioner possess. The ALS provider may perform advanced procedures and skills on a patient involving invasive and non-invasive procedures including;

  1. Cardiac monitoring
  2. Cardiac defibrillation
  3. Transcutaneous pacing
  4. Intravenous cannulation (IV)
  5. Iinterosseous (IO) access and intraosseous infusion
  6. Surgical cricothyrotomy
  7. Needle cricothyrotomy
  8. needle decompression of tension pneumothorax
  9. Advanced medication administration through parental and enteral routes (IV, IO, PO, PR, ET, SL, topical, and transdermal)
  10. Following protocols as set forth by AHA Advanced Cardiac Life Support (ACLS)
  11. Following protocols as set forth by AHA Pediatric Advanced Life Support (PALS)
  12. Following protocols as set forth by Pre-Hospital Trauma Life Support (PHTLS)

ALS terminology In the United States, Advanced, Intermediate and Paramedic level services are referred to as Advanced Life Support. Services staffed by basic EMTs are referred to as Basic Life Support. This terminology extends beyond emergency cardiac care to describe all capabilities of the providers. ALS is a treatment consensus for cardiopulmonary resuscitation in cardiac arrest and related medical problems, as agreed in Europe by the European Resuscitation Council, most recently in 2005. It is practiced by in-hospital cardiac arrest teams, which generally consist of junior doctors from various specialties (anesthetics, general or internal medicine). Emergency medical technicians (EMTs) are often skilled in ALS, although they may employ slightly modified version of the algorithm.

ALS algorithms

ALS presumes that basic life support (bag-mask administration of oxygen and chest compressions) are administered. The main algorithm of ALS, which is invoked when actual cardiac arrest has been established, relies on the monitoring of the electrical activity of the heart on a cardiac monitor. Depending on the type of cardiac arrhythmia, defibrillation is applied, and medication is administered. Oxygen is administered and endotracheal intubation may be attempted to secure the airway. At regular intervals, the effect of the treatment on the heart rhythm, as well as the presence of cardiac output, is assessed. Medication that may be administered may include adrenaline (epinephrine), amiodarone, atropine, bicarbonate, calcium, potassium and magnesium. Saline or colloids may be administered to increase the circulating volume. While CPR is given (either manually, or through automated equipment such as AutoPulse), members of the team consider eight forms of potentially reversible causes for cardiac arrest, commonly abbreviated as 6H!!!s & 5T!!!s according to the new 2005 AHA ACLS . Note these reversible causes are usually taught and remembered as 4H!!!s and 4T!!!s - including hypoglycaemia and acidosis with hyper/hypokalaemia and !!!metabolic causes!!! and omitting trauma from the T!!!s as this is redundant with hypovolaemia - this simplification aids recall during resuscitation.

H!!!s and T!!!s


  1. Hypoxia (low oxygen levels in the blood)
  2. Hypovolemia (low amount of circulating blood, either absolutely due to blood loss or relatively due to vasodilation)
  3. Hyperkalemia or hypokalemia (disturbances in the level of potassium in the blood) and related disturbances of calcium or magnesium levels.
  4. Hypothermia (body temperature not maintained)
  5. Hydrogen ions (Acidosis)
  6. Hypoglycemia - Low blood glucose levels


  1. Tension pneumothorax (tear in the lung leading to collapsed lung and twisting of the large blood vessels)
  2. Tamponade (fluid or blood in the pericardium, compressing the heart)
  3. Toxic and/or therapeutic (chemicals, whether medication or poisoning)
  4. Thromboembolism and related mechanical obstruction (blockage of the blood vessels to the lungs or the heart by a blood clot or other material)
  5. Trauma (Hypovolemia) - Reduced blood volume.

As of December 2005, Advanced Life Support guidelines have changed significantly. A major new worldwide consensus has been sought based upon the best available scientific evidence. The ratio of compressions to ventilations is now recommended as 30:2 for adults, to produce higher coronary and cerebral perfusion pressures. Defibrillation is now administered as a single shock, each followed immediately by 2 minutes of CPR before rhythm is re-assessed (5 cycles of CPR). ---> see Advanced Cardiac Life Support

Other conditions

ALS also covers various conditions related to cardiac arrest, such as cardiac arrhythmias (atrial fibrillation, ventricular tachycardia), poisoning and effectively all conditions that may lead to cardiac arrest if untreated, apart from the truly surgical emergencies (which are covered by Advanced Trauma Life Support).