basic life support basic life support basic life support (bls) is a level of medical care which is used for patients with life-threatening illnesses or injuries until they can be given full medical care by advanced life support providers (paramedics, nurses, physicians). it can be provided by trained medical personnel, such as emergency medical technicians, and by qualified bystanders. for techniques and equipment for keeping a patient alive longer term, see life support. background the international liaison committee on resuscitation (ilcor) was formed in 1992 to coordinate the efforts of resuscitation worldwide. the ilcor representatives come from various countries such as the united states, canada, australia, new zealand, and from the european, asian, and african continents. in 2000, the committee published the first resuscitation guideline. in 2005, the committee published international consensus on cardiopulmonary resuscitation (cpr) and emergency cardiovascular care (ecc) science with treatment recommendations. since 2010, the committee has provided materials for regional resuscitation providers such as european resuscitation council and american heart association to write their own guidelines. since 2015, ilcor has used a new methodology called consensus on science with treatment recommendations (costr) to evaluate the quality of latest evidence available and to reach a conclusion on the best treatments available in resuscitation. using the costr methodology, ilcor also started to conduct yearly reviews and published updates on the latest evidence in resuscitation, changing it from the previous 5-yearly review on resuscitation. 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. method d - danger one of the first checks done in emergency response is to assess the situation for any danger. if the person does not remove themselves or others from the danger then they are liable to become a patient and require emergency assistance themselves or become unable to render assistance for the other patient. examples of dangerous situations which should cease before bls is administered are electrocution, assault, drowning, burning etc. r - response checking for response is the next step in emergency situations as continuing with other forceful methods of bls could exacerbate the patient's condition and can be seen as assault. avpu (alert, verbal, pain, unconscious) is the commonly used acronym for quickly assessing the level of consciousness in a patient. pain stimulus in particular should be used with caution as many methods if done incorrectly can leave bruises (sternal rub for example) commonly used methods for central stimulus are the trapezius squeeze and for peripheral stimulus it is squeezing the side of the finger. s - send for help sending for help allows much more assistance to be rendered upon the patient and increases their chances of receiving als. a - airway opening of the airway via the jaw thrust maneuver is the preferred method as the head-tilt maneuver is thought to be more risky for people with suspected spinal injury. if the person is in danger of pulmonary aspiration then they should be placed in the recovery position or more advanced airway management should be used. b - breathing once the airway has been opened checking for breathing should begin, if the respiratory rate is below 12-20 breaths per minute then cpr should begin, however if the patient is breathing normally then the rescuer should place them in the recovery position and summon an ambulance. c - cpr main article: cardiopulmonary resuscitation d - defibrillation once an automated external defibrillator (aed) has been acquired the rescuer should then finish the round of cpr, use the aed and then begin another round of cpr. however the aed will usually notify the rescuer of any impediments to continued cpr (such as a sinus rhythm or asystole) in which case the rescuer may be prompted to cease cpr. indications cardiac arrest cardiac arrest occurs when the heart stops pumping in a regular rhythm. in this situation, early defibrillation is the key to returning the patient's heart back to a normal rhythm. when a defibrillator is not readily available, a rescuer or bystander should keep the blood flowing by performing chest compressions and rescue breaths at an age-appropriate rate until it is. respiratory arrest respiratory arrest is when there is no measurable breathing in a patient. it tends to occur in conjunction with cardiac arrest, but this is not always the case. respiratory arrest is the most common indication of bls in infants and toddlers. the most critical factor in restoring breathing in the patient is to provide high quality rescue breaths. drowning in cases of drowning, rescuers should provide cpr as soon as an unresponsive patient 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 patient to call emergency medical services. since the primary cause of cardiac arrest and death in drowning and choking patients is hypoxemia, it is recommended to start with rescue breaths before proceeding to chest compressions (if pulseless). if the patient presents in a shockable rhythm, early defibrillation is still recommended. choking