Advanced cardiac life support, or advanced cardiovascular life support, often referred to by its abbreviation as 'ACLS', refers to a set of clinical algorithms for the urgent treatment of cardiac arrest, stroke, myocardial infarction, and other life-threatening cardiovascular emergencies. Outside North America, Advanced Life Support (ALS) is used. Advanced cardiac life support, or advanced cardiovascular life support, often referred to by its abbreviation as 'ACLS', refers to a set of clinical algorithms for the urgent treatment of cardiac arrest, stroke, myocardial infarction, and other life-threatening cardiovascular emergencies. Outside North America, Advanced Life Support (ALS) is used. Only qualified health care providers can provide ACLS, as it requires the ability to manage the person's airway, initiate vascular access, read and interpret electrocardiograms, and understand emergency pharmacology; these include physicians, pharmacists, dentists, advanced practice providers (physician assistants and nurse practitioners), respiratory therapists, nurses, paramedics and advanced emergency medical technicians. Other emergency responders may also be trained. Some health professionals, or even lay rescuers, may be trained in basic life support (BLS), especially cardiopulmonary resuscitation (CPR), which makes up the core foundation of ACLS. When a sudden cardiac arrest occurs, immediate CPR is a vital link in the chain of survival. Another important link is early defibrillation, which has improved greatly with the widespread availability of automated external defibrillators (AEDs). ACLS often starts with analyzing the patient's heart rhythms with a manual defibrillator. In contrast to an AED in BLS, where the machine makes the determination as to when to defibrillate (shock) a patient, the ACLS team leader makes those decisions based on rhythms on the monitor and the patient's vital signs. The next steps in ACLS are insertion of intravenous (IV) lines and placement of various airway devices, such as an endotracheal tube (an advanced airway used in intubations). Commonly used ACLS drugs, such as epinephrine and amiodarone, are then administered. The ACLS personnel quickly search for possible reversible causes of cardiac arrest (i.e. the H's and T's, heart attack). Based on their diagnosis, more specific treatments are given. These treatments may be medical such as IV injection of an antidote for drug overdose, or surgical such as insertion of a chest tube for those with tension pneumothoraces or hemothoraces. The American Heart Association and the International Liaison Committee on Resuscitation performs a science review every five years and publishes an updated set of recommendations and educational materials. These guidelines are often synonymously referred to as Emergency Cardiovascular Care (ECC) Guidelines. Following are recent changes.