Basic life support.

The term basic life support (BLS) refers to maintaining an airway and supporting breathing and the circulation. It comprises the following elements: initial assessment, airway maintenance, expired air ventilation (rescue breathing; mouth-to-mouth ventilation) and chest compression. When all are combined the term cardiopulmonary resuscitation (CPR) is used. BLS implies that no equipment is used; when a simple airway or face mask for mouthto-mask resuscitation is used, this is defined as “basic life support with airway adjunct”. The purpose of BLS is to maintain adequate ventilation and circulation until a means can be obtained to reverse the underlying cause of the arrest. It is therefore a “holding operation”, although on occasion, particularly when the primary pathology is respiratory failure, it may itself reverse the cause and allow full recovery.