Search Terms: Adult basic life support, basic life support (BLS), emergency cardiac care (ECC), major objective, citizen response, indications, activate the EMS system, JAMA, 1992, early defibrillation, prearrival instructions, emergency medical dispatcher (EMD), assessment
Journal of American Medical Association (JAMA), October 28, 1992, Vol. 268, No. 16
Adult Basic Life Support
BASIC life support (BLS) is the phase of emergency cardiac care (ECC) that (1) prevents respiratory or circulatory arrest or insufficiency through prompt recognition and intervention or (2) supports the ventilation of a victim of respiratory arrest with rescue breathing or the ventilation and circulation of a victim of cardiac arrest with cardiopulmonary resuscitation (CPR). The major objective of performing rescue breathing or CPR is to provide oxygen to the brain and heart until appropriate, definitive medical treatment (advanced cardiac life support [ACLS] can restore normal heart and ventilatory action. The prompt administration of BLS is the key to success. In respiratory arrest, the survival rate may be very high if airway control and rescue breathing are started promptly . For cardiac arrest the highest hospital discharge rate has been achieved in patients in whom CPR was initiated within 4 minutes of arrest and ACLS within 8 minutes. Early bystander rescue breathing or CPR intervention and fast emergency medical services (EMS) response are therefore essential in improving survival rates and good neurological recovery rates.
BLS includes the teaching of primary and secondary prevention. The basic concept, presented by the American Heart Association (AHA) during the last 20 years, that it is possible to prevent and control coronary heart disease, should be reinforced during the teaching of BLS, with an emphasis on prudent heart living and risk factor modification. The earlier this information is transmitted to the community, the stronger the impact on mortality and morbidity. Therefore, efforts should be made to teach BLS in the schools. Training in CPR should include information on danger signals, actions for survival, and entry into the EMS system to help prevent sudden death following myocardial infarction. For the purpose of the discussion that follows, an "adult" is defined as anyone over 8 years of age. Specific pediatric and neonatal issues are discussed in Parts V and VII.
Citizen Response to Cardiopulmonary Emergencies
Previous guidelines have called for a single rescuer who is alone to perform CPR for 1 minute and then call the EMS system. Anecdotal evidence, however, suggests that trained single rescuers often perform much more than 1 minute of CPR, thereby delaying the call to an EMS system and ACLS care. In addition, witnesses of a collapse may call neighbors, relatives, or family physicians before activating the EMS system, further delaying defibrillation and decreasing the opportunity for survival from sudden cardiac arrest. Recent studies of early defibrillation and EMS activation have demonstrated a need to change this guideline.
The majority of adults (80% to 90%) with sudden, nontraumatic cardiac arrest are found to be in ventricular fibrillation when the initial electrocardiogram (ECG) is obtained. For these victims early defibrillation coupled with early bystander CPR has been shown to significantly increase the chance of survival. The time from collapse to defibrillation is critical. Most survivors of ventricular fibrillation
received early defibrillation. The benefit of early defibrillation is demonstrated by the improved survival rates in communities that have initiated an emergency medical technician-defibrillation (EMT-D) program.
The window of opportunity for survival from sudden cardiac arrest is very narrow. Structured EMS systems that can be assessed quickly by telephoning 911 (or another easily remembered number) have recently been shown to improve survival from sudden cardiac death. Because of these compelling data in adult victims, both trained and untrained bystanders should be instructed to call 911 or local emergency telephone numbers as soon as they have determined that an adult victim is unresponsive.
A potential concern about activating the EMS system before full assessment (by the single trained rescuer) is the delay incurred in treating the patient with primary respiratory arrest or an obstructed airway. In many adult patients with primary respiratory compromise-such as asphyxiation, drowning, strangulation, respiratory arrest duet to epileptic seizures, drug overdoses, or obstructed airway-airway opening and rescue breathing are indicated, not chest compression or defibrillation. However, even trained rescuers may be unable to distinguish between primary and cardiac arrest and a collapse secondary to airway and breathing problems. In addition, the vast majority of sudden death victims will not have a primary obstructed airway. More than 80% of such victims of out-of-hospital cardiac arrest will be ventricular fibrillation, and defibrillation is the key to survival in such patients. Hence, for all adult patients, activating the EMS system immediately after determining unresponsiveness is justified.
When the emergency involves an infant (ages less than 1 year) or a child (aged 1 to 8 years) instead of an adult (aged more than 8 years), an airway problem is the most likely cause of distress or collapse. In such situations rescue support is essential and should be attempted first if the rescuer is trained and can perform the appropriate technique. If an apparent foreign-body airway obstruction is present in either a conscious adult or child and the trained rescuer knows and can perform the proper technique, the Heimlich maneuver should be attempted before activating the EMS system. If the rescuer is untrained, the EMS system should be activated immediately. For adult victims of cardiac arrest, if two bystanders are present, one should determine unresponsiveness and activate the EMS system, and the other should begin CPR. Emergency medical dispatchers (EMDs) will need to know that the victim is unresponsive or that CPR is in progress in order to dispatch the appropriate rescue personnel and vehicle. EMDs have been identified as a vital but often neglected part of the EMS system. All communities should provide formal training in emergency medical dispatch and require the use of medical dispatch protocols, including prearrival instructions for airway control, foreign-body airway obstruction, and CPR by telephone. In 1989 the National Association of EMS Physicians stated that "pre-arrival instructions are a mandatory function of each (emergency medical dispatcher) in a medical dispatch center" and "standard medically approved telephone instructions by trained EMDs are safe to give and in many instances are a moral necessity." By following a written protocol, the dispatcher can rapidly assess the patient's condition and activate the necessary emergency service. If the rescuer does not know how to perform CPR or does not remember what steps to take, the EMD can instruct the rescuer in emergency measures, including CPR. Several studies have confirmed that dispatch-assisted CPR is practical and effective and can increase the percentage of cardiac arrests in which bystander CPR is performed.
Public service announcements by CPR training organization should promulgate a single message÷to activate the EMS system first. Early activation of the EMS system is a vital part of the guidelines that follow. In addition, assessment and early performance of bystander CPR are critical, and laypersons should be encouraged to learn BLS.
Indications for BLS
When primary respiratory arrest occurs, the heart and lungs can continue to oxygenate the blood for several minutes, and oxygen will continue to circulate to the brain and other vital organs. Such patients commonly have a pulse. Respiratory arrest can result from a number of causes, including drowning, stroke, foreign-body airway obstruction, smoke inhalation, epilottitis, drug overdose, electrocution, suffocation, injuries, myocardial infarction, lightning strike, and coma of any cause. Establishing a patent airway and delivering only rescue breathing when respirations have stopped or are inadequate can save many lives in such patients who still have a pulse. In addition, early intervention for victims in whom respirations have stopped or the airway is obstructed may prevent cardiac arrest.
In primary cardiac arrest, circulation ceases and vital organs are deprived of oxygen. Ineffective "gasping" ventilatory efforts ("agonal" respirations) may occur early in cardiac arrest and should not be confused with spontaneous respirations. Cardiac arrest can be accomplished by the following electrical phenomena: ventricular fibrillation, ventricular tachycardia, asystole, or pulseness electrical activity (incorporating electromechanical dissociation).
The Sequence of BLS: Assessment EMS Activation, and the ABCs of CPR
The assessment phases of BLS are crucial. No victim should undergo the more intrusive procedures of CPR (positioning, opening the airway, rescue breathing, or chest compression) until the need has been established by the appropriate assessment. Assessment also involves a more subtle, constant process of observing and interacting with victim. The importance of the assessment phases should be stressed in teaching CPR.
Each of the ABCs of CPR-airway, breathing, and circulation-begins with an assessment phase: determine unresponsiveness, determine breathlessness, and determine pulselessness, respectively. After responsiveness has been assessed, the EMS system should be immediately activated
Assessment: Determine Unresponsiveness.-The rescuer arriving at the side of the collapsed victim must quickly assess any injury and determine whether the person is unconscious. The rescuer should tap or gently shake the victim and shout, "Are you OK?" If the victim has sustained trauma to the head and neck or trauma is suspected, the rescuer should move the victim only if absolutely necessary. Improper movement may cause paralysis in the victim with a neck injury.
Activate the EMS System-The EMS system is activated by calling the local emergency telephone number (911, if available). This number should be wisely publicized in each community. The person who calls the EMS system should be prepared to give the following information as calmly as possible: (1) the location of the emergency (with the names of cross streets or roads, if possible); (2) the telephone number from which the call is being made; (3) what happened-heart attack, auto accident, etc; (4) how many persons need help; (5) condition of the victim (s); (6) what aid is being given to the victim (s); and (7) any other information requested. To ensure that EMS personnel have no more questions, the caller should hang up last.