Most cases of sudden cardiac death do not occur in the hospital and, thus, immediate medical therapy may not be available. Over two thirds of patients who suffer an out-of-hospital cardiac arrest die before ever reaching a hospital.
Less than half of the remainder survive to hospital discharge. Basic cardiac life support(BCLS) performed by civilian bystanders may allow for circulatory and ventilatory support until trained medical personnel arrive and can institute advanced cardiac support(ACLS) techniques. These interventions have significantly improved the probability of survival in SCD patients.
The time interval between the onset of SCD and the institution of these lifesaving measures is critical. Ideally, BCLS should be instituted within 2 minute of SCD and ACLS by 8 minutes. A delay of 5 minutes before cardiopulmonary resuscitation(CPR) is performed is associated with a very low survival rate. On identifying a patient with presumed cardiac arrest, the rescuer should first establish that the patient is truly unresponsive. If so, help should immediately be summoned , including leaving the patient for 1 or 2 minutes to telephone for emergency medical care. Once help has been called for, or if no mechanism of obtaining help is available, the rescuer should check to see whether the patient is breathing and has a pulse. If the arrest is witnessed and the patient is pulseless, a precordial thump to the midsternum may be tried and occasionally will terminate a ventricular tachyarrhythmia Subsequently, the”ABCDs” of resuscitation should be employed; airway, breathing, circulation, and defibrillation. The airway should be cleared of any obstruction and the tongue moved from the posterior pharynx by tilting the head back and lifting the chin. This maneuver occasionally results in the resumption of spontaneous breathing.
If no breathing occurs, mouth-to-mouth breathing should be instituted, ideally with a barrier ventilation device. Two breaths are given while the chest is observed for evidence of adequate ventilation.
If the patient remains pulseless after the initial ventilation ,external cardiac compression should be started .