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Every year, approximately 6.8 to 8.5 million persons throughout the world1 sustain cardiac arrest. About 70% of cardiac arrests occur out of hospital. The proportion of cardiac arrest patients who are treated varies from about 54.6% (United States) to about 28.3% (Asia). The proportions with ventricular fibrillation (VF) and survival vary from 11% and 2%, respectively, in Asia, to 28% and 6% in North America, 35% and 9% in Europe, and 40% and 11% in Australia.2 About half of cardiac arrest victims are <65 years old.

Ventricular tachyarrhythmias are the initiating event in about 80% of patients with out-of-hospital primary cardiac arrest. During ambulatory electrocardiogram (ECG) monitoring of 157 witnessed cardiac arrests, Bayés de Luna et al3 documented 70% with ventricular tachycardia (VT) and VF, 13% with torsades de pointes, and 17% with bradyarrhythmias. Untreated VF deteriorates to asystole in about 15 minutes.4 For patients with sudden cardiac arrest, the rate of survival declines rapidly by about 7% to 10% for each minute without defibrillation.5 If delay to defibrillation exceeds 12 minutes,6 survival is of the order of 0% to 5%.

The Chain of Survival

The structured emergency care system concept for treatment of cardiac arrest is called the Chain of Survival and includes four components: Early Access, Early CPR, Early Defibrillation, and Early Advanced Care. If a community's prehospital EMS can be activated promptly, reach the patient within 5 minutes of collapse, and deliver the first shock shortly thereafter, survival in excess of 15% to 20% can be expected, with recent reports of >30% survival.7,8 With delayed initiation of CPR, defibrillation, and access to the patient by the emergency services, the impact of advanced life support measures is small (Figure 13B-1). Improved survival can only occur if structured emergency care systems allow trained providers to access the patient rapidly and deliver the appropriate treatment in a timely fashion. Delays in initiating the various links weaken the chain and adversely affect the next link, resulting in a decreased chance of a good outcome for the patient.

Figure 13B-1.

Incremental survival benefits by the links in the Chain of Survival. ACLS, advanced cardiac life support. [Reproduced, with permission, from the National Resuscitation Council, Singapore.]

The basic life support assessments and interventions are often called the Primary ABCD Survey, and the advanced life support assessments and interventions are often called the Secondary ABCD Survey.

An organized approach to resuscitation begins with the Primary ABCD and blends smoothly with the Secondary ABCD. These are summarized in the Universal ACLS Algorithm (Figure 13B-2). This method helps any ACLS provider remember the sequence of resuscitation actions and, therefore, be less likely to miss any of the vital steps in the care of the patient.

Figure 13B-2.

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