Part 4: Adult Basic Life Support B asic life support(BLS)includes recognition of signs of means that in the first minutes after collapse the victims sudden cardiac arrest(SCA), heart attack, stroke, and chance of survival is in the hands of bystander foreign-body airway obstruction(FBAO); cardiopulmonary Shortening the EMS response interval increases survival resuscitation (CPR); and defibrillation with an automated from SCA, but the effect is minimal once the EMS response external defibrillator(AED). This section summarizes BLs interval (from the time of EMS call until arrival) exceeds 5 to guidelines for lay rescuers and healthcare providers 6 minutes(OE 3).2-3I EMS systems should evaluate their protocols for cardiac arrest patients and try to shorten Introduction response intervals when improvements are feasible and re- As noted in Part 3: "Overview of CPR, "SCA is a leading sources are available(Class D). Each EMS system should cause of death in the United States and Canada. l-3 At the first measure the rate of survival to hospital discharge for victims analysis of heart rhythm, about 40% of victims of out-of- of vf sca and use these measurements to document the hospital SCA demonstrate ventricular fibrillation (VP) -VF impact of changes in procedures(Class Ila).32-35 Victims of cardiac arrest need immediate CPRCPR izations that cause the heart to quiver so that it is unable to pump blood effectively. 6 It is likely that an even large provides a small but critical amount of blood flow to the heart number of SCA victims have VF or rapid ventricul and brain. CPR prolongs the time VF is present and increases tachycardia (VT)at the time of collapse, but by the time of the likelihood that a shock will terminate vf(defibrillate the first rhythm analysis the rhythm has deteriorated to asystole. 7 heart) and allow the heart to resume an effective rhythm and Many sca victims can survive if bystanders act immedi- effective systemic perfusion. CPR is especially important if a ately while VF is still present, but successful resuscitation is unlikely once the rhythm deteriorates to asystole. Treatment minutes after collapse. Defibrillation does not"restart for VF SCA is immediate bystander CPR plus delivery of heart; defibrillation "stuns"the heart, briefly stopping VF and shock with a defibrillator. The mechanism of cardiac arrest other cardiac electrical activity. If the heart is still viable, its victims of trauma, drug overdose, drowning. normal pacemakers may then resume firing and produce an children is asphyxia. CPR with both compressions and rescue effective ECG rhythm that may ultimately produce adequate breaths is critical for resuscitation of these victims blood flow The American Heart Association uses 4 links in a chain In the first few minutes after successful defibrillation (the"Chain of Survival")to illustrate the important time asystole or bradycardia may be present and the heart may sensitive actions for victims of VF SCA(Figure 1). Three and pump ineffectively. In one recent study of VF SCA, only 25% possibly all 4 of these links are also relevant for victims of to 40% of victims demonstrated an organized rhythm 60 asphyxial arrest. 9 These links are seconds after shock delivery; it is likely that even fewer had Early recognition of the emergency and activation of the needed for several minutes following defibrillation until emergency medical services (E or local emergency adequate perfusion is present. 39 response system: "phone 911. 10,11 Lay rescuers can be trained to use a computerized device Early bystander CPR: immediate CPR can double or triple called an AED to analyze the victims rhythm and deliver a the victims chance of survival from VF SCA. 8 12-14 shock if the victim has VF or rapid VT. The AED uses audio Early delivery of a shock with a defibrillator: CPR plus and visual prompts to guide the rescuer. It analyzes the defibrillation within 3 to 5 minutes of collapse can produce victims rhythm and informs the rescuer if a shock is needed. Irvival rates as high as 49% to 75%. 5- Early advanced life support followed by postresuscitation AEDs are extremely accurate and will deliver a shock onl care delivered by healthcare providers when VF (or its precursor, rapid VT) is present. 0 AED function and operation are discussed in Part 5: Electrical Bystanders can perform 3 of the 4 links in the Chain of herapies: Automated External Defibrillators, Defibril survival. When bystanders recognize the emergency and Cardioversion, and Pacing ctivate the EMS system, they ensure that basic and advanced Successful rescuer actions at the scene of an SCa are time life support providers are dispatched to the site of the critical. Several studies have shown the beneficial effects of nities the time interval from immediate CPR and the detrimental impact of delays in EMS call to EMS arrival is 7 to 8 minutes or longer. 24 This defibrillation on survival from SCA. For every minute with out CPR. survival from witnessed VF SCA decreases 7% to (Circulation. 2005: 112: IV-19.IV-34) 10%0. When bystander CPR is provided, the decrease in o 2005 American Heart Associatio survival is more gradual and averages 3% to 4% per minute This special supplement to Circulation is freely available at http://www.circulationaha.org from collapse to defibrillation 8.12 CPR has been shown to double&, 12 or triplet survival from witnessed SCA at many DOI: 10.1161/CIRCULATIONAHA 105. 166553 intervals to defibrillate IV-19Part 4: Adult Basic Life Support Basic life support (BLS) includes recognition of signs of sudden cardiac arrest (SCA), heart attack, stroke, and foreign-body airway obstruction (FBAO); cardiopulmonary resuscitation (CPR); and defibrillation with an automated external defibrillator (AED). This section summarizes BLS guidelines for lay rescuers and healthcare providers. Introduction As noted in Part 3: “Overview of CPR,” SCA is a leading cause of death in the United States and Canada.1–3 At the first analysis of heart rhythm, about 40% of victims of out-of￾hospital SCA demonstrate ventricular fibrillation (VF).3–5 VF is characterized by chaotic rapid depolarizations and repolar￾izations that cause the heart to quiver so that it is unable to pump blood effectively.6 It is likely that an even larger number of SCA victims have VF or rapid ventricular tachycardia (VT) at the time of collapse, but by the time of first rhythm analysis the rhythm has deteriorated to asystole.7 Many SCA victims can survive if bystanders act immedi￾ately while VF is still present, but successful resuscitation is unlikely once the rhythm deteriorates to asystole.8 Treatment for VF SCA is immediate bystander CPR plus delivery of a shock with a defibrillator. The mechanism of cardiac arrest in victims of trauma, drug overdose, drowning, and in many children is asphyxia. CPR with both compressions and rescue breaths is critical for resuscitation of these victims. The American Heart Association uses 4 links in a chain (the “Chain of Survival”) to illustrate the important time￾sensitive actions for victims of VF SCA (Figure 1). Three and possibly all 4 of these links are also relevant for victims of asphyxial arrest.9 These links are ● Early recognition of the emergency and activation of the emergency medical services (EMS) or local emergency response system: “phone 911.”10,11 ● Early bystander CPR: immediate CPR can double or triple the victim’s chance of survival from VF SCA.8,12–14 ● Early delivery of a shock with a defibrillator: CPR plus defibrillation within 3 to 5 minutes of collapse can produce survival rates as high as 49% to 75%.15–23 ● Early advanced life support followed by postresuscitation care delivered by healthcare providers. Bystanders can perform 3 of the 4 links in the Chain of Survival. When bystanders recognize the emergency and activate the EMS system, they ensure that basic and advanced life support providers are dispatched to the site of the emergency. In many communities the time interval from EMS call to EMS arrival is 7 to 8 minutes or longer.24 This means that in the first minutes after collapse the victim’s chance of survival is in the hands of bystanders. Shortening the EMS response interval increases survival from SCA, but the effect is minimal once the EMS response interval (from the time of EMS call until arrival) exceeds 5 to 6 minutes (LOE 3).25–31 EMS systems should evaluate their protocols for cardiac arrest patients and try to shorten response intervals when improvements are feasible and re￾sources are available (Class I). Each EMS system should measure the rate of survival to hospital discharge for victims of VF SCA and use these measurements to document the impact of changes in procedures (Class IIa).32–35 Victims of cardiac arrest need immediate CPR. CPR provides a small but critical amount of blood flow to the heart and brain. CPR prolongs the time VF is present and increases the likelihood that a shock will terminate VF (defibrillate the heart) and allow the heart to resume an effective rhythm and effective systemic perfusion. CPR is especially important if a shock is not delivered for 4 (LOE 4),36 5 (LOE 2),37 or more minutes after collapse. Defibrillation does not “restart” the heart; defibrillation “stuns” the heart, briefly stopping VF and other cardiac electrical activity. If the heart is still viable, its normal pacemakers may then resume firing and produce an effective ECG rhythm that may ultimately produce adequate blood flow. In the first few minutes after successful defibrillation, asystole or bradycardia may be present and the heart may pump ineffectively. In one recent study of VF SCA, only 25% to 40% of victims demonstrated an organized rhythm 60 seconds after shock delivery; it is likely that even fewer had effective perfusion at that point.38 Therefore, CPR may be needed for several minutes following defibrillation until adequate perfusion is present.39 Lay rescuers can be trained to use a computerized device called an AED to analyze the victim’s rhythm and deliver a shock if the victim has VF or rapid VT. The AED uses audio and visual prompts to guide the rescuer. It analyzes the victim’s rhythm and informs the rescuer if a shock is needed. AEDs are extremely accurate and will deliver a shock only when VF (or its precursor, rapid VT) is present.40 AED function and operation are discussed in Part 5: “Electrical Therapies: Automated External Defibrillators, Defibrillation, Cardioversion, and Pacing.” Successful rescuer actions at the scene of an SCA are time critical. Several studies have shown the beneficial effects of immediate CPR and the detrimental impact of delays in defibrillation on survival from SCA. For every minute with￾out CPR, survival from witnessed VF SCA decreases 7% to 10%.8 When bystander CPR is provided, the decrease in survival is more gradual and averages 3% to 4% per minute from collapse to defibrillation.8,12 CPR has been shown to double8,12 or triple41 survival from witnessed SCA at many intervals to defibrillation.42 (Circulation. 2005;112:IV-19-IV-34.) © 2005 American Heart Association. This special supplement to Circulation is freely available at http://www.circulationaha.org DOI: 10.1161/CIRCULATIONAHA.105.166553 IV-19