Part 5: Electrical Therapies Automated External Defibrillators Defibrillation Cardioversion, and Pacing his chapter presents guidelines for defibrillation with Delays to either start of CPR or defibrillation can reduce automated external defibrillators(AEDs) and manual survival from SCA. In the 1990s some predicted that CPR defibrillators, synchronized cardioversion, and pacing. AEDs could be rendered obsolete by the widespread development of may be used by lay rescuers and healthcare providers as part community AED programs. Cobb noted, however, that as of basic life support. Manual defibrillation, cardioversion, more Seattle first responders were equipped with AEDs, and pacing are advanced life support therapies. survival rates from SCA unexpectedly fell. He attributed this decline to reduced emphasis on CPR, and there is growing Defibrillation Plus CPR: evidence to support this view. Part 4: Adult Basic Life a Critical Combination Support" summarizes the evidence on the importance of Early defibrillation is critical to survival from sudden cardiac effective chest compressions and minimizing interruptions in arrest(SCA)for several reasons: (I)the most frequent initial providing compressions. rhythm in witnessed SCA is ventricular fibrillation (VF),(2 the treatment for VF is electrical defibrillation, (3)the defibrillation were evaluated during the 2005 Consensus probability of successful defibrillation diminishes rapidly Conference. I The first question concerns whether CPR over time, and (4)VF tends to deteriorate to asystole within should be provided before defibrillation is attempted. The Several studies have documented the effects of time second question concerns the number of shocks to be deli defibrillation and the effects of bystander CPR on survival ered in a sequence before the rescuer resumes CPR. from SCA. For every minute that passes between collapse and Shock First Versus CPR First defibrillation, survival rates from witnessed VF SCA de- When any rescuer witnesses an out-of-hospital arrest and an crease 7% to 10% if no CPR is provided. When bystander AED is immediately available on-site, the rescuer should use CPR is provided, the decrease in survival rates is more the AED as soon as possible. Healthcare providers who treat gradual and averages 3% to 4% per minute from collapse to cardiac arrest in hospitals and other facilities with AEDs defibrillation. 2 CPR can doublel- or triple+ survival from on-site should provide immediate CPR and should use the itnessed sca at most intervals to defibrillation AED/defibrillator as soon as it is available. These recommen- If bystanders provide immediate CPR, many adults in VF dations are designed to support early CPR and early defibrin- can survive with intact neurologic function, especially if lation, particularly when an AED is available within moments defibrillation is performed within about 5 minutes after of the onset of sca SCA.5.6 CPR prolongs VF-9(ie, the window of time during When an out-of-hospital cardiac arrest is not witnessed by h defibrillation can occur) and provides a small amount EMS personnel, they may give about 5 cycles of CPR before f blood flow that may maintain some oxygen and substrate checking the ECG rhythm and attempting defibrillation delivery to the heart and brain. o Basic CPR alone, however, (Class IIb). One cycle of CPR consists of 30 compressions is unlikely to eliminate VF and restore a perfusing rhythm and 2 breaths. When compressions are delivered at a rate of New Recommendations to Integrate CPr and about 100 per minute, 5 cycles of CPR should take roughly 2 AED USe minutes (range: about 1h to 3 minutes ). This recommenda- To treat VF SCA, rescuers must be able to rapidly integrate tion regarding CPR prior to attempted defibrillation is sup- CPR with use of the AED. To give the victim the best chance ported by 2 clinical studies (LOE 25: LOE 36)of adult of survival, 3 actions must occur within the first moments of out-of-hospital VF SCA. In those studies when EMS call-to- a cardiac arrest:(1) activation of the emergency medical arrival intervals were 46 to 55 minutes or le services(EMS)system or emergency medical response sys- received 1/ to 3 minutes of CPR before defibrillation tem,(2)provision of CPR, and (3)operation of an AED showed an increased rate of initial resuscitation. survival to When 2 or more rescuers are present, activation of EMS and hospital discharge, 5.6 and 1-year survival when compared Imitaton of CPR can occur simultaneously. with those who received immediate defibrillation for VF SCA. One randomized study, 2 however, found no benefit to CPR before defibrillation for non-paramedic-witnessed SCA (Circulation. 2005: 112: IV-35-IV-46) EMS system medical directors may consider implement o 2005 American Heart Associa protocol that would allow EMS responders to provide abou This special supplement to Circulation is freely available http://www.circulationaha.org 5 cycles(about 2 minutes)of CPR before defibrillation of patients found by EMS personnel to be in VF, particularly DOI: 10.1161/CIRCULATIONAHA. 105.166554 when the EMs system call-to-response interval is >4 to 5Part 5: Electrical Therapies Automated External Defibrillators, Defibrillation, Cardioversion, and Pacing This chapter presents guidelines for defibrillation with automated external defibrillators (AEDs) and manual defibrillators, synchronized cardioversion, and pacing. AEDs may be used by lay rescuers and healthcare providers as part of basic life support. Manual defibrillation, cardioversion, and pacing are advanced life support therapies. Defibrillation Plus CPR: A Critical Combination Early defibrillation is critical to survival from sudden cardiac arrest (SCA) for several reasons: (1) the most frequent initial rhythm in witnessed SCA is ventricular fibrillation (VF), (2) the treatment for VF is electrical defibrillation, (3) the probability of successful defibrillation diminishes rapidly over time, and (4) VF tends to deteriorate to asystole within a few minutes.1 Several studies have documented the effects of time to defibrillation and the effects of bystander CPR on survival from SCA. For every minute that passes between collapse and defibrillation, survival rates from witnessed VF SCA de￾crease 7% to 10% if no CPR is provided.1 When bystander CPR is provided, the decrease in survival rates is more gradual and averages 3% to 4% per minute from collapse to defibrillation.1,2 CPR can double1–3 or triple4 survival from witnessed SCA at most intervals to defibrillation. If bystanders provide immediate CPR, many adults in VF can survive with intact neurologic function, especially if defibrillation is performed within about 5 minutes after SCA.5,6 CPR prolongs VF7–9 (ie, the window of time during which defibrillation can occur) and provides a small amount of blood flow that may maintain some oxygen and substrate delivery to the heart and brain.10 Basic CPR alone, however, is unlikely to eliminate VF and restore a perfusing rhythm. New Recommendations to Integrate CPR and AED Use To treat VF SCA, rescuers must be able to rapidly integrate CPR with use of the AED. To give the victim the best chance of survival, 3 actions must occur within the first moments of a cardiac arrest: (1) activation of the emergency medical services (EMS) system or emergency medical response sys￾tem, (2) provision of CPR, and (3) operation of an AED. When 2 or more rescuers are present, activation of EMS and initiation of CPR can occur simultaneously. Delays to either start of CPR or defibrillation can reduce survival from SCA. In the 1990s some predicted that CPR could be rendered obsolete by the widespread development of community AED programs. Cobb6 noted, however, that as more Seattle first responders were equipped with AEDs, survival rates from SCA unexpectedly fell. He attributed this decline to reduced emphasis on CPR, and there is growing evidence to support this view. Part 4: “Adult Basic Life Support” summarizes the evidence on the importance of effective chest compressions and minimizing interruptions in providing compressions. Two critical questions about integration of CPR with defibrillation were evaluated during the 2005 Consensus Conference.11 The first question concerns whether CPR should be provided before defibrillation is attempted. The second question concerns the number of shocks to be deliv￾ered in a sequence before the rescuer resumes CPR. Shock First Versus CPR First When any rescuer witnesses an out-of-hospital arrest and an AED is immediately available on-site, the rescuer should use the AED as soon as possible. Healthcare providers who treat cardiac arrest in hospitals and other facilities with AEDs on-site should provide immediate CPR and should use the AED/defibrillator as soon as it is available. These recommen￾dations are designed to support early CPR and early defibril￾lation, particularly when an AED is available within moments of the onset of SCA. When an out-of-hospital cardiac arrest is not witnessed by EMS personnel, they may give about 5 cycles of CPR before checking the ECG rhythm and attempting defibrillation (Class IIb). One cycle of CPR consists of 30 compressions and 2 breaths. When compressions are delivered at a rate of about 100 per minute, 5 cycles of CPR should take roughly 2 minutes (range: about 11⁄2 to 3 minutes). This recommenda￾tion regarding CPR prior to attempted defibrillation is sup￾ported by 2 clinical studies (LOE 25; LOE 36) of adult out-of-hospital VF SCA. In those studies when EMS call-to￾arrival intervals were 46 to 55 minutes or longer, victims who received 11⁄2 to 3 minutes of CPR before defibrillation showed an increased rate of initial resuscitation, survival to hospital discharge,5,6 and 1-year survival5 when compared with those who received immediate defibrillation for VF SCA. One randomized study,12 however, found no benefit to CPR before defibrillation for non–paramedic-witnessed SCA. EMS system medical directors may consider implementing a protocol that would allow EMS responders to provide about 5 cycles (about 2 minutes) of CPR before defibrillation of patients found by EMS personnel to be in VF, particularly when the EMS system call-to-response interval is
4 to 5 (Circulation. 2005;112:IV-35-IV-46.) © 2005 American Heart Association. This special supplement to Circulation is freely available at http://www.circulationaha.org DOI: 10.1161/CIRCULATIONAHA.105.166554 IV-35