Part 1: Executive summary: 2010 International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science With Treatment Recommendations.

Abstract

The International Liaison Committee on Resuscitation (ILCOR) was founded on November 22, 1992, and currently includes representatives from the American Heart Association (AHA), the European Resuscitation Council (ERC), the Heart and Stroke Foundation of Canada (HSFC), the Australian and New Zealand Committee on Resuscitation (ANZCOR), Resuscitation Council of Southern Africa (RCSA), the InterAmerican Heart Foundation (IAHF), and the Resuscitation Council of Asia (RCA). Its mission is to identify and review international science and knowledge relevant to cardiopulmonary resuscitation (CPR) and emergency cardiovascular care (ECC) and when there is consensus to offer treatment recommendations. Emergency cardiovascular care includes all responses necessary to treat sudden life-threatening events affecting the cardiovascular and respiratory systems, with a particular focus on sudden cardiac arrest. In 1999, the AHA hosted the first ILCOR conference to evaluate resuscitation science and develop common resuscitation guidelines. The conference recommendations were published in the International Guidelines 2000 for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care.1American Heart Association in collaboration with International Liaison Committee on ResuscitationGuidelines 2000 for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care.Circulation. 2000; 102: I1-I384PubMed Google Scholar Since 2000, researchers from the ILCOR member councils have evaluated resuscitation science in 5-year cycles. The conclusions and recommendations of the 2005 International Consensus Conference on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care With Treatment Recommendations were published at the end of 2005.2Proceedings of the 2005 International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science with Treatment Recommendations. Resuscitation 2005;67:157–341.Google Scholar, 3International Liaison Committee on Resuscitation International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science With Treatment Recommendations.Circulation. 2005; 112: III-1-III-136Google Scholar The most recent International Consensus Conference was held in Dallas in February 2010, and this publication contains the consensus science statements and treatment recommendations developed with input from the invited participants. The goal of every resuscitation organisation and resuscitation expert is to prevent premature cardiovascular death. When cardiac arrest or life-threatening emergencies occur, prompt and skillful response can make the difference between life and death and between intact survival and debilitation. This document summarises the 2010 evidence evaluation of published science about the recognition and response to sudden life-threatening events, particularly sudden cardiac arrest and peri-arrest events in victims of all ages. The broad range and number of topics reviewed necessitated succinctness in the consensus science statements and brevity in treatment recommendations. This supplement is not a comprehensive review of every aspect of resuscitation medicine; not all topics reviewed in 2005 were reviewed in 2010. This executive summary highlights the evidence evaluation and treatment recommendations of the 2010 evidence evaluation process. More detailed information is available in other parts of this publication. To begin the current evidence evaluation process, ILCOR representatives established 6 task forces: basic life support (BLS); advanced life support (ALS); acute coronary syndromes (ACS); paediatric life support; neonatal life support; and education, implementation, and teams (EIT). Separate writing groups were formed to coordinate evidence evaluation for defibrillation and mechanical devices because these overlapped with both BLS and ALS. Each task force identified topics requiring evidence evaluation and invited international experts to review them. To ensure a consistent and thorough approach, a worksheet template was created with step-by-step directions to help the experts document their literature reviews, evaluate studies, determine levels of evidence (Table 1), and develop treatment recommendations (see Part 3: Evidence Evaluation Process).4Morley P.T. Atkins D.L. Billi J.E. et al.Part 3: Evidence evaluation process: 2010 International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science With Treatment Recommendations.Resuscitation. 2010; 81: e32-e40Abstract Full Text Full Text PDF PubMed Scopus (44) Google Scholar When possible, 2 expert reviewers were invited to perform independent evaluations for each topic. The worksheet authors submitted their search strategies to 1 of 3 worksheet review experts. The lead evidence evaluation expert also reviewed all worksheets and assisted the worksheet authors in ensuring consistency and quality in the evidence evaluation. This process is described in detail in Part 3.4Morley P.T. Atkins D.L. Billi J.E. et al.Part 3: Evidence evaluation process: 2010 International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science With Treatment Recommendations.Resuscitation. 2010; 81: e32-e40Abstract Full Text Full Text PDF PubMed Scopus (44) Google Scholar In conjunction with the International First Aid Science Advisory Board, the AHA established an additional task force to review evidence on first aid. This topic is summarised in Part 13. The evidence review followed the same process but was not part of the formal ILCOR review.Table 1Levels of Evidence.C2010 Levels of Evidence for Studies of Therapeutic Interventions LOE 1: Randomized controlled trials (RCTs) (or meta-analyses of RCTs) LOE 2: Studies using concurrent controls without true randomization (eg, “pseudo”-randomized) LOE 3: Studies using retrospective controls LOE 4: Studies without a control group (eg, case series) LOE 5: Studies not directly related to the specific patient/population (eg, different patient/population, animal models, mechanical models, etc)C2010 Levels of Evidence for Prognostic Studies LOE P1: Inception (prospective) cohort studies (or meta-analyses of inception cohort studies), or validation of Clinical Decision Rule (CDR) LOE P2: Follow-up of untreated control groups in RCTs (or meta-analyses of follow-up studies), or derivation of CDR, or validated on split-sample only LOE P3: Retrospective cohort studies LOE P4: Case series LOE P5: Studies not directly related to the specific patient/population (eg, different patient/population, animal models, mechanical models, etc)C2010 Levels of Evidence for Diagnostic Studies LOE D1: Validating cohort studies (or meta-analyses of validating cohort studies) or validation of Clinical Decision Rule (CDR) LOE D2: Exploratory cohort study (or meta-analyses of follow-up studies), or derivation of CDR, or a CDR validated on a split-sample only LOE D3: Diagnostic case-control study LOE D4: Study of diagnostic yield (no reference standard) LOE D5: Studies not directly related to the specific patient/population (eg, different patient/population, animal models, mechanical models, etc) Open table in a new tab The evidence evaluation process from 2007 to 2009 initially involved 509 worksheet authors with 569 worksheets. Some of the worksheets were merged while in other cases there was no new evidence and the worksheets/topics were deleted. The 2010 International Consensus Conference in February, 2010 involved 313 experts from 30 countries. A final total of 277 specific resuscitation questions, each in standard PICO (Population, Intervention, Comparison, Outcome) format, were considered by 356 worksheet authors who reviewed thousands of relevant, peer-reviewed publications. Many of these worksheets were presented and discussed at monthly or semimonthly task force international web conferences (i.e., “webinars” that involved conference calls with simultaneous internet conferencing). Beginning in May 2009 the evidence review and summary portions of the evidence evaluation worksheets, with worksheet author conflict of interest (COI) statements, were posted on the ILCOR Web site (www.ilcor.org). Journal advertisements and emails invited public comment. Persons who submitted comments were required to indicate their potential conflicts of interest. Public comments and potential conflicts of interest were sent to the appropriate ILCOR task force chair and worksheet author for consideration. To provide the widest possible dissemination of the science reviews performed for the 2010 International Consensus Conference, the worksheets prepared for the conference are linked from this document and can be accessed by clicking on the superscript worksheet numbers (each begins with a W) located adjacent to headings. During the 2010 Consensus Conference, wireless Internet access was available to all conference participants to facilitate real-time verification of the literature. Expert reviewers presented summaries of their evidence evaluation in plenary and concurrent sessions. Presenters and participants then debated the evidence, conclusions, and draft summary statements. The ILCOR task forces met daily during the conference to discuss and debate the experts’ recommendations and develop interim consensus science statements. Each science statement summarised the experts’ interpretation of all relevant data on a specific topic, and included consensus draft treatment recommendations. The wording of science statements and treatment recommendations was revised after further review by ILCOR member organisations and the editorial board. This format ensures that the final document represents a truly international consensus process. At the time of submission this document represented the state-of-the-art science of resuscitation medicine. With the permission of the relevant journal editors, several papers were circulated among task force members if they had been accepted for publication in peer-reviewed journals but had not yet been published. These peer-reviewed and accepted manuscripts were included in the consensus statements. This manuscript was ultimately approved by all ILCOR member organisations and an international editorial board (listed on the title page of this supplement). Reviewers solicited by the editor of Circulation and the AHA Science Advisory and Coordinating Committee performed parallel peer reviews of this document before it was accepted for publication. This document is being published online simultaneously by Circulation and Resuscitation, although the version in the latter publication does not include the section on first aid. In order to ensure the evidence evaluation process was free from commercial bias, extensive conflict of interest management principles were instituted immediately following the completion of the 2005 Consensus on CPR and ECC Science and Treatment Recommendations (CoSTR), concurrent with the start of the 2010 CoSTR process. All of the participants were governed by the COI management principles regardless of their role in the CoSTR process. COI disclosure was required from all participants and was updated annually or when changes occurred. Commercial relationships were considered at every stage of the evidence evaluation process and, depending on the nature of the relationship and their role in the evidence evaluation process, participants were restricted from some activities (i.e., leading, voting, deciding, writing, discussing) that directly or indirectly related to that commercial interest. While the focus of the process was the evaluation of the scientific evidence, attention was given to potential COI throughout the CoSTR process.5Davidoff F. DeAngelis C.D. Drazen J.M. et al.Sponsorship, authorship, and accountability.Lancet. 2001; 358: 854-856Abstract Full Text Full Text PDF PubMed Scopus (139) Google Scholar, 6Choudhry N.K. Stelfox H.T. Detsky A.S. Relationships between authors of clinical practice guidelines and the pharmaceutical industry.JAMA. 2002; 287: 612-617Crossref PubMed Scopus (524) Google Scholar, 7Billi J.E. Zideman D.A. Eigel B. Nolan J.P. Montgomery W.H. Nadkarni V.M. Conflict of interest management before, during, and after the 2005 International Consensus Conference on cardiopulmonary resuscitation and emergency cardiovascular care science with treatment recommendations.Resuscitation. 2005; 67: 171-173Abstract Full Text Full Text PDF PubMed Scopus (19) Google Scholar This policy is described in detail in Part 4: “Management of Potential Conflicts of Interest.”8Billi J.E. Shuster M. Bossaert L. et al.for the International Liaison Committee on Resuscitation, the American Heart AssociationPart 4: Conflict of interest management before, during, and after the 2010 International Consensus Conference on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science With Treatment Recommendations.Resuscitation. 2010; 81: e41-e47PubMed Google Scholar This document presents international consensus statements that summarise the science of resuscitation and, wherever possible, treatment recommendations. ILCOR member organisations will subsequently publish resuscitation guidelines that are consistent with the science in this consensus document, but the organisations will also take into account geographic, economic, and system differences in practice; availability of medical devices and drugs (e.g., not all devices and drugs reviewed in this publication are available and approved for use in all countries); and ease or difficulty of training. All ILCOR member organisations are committed to minimising international differences in resuscitation practice and optimising the effectiveness of resuscitation practice, instructional methods, teaching aids, training networks and outcomes (see Part 2: ILCOR Collaboration). The recommendations of the 2010 International Consensus Conference confirm the safety and effectiveness of current approaches, acknowledge other approaches as ineffective, and introduce new treatments resulting from evidence-based evaluation. New and revised treatment recommendations do not imply that clinical care that involves the use of previously published guidelines is either unsafe or ineffective. Implications for education and retention were also considered when developing the final treatment recommendations. Ischaemic heart disease is the leading cause of death in the world.9Murray C.J. Lopez A.D. Mortality by cause for eight regions of the world: Global Burden of Disease Study.Lancet. 1997; 349: 1269-1276Abstract Full Text Full Text PDF PubMed Scopus (3433) Google Scholar, 10Zheng Z.J. Croft J.B. Giles W.H. Mensah G.A. Sudden cardiac death in the United States, 1989 to 1998.Circulation. 2001; 104: 2158-2163Crossref PubMed Scopus (1355) Google Scholar In addition, many newly born infants die worldwide as the result of respiratory distress immediately after birth. However, most out-of-hospital victims die without receiving the interventions described in this publication. The actions linking the adult victim of sudden cardiac arrest with survival are called the adult Chain of Survival. The links in the Chain of Survival used by many resuscitation councils include prevention of the arrest, early recognition of the emergency and activation of the emergency medical services (EMS) system, early and high-quality CPR, early defibrillation, rapid ALS, and postresuscitation care. The links in the infant and child Chain of Survival are prevention of conditions leading to cardiopulmonary arrest, early and high-quality CPR, early activation of the EMS system, and early ALS. The most important determinant of survival from sudden cardiac arrest is the presence of a trained lay rescuer who is ready, willing, and able to act. Although some ALS techniques improve survival,11Mild therapeutic hypothermia to improve the neurologic outcome after cardiac arrest. N Engl J Med 2002;346:549–56.Google Scholar, 12Bernard S.A. Gray T.W. Buist M.D. et al.Treatment of comatose survivors of out-of-hospital cardiac arrest with induced hypothermia.N Engl J Med. 2002; 346: 557-563Crossref PubMed Scopus (4295) Google Scholar these improvements are usually less significant than the increase in survival rates that can result from higher rates of lay rescuer (bystander) CPR and establishment of automated external defibrillation programs in the community.13Holmberg M. Holmberg S. Herlitz J. Effect of bystander cardiopulmonary resuscitation in out-of-hospital cardiac arrest patients in Sweden.Resuscitation. 2000; 47: 59-70Abstract Full Text Full Text PDF PubMed Scopus (250) Google Scholar, 14Valenzuela T.D. Bjerke H.S. Clark L.L. et al.Rapid defibrillation by nontraditional responders: the Casino Project.Acad Emerg Med. 1998; 5: 414-415Google Scholar, 15Culley L.L. Rea T.D. Murray J.A. et al.Public access defibrillation in out-of-hospital cardiac arrest: a community-based study.Circulation. 2004; 109: 1859-1863Crossref PubMed Scopus (114) Google Scholar, 16Caffrey S.L. Willoughby P.J. Pepe P.E. Becker L.B. Public use of automated external defibrillators.N Engl J Med. 2002; 347: 1242-1247Crossref PubMed Scopus (685) Google Scholar, 17Kitamura T. Iwami T. Kawamura T. Nagao K. Tanaka H. Hiraide A. Nationwide public-access defibrillation in Japan.N Engl J Med. 2010; 362: 994-1004Crossref PubMed Scopus (442) Google Scholar Thus, our greatest challenges remain the education of the lay rescuer and understanding and overcoming the barriers that prevent even trained rescuers from performing high-quality CPR. We must increase the effectiveness and efficiency of instruction, improve skills retention, and reduce barriers to action for both basic and ALS providers. Similarly, the placement and use of automated external defibrillators (AEDs) in the community should be encouraged to enable defibrillation within the first minutes after a ventricular fibrillation (VF) sudden cardiac arrest. Several of the new treatment recommendations cited in this document are included in the updated ILCOR Universal Cardiac Arrest Algorithm (Fig. 1). This algorithm is intended to apply to attempted resuscitation of infant, child, and adult victims of cardiac arrest (excluding newly borns). Every effort has been made to keep this algorithm simple yet make it applicable to treatment of cardiac arrest victims of all ages and in most circumstances. Modification will be required in some situations, and these exceptions are highlighted elsewhere in this document. Each resuscitation organisation has based its guidelines on this ILCOR algorithm, although there will be regional modifications. Rescuers begin CPR if the adult victim is unresponsive with absent or abnormal breathing, such as an occasional gasp. A single compression–ventilation ratio of 30:2 is used for the lone lay rescuer of an infant, child, or adult victim (excluding newly borns). This single ratio is designed to simplify teaching, promote skills retention, increase the number of compressions given, and decrease interruptions in compressions. The most significant adult BLS change in this document is a recommendation for a CAB (compressions, airway, breathing) sequence instead of an ABC (airway, breathing, compressions) sequence to minimise delay to initiation of compressions and resuscitation. In other words, rescuers of adult victims should begin resuscitation with compressions rather than opening the airway and delivery of breaths. Once a defibrillator is attached, if a shockable rhythm is confirmed, a single shock is delivered. Irrespective of the resultant rhythm, CPR starting with chest compressions should resume immediately after each shock to minimise the “no-flow” time (i.e., time during which compressions are not delivered, for example, during rhythm analysis). ALS interventions are outlined in a box at the center of the algorithm. Once an advanced airway (tracheal tube or supraglottic airway) has been inserted, rescuers should provide continuous chest compressions (without pauses for ventilations) and ventilations at a regular rate (avoiding hyperventilation). The 2005 International Consensus on Science emphasised the importance of minimal interruption of chest compressions because 2005 evidence documented the frequency of interruptions in chest compressions during both in-hospital and out-of-hospital CPR and the adverse effects of such interruptions in attaining resumption of spontaneous circulation (ROSC).18Wik L. Kramer-Johansen J. Myklebust H. et al.Quality of cardiopulmonary resuscitation during out-of-hospital cardiac arrest.JAMA. 2005; 293: 299-304Crossref PubMed Scopus (1073) Google Scholar, 19Abella B.S. Alvarado J.P. Myklebust H. et al.Quality of cardiopulmonary resuscitation during in-hospital cardiac arrest.JAMA. 2005; 293: 305-310Crossref PubMed Scopus (1037) Google Scholar, 20Abella B.S. Sandbo N. Vassilatos P. et al.Chest compression rates during cardiopulmonary resuscitation are suboptimal: a prospective study during in-hospital cardiac arrest.Circulation. 2005; 111: 428-434Crossref PubMed Scopus (555) Google Scholar In 2010, experts agree that rescuers should be taught to adhere to all four metrics of CPR: adequate rate, adequate depth, allowing full chest recoil after each compression and minimising pauses (e.g., hands off time) in compressions. Although resuscitation practices are usually studied as single interventions, they are actually performed as a large sequence of actions, each with its own timing and quality of performance. It may be difficult or impossible to assess the contribution of any one action (energy level for defibrillation, airway maneuver, drug) on the most important outcomes, such as neurologically intact survival to discharge. In fact, it is likely that it is the combination of actions, each performed correctly, in time and in order, that results in optimal survival and function. A few studies give insight into this necessary shift from studying of changes in individual actions (point improvements) to studying the effects of changing the entire sequence of actions (flow improvement).21Olasveengen T.M. Sunde K. Brunborg C. Thowsen J. Steen P.A. Wik L. Intravenous drug administration during out-of-hospital cardiac arrest: a randomized trial.JAMA. 2009; 302: 2222-2229Crossref PubMed Scopus (373) Google Scholar, 22Sunde K. Pytte M. Jacobsen D. et al.Implementation of a standardised treatment protocol for post resuscitation care after out-of-hospital cardiac arrest.Resuscitation. 2007; 73: 29-39Abstract Full Text Full Text PDF PubMed Scopus (713) Google Scholar The compression–ventilation ratio was one of the most controversial topics of the 2005 International Consensus Conference. The experts began the 2005 conference acknowledging that rates of survival from cardiac arrest to hospital discharge were low, averaging ≤6% internationally,23Fredriksson M. Herlitz J. Nichol G. Variation in outcome in studies of out-of-hospital cardiac arrest: a review of studies conforming to the Utstein guidelines.Am J Emerg Med. 2003; 21: 276-281Abstract Full Text Full Text PDF PubMed Scopus (95) Google Scholar, 24Nichol G. Stiell I.G. Hebert P. Wells G.A. Vandemheen K. Laupacis A. What is the quality of life for survivors of cardiac arrest? A prospective study.Acad Emerg Med. 1999; 6: 95-102Crossref PubMed Scopus (135) Google Scholar and that survival rates had not increased substantially in recent years. That observation led to the 2005 change to a universal compression–ventilation ratio for all lone rescuers of victims of all ages and to an emphasis on the importance of CPR quality throughout the 2005 Consensus on CPR and ECC Science With Treatment Recommendations (CoSTR) document and subsequent ILCOR member council guidelines.25Olasveengen T.M. Vik E. Kuzovlev A. Sunde K. Effect of implementation of new resuscitation guidelines on quality of cardiopulmonary resuscitation and survival.Resuscitation. 2009; 80: 407-411Abstract Full Text Full Text PDF PubMed Scopus (101) Google Scholar Resuscitation outcomes vary considerably among regions.26Nichol G. Thomas E. Callaway C.W. et al.Regional variation in out-of-hospital cardiac arrest incidence and outcome.JAMA. 2008; 300: 1423-1431Crossref PubMed Scopus (1546) Google Scholar, 27Callaway C.W. Schmicker R. Kampmeyer M. et al.Receiving hospital characteristics associated with survival after out-of-hospital cardiac arrest.Resuscitation. 2010; 81: 524-529Abstract Full Text Full Text PDF PubMed Scopus (133) Google Scholar In recent studies the outcome from cardiac arrest, particularly from shockable rhythms, is improved.28Hollenberg J. Herlitz J. Lindqvist J. et al.Improved survival after out-of-hospital cardiac arrest is associated with an increase in proportion of emergency crew—witnessed cases and bystander cardiopulmonary resuscitation.Circulation. 2008; 118: 389-396Crossref PubMed Scopus (203) Google Scholar, 29Lund-Kordahl I. Olasveengen T.M. Lorem T. Samdal M. Wik L. Sunde K. Improving outcome after out-of-hospital cardiac arrest by strengthening weak links of the local Chain of Survival; quality of advanced life support and post-resuscitation care.Resuscitation. 2010; 81: 422-426Abstract Full Text Full Text PDF PubMed Scopus (124) Google Scholar, 30Iwami T. Nichol G. Hiraide A. et al.Continuous improvements in “chain of survival” increased survival after out-of-hospital cardiac arrests: a large-scale population-based study.Circulation. 2009; 119: 728-734Crossref PubMed Scopus (274) Google Scholar, 31Rea T.D. Helbock M. Perry S. et al.Increasing use of cardiopulmonary resuscitation during out-of-hospital ventricular fibrillation arrest: survival implications of guideline changes.Circulation. 2006; 114: 2760-2765Crossref PubMed Scopus (232) Google Scholar, 32Bobrow B.J. Clark L.L. Ewy G.A. et al.Minimally interrupted cardiac resuscitation by emergency medical services for out-of-hospital cardiac arrest.JAMA. 2008; 299: 1158-1165Crossref PubMed Scopus (412) Google Scholar, 33Hinchey P.R. Myers J.B. Lewis R. et al.Improved Out-of-Hospital Cardiac Arrest Survival After the Sequential Implementation of 2005 AHA Guidelines for Compressions, Ventilations, and Induced Hypothermia: The Wake County Experience.Ann Emerg Med. 2010; PubMed Google Scholar Moreover, there is an association between implementation of new resuscitation guidelines and improved outcome.31Rea T.D. Helbock M. Perry S. et al.Increasing use of cardiopulmonary resuscitation during out-of-hospital ventricular fibrillation arrest: survival implications of guideline changes.Circulation. 2006; 114: 2760-2765Crossref PubMed Scopus (232) Google Scholar, 33Hinchey P.R. Myers J.B. Lewis R. et al.Improved Out-of-Hospital Cardiac Arrest Survival After the Sequential Implementation of 2005 AHA Guidelines for Compressions, Ventilations, and Induced Hypothermia: The Wake County Experience.Ann Emerg Med. 2010; PubMed Google Scholar However, there is also evidence that new guidelines can take from 1.5 to 4 years to implement.34Berdowski J. Schmohl A. Tijssen J.G. Koster R.W. Time needed for a regional emergency medical system to implement resuscitation Guidelines 2005—The Netherlands experience.Resuscitation. 2009; 80: 1336-1341Abstract Full Text Full Text PDF PubMed Scopus (48) Google Scholar, 35Binks A.C. Murphy R.E. Prout R.E. et al.Therapeutic hypothermia after cardiac arrest—implementation in UK intensive care units.Anaesthesia. 2010; 64: 260-265Crossref Scopus (59) Google Scholar There have been many developments in resuscitation science since 2005 and these are highlighted below. During the past 5 years, there has been an effort to simplify CPR recommendations and emphasise the importance of high-quality CPR. Large observational studies from investigators in member countries of the RCA, the newest member of ILCOR,36Iwami T. Kawamura T. Hiraide A. et al.Effectiveness of bystander-initiated cardiac-only resuscitation for patients with out-of-hospital cardiac arrest.Circulation. 2007; 116: 2900-2907Crossref PubMed Scopus (298) Google Scholar, 37SOS-KANTO Study Group Cardiopulmonary resuscitation by bystanders with chest compression only (SOS-KANTO): an observational study.Lancet. 2007; 369: 920-926Abstract Full Text Full Text PDF PubMed Scopus (470) Google Scholar, 38Kitamura T. Iwami T. Kawamura T. et al.Conventional and chest-compression-only cardiopulmonary resuscitation by bystanders for children who have out-of-hospital cardiac arrests: a prospective, nationwide, population-based cohort study.Lancet. 2010; 375: 1347-1354Abstract Full Text Full Text PDF PubMed Scopus (335) Google Scholar, 39Ong M.E. Ng F.S. Anushia P. et al.Comparison of chest compression only and standard cardiopulmonary resuscitation for out-of-hospital cardiac arrest in Singapore.Resuscitation. 2008; 78: 119-126Abstract Full Text Full Text PDF PubMed Scopus (112) Google Scholar and other studies40Bohm K. Rosenqvist M. Herlitz J. Hollenberg J. Svensson L. Survival is similar after standard treatment and chest compression only in out-of-hospital bystander cardiopulmonary resuscitation.Circulation. 2007; 116: 2908-2912Crossref PubMed Scopus (172) Google Scholar, 41Olasveengen T.M. Wik L. Steen P.A. Standard basic life support vs. continuous chest compressions only in out-of-hospital cardiac arrest.Acta Anaesthesiol Scand. 2008; 52: 914-919Crossref PubMed Scopus (60) Google Scholar have provided significant data about the effects of bystander CPR. Strategies to reduce the interval between stopping chest compressions and delivery of a shock (the preshock pause) will improve the chances of shock success.42Edelson D.P. Abella B.S. Kramer-Johansen J. et al.Effects of compression depth and pre-shock pauses predict defibrillation failure during cardiac arrest.Resuscitation. 2006; 71: 137-145Abstract Full Text Full Text PDF PubMed Scopus (532)