摘要
The incidence of sudden cardiac death (SCD) in children is not entirely certain; it is much less frequent than in adults. However, even at the estimated incidence of one to two children per 100,000 per year, it is a devastating event with severe consequences for families and communities. It can result in the death of an ostensibly healthy child or adolescent who is in the prime of his or her life. Therefore, strategies to prevent sudden cardiac arrest (SCA) and SCD in children are critically important. Such strategies include primary prevention or screening, as well as secondary prevention. Strategies and controversies with regard to screening will be addressed elsewhere. Rather, the present article will focus on the concepts and controversies related to secondary prevention (ie, the establishment of cardiopulmonary resuscitation – automated external defibrillation [CPR-AED] programs).
The efficacy of current screening in North America continues to be a focus of debate. The utility and feasibility of routine electrocardiogram screening is similarly under intense scrutiny. However, it is accurate to conclude that even if routine screening involved a mandatory electrocardiogram and echocardiogram in addition to a comprehensive history, family history and physical examination, not all young people at risk for SCA will be identified. Therefore, secondary prevention with timely CPR and AED use is paramount for survival in individuals who cannot be diagnosed with standard screening techniques, and who suffer a cardiac arrest.
The Public Access Defibrillation (PAD) trial was a National Heart, Lung and Blood Institute (USA)-sponsored multicentre, multisite trial designed to determine whether a strategy of training laypersons to use automated external defibrillators would result in increased survival from SCAs in adults. The PAD trial found an overall doubling in the number of out-of-hospital SCA survivors when a lay-responder team was equipped with AEDs compared with the teams that used CPR only (1). Recent data have also focused on the importance of chest compressions and the minimization of interruptions in CPR, eliminating rescue breathing, specifically in the scenario of an unwitnessed SCA due to ventricular fibrillation (2). AED use continues to be an important part of the successful therapy in this scenario, as well as in the scenario of a witnessed SCA.
The results of the PAD trial and other studies discussed a rationale for cost-effective placement of AEDs within the community. The PAD trial results suggested that a cost-effective strategy of AED placement should include sites where there would be one cardiac arrest every few years, where there are at least 250 adults older than 50 years of age during waking hours, where there are known high-risk individuals and/or where the frequency of SCA is higher. Becker et al (3) determined that locations for AED placement should be community-specific but should also include airports, golf clubs, health clubs, large industrial areas, sporting events, shopping malls and casinos. The data from PAD implementation in casinos in Las Vegas, USA, were reported in 2000 (4). In this prospective study, AEDs were used in 32 casinos over a 32-month period of time in 105 patients whose initial rhythms were ventricular fibrillation. Fifty-six of the patients survived to hospital discharge. Among the 90 patients (86%) whose collapse was witnessed, the survival rate was 74% if a shock was delivered within 3 min and 49% if the first defibrillation was delivered after 3 min.
It should be noted, of course, that neither having schools as sites of AED placement nor discussion of programs targeted toward children and adolescents was addressed in any of the above literature.
Where PAD fits in the scenario of SCA and SCD in children and adolescents is, therefore, not entirely clear. The incidence of SCD is lower in children than in adults, as described above. Where might PAD fit as it relates to the school environment – an environment in which our youth spend a considerable amount of time?
Very little data exist about the school environment and the incidence of SCA. Lofti et al (5) recently provided some information on this topic. In a retrospective analysis of the school system in Seattle and King County (USA) between 1990 and 2005, 97 SCAs occurred in schools (0.4% of all SCAs and 2.6% of all public location SCAs). Of the 97 SCAs in this 15-year period, 12 occurred among students, 33 among faculty and staff, and 45 among additional adults within the school. School-based SCAs occurred on an average of one in 111 schools annually, with the greatest annual incidence in colleges (one in eight), followed by high schools (one in 125) and then lower-level schools (one in 200 preschools through middle schools).
In 2007, Rothmier et al (6) reviewed the experience with high schools in Washington, USA. Of 407 principals who were polled, 118 (29%) responded. Sixty-four (54%) of the 118 schools that responded had at least one AED. There was one successful use of an AED in an adult, with the estimated probability of AED use of one in 154 schools per year.
Meredith (7) reviewed the data on SCD in high schools in Tennessee, USA, between 2001 and 2006. It was noted that there were deaths in five students and 16 adults in 378 schools. These data translated to one episode of SCD per 61 schools per year – an incidence that was slightly greater than in the Seattle study. Additionally, schools with an SCA event had a larger enrollment than schools without an SCA event, and all five students who had SCAs were enrolled in a school with more than 1000 students. This report suggested that AED programs might be targeted for schools with a larger enrollment if resources were limited.
Therefore, what might the above data help us conclude with regard to the utility, feasibility and rationale for school CPR-AED programs? An American Heart Association panel on school medical emergency response planning issued a consensus statement in 2004 (8). The panel suggested that a school CPR-AED program should be part of a comprehensive medical emergency response plan. This report emphasized communication and planning, and advocated that all high school students learn CPR before graduation. The panel also recommended that lay-rescuer CPR-AED programs be placed in schools with an established need. Such a need, according to the report, was defined as follows:
Schools with a reasonable probability of a SCA in the next five years;
Schools with any student at high-risk; or
Schools with an emergency to shock time of more than 5 min.
In the absence of any of the above, a specific school may not necessarily benefit from the presence of an AED. It is probably true that the majority of schools may not be able to achieve an emergency to shock time of less than 5 min and, therefore, may benefit from having an AED and CPR-AED program on the premises.
There may be additional data to support the establishment of school CPR-AED programs. Though cost-effectiveness studies require assumptions that could be challenged, at least one cost-effectiveness study (9) supports the establishment of school CPR-AED programs. In addition, a school CPR-AED program has additional benefits. First, it is clear that school CPR-AED programs will save the lives of adults as well as children and adolescents. Second, the benefits of training a new community of first responders by training high school students on CPR-AED use is important and difficult to measure. Undoubtedly, a more informed and capable lay public will be beneficial. One needs to determine how such training might be paid for, and if and how this training might be legislated and placed within the school curriculum.
Multiple examples of successful school CPR-AED programs have been well documented. Project ADAM (Automated Defibrillators in Adam’s Memory), a school-based CPR-AED program in southeastern Wisconsin, and now several other Project ADAM affiliates in other states such as Georgia, Florida, Pennsylvania, Alabama and Illinois, has been in existence since 1999. Thus far, Project ADAM Wisconsin has placed 700 CPR-AED programs in schools within the state, which represents approximately 25% of the total number of schools in Wisconsin. Nine saves have been directly associated with Project ADAM Wisconsin, five in adults and four in children and adolescents. Many other successful resuscitations have been reported in both children and adults as a result of school CPR-AED programs.