Automated external defibrillators: What`s established? What`s new?
Transcription
Automated external defibrillators: What`s established? What`s new?
162 H.-J. Trappe Applied Cardiopulmonary Pathophysiology 16: 162-173, 2012 Automated external defibrillators: What’s established? What’s new? Hans-Joachim Trappe Department of Cardiology and Angiology, University of Bochum, Germany Abstract Prognosis of patients (pts) with out-of-hospital cardiac arrest (CA) due to ventricular fibrillation (VF) or ventricular tachycardia (VT) is bad and the survival rate is 5-8%. Bystander first aid, defibrillation and advanced life support is essential for neurologic outcome in pts after cardiac arrest due to VF/VT. In those pts defibrillation should be performed as soon as possible, at least within 5 minutes after CA. Public access defibrillation in the hands of trained laypersons (first responder) with automated external defibrillators (AED) seems to be a good approach in the treatment of VF or VT. The use of AEDs by basic life support ambulance providers or first responder in early defibrillation programs has been associated with a significant increase in survival rates. This is caused by a shorter “call-to-arrival-time” in first responders compared to professionals. Nevertheless, ideal places for installation of AED are still unclear and further studies are necessary. Key words: emergency medicine, automated external defibrillators, out-of-hospital cardiac arrest Introduction Emergency medicine and critical care are fields that often require rapid diagnosis and intervention for specific situations (1). These critical interventions can be life-saving or severely debilitating depending on their appropriateness and timeliness. In cardiac emergencies, accurate differentiation of ventricular and supraventricular tachyarrhythmias is essential for appropriate management (2). Most frequently, the diagnosis of the underlying arrhythmia is readily apparent, but occasionally it is necessary to use clues from the physical examination, the response to maneuvers or drugs, in addition to the 12-lead surface electrocardiogram (3,4). Treatment of cardiac arrhythmias in intensive care and emergency medicine is sometimes difficult. Correct therapy based on an understanding of the mechanism that caused the arrhythmia may not only be life-saving in the immediate situation but may also improve the quality of life. The purpose of the present manuscript is to summarize the experiences of automated external defibrillators (AED) in the management of patients with cardiac arrest due to ventricular fibrillation or fast ventricular tachycardia. Ventricular fibrillation and cardiac arrest Approximately 1.000 people in the United States suffer from cardiac arrest each day, Automated external defibrillators: What’s established? What’s new? most often as a complication of an acute myocardial infarction with accompanying ventricular fibrillation or unstable ventricular tachycardia. The American Heart Association (AHA) reported several times about the chain of survival concept, with four links – early access, cardiopulmonary resuscitation, defibrillation, and advanced care – as the way to approach cardiac arrest (5). It has been pointed out that the highest potential survival rate from cardiac arrest can be achieved only when the following sequence of events occurs as rapidly as possible: (a) recognition of early warning signs, (b) activation of the emergency medical services system, (c) basic cardiopulmonary resuscitation, (d) defibrillation, (e) management of the airway and ventilation, and (f) intravenous administration of medications (5). Neurologic outcome in patients with cardiac arrest Bystander first aid, defibrillation and advanced life support is essential for neurologic outcome in patients after cardiac arrest. Bur et al. (6) evaluated the effects of basic life support, time to first defibrillation and emergency medical service arrival on neurologic outcome in 276 patients after cardiac arrest. In contrast to intubation (odds ratio 1.08; 95% CI, 0.51-2.31; p=0.84), basic life support (odds ratio 0.44; 95% CI, 0.24-0.77; p=0.004) and time to first defibrillation (odds ratio 1.08; 95% CI, 1.03-1.13; p=0.001) were significantly correlated with good neurologic outcome. In addition to the better neurologic outcome, among the patients who did not receive basic life support, the average cost per patient with good neurologic outcome significantly increased with the delay of the first defibrillation (p<0.001). The importance of cerebral perfusion and pressure and cerebral tissue oxygen tension during cardiopulmnonary resuscitation has been described also by others (7). 163 Early defibrillation Public access defibrillation, which places automatic external defibrillators (AED) in the hands of trained laypersons (first responder) has the potential to be the single greatest advance in the treatment of ventricular fibrillation since the development of cardiopulmonary resuscitation. Time to defibrillation is the most important determinant of survival from cardiac arrest (8). The earlier the defibrillation is performed the better the success rates for resuscitation, irrespective of who is doing the first defibrillation (9). In the last few years there has been a significant increase in the use of AEDs in early defibrillation programs in a variety of settings, including hospitals, emergency medical service, police departments, casinos, airport terminals, and commercial aircraft, among others. In most of these settings, use of AEDs by basic life support ambulance providers or first responder in early defibrillation programs has been associated with a significant increase in survival rates (10-12). Importance of the time interval between cardiac arrest and defibrillation Expert guidelines advocate defibrillation within 2 minutes after an in-hospital cardiac arrest caused by ventricular fibrillation or fast ventricular tachycardia. However, empirical data on the prevalence of delayed defibrillation in the United States and its effect on survival are limited. Chan et al. (13) identified 6789 patients who had cardiac arrest due to ventricular fibrillation or pulseless ventricular tachycardia at 369 hospitals participating in the National Registry of Cardiopulmonary Resuscitation. Using multivariable logistic regression, they identified characteristics associated with delayed defibrillation and examined the association between delayed defibrillation (more than 2 minutes) and survival to discharge after adjusting for differences in patient and hospital characteristics. Delayed de- 164 fibrillation occurred in 2045 patients (30.1%). Characteristics associated with delayed defibrillation included black race, noncardiac admitting diagnosis, and occurrence of cardiac arrest at a hospital with fewer than 250 beds, in an unmonitored hospital unit, and during after-hours periods (5 p.m. to 8 a.m. or weekends). Delayed defibrillation was associated with a significantly lower probability of surviving to hospital discharge (22.2%, vs. 39.3% when defibrillation was not delayed; adjusted odds ratio, 0.48; 95% confidence interval, 0.42 to 0.54; p<0.001). In addition, a graded association was seen between increasing time to defibrillation and lower rates of survival to hospital discharge for each minute of delay (p < 0.001). Chan et al. (13) concluded that delayed defibrillation was common and associated with lower rates of survival after in-hospital cardiac arrest. Beginning of the “AED-era”: First clinical results AEDs were used in 105 patients with ventricular fibrillation suffered in casinos (10). Fiftysix of the patients (53%) survived to discharge from the hospital. Among the 90 patients whose collaps was witnessed (86%), the clinically relevant time intervals were a mean of 3.5±2.9 minutes from collapse to the delivery of the first defibrillation shock, and 9.8±4.3 minutes from collapse to the arrival of the paramedics. The survival rate was 74% for those who received their first defibrillation no later than three minutes after a witnessed collapse and 49% for those who received their first defibrillation after more than three minutes. Caffrey et al. reported the public use of AEDs in three Chicago airports (12). During a two-year period, 21 persons had nontraumatic cardiac arrest, 18 of whom had ventricular fibrillation. In the case of four patients with ventricular fibrillation, defibrillators were neither nearby nor used within five minutes, and none of these patients survived. Three others remained in ventricular fibrillation and eventually died later, H.-J. Trappe despite the rapid use of a defibrillator within five minutes. Eleven patients with ventricular fibrillation were successfully resuscitated, including eight who regained consciousness before hospital admission. No shock was delivered in four cases of suspected cardiac arrest, and the device correctly indicated that the problem was not due to ventricular fibrillation (Tab. 1) (14-22). Capucci et al. (23) established Piacenza Progetto Vita (PPV), the first system of out-ofhospital early defibrillation by first-responder volunteers. The system serves a population of 173 114 residents in the Piacenza region of Italy. Equipment for the system comprises 39 semiautomatic external biphasic defibrillators (AEDs): 12 placed in high-risk locations, 12 in lay-staffed ambulances, and 15 in police cars; 1285 lay volunteers trained in use of the AED, without traditional education in cardiac pulmonary resuscitation, responded to all cases of suspected SCA, in coordination with the Emergency Medical System (EMS). During the first 22 months, 354 SCA occurred (72±12 years, 73% witnessed). The PPV volunteers treated 143 SCA cases (40.4%), with an EMS call-to-arrival time of 4.8±1.2 minutes (versus 6.2±2.3 minutes for EMS, p=0.05). Overall survival rate to hospital discharge was tripled from 3.3% (7 of 211) for EMS intervention to 10.5% (15 of 143) for PPV intervention (P=0.006). The survival rate for witnessed SCA was tripled by PPV: 15.5% versus 4.3% in the EMS-treated group (p=0.002). A “shockable” rhythm was present in 23.8% (34 of 143) of the PPV patients versus 15.6% (33 of 211) of the EMS patients (p=0.055). The survival rate from shockable dysrhythmias was higher for PPV versus EMS: 44.1% (15 of 34) versus 21.2% (7 of 33), p=0.046. The neurologically intact survival rate was higher in PPV-treated versus EMStreated patients: 8.4% (12 of 143) versus 2.4% (5 of 211), p=0.009. 165 Automated external defibrillators: What’s established? What’s new? Table 1a: AED programs in communities Author Study design Patients SR p Eisenberg (14) Paramedics+BLS vs BLS+AED 179 with CA 18% 38% < 0,05 Paramedics vs FR+AED 610337 IN 10% 14% * Police+AED vs Paramedics-AED 1181612 IN 17% 9% 0,047 FR+AED vs PM 173114 IN 11% 3% 0,006 FM+BLS vs FM+AED 1287 IN 19% 30% * Police+AED vs PM 7 urban communi- 26% ties 3% BLS vs BLS+AED 993 communities in 24 regions of North America 14% 23% 0,03 FM+police vs PM 469 CA 25% 21% ns Kellermann (15) Myerburg (16) Capucci (17) Weaver (18) Mosesso (19) PAD Trial (20) Van Alem (21) 0,01 Abbreviations: AED=automated external defibrillator, BLS=„Basic life support“, CA=out-of-hospital cardiac arrest, FR=first responder, IN=inhabitants, FM=fireman, PM=paramedics, ns=non significant, SR=survival rate, *=no data Table 1b: AED programs in public places Author No of persons AED-location AED-user Patients SR Venezuela (10) casinos FR 105 pts VF 53% Caffrey (12) 100 mill pass, AI O’Hare, Midway, Meig Field (per year) FR/Paramedics 18 pts CA 56% Page (11) 70801874 pass 727956 flights American Airlines (per year) FR 14 pts VF 40% O’Rourke (22) 31 mill pass 203191 flights Quantas (per year) FR 46 pts CA 26% Abbreviations: AED=automated external defibrillator, FR=first responder, AI=airport, CA=out-of-hospital cardiac arrest, VF=ventricular fibrillation, mill=millions, pass=passangers, SR=survival rate 166 Resuscitation with or without AED use? The rate of survival after out-of-hospital cardiac arrest is low. It is not known whether this rate will increase if laypersons are trained to attempt defibrillation with the use of automated external defibrillators (AEDs). The Public Access Defibrillation Trial (PAD trial) was a prospective, community-based, multicenter clinical trial in which randomly assigned community units (e.g., shopping malls and apartment complexes) were studied with regard to a structured and monitored emergency-response system involving lay volunteers trained in cardiopulmonary resuscitation (CPR) alone or in CPR and the use of AEDs (20). The primary outcome was survival to hospital discharge. More than 19,000 volunteer responders from 993 community units in 24 North American regions participated. The two study groups had similar unit and volunteer characteristics. Patients with treated outof-hospital cardiac arrest in the two groups were similar in age (mean, 69.8 years), proportion of men (67%), rate of cardiac arrest in a public location (70%), and rate of witnessed cardiac arrest (72%). No inappropriate shocks were delivered. There were more survivors to hospital discharge in the units assigned to have volunteers trained in CPR plus the use of AEDs (30 survivors among 128 arrests) than there were in the units assigned to have volunteers trained only in CPR (15 among 107; p=0.03; relative risk, 2.0; 95% confidence interval, 1.07 to 3.77); there were only 2 survivors in residential complexes. Functional status at hospital discharge did not differ between the two groups. Training and equipping volunteers to attempt early defibrillation within a structured response system can increase the number of survivors to hospital discharge after out-of-hospital cardiac arrest in public locations. Trained laypersons can use AEDs safely and effectively. H.-J. Trappe Experience with AED in Japan It is unclear whether dissemination of automated external defibrillators (AEDs) in public places can improve the rate of survival among patients who have had an out-of-hospital cardiac arrest. From January 1, 2005, through December 31, 2007, Kitamura et al. (24) conducted a prospective, population-based, observational study involving consecutive patients across Japan who had an out-of-hospital cardiac arrest and in whom resuscitation was attempted by emergency responders. They evaluated the effect of nationwide dissemination of public-access AEDs on the rate of survival after an out-of-hospital cardiac arrest. The primary outcome measure was the 1month rate of survival with minimal neurologic impairment. A multivariate logistic-regression analysis was performed to assess factors associated with a good neurologic outcome. A total of 312,319 adults who had an out-ofhospital cardiac arrest were included in the study; 12,631 of these patients had ventricular fibrillation and had an arrest that was of cardiac origin and that was witnessed by bystanders. In 462 of these patients (3.7%), shocks were administered by laypersons with the use of public-access AEDs, and the proportion increased, from 1.2% to 6.2%, as the number of public-access AEDs increased (p<0.001). Among all patients who had a bystander-witnessed arrest of cardiac origin and who had ventricular fibrillation, 14.4% were alive at 1 month with minimal neurologic impairment; among patients who received shocks from public-access AEDs, 31.6% were alive at 1 month with minimal neurologic impairment. Early defibrillation, regardless of the type of provider (bystander or emergency-medical-services personnel), was associated with a good neurologic outcome after a cardiac arrest with ventricular fibrillation (adjusted odds ratio per 1-minute increase in the time to administration of shock, 0.91; 95% confidence interval, 0.89 to 0.92; p<0.001). The mean time to shock was reduced from 3.7 to 2.2 minutes, and the annu- Automated external defibrillators: What’s established? What’s new? al number of patients per 10 million population who survived with minimal neurologic impairment increased from 2.4 to 8.9 as the number of public-access AEDs increased from fewer than 1 per square kilometer of inhabited area to 4 or more. Nationwide dissemination of public-access AEDs in Japan resulted in earlier administration of shocks by laypersons and in an increase in the 1-month rate of survival with minimal neurologic impairment after an out-of-hospital cardiac arrest. 167 tients, 14 received an appropriate shock, and 4 survived to hospital discharge. There were no documented inappropriate shocks. Bardy et al. (25) concluded from their study that survivors of anterior-wall myocardial infarction who were not candidates for implantation of a cardioverter-defibrillator, access to a home AED did not significantly improve overall survival, as compared with reliance on conventional resuscitation methods. AED-strategies in Germany AED therapy at home: Useful or not? The most common location of out-of-hospital sudden cardiac arrest is the home, a situation in which emergency medical services are challenged to provide timely care. Consequently, home use of an automated external defibrillator might offer an opportunity to improve survival for patients at risk. Bardy et al. (25) randomly assigned 7001 patients with previous anterior-wall myocardial infarction who were not candidates for an implantable cardioverter–defibrillator to receive one of two responses to sudden cardiac arrest occurring at home: either the control response (calling emergency medical services and performing cardiopulmonary resuscitation [CPR]) or the use of an AED, followed by calling emergency medical services and performing CPR. The primary outcome was death from any cause. The median age of the patients was 62 years; 17% were women. The median follow-up was 37.3 months. Overall, 450 patients died: 228 of 3506 patients (6.5%) in the control group and 222 of 3495 patients (6.4%) in the AED group (hazard ratio, 0.97; 95% confidence interval, 0.81 to 1.17; p=0.77). Mortality did not differ significantly in major prespecified subgroups. Only 160 deaths (35.6%) were considered to be from sudden cardiac arrest from tachyarrhythmia. Of these deaths, 117 occurred at home; 58 at-home events were witnessed. AEDs were used in 32 patients. Of these pa- In Germany, three pilot AED projects were performed in cooperation of the Ruhr-University Bochum, the German Society of Cardiology and the German Heart Foundation. AED projects were started at the LAGO-die Therme in Herne, a well known European waterpark, at Frankfurt airport and the parliament of North Rhine Westfalia. LAGO – die Therme Herne LAGO-die Therme in Herne, is a well known European waterpark with approximately 700,000 visitors per year. The total area of this waterpark is five ha, the area with roof is 12.000 m2, with a water area of 3000 m2. There are 16 sweating bathes and three Turkish bathes. Within this waterpark eight automated external defibrillators were placed (Typ AED 500, Fa. Physiocontrol, Düsseldorf). The locations where the defibrillators were stored were chosen to make possible a target interval of 60 seconds from collapse to first defibrillation (fig. 1). Twenty waterpark officers were instructed in cardiopulmonary resuscitation and in the use of the AED. Every six months the training was repeated. The project was started November 16th, 2001. During the last ten years 10,05 million visitors were seen in the waterpark. None of the visitors died due to ventricular tachyarrhythmias. AED were used in two visitors with nonarrhythmogenic syncope; no AED shock was delivered. 168 H.-J. Trappe Figure 1: Installation of automated external defibrillators in the LAGO – die Therme, Herne International airport Frankfurt The pilot project „ automated external defibrillators“ at the International airport Frankfurt/Main was started 13.12.2002 in cooperation with the Ruhr-University Bochum, Fraport AG, German Society of Cardiology and Unfallkasse Hessen. There are 52 million passengers per year in Frankfurt airport and 68.000 staff members who take care of them. In the airport hospital 26.000 patients per year were treated, the emergency medical system has 18.000 rescue efforts. In the beginning of the project, 16 AED (Typ AED 500, Firma Physiocontrol) were installed in the terminals 1 and 2 in regions with high passenger numbers (baggage belts) (fig. 2,3). In the mean time additional AED were installed (type „ Heartsave“ der Fa. PrimedicTM), and until december 2010 44 AED are available. In the beginning of the study, 514 staff members of Fraport were trained in cardiopulmary resuscitation and AED use. Until December 2010 a total of 2514 trained first responders are present at Frankfurt airport. During the time interval 2003-2010 more than 400 million passengers went through Frankfurt airport (50-52 million passengers per year). During the eight-year follow-up a total of 21 cardiac arrests with AED use was observed. There were 14 cardiac arrest from 2003-2008 and seven cardiac arrests during the time interval 2009-2010. 18/21 patients (86%) were males, three patients (14%) females. Nine patients (43%) had an age of >70 years, eight patients (37%) between 6170 years. Two patients (10%) between 41-50 years and the remaining two patients (10%) less than 41 years. Cardiac arrests with resuscitation and AED use occurred in 17 patients (81%) in terminal 1 and in four patients (19%) in terminal 2 (fig. 4). Between 2003 and 2008 cardiac arrests occurred in 14 patients, eight of them (57%) survived, six patients (43%) died despite cardiopulmonary resuscitation and defibrilla- Automated external defibrillators: What’s established? What’s new? 169 Figure 2: Map of the Rhein-Main Airport Frankfurt/Main showing the locations of automated external defibrillators in the terminals 1 and 2. Figure 3: Examples of automated external defibrillators in the hall B (international flights) of the RheinMain Airport Frankfurt/Main. 170 H.-J. Trappe Figure 4: Ventricular fibrillation recorded in the terminal 1 of the Rhein-Main Airport. Ventricular fibrillation was successful converted in this passanger after a total recording of 21 seconds, resulting in a pause followed by sinus rhythmus. This passanger survived to be discharged from the hospital. The labels shown depict the activity of the device as displayed on the electrocardiographic tracing. tion. During the time interval 2009-2010 seven patients underwent resuscitation and AED use: 57% of them survived and 43% of the patients died. million visitors were observed in the parliament. No visitor had cardiac arrest and no AED use was necessary. Conclusions AED use in the Parliament of North Rhine Westfalia 100.000 visitors per year were observed in the parliament of North Rhine Westfalia in Düsseldorf. Eight hundreds staff members are working in this institution. To avoid sudden cardiac death and to take care for the visitors, six AED (type Heartstream, Firma Leardal, München) were installed in the parliament building (fig. 5). The AED project was started in March 2003. Fourty-five staff members of the parliament were trained in cardiopulmonary resuscitation and AED use with repeated training sessions every six months. Until December 31, 2010, approximately 1 It has been shown in many studies that outcome is poor in patients with cardiac arrest due to ventricular fibrillation or fast ventricular tachycardia. It has become clear that cardiopulmonary resuscitation with fast defibrillation is essential for survival and good neurological outcome. The concept of automated external defibrillators (AED) and first responder defibrillation was exciting and promised a new era of therapy in these “poor” patients. After the enthusiastic results of the “casino study” by Valenzuela et al. (10) and the initial results of the “Piazenza trial” by Capucci et al. (23) several “AED projects” were Automated external defibrillators: What’s established? What’s new? 171 Figure 5: Installation of an automated external defibrillator in the parliament of North Rhine Westfalia, Düsseldorf. started in different locations and in different countries. However, more than ten years later, we have to recognize that different questions are open and a “final solution” of the problems is not visible. First of all, it is difficult to select “ideal” places for AED installation. It seems logical to install AED in places with high number of human beings, but the results of our three studies in Germany are very disappointing concerning this: More than 411 million people were followed and only few of them had a need of AED use and survived. Comparing the results of three Chicago airports with the results of Frankfurt airport a low incidence of cardiac arrests due to ventricular fibrillation is visible despite millions of passengers. In addition to these observations, there is a low incidence in waterparks despite millions of visitors. And at thome? Several years it has been pointed out that sudden cardiac deaths occur at home and “home AED” are the answer to this. After the study of Bardy et al. (25) it has become clear that the hypothesis to increase the survival rate of patients with cardiac arrest at home by AED use was impossible. The survival rate was similar in patients with or without AED use in “home cardiac arrests”. What to do? It is certainly necessary to perform further studies evaluating the incidence of sudden death and predicting risk factors. 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N Engl J Med 2008; 358: 1793-1804 173 Correspondence address Prof. Hans-Joachim Trappe, M.D. Department of Cardiology and Angiology University of Bochum Hoelkeskampring 40 44625 Herne Germany hans-joachim.trappe@ruhr-uni-bochum.de