Automated External Defibrillators Shock Research Articles

Neurological outcome of cardiac arrest patients in mountain areas: An analysis of the Northern French Alps Emergency Network

BackgroundMountainous areas pose a challenge for the out-of-hospital cardiac arrest (OHCA) chain of survival. Survival rates for OHCAs in mountainous areas may differ depending on the location. Increased survival has been observed compared to standard location when OHCA occurred on ski slopes. Limited data is available about OHCA in other mountainous areas. The objective was to compare the survival rates with a good neurological outcome of OHCAs occurring on ski slopes (On-S) and off the ski slopes (OffS) compared to other locations (OL). MethodsAnalysis of prospectively collected data from the cardiac arrest registry of the Northern French Alps Emergency Network (RENAU) from 2015 to 2021. The RENAU corresponding to an Emergency Medicine Network between all Emergency Medical Services and hospitals of 3 counties (Isère, Savoie, Haute-Savoie). The primary outcome was survival at 30 days with a Cerebral Performance Category scale (CPC) of 1 or 2 (1: Good Cerebral Performance, 2: Moderate Cerebral Disability). ResultsA total of 9589 OHCAs were included: 213 in the On-S group, 141 in the Off-S group, and 9235 in the OL group. Cardiac etiology was more common in On-S conditions (On-S: 68.9% vs OffS: 51.1% vs OL: 66.7%, p < 0.001), while Off-S cardiac arrests were more often due to traumatic circumstances (OffS: 39.7% vs On-S: 21.7% vs OL: 7.7%, p < 0.001). Automated external defibrillator (AED) use before rescuers' arrival was lower in the Off-S group than in the other two groups (On-S: 15.2% vs OL: 4.5% vs OffS: 3.7%; p < 0.002). The first AED shock was longer in the Off-S group (median time in minutes: OffS: 22.0 (9.5–35.5) vs On-S: 10.0 (3.0–19.5) vs OL: 16.0 (11.0–27.0), p = 0.03). In multivariate analysis, on-slope OHCA remained a positive factor for 30-day survival with a CPC score of 1 or 2 with a 1.96 adjusted odds ratio (95% confidence interval (CI), 1.02–3.75, p = 0.04), whereas off-slope OHCA had an 0.88 adjusted odds ratio (95% CI, 0.28–2.72, p = 0.82). ConclusionsOHCAs in ski-slopes conditions were associated with an improvement in neurological outcomes at 30 days, whereas off-slopes OHCAs were not. Ski-slopes rescue patrols are efficient in improving outcomes.

Incorporation of Drone Technology Into the Chain of Survival for OHCA: Estimation of Time Needed for Bystander Treatment of OHCA and CPR Performance.

Drone-delivered automated external defibrillators (AEDs) hold promises in the treatment of out-of-hospital cardiac arrest. Our objective was to estimate the time needed to perform resuscitation with a drone-delivered AED and to measure cardiopulmonary resuscitation (CPR) quality. Mock out-of-hospital cardiac arrest simulations that included a 9-1-1 call, CPR, and drone-delivered AED were conducted. Each simulation was timed and video-recorded. CPR performance metrics were recorded by a Laerdal Resusci Anne Quality Feedback System. Multivariable regression modeling examined factors associated with time from 9-1-1 call to AED shock and CPR quality metrics (compression rate, depth, recoil, and chest compression fraction). Comparisons were made among those with recent CPR training (≤2 years) versus no recent (>2 years) or prior CPR training. We recruited 51 research participants between September 2019 and March 2020. The median age was 34 (Q1-Q3, 23-54) years, 56.9% were female, and 41.2% had recent CPR training. The median time from 9-1-1 call to initiation of CPR was 1:19 (Q1-Q3, 1:06-1:26) minutes. A median time of 1:59 (Q1-Q3, 01:50-02:20) minutes was needed to retrieve a drone-delivered AED and deliver a shock. The median CPR compression rate was 115 (Q1-Q3, 109-124) beats per minute, the correct compression depth percentage was 92% (Q1-Q3, 25-98), and the chest compression fraction was 46.7% (Q1-Q3, 39.9%-50.6%). Recent CPR training was not associated with CPR quality or time from 9-1-1 call to AED shock. Younger age (per 10-year increase; β, 9.97 [95% CI, 4.63-15.31] s; P<0.001) and prior experience with AED (β, -30.0 [95% CI, -50.1 to -10.0] s; P=0.004) were associated with more rapid time from 9-1-1 call to AED shock. Prior AED use (β, 6.71 [95% CI, 1.62-11.79]; P=0.011) was associated with improved chest compression fraction percentage. Research participants were able to rapidly retrieve an AED from a drone while largely maintaining CPR quality according to American Heart Association guidelines. Chest compression fraction was lower than expected.

High accuracy distinction of shockable and non-shockable arrhythmias in abnormal classes through wavelet transform with pseudo differential like operators

Arrhythmia is an abnormal rhythm of the heart which leads to sudden death. Among these arrhythmias, some are shockable, and some are non-shockable arrhythmias with external defibrillation. The automated external defibrillator (AED) is used as the automated arrhythmia diagnosis system and requires an accurate and rapid decision to increase the survival rate. Therefore, a precise and quick decision by the AED has become essential in improving the survival rate. This paper presents an arrhythmia diagnosis system for the AED by engineering methods and generalized function theories. In the arrhythmia diagnosis system, the proposed wavelet transform with pseudo-differential like operators-based method effectively generates a distinguishable scalogram for the shockable and non-shockable arrhythmia in the abnormal class signals, which leads to the decision algorithm getting the best distinction. Then, a new quality parameter is introduced to get more details by quantizing the statistical features on the scalogram. Finally, design a simple AED shock and non-shock advice method by following this information to improve the precision and rapid decision. Here, an adequate topology (metric function) is adopted to the space of the scatter plot, where we can give different scales to select the best area of the scatter plot for the test sample. As a consequence, the proposed decision method gives the highest accuracy and rapid decision between shockable and non-shockable arrhythmias. The proposed arrhythmia diagnosis system increases the accuracy to 97.98%, with a gain of 11.75% compared to the conventional approach in the abnormal class signals. Therefore, the proposed method contributes an additional 11.75% possibility for increasing the survival rate. The proposed arrhythmia diagnosis system is general and could be applied to distinguish different arrhythmia-based applications. Also, each contribution could be used independently in various applications.

Evaluation of automated external defibrillator designed for people in dogs.

To determine if human automated external defibrillators (AEDs) could successfully record cardiac electrical activity in dogs, make appropriate recommendations regarding shock delivery, and characterize skin preparation required for a readable ECG based on dog haircoat characteristics. Prospective study of AED use in dogs conducted between January and March 2021. University teaching hospital. Three groups of client-owned dogs were evaluated. Group 1 consisted of 23 healthy dogs with sinus rhythms, group 2 consisted of 9 dogs with documented cardiac arrhythmias, and group 3 consisted of 9 dogs receiving CPR following naturally occurring cardiopulmonary arrest. Haircoat characteristics and clipping or ECG paste required to obtain a readable ECG were recorded. The time interval from a readable ECG by the investigator until AED shock advisement was measured. Correctness of shock advice was recorded. Analyses were performed using commercial statistical software. P-values <0.05 were considered significant. The attending veterinarian judged the ECG on the AED to be readable in all dogs. Time to shock advisement in all dogs was median 18 (range: 7-180) seconds. Dogs with heavy, long, or double haircoats required clipping in 24 of 27 (89%) cases to obtain a readable ECG. ECG paste on the AED pad was required in 36 of 40 dogs (90%) in order to obtain a readable ECG. The AED advice for delivery of shock was appropriate in 51 of 52 (98%) queries of the machine across all groups. Human AEDs can successfully record cardiac electrical activity in dogs. AEDs appropriately recommend delivery of a shock most times, contingent on skin preparation. Dogs with double, long, or heavy haircoats should be clipped prior to pad application. ECG paste will aid AED reading in all haircoat types. Further investigation is warranted into AED use in dogs, particularly in general practices.

Impact of defibrillation with automated external defibrillator by bystander before defibrillation by emergency medical system personnel on neurological outcome of out-of-hospital cardiac arrest with non-cardiac etiology

Aim of the studyAlthough defibrillation using automated external defibrillator (AED) by bystander prior to emergency medical system (EMS) arrival was associated with favorable outcomes in out-of-hospital cardiac arrest (OHCA) of cardiac cause, whether it improves outcomes of OHCA due to non-cardiac cause is not clear. We aimed to investigate the impact of defibrillation with AED by bystander before defibrillation by EMS personnel on the outcomes of OHCA of presumed non-cardiac cause. MethodsThis was a retrospective cohort study using the All-Japan Utstein registry (reference period: 2013 to 2017). We included adult patients with OHCA of presumed non-cardiac cause, who had initial shockable rhythm, and who received witnessed arrest bystander cardiopulmonary resuscitation (CPR). Exposure variable was defibrillation with AED by bystander in comparison with initial defibrillation by EMS. Logistic regression analyses were conducted to assess the association between bystander AED shock and favorable neurological outcome (Cerebral Performance Category scale 1 or 2) at one month. ResultsAmong the 1,053 patients included for analysis, 57 (5.4%) received bystander AED shock. There was no statistically significant difference in the rate of favorable neurological outcome at one month between groups [9 (15.8%) vs 109 (10.9%), p = 0.26]. Logistic regression analysis adjusted for characteristics, intervention, and time course of CPR showed no association between bystander AED shock and favorable neurological outcome [OR (95% CI): 1.63 (0.70–3.77), p = 0.25]. ConclusionIn this study, defibrillation with AED by bystander before defibrillation by EMS personnel was not associated with the favorable outcomes of OHCA of presumed non-cardiac cause.

Abstract 233: Characterizing Impact of State Legislation on Cardiac Arrest Outcomes at K-12 Schools

Background: Cardiac arrests that occur in schools are infrequent, but high-profile events. Many states have enacted school specific legislation regarding automated external defibrillators (AEDs) placement, CPR training and emergency response plans (EAP). Objective/Aim: To characterize out-of-hospital cardiac arrests (OHCA) that occur in K-12 schools; and, assess the relationship of U.S. state AED and CPR laws to outcomes of in school cardiac arrests. Methods: A retrospective review of in school OHCA was completed with data from the National EMS Information System (NEMSIS) 3.4 database, calendar years 2017-2018. Study subjects were non-traumatic OHCA occurring prior to EMS arrival on K-12 school grounds. Additionally, we conducted a search of Westlaw (Thomson Reuters) to identify current school specific AED, CPR and EAP laws for all 50 states, and created a structured taxonomy for these laws. Datasets were linked by an honest broker and the K-12 school CPR and AED provisions were compared to state legislation. Results: During the study period, there were 454 cases of in school cardiac arrest out of the 25.3 million incidents submitted to NEMSIS. We excluded 140, thus leaving 314 arrests for analysis. The average age was 46.7 (SD=24.1), most were over 18 years old (79.4%), and male 221 (70.4%). Bystander CPR (BCPR) was performed in 240 (76.4%) of cases, bystander AEDs were used in 160 (51.0%) cases, and 107 (34.1%) patients received an AED shock. State AED and CPR laws required student CPR training in 78%, school AED placement in 46%, teacher CPR certification in 14%, and school specific cardiac emergency response plans in 32%. We found no increase in BCPR or AED placement in states with school CPR, AED or EAP legislation. These findings persisted regardless of patient age, school type, or legislative mandate (all P &gt; 0.05). Conclusion: Despite the perceived benefit of legislation supporting CPR and AED use in schools, we identified no improved provision of BCPR or AED use in schools in states with such legislation. Given the high proportions of BCPR and AED in states with and without statutes, we believe this data suggests that non-legislative initiatives, which exist in many states, may be an important driver of emergency cardiac care in K-12 schools.

Mixed convolutional and long short-term memory network for the detection of lethal ventricular arrhythmia.

Early defibrillation by an automated external defibrillator (AED) is key for the survival of out-of-hospital cardiac arrest (OHCA) patients. ECG feature extraction and machine learning have been successfully used to detect ventricular fibrillation (VF) in AED shock decision algorithms. Recently, deep learning architectures based on 1D Convolutional Neural Networks (CNN) have been proposed for this task. This study introduces a deep learning architecture based on 1D-CNN layers and a Long Short-Term Memory (LSTM) network for the detection of VF. Two datasets were used, one from public repositories of Holter recordings captured at the onset of the arrhythmia, and a second from OHCA patients obtained minutes after the onset of the arrest. Data was partitioned patient-wise into training (80%) to design the classifiers, and test (20%) to report the results. The proposed architecture was compared to 1D-CNN only deep learners, and to a classical approach based on VF-detection features and a support vector machine (SVM) classifier. The algorithms were evaluated in terms of balanced accuracy (BAC), the unweighted mean of the sensitivity (Se) and specificity (Sp). The BAC, Se, and Sp of the architecture for 4-s ECG segments was 99.3%, 99.7%, and 98.9% for the public data, and 98.0%, 99.2%, and 96.7% for OHCA data. The proposed architecture outperformed all other classifiers by at least 0.3-points in BAC in the public data, and by 2.2-points in the OHCA data. The architecture met the 95% Sp and 90% Se requirements of the American Heart Association in both datasets for segment lengths as short as 3-s. This is, to the best of our knowledge, the most accurate VF detection algorithm to date, especially on OHCA data, and it would enable an accurate shock no shock diagnosis in a very short time.

Changes in automated external defibrillator use and survival after out-of-hospital cardiac arrest in the Nijmegen area.

PurposeOut-of-hospital cardiac arrests (OHCAs) are a major healthcare problem. Over the years, several initiatives have contributed to more lay volunteers providing cardiopulmonary resuscitation (CPR) and increased use of automated external defibrillators (AEDs) in the Netherlands. As part of a quality and outcomes program, we registered bystander CPR, AED use and outcome in the Nijmegen area.MethodsProspective resuscitation registry with a study cohort of non-traumatic OHCA cases from 2013–2016 and historical controls from 2008–2011. In line with previous reports, we studied patients transported to the hospital (Radboudumc, Nijmegen, the Netherlands) and excluded arrests witnessed by the emergency medical service (EMS). Primary outcomes were return of spontaneous circulation (ROSC) and survival to discharge.ResultsIn the study cohort (n = 349) the AED was attached more often than in the historical cohort (n = 180): 46% vs. 23% and the proportion of bystander CPR was higher: 78% vs. 63% (both p < 0.001). A higher proportion of patients received an AED shock (39% vs. 15%, p < 0.001) and the number of required shocks by the EMS was lower (2 vs. 4, p = 0.004). Survival to discharge was higher (47% vs. 33%, p = 0.002) without differences in ROSC. The survival benefit was restricted to patients with a shockable initial rhythm. In both cohorts, bystander CPR and AED use were independently associated with survival.ConclusionIn patients admitted after OHCA, survival to discharge has markedly improved to 40–50%, comparable with other Dutch registries. As increased bystander CPR and the doubled use of AEDs seem to have contributed, all civilian-based resuscitation initiatives should be encouraged.

Return of spontaneous circulation and long‐term survival according to feedback provided by automated external defibrillators

BackgroundWe aimed to investigate the effect of automated external defibrillator (AED) feedback mechanisms on survival in out‐of‐hospital cardiac arrest (OHCA) victims. In addition, we investigated converting rates in patients with shockable rhythms according to AED shock waveforms and energy levels.MethodsWe collected data on OHCA occurring between 2011 and 2014 in the Capital Region of Denmark where an AED was applied prior to ambulance arrival. Patient data were obtained from the Danish Cardiac Arrest Registry and medical records. AED data were retrieved from the Emergency Medical Dispatch Centre (EMDC) and information on feedback mechanisms, energy waveform and energy level was downloaded from the applied AEDs.ResultsA total of 196 OHCAs had an AED applied prior to ambulance arrival; 62 of these (32%) provided audio visual (AV) feedback while no feedback was provided in 134 (68%). We found no difference in return of spontaneous circulation (ROSC) at hospital arrival according to AV‐feedback; 34 (55%, 95% confidence interval (CI) [13–67]) vs. 72 (54%, 95% CI [45–62]), P = 1 (odds ratio (OR) 1.1, 95% CI [0.6–1.9]) or 30‐day survival; 24 (39%, 95% CI [28–51]) vs. 53 (40%, 95% CI [32–49]), P = 0.88 (OR 1.1 (95% CI [0.6–2.0])). Moreover, we found no difference in converting rates among patients with initial shockable rhythm receiving one or more shocks according to AED energy waveform and energy level.ConclusionsNo difference in survival after OHCA according to AED feedback mechanisms, nor any difference in converting rates according to AED waveform or energy levels was detected.

Automated external defibrillator and operator performance in out-of-hospital cardiac arrest

AimAn increasing number of failing automated external defibrillators (AEDs) is reported: AEDs not giving a shock or other malfunction. We assessed to what extent AEDs are ‘failing’ and whether this had a device-related or operator-related cause. MethodsWe studied analysis periods from AEDs used between January 2012 and December 2014. For each analysis period we assessed the correctness of the (no)-shock advice (sensitivity/specificity) and reasons for an incorrect (no)-shock advice. If no shock was delivered after a shock advice, we assessed the reason for no-shock delivery. ResultsWe analyzed 1114 AED recordings with 3310 analysis periods (1091 shock advices; 2219 no-shock advices). Sensitivity for coarse ventricular fibrillation was 99% and specificity for non-shockable rhythm detection 98%. The AED gave an incorrect shock advice in 4% (44/1091) of all shock advices, due to device-related (n=15) and operator-related errors (n=28) (one unknown). Of these 44 shock advices, only 2 shocks caused a rhythm change. One percent (26/2219) of all no-shock advices was incorrect due to device-related (n=20) and operator-related errors (n=6). In 5% (59/1091) of all shock advices, no shock was delivered: operator failed to deliver shock (n=33), AED was removed (n=17), operator pushed ‘off' button (n=8) and other (n=1). Of the 1073 analysis periods with a shockable rhythm, 67 (6%) did not receive an AED shock. ConclusionErrors associated with AED use are rare (4%) and when occurring are in 72% caused by the operator or circumstances of use. Fully automatic AEDs may prevent the majority of these errors.

Human Factors Approach to Comparative Usability of Hospital Manual Defibrillators

IntroductionEquipment-related issues have recently been cited as a significant contributor to the suboptimal outcomes of resuscitation management. A systematic evaluation of the human-device interface was undertaken to evaluate the intuitive nature of three different defibrillators. Devices tested were the Physio-Control LifePak 15, the Zoll R Series Plus, and the Philips MRx. MethodsA convenience sample of 73 multidisciplinary health care providers from 5 different hospitals participated in this study. All subjects’ performances were evaluated without any training on the devices being studied to assess the intuitiveness of the user interface to perform the functions of delivering an Automated External Defibrillator (AED) shock, a manual defibrillation, pacing to achieve 100% capture, and synchronized cardioversion on a rhythm simulator. ResultsTimes to deliver an AED shock were fastest with the Zoll, whereas the Philips had the fastest times to deliver a manual defibrillation. Subjects took the least time to attain 100% capture for pacing with the Physio-Control device. No differences in performance times were seen with synchronized cardioversion among the devices. Human factors issues uncovered during this study included a preference for knobs over soft keys and a desire for clarity in control panel design. This study demonstrated no clearly superior defibrillator, as each of the models exhibited strengths in different areas. When asked their defibrillator preference, 67% of subjects chose the Philips. ConclusionsThis comparison of user interfaces of defibrillators in simulated situations allows the assessment of usability that can provide manufacturers and educators with feedback about defibrillator implementation for these critical care devices.

Locating AED Enabled Medical Drones to Enhance Cardiac Arrest Response Times

Background: Out-of-hospital cardiac arrest (OOHCA) is prevalent in the United States. Each year between 180,000 and 400,000 people die due to cardiac arrest. The automated external defibrillator (AED) has greatly enhanced survival rates for OOHCA. However, one of the important components of successful cardiac arrest treatment is emergency medical services (EMS) response time (i.e., the time from EMS “wheels rolling” until arrival at the OOHCA scene). Unmanned Aerial Vehicles (UAV) have regularly been used for remote sensing and aerial imagery collection, but there are new opportunities to use drones for medical emergencies. Objective: The purpose of this study is to develop a geographic approach to the placement of a network of medical drones, equipped with an automated external defibrillator, designed to minimize travel time to victims of out-of-hospital cardiac arrest. Our goal was to have one drone on scene within one minute for at least 90% of demand for AED shock therapy, while minimizing implementation costs. Methods: In our study, the current estimated travel times were evaluated in Salt Lake County using geographical information systems (GIS) and compared to the estimated travel times of a network of AED enabled medical drones. We employed a location model, the Maximum Coverage Location Problem (MCLP), to determine the best configuration of drones to increase service coverage within one minute. Results: We found that, using traditional vehicles, only 4.3% of the demand can be reached (travel time) within one minute utilizing current EMS agency locations, while 96.4% of demand can be reached within five minutes using current EMS vehicles and facility locations. Analyses show that using existing EMS stations to launch drones resulted in 80.1% of cardiac arrest demand being reached within one minute Allowing new sites to launch drones resulted in 90.3% of demand being reached within one minute. Finally, using existing EMS and new sites resulted in 90.3% of demand being reached while greatly reducing estimated overall costs. Conclusion: Although there are still many factors to consider, drone networks show potential to greatly reduce life-saving equipment travel times for victims of cardiac arrest.

Sudden Cardiac Arrests, Automated External Defibrillators, and Medical Emergency Response Plans in Tennessee High Schools

Schools are important public locations of sudden cardiac arrest (SCA), and the American Heart Association (AHA) recommends medical emergency response plans (MERPs), which may include an automated external defibrillator (AED) in schools. The objective of this study was to determine the incidence of SCA and the prevalence of AEDs and MERPs in Tennessee high schools. Tennessee Secondary School Athletic Association member schools were surveyed regarding SCA on campus within 5 years, AED presence, and MERP characteristics. Of 378 schools, 257 (68%) completed the survey. There were 21 (5 student and 16 adult) SCAs on school grounds, yielding a 5-year incidence of 1 SCA per 12 high schools. An AED was present at 11 of 21 schools with SCA, and 6 SCA victims were treated with an AED shock. A linear increase in SCA frequency was noted with increasing school size (<500 students: 3.3% incidence, 500-1000: 6.5%, 1000-1500: 12.5%, ≥1500: 18.2%; P = 0.003). Of 257 schools, 71% had an MERP, 48% had an AED, and only 4% were fully compliant with AHA recommendations. Schools with a history of SCA were more likely to be compliant (19% vs. 3%, P = 0.011). The 5-year incidence of SCA in Tennessee high schools is 1 in 12, but increases to 1 in 7 for schools with more than 1000 students. Compliance with AHA guidelines for MERPs is poor, but improved in schools with recent SCA. Future recommendations should encourage the inclusion of AED placement in schools with more than 1000 students.

Public Access Defibrillation

Sudden cardiac arrest (SCA) is recognized as a serious public health problem, accounting for 250 000 to 300 000 deaths per year; it is now the third-leading cause of death behind cancer and nonsudden cardiovascular deaths.1,2 Immediate, well-performed cardiopulmonary resuscitation (CPR) and early defibrillation are the only out-of-hospital interventions that improve outcomes.3 The chain of survival relies on lay responders and emergency medical services (EMS) to initiate the potentially life-saving procedures of CPR and defibrillation. Articles see pp 510 and 518 In 1994, the American Heart Association (AHA) convened the first conference on public access defibrillation (PAD) to introduce the strategy of placing easy-to-use defibrillators in public places to decrease the death rate from SCA.4 Specific recommendations encouraged the stakeholders (the AHA, the US Food and Drug Administration, the National Institutes of Health, industry, and communities) to facilitate PAD by developing user-friendly, less-expensive automated external defibrillators (AEDs); testing the concept within large clinical trials; and organizing communities to promote and support effective PAD programs. Widespread CPR and AED training of the public was emphasized. In the ensuing 15 years, many of these recommendations have been heeded, and PAD programs are now commonplace. The National Institutes of Health–sponsored PAD trial demonstrated that survival doubled when events occurred in communities equipped and trained with CPR and AEDs compared with CPR alone.5 Within the Resuscitations Outcomes Consortium (ROC), out-of-hospital cardiac arrest victims had a markedly increased chance of survival if the first shock was delivered by a bystander using an AED rather than by EMS.6 PAD programs in airports, airlines, and casinos have also validated the effectiveness of the concept. Out-of hospital cardiac arrest is treatable, and outcomes can be improved with currently available approaches. Multiple locations have been recognized as having a higher incidence of cardiac arrest …

External artifacts by advanced life support providers misleading automated external defibrillators

The ECG analysis algorithm of automated external defibrillators (AEDs) shows reduced sensitivity and specificity in the presence of external artifacts. Therefore, ECG analyses are preceded by voice prompts. We investigated if advanced life support (ALS) providers follow these prompts, and the consequences if they do not. In a two-tiered EMS system all 510 ECG analyses from 135 resuscitation attempts with a Laerdal FR2 AED (applied by emergency medical technicians [EMTs] and subsequently used by ALS providers) were prospectively evaluated. The ALS data were compared with data before arrival of ALS providers (EMT data) using Mc Nemar test. In the presence of ALS providers, 286 ECG rhythm analyses were performed. In the 96 analyses with shockable rhythms, artifacts were detected in 35 (36%), leading to a wrongful no shock decision in 19 (20%). Corresponding EMT data were 67 analyses with shockable rhythms, with artifacts in 18 (27%; p<0.001) but a wrongful no shock decision in only 3 (4%; p<0.001). ALS providers also failed to deliver the AED shock in 7 of the 77 analyses with an appropriate shock decision (9%). This was never found in the EMT data. In the 190 analyses of a non-shockable rhythm in the presence of ALS providers, artifacts were detected in 120 (63%) leading to one spurious shock (0.5%). Corresponding EMT data were 157 analyses, with artifacts in 87 (55%; p=0.20) but no spurious shocks. External artifacts were frequently found, sometimes leading to important errors. Consequently, more training is needed, especially for ALS providers.

“Shock Advised”

HomeCirculationVol. 113, No. 13“Shock Advised” Free AccessReview ArticlePDF/EPUBAboutView PDFView EPUBSections ToolsAdd to favoritesDownload citationsTrack citationsPermissions ShareShare onFacebookTwitterLinked InMendeleyReddit Jump toFree AccessReview ArticlePDF/EPUB“Shock Advised”Inappropriate Public Access Defibrillation Kumaraswamy Nanthakumar, MD and Satish C. Toal, MD Kumaraswamy NanthakumarKumaraswamy Nanthakumar From the Division of Cardiology, University Health Network, Toronto General Hospital, Toronto, Canada. Search for more papers by this author and Satish C. ToalSatish C. Toal From the Division of Cardiology, University Health Network, Toronto General Hospital, Toronto, Canada. Search for more papers by this author Originally published4 Apr 2006https://doi.org/10.1161/CIRCULATIONAHA.105.580829Circulation. 2006;113:e672The use of automated external defibrillators (AEDs) holds the promise of an increase in the number of survivors of out-of-hospital cardiac arrest. One of the basic tenets behind this strategy is the claim that lay people can use an AED. This is dependent on the performance of a critical rhythm analysis algorithm that interprets the ECG. Currently used algorithms claim a specificity of 100% for all shockable rhythms. However, surveillance for inappropriate shock decisions and improvement of analytical algorithms by AEDs are necessary to provide appropriate resuscitation by first responders. A 75-year-old man collapsed in a public place. Emergency personnel with the aid of an AED successfully resuscitated him. Analysis of the initial rhythm by the AED correctly identified ventricular fibrillation (VF), and a shock was delivered appropriately and successfully (Figure, A). After this, P waves could be observed during the second analysis (Figure, B) and were clearer soon afterward (Figure, C and D). The algorithm also analyzed this rhythm to be VF and advised a shock. Panel B of the Figure demonstrates medium-frequency artifacts of 0.1 to 1 mV in amplitude of unknown origin, causing an inappropriate AED shock. This inappropriate decision highlights the need for registries to be maintained of AED discharges so that AED detection algorithms can be refined to achieve higher specificity. Cardiac life support training should also continue to be given to potential AED users, along with a visual display of rhythm and capacity, to manually override the AED decision to prevent inappropriate shocks. Download figureDownload PowerPointRecordings retrieved from an AED. A, The AED appropriately identified VF and advised a shock, which was delivered. B, Postshock presence of P waves with no ventricular rhythm. Note medium-frequency artifacts of 0.1 to 1 mV in amplitude throughout analysis 2 (segments 1 and 2). C, The artifacts noted in B caused the AED to inappropriately identify the rhythm as VF, and hence, a second shock was advised. D, Delivery of an inappropriate shock as advised by the AED, although the rhythm appears to be ventricular asystole. E, Correct analysis by the AED of a junctional escape rhythm after shock 2 as a nonshockable rhythm. F, Persisting junctional escape rhythm.DisclosuresNone.FootnotesCorrespondence to Kumaraswamy Nanthakumar, MD, Division of Cardiology, University Health Network, Toronto General Hospital, 150 Gerrard St W, PMCC 3-522, Toronto, ON, Canada M5G 2C4. E-mail [email protected] Previous Back to top Next FiguresReferencesRelatedDetailsCited By Nanthakumar K (2008) Trying to make “sense” of extra thoracic implantable defibrillator, Heart Rhythm, 10.1016/j.hrthm.2007.09.010, 5:1, (35-36), Online publication date: 1-Jan-2008. April 4, 2006Vol 113, Issue 13 Advertisement Article InformationMetrics https://doi.org/10.1161/CIRCULATIONAHA.105.580829PMID: 16585397 Originally publishedApril 4, 2006 PDF download Advertisement

Post-shock chest compression delays with automated external defibrillator use

Primary objective: In a swine model of out-of-hospital ventricular fibrillation (VF) cardiac arrest, we established that automated external defibrillator (AED) defibrillation could worsen outcome from prolonged VF compared with manual defibrillation. Worse outcomes were due to substantial interruptions and delays in chest compressions for AED rhythm analyses and shock advice. In particular, the mean interval from first AED shock to first post-shock compressions was 46 ± 6 s. We hypothesized that the delay from shock to provision of chest compressions is similar in the out-of-hospital setting. Materials and methods: We conducted a retrospective observational review of AED-treated adult VF cardiac arrest victims over a 26-month period to determine the interval from the first AED defibrillation attempt to the initial provision of post-shock chest compressions for out-of-hospital VF cardiac arrests. A two-tiered, single emergency medical service (EMS) system with AED-equipped first responders serves our area of 400 km 2 with a population of 487,000 people. The defibrillators record a detailed sequence of events during the resuscitation effort that includes the electrocardiogram with real clock times and a recording of surrounding audible actions. Results: A median of 38 s (IQR 15, 61 s) elapsed between the first shock and the initiation of chest compressions. Approximately half of the delay was due to mechanical/electronic factors and the remainder due to human factors. Of 64 adults in VF, 45 (70%) died before hospital admission, 19 (30%) survived to admission and 10 (16%) survived to hospital discharge. Conclusion: Substantial delays in the provision of post-shock chest compressions are typical in this EMS system with AED-equipped first responders.

Impact of community-wide deployment of biphasic waveform automated external defibrillators on out-of-hospital cardiac arrest in Taipei

To determine the impact and outcome of out-of-hospital cardiac arrests (OHCA) while using automated external defibrillators (AED) with biphasic waveforms and its effectiveness when using the Utstein Style community-wide in Taipei. A one-year study was conducted to collect OHCA patients with AED utilization prospectively in Taipei City. All events and variables were recorded in the Utstein Style. Electrocardiography and voice records recovered from AED data cards were analysed. The endpoints were survival outcomes. Of 653 OHCA patients with AED utilization, only 80 (12.6%) patients with 635 true arrests presented with ventricular fibrillation or tachycardia (VF/VT) as the initial rhythm. The interval between call-to-shock was 5 min longer than call-to-EMS arrival (9.3 min versus 4.0 min). Fourteen (25%) of the 55 witnessed VF/VT arrests survived to home discharge. Ninety-seven percent of shockable rhythms were successfully terminated with less than three shocks. For all OHCA patients, initial rhythm of VF/VT (OR 3.4; 95% CI = 1.2-9.4), witnessed status (OR 4.7; 95% CI = 1.3-16.6), and presence of organised rhythm irrespective of pulse during prehospital resuscitation (OR 9.2; 95% CI = 3.2-26.8) demonstrated an independent association with survival to home discharge. For VF/VT arrests, witnessed status, shorter call-to-shock time, high successful rate of the first shock, fewer averaged number of shocks delivered for each patient, and presence of an organised rhythm during prehospital resuscitation showed a likelihood to predict to predict discharged survival in univariate analysis. Low frequency of VF arrests is unique to certain eastern populations but without a reduction of AED shock efficacy with biphasic waveform. Besides initial VF and witnessed status, a prehospital post-shock organized rhythm irrespective of pulse appears to be correlated to survival. Certain circumstances in a congested metropolitan city consume time to deliver shocks even after EMS arrival, and might require bystander or public access defibrillation.

Saving Time Saves Lives

Consider the following 3 patient stories: Reluctantly, A.B. heaved his bulk out of the air-conditioned car and into the hot, bright afternoon sun. The walk across the steaming macadam parking lot left him breathless, and his hand shook as he buried the cigarette butt into the sand on top of the shining brass receptacle guarding the entrance to the casino. His head pounded with the exertion, and he realized he forgot to take his blood pressure pill. Once he adjusted to the dimly lit interior and breathed the cool air, he caught his breath and cashed in $500 worth of chips. He quickly gravitated to the blackjack table, but in 30 minutes was cleaned out. His chest now ached with a soreness that had been waking him up at night for the last 2 weeks. As A.B. massaged his left breast, he began to feel lightheaded, and then the room went black. When C.D. heard the overhead page announcing that his flight was finally ready for boarding, he gulped down his wine and hurried out of the VIP lounge, lugging the distended briefcase over his shoulder. After showing his passport for what seemed the tenth time, he boarded the DC 10 and headed for the business section. The plane was already 2 hours late, and he was angry that he would miss his connection at Heathrow. But that seemed unimportant now as the fluttering in his chest started again. The doctor had told him it was ventricular tachycardia because of his enlarged heart and suggested a new medication, but he didn’t want to take it. The fluttering increased as the plane took off and continued through dinner. As C.D. settled back with his cognac, he looked down on the Atlantic, making out a few diamonds of light sparkling on the …

Strengthening the In-Hospital Chain of Survival With Rapid Defibrillation by First Responders Using Automated External Defibrillators: Training and Retention Issues

Study objective: To determine whether staff outside critical care areas who were proficient in basic life support (BLS) could be easily trained to use automated external defibrillators (AEDs) and whether they would retain these skills. Design: Prospective, longitudinal cohort series. Setting: Two university teaching hospitals. Participants: One hundred forty nurses who had previously learned BLS and constituted the staff from three medical/surgical nursing units from each study hospital. Interventions: The nurses were taught how to use the Heartstart 1000s, a lightweight portable shock-advisory AED, in a 2-hour class with an instructor and manikin-to-student ratio of 1:5. The course emphasized hands-on practice of the BLS-AED algorithm on a computerized manikin. Results: Using a similar scenario, each nurse was evaluated on the computerized manikin immediately after training (posttest). At 1 to 3, 4 to 6, and 7 to 9 months after the initial training, convenience samples of the cohort in three different groups were evaluated for retention. Satisfactory performance was defined as delivery of the first AED shock within 2 minutes of recognition of the arrest. At the posttest after training, 139 of 140 nurses (99%) demonstrated satisfactory performance. Of 77 nurses evaluated, 31 of 32 at 1 to 3 months, 18 of 18 at 4 to 6 months, and 24 of 27 at 7 to 9 months after initial training (95% overall) performed satisfactorily. Conclusion: As has been demonstrated with prehospital emergency personnel, nurses outside critical care areas who are proficient in BLS can easily learn and retain the knowledge and skills to use AEDs. Automated external defibrillation, a BLS skill, should be incorporated into BLS programs (BLS-AED) for all hospital personnel expected to respond to a patient in cardiac arrest, with rapid defibrillation taking priority over CPR. [Kaye W, Mancini ME, Giuliano KK, Richards N, Nagid DM, Marler CA, Sawyer-Silva S: Strengthening the in-hospital chain of survival with rapid defibrillation by first responders using automated external defibrillators: Training and retention issues. Ann Emerg Med February 1995;25:163-168.]