Analysis of out-of-hospital cardiac arrest location and public access defibrillator placement in Metropolitan Phoenix,Arizona

ObjectivesAutomated external defibrillators (AEDs) improve outcomes from out-of-hospital cardiac arrest (OHCA) but are infrequently used. We sought to compare the locations of OHCAs and AEDs in metropolitan Phoenix, Arizona.MethodsPublic location OHCAs and AEDs were geocoded utilizing a statewide OHCA database (1/2010–12/2012) and AED registry. OHCAs were mapped using kernel-density estimation and overlapped with AED placements. Spearman's rho was obtained to determine the correlation between OHCA incidents and AED locations.ResultsA total of 654 consecutive public location OHCAs and all 1704 non-medical facility AEDs registered in the study area were included in the analysis. High OHCA incident areas lacking AEDs were identified in the kernel-density surface map. OHCA event/AED correlation analysis showed a weak correlation (Spearman's rho = 0.283; p = 0.002). Events occurred most frequently at locations categorized as “In Cars/Roads/Parking lots” (190/654, 29.1%) and there were no identified AEDs for these areas. AEDs were placed most frequently in “Public business/Office/Workplace” and cardiac arrests occurred with the second highest frequency in this location type.ConclusionThere was a weak correlation between OHCA events and deployed AEDs. It was possible to identify areas where OHCAs occurred frequently but AEDs were lacking. The ability to correlate the sites of OHCAs and AED locations is a necessary step toward improving the effectiveness of public access defibrillation.     

Retrospective evaluation of current-based impedance compensation defibrillation in out-of-hospital cardiac arrest

Objective

Transthoracic impedance (TTI) is a principal parameter that influences the intracardiac current flow and defibrillation outcome. In this study, we retrospectively evaluated the performance of current-based impedance compensation defibrillation in out-of-hospital cardiac arrest (OHCA) patients.

Methods

ECG recordings, along with TTI measurements were collected from multiple emergency medical services (EMSs) in the USA. All the EMSs in this study used automated external defibrillators (AEDs) which employing rectilinear biphasic (RLB) waveform. The distribution and change of TTI between successive shocks, the influence of preceding shock results on the subsequent shock outcome, and the performance of current-based impedance compensation defibrillation was evaluated.

Results

A total of 1166 shocks from 594 OHCA victims were examined in this study. The average TTI for the 1st shock was 134.8 Ω and a significant decrease in TTI was observed for the 2nd (p < 0.001) and 3rd (p = 0.033) sequential escalating shock. But TTI did not change after the 3rd shock. A higher success rate was observed for shocks with preceding defibrillation success. The success rate remained unchanged over the whole spectrum of TTI.

Conclusion

The average TTI was relatively higher in this OHCA population treated with RLB defibrillation as compared with previously reported data. TTI was significantly decreased after 1st and 2nd successive escalating shock but kept constant after the 3rd shock. Preceding shock success was a better predictor of subsequent defibrillation outcome other than TTI. Current-based impedance compensation defibrillation resulted in equivalent success rate for high impedance patients when compared with those of low impedance.     

Increasing first responder CPR during resuscitation of out-of-hospital cardiac arrest using automated external defibrillators

OBJECTIVE: Evidence supports that increasing the balance of "hands-on" CPR may improve survival in ventricular fibrillation out-of-hospital cardiac arrest (OHCA). We assessed whether training and/or AED reconfiguration was associated with an increase in the proportion of time during which CPR was performed between first and second stacks of shocks. METHODS: The investigation was a cohort study of 291 persons who suffered ventricular fibrillation OHCA and were treated with at least two stacks of AED shocks by emergency medical services (EMS) first-tier responders. In January 2003, first-tier providers were retrained regarding the importance of CPR. In addition, a subset of AEDs was reconfigured to remove continuous fibrillation detection and its associated voice prompts as to be comparable with other AED models. The amount of time spent on CPR was assessed through review of AED electronic and audio recordings to compare the pre-intervention (n = 241) and post-intervention periods (n = 50). RESULTS: The proportion of time spent performing hands-on CPR between first and second stacks of shocks was 0.40 in the pre-intervention period compared to 0.51 in the post-intervention period (p = 0.001). The difference was greatest for AEDs where EMS was retrained and the AED reconfigured (0.33 versus 0.50, p = 0.01). No difference in survival was detected between the pre- and post-intervention periods (24.9% versus 28.0%, p = 0.65). CONCLUSIONS: An intervention consisting of retraining and AED reconfiguration was associated with an increase in the proportion of time spent performing CPR between first and second stacks of shocks by first-tier EMS. Whether this increase improves patient outcomes requires additional study.     

Electrical therapies in cardiac arrest

Recognition and appropriate treatment of ventricular fibrillation or pulseless ventricular tachycardia is an essential skill for healthcare providers. Appropriate defibrillation can improve survival and benefit patient outcome. Similarly, increased public access to automatic electronic defibrillators has been shown to improve out-of-hospital survival for cardiac arrest. When combined with high-quality cardiopulmonary resuscitation, electrical therapies are an important aspect of resuscitation in the patient with cardiac arrest. This article focuses on the use of electrical therapies, including defibrillation, cardiac pacing, and automated external defibrillators, in cardiac arrest.     

Fully automatic rhythm analysis during chest compression pauses

Aim: Chest compression artefacts impede a reliable rhythm analysis during cardiopulmonary resuscitation (CPR). These artefacts are not present during ventilations in 30:2 CPR. The aim of this study is to prove that a fully automatic method for rhythm analysis during ventilation pauses in 30:2 CPR is reliable an accurate.Methods: For this study 1414 min of 30:2 CPR from 135 out-of-hospital cardiac arrest cases were analysed. The data contained 1942 pauses in compressions longer than 3.5 s. An automatic pause detector identified the pauses using the transthoracic impedance, and a shock advice algorithm (SAA) diagnosed the rhythm during the detected pauses. The SAA analysed 3-s of the ECG during each pause for an accurate shock/no-shock decision.Results: The sensitivity and PPV of the pause detector were 93.5% and 97.3%, respectively. The sensitivity and specificity of the SAA in the detected pauses were 93.8% (90% low CI, 90.0%) and 95.9% (90% low CI, 94.7%), respectively. Using the method, shocks would have been advanced in 97% of occasions. For patients in nonshockable rhythms, rhythm reassessment pauses would be avoided in 95.2% (95% CI, 91.6–98.8) of occasions, thus increasing the overall chest compression fraction (CCF).Conclusion: An automatic method could be used to safely analyse the rhythm during ventilation pauses. This would contribute to an early detection of refibrillation, and to increase CCF in patients with nonshockable rhythms.     

An investigation of thrust,depth and the impedance cardiogram as measures of cardiopulmonary resuscitation efficacy in a porcine model of cardiac arrest

ObjectiveOptimising the depth and rate of applied chest compressions following out of hospital cardiac arrest is crucial in maintaining end organ perfusion and improving survival. The impedance cardiogram (ICG) measured via defibrillator pads produces a characteristic waveform during chest compressions with the potential to provide feedback on cardiopulmonary resuscitation (CPR) and enhance performance. The objective of this pre-clinical study was to investigate the relationship between mechanical and physiological markers of CPR efficacy in a porcine model and examine the strength of correlation between the ICG amplitude, compression depth and end-tidal CO₂ (ETCO₂).MethodsTwo experiments were performed using 24 swine (12 per experiment). For experiment 1, ventricular fibrillation (VF) was induced and mechanical CPR commenced at varying thrusts (0–60 kg) for 2 min intervals. Chest compression depth was recorded using a Philips QCPR device with additional recording of invasive physiological parameters: systolic blood pressure, ETCO2, cardiac output and carotid flow. For experiment 2, VF was induced and mechanical CPR commenced at varying depths (0–5 cm) for 2 min intervals. The ICG was recorded via defibrillator pads attached to the animal's sternum and connected to a Heartsine 500P defibrillator. ICG amplitude, chest compression depth, systolic blood pressure and ETCO₂ were recorded during each cycle. In both experiments the within-animal correlation between the measured parameters was assessed using a mixed effect model.ResultsIn experiment 1 moderate within-animal correlations were observed between physiological parameters and compression depth (r = 0.69–0.77) and thrust (r = 0.66–0.82). A moderate correlation was observed between compression depth and thrust (r = 0.75). In experiment 2 a strong within-animal correlation and moderate overall correlations were observed between ICG amplitude and compression depth (r = 0.89, r = 0.79) and ETCO₂ (r = 0.85, r = 0.64).ConclusionIn this porcine model of induced cardiac arrest moderate within animal correlations were observed between mechanical and physiological markers of chest compression efficacy demonstrating the challenge in utilising a single mechanical metric to quantify chest compression efficacy. ICG amplitude demonstrated strong within animal correlations with compression depth and ETCO₂ suggesting its potential utility to provide CPR feedback in the out of hospital setting to improve performance.     

Clinical experience with a low-energy pulsed biphasic waveform in out-of-hospital cardiac arrest

The efficiency of a pulsed biphasic waveform (PBW) was compared with that of biphasic truncated exponential (BTE) waveforms. First defibrillation shock outcome was studied in a population of 104 out-of-hospital cardiac arrest patients in ventricular fibrillation as the presenting rhythm. The call to first shock time was 8.2+/-5.4 min. At 5s post-shock, defibrillation efficiency was 90%. The arrest was witnessed in only 50% of the patients and only 5% received bystander CPR. Despite these limitations 38% of the patients achieved restoration of a spontaneous circulation at departure from scene and 9.8% were discharged from the hospital. These observations demonstrate a rate of first shock success in termination of ventricular fibrillation comparable to that reported with biphasic truncated exponential waveforms in out-of-hospital cardiac arrest.     

Early cardiopulmonary resuscitation and use of Automated External Defibrillators by laypersons in out-of-hospital cardiac arrest using an SMS alert service

Aim

To evaluate an SMS service (SMS = short message service = text message) with which laypersons are alerted to go to patients with suspected out-of-hospital cardiac arrest and perform early cardiopulmonary resuscitation (CPR) and use an Automated External Defibrillator (AED). This study is the first to report on a program in which an emergency medical service (EMS) is able to alert citizens by sending them SMS messages on their mobile phone.

Methods

Web-based questionnaires were completed by laypersons who were sent an alert by the AED-Alert system between February 1, 2010 and April 30, 2010. Questions concerned the process of training, receiving alerts, actions taken and follow-up care.

Results

AED-Alert was activated for 52 patients suspected of cardiac arrest, sending 3227 alerts to 2287 laypersons. Out of 2168 eligible laypersons 1679 (77%) completed 2098 questionnaires, one for each alert. Action was taken in only 579 alerts. Laypersons were not in the patient's vicinity (41%), noticed alerts too late (35%), or other reasons (24%). In 298 alerts laypersons faced problems with retrieving AEDs (51%), finding addresses (29%), traffic (5%), or other (15%). Aid was provided in 75 alerts, involving 47 patients. Laypersons started early CPR and defibrillation (49%), assisted EMS personnel (52%), or took care of family (39%). Laypersons arrived before EMS personnel in 21 patients, started CPR and defibrillation in 18, and assisted EMS personnel in 9 patients.

Conclusion

Improvements of the SMS alert service by laypersons, the EMS, and through technical adjustments, could increase the number of laypersons who provide early aid.     

Automatic detection of chest compressions for the assessment of CPR-quality parameters

Aim

Accurate chest compression detection is key to evaluate cardiopulmonary resuscitation (CPR) quality. Two automatic compression detectors were developed, for the compression depth (CD), and for the thoracic impedance (TI). The objective was to evaluate their accuracy for compression detection and for CPR quality assessment.

Methods

Compressions were manually annotated using the force and ECG in 38 out-of-hospital resuscitation episodes, comprising 869 min and 67,402 compressions. Compressions were detected using a negative peak detector for the CD. For the TI, an adaptive peak detector based on the amplitude and duration of TI fluctuations was used. Chest compression rate (CC-rate) and chest compression fraction (CCF) were calculated for the episodes and for every minute within each episode. CC-rate for rescuer feedback was calculated every 8 consecutive compressions.

Results

The sensitivity and positive predictive value were 98.4% and 99.8% using CD, and 94.2% and 97.4% using TI. The mean CCF and CC-rate obtained from both detectors showed no significant differences with those obtained from the annotations (P > 0.6). The Bland–Altman analysis showed acceptable 95% limits of agreement between the annotations and the detectors for the per-minute CCF, per-minute CC-rate, and CC-rate for feedback. For the detector based on TI, only 3.7% of CC-rate feedbacks had an error larger than 5%.

Conclusion

Automatic compression detectors based on the CD and TI signals are very accurate. In most cases, episode review could safely rely on these detectors without resorting to manual review. Automatic feedback on rate can be accurately done using the impedance channel.     

Feasibility of automated rhythm assessment in chest compression pauses during cardiopulmonary resuscitation

Aim

To demonstrate the feasibility of doing a reliable rhythm analysis in the chest compression pauses (e.g. pauses for two ventilations) during cardiopulmonary resuscitation (CPR).

Methods

We extracted 110 shockable and 466 nonshockable segments from 235 out-of-hospital cardiac arrest episodes. Pauses in chest compressions were already annotated in the episodes. We classified pauses as ventilation or non-ventilation pause using the transthoracic impedance. A high-temporal resolution shock advice algorithm (SAA) that gives a shock/no-shock decision in 3 s was launched once for every pause longer than 3 s. The sensitivity and specificity of the SAA for the analyses during the pauses were computed.

Results

We identified 4476 pauses, 3263 were ventilation pauses and 2183 had two ventilations. The median of the mean duration per segment of all pauses and of pauses with two ventilations were 6.1 s (4.9–7.5 s) and 5.1 s (4.2–6.4 s), respectively. A total of 91.8% of the pauses and 95.3% of the pauses with two ventilations were long enough to launch the SAA. The overall sensitivity and specificity were 95.8% (90% low one-sided CI, 94.3%) and 96.8% (CI, 96.2%), respectively. There were no significant differences between the sensitivities (P = 0.84) and the specificities (P = 0.18) for the ventilation and the non-ventilation pauses.

Conclusion

Chest compression pauses are frequent and of sufficient duration to launch a high-temporal resolution SAA. During these pauses rhythm analysis was reliable. Pre-shock pauses could be minimised by analysing the rhythm during ventilation pauses when CPR is delivered at 30:2 compression:ventilation ratio.     

Pauses in chest compression and inappropriate shocks: a comparison of manual and semi-automatic defibrillation attempts

BACKGROUND: Semi-automatic defibrillation requires pauses in chest compressions during ECG analysis and charging, and prolonged pre-shock compression pauses reduce the chance of a return of spontaneous circulation (ROSC). We hypothesised that pauses are shorter for manual defibrillation by trained rescuers, but with an increased number of inappropriate shocks given for a non-VF/VT rhythm. METHODS: From a prospective study of CPR quality during in- and out-of-hospital cardiac arrest, the duration of pre-shock, inter-shock, and post-shock pauses were compared with Mann-Whitney U-test during manual and AED mode with the same defibrillator, and proportions of inappropriate shocks were compared with Chi-squared tests. RESULTS: A 635 manual and 530 semi-automatic shocks were studied. Number of shocks per episode was similar for the two groups. All pauses measured in seconds (s) were shorter for manual use (P<0.0001); median (25, 75 percentiles); 15 (11, 21) versus 22 (18, 28) pre-shock, 13 (9, 20) versus 23 (22, 26) inter-shock, and 9 (6, 18) versus 20 (11, 31) post-shock, but 163 (26%) manual shocks were inappropriate compared with 30 (6%) AED shocks, odds ratio (OR) 5.7 (95% CI; 3.8-8.7). A 150 (78%) of the inappropriate shocks were delivered for organised rhythms. The proportion of inappropriate manual shocks was higher for resident physicians in-hospital than paramedics out-of-hospital; 77/228 (34%) versus 86/407 (21%), OR 1.9 (1.3-2.7). CONCLUSION: Manual defibrillation resulted in shorter pauses in chest compressions, but a higher frequency of inappropriate shocks. A higher formal level of education did not prevent inappropriate shocks. Trial registrationhttp://www.clinicaltrials.gov/ (NCT00138996 and NCT00228293).     

The Los Angeles public access defibrillator (PAD) program: Ten years after

Background

Public access automated external defibrillator (PAD) programs have been shown to be successful in several municipalities. This study sought to determine the usage of and survival rate from a large, urban PAD program in the first 10 years since its implementation.

Methods

This was a prospective, longitudinal, observational study from January 2002–2012 conducted in Los Angeles, California, a city with a population of 3.8 million. An incremental rollout resulted in a current total of 1300 automated external defibrillators (AEDs) in place in city-owned buildings and other public places, including all 3 area airports, golf-courses, and public pools. All instances where an AED was applied were included in the study.

Results

There were 59 incidents of cardiac arrest with a public access AED applied, of which 42 (71%) occurred at an airport. 51 (86%) of the patients were male, with a median age of 64 years (interquartile range, 56.5 to 70 years). A shockable rhythm was detected and shocks were applied in 39 (66%) patients, with 30 (77%) of these patients achieving a return of spontaneous circulation (ROSC). Of those patients who received shock(s) by public access AED, 27 (69%) survived to hospital discharge. The youngest survivors were a 25 year old male and a 34 year old female.

Conclusion

While the majority of PAD cases occurred at an airport, there were also survivors from other public locations. AEDs deployed as part of a large PAD program resulted in a very high survival rate for patients with cardiac arrest.     

Local lay rescuers with AEDs,alerted by text messages,contribute to early defibrillation in a Dutch out-of-hospital cardiac arrest dispatch system

Aim

Public access defibrillation rarely reaches out-of-hospital cardiac arrest (OHCA) patients in residential areas. We developed a text message (TM) alert system, dispatching local lay rescuers (TM-responders). We analyzed the functioning of this system, focusing on response times and early defibrillation in relation to other responders.

Methods

In July 2013, 14 112 TM-responders and 1550 automated external defibrillators (AEDs) were registered in a database residing with the dispatch center of two regions of the Netherlands. TM-responders living <1000 m radius of the patient received a TM to go to the patient directly, or were directed to retrieve an AED first. We analyzed 1536 OHCA patients where a defibrillator was connected from February 2010 until July 2013. Electrocardiograms from all defibrillators were analyzed for connection and defibrillation time.

Results

Of all OHCAs, the dispatcher activated the TM-alert system 893 times (58.1%). In 850 cases ≥1 TM-responder received a TM-alert and in 738 cases ≥1 AED was available. A TM-responder AED was connected in 184 of all OHCAs (12.0%), corresponding with 23.1% of all connected AEDs. Of all used TM-responder AEDs, 87.5% were used in residential areas, compared to 71.6% of all other defibrillators. TM-responders with AEDs defibrillated mean 2:39 (min:sec) earlier compared to emergency medical services (median interval 8:00 [25–75th percentile, 6:35–9:49] vs. 10:39 [25–75th percentile, 8:18–13:23], P < 0.001). Of all shocking TM-responder AEDs, 10.5% delivered a shock ≤6 min after call.

Conclusion

A TM-alert system that includes local lay rescuers and AEDs contributes to earlier defibrillation in OHCA, particularly in residential areas.     

Recurrent ventricular fibrillation during advanced life support care of patients with prehospital cardiac arrest

AIM OF THE STUDY: The response of recurrent episodes of ventricular fibrillation (VF) to defibrillation shocks has not been systematically studied. We analyzed outcomes from countershocks delivered for VF during advanced life support (ALS) care of patients with out-of-hospital cardiac arrest. METHODS: Cohort of patients with prehospital cardiac arrest presenting with VF, treated by ALS ambulance staff following ERC Guidelines 2000. Biphasic defibrillators provided shocks increasing from 200 to 360J. Recorded signals were analyzed to determine, for each shock, if VF was terminated and if a sustained organized rhythm was restored within 60s. RESULTS: In 465 of the 467 patients enrolled, the initial VF episode was terminated within three shocks: 92%, 61%, and 83% responded to 200J first, 200J second and 360J third shocks, respectively. VF recurred in 48% of patients within 2min of the first episode, and in 74% sometime during prehospital care. In the 175 patients experiencing five or more VF episodes, single shock VF termination dropped from the first to the fifth episode (90-80%, p<0.001) without change in transthoracic impedance, yet the proportion returning to organized rhythms increased (11-42%, p<0.0001). CONCLUSIONS: Repeated refibrillation is common in patients with VF cardiac arrest. The likelihood of countershocks to terminate VF declines for repeated episodes of VF, yet shocks that terminate these episodes result increasingly in a sustained organized rhythm.     

Detrended fluctuation analysis predicts successful defibrillation for out-of-hospital ventricular fibrillation cardiac arrest

Aims

Repeated failed shocks for ventricular fibrillation (VF) in out-of-hospital cardiac arrest (OOHCA) can worsen the outcome. It is very important to rapidly distinguish between early and late VF. We hypothesised that VF waveform analysis based on detrended fluctuation analysis (DFA) can help predict successful defibrillation.

Methods

Electrocardiogram (ECG) recordings of VF signals from automated external defibrillators (AEDs) were obtained for subjects with OOHCA in Taipei city. To examine the time effect on DFA, we also analysed VF signals in subjects who experienced sudden cardiac death during Holter study from PhysioNet, a publicly accessible database. Waveform parameters including root-mean-squared (RMS) amplitude, mean amplitude, amplitude spectrum analysis (AMSA), frequency analysis as well as fractal measurements including scaling exponent (SE) and DFA were calculated. A defibrillation was regarded as successful when VF was converted to an organised rhythm within 5 s after each defibrillation.

Results

A total of 155 OOHCA subjects (37 successful and 118 unsuccessful defibrillations) with VF were included for analysis. Among the VF waveform parameters, only AMSA (7.61 ± 3.30 vs. 6.30 ± 3.13, P = 0.028) and DFAα2 (0.38 ± 0.24 vs. 0.49 ± 0.24, P = 0.013) showed significant difference between subjects with successful and unsuccessful defibrillation. The area under the curves (AUCs) for AMSA and DFAα2 was 0.63 (95% confidence interval (CI) = 0.52-0.73) and 0.65 (95% CI = 0.54-0.75), respectively. Among the waveform parameters, only DFAα2, SE and dominant frequency showed significant time effect.

Conclusions

The VF waveform analysis based on DFA could help predict first-shock defibrillation success in patients with OOHCA. The clinical utility of the approach deserves further investigation.     

Incidence of sudden cardiac arrest is higher in areas of low socioeconomic status: a prospective two year study in a large United States community

BACKGROUND: A potential effect of socioeconomic status on occurrence of sudden cardiac arrest in the community is likely, but has not been evaluated fully. METHODS: All cases of sudden cardiac arrest in Multnomah County Oregon (population 660,486; February 2002-January 2004) were identified prospectively and categorized by census tract based on the address of residence and specific geographic location of occurrence of cardiac arrest. Each census tract was assigned to quartiles of median income, poverty level, median home value, and educational attainment. RESULTS: Of 714 cases (annual incidence 54 per 100,000), 697 (98%) had residential addresses that matched a county census tract successfully. For each socioeconomic status measure, the incidence of cardiac arrest was 30-80% higher in the lowest compared to the highest socioeconomic status census tracts. Annual incidence in census tracts in the lowest compared to the highest quartiles of median home value was 60.5 versus 35.1 per 100,000 (RR 1.7, 95% CI 1.4-2.2). This gradient was exaggerated significantly for age<65 years (34.5 versus 15.1 per 100,000, RR 2.3, 95% CI 1.6-3.3). Identical trends were observed for sudden cardiac arrest based on location, with 60% of all cases and 66% of cases age<65 years occurring in the two quartiles with lowest socioeconomic status. CONCLUSIONS: Low neighborhood socioeconomic status was associated with a significantly higher incidence of sudden cardiac arrest based on address of residence as well as location of cardiac arrest. For effective deployment of strategies for community-based prevention such as the automated external defibrillator, neighborhood socioeconomic status is likely to be an important consideration.     

Defibrillation in the movies: A missed opportunity for public health education

AimTo characterize defibrillation and cardiac arrest survival outcomes in movies.MethodsMovies from 2003 to 2012 with defibrillation scenes were reviewed for patient and rescuer characteristics, scene characteristics, defibrillation characteristics, additional interventions, and cardiac arrest survival outcomes. Resuscitation actions were compared with chain of survival actions and the American Heart Association (AHA) Emergency Cardiovascular Care (ECC) 2020 Impact Goals. Cardiac arrest survival outcomes were compared with survival rates reported in the literature and targeted by the AHA ECC 2020 Impact Goals.ResultsThirty-five scenes were identified in 32 movies. Twenty-five (71%) patients were male, and 29 (83%) rescuers were male. Intent of defibrillation was resuscitation in 29 (83%) scenes and harm in 6 (17%) scenes. Cardiac arrest was the indication for use in 23 (66%) scenes, and the heart rhythm was made known in 18 scenes (51%). When the heart rhythm was known, defibrillation was appropriately used for ventricular tachycardia or ventricular fibrillation in 5 (28%) scenes and inappropriately used for asystole in 7 (39%) scenes. In 8 scenes with in-hospital cardiac arrest, 7 (88%) patients survived, compared to survival rates of 23.9% reported in the literature and 38% targeted by an AHA ECC 2020 Impact Goal. In 12 movie scenes with out-of-hospital cardiac arrest, 8 (67%) patients survived, compared to survival rates of 7.9–9.5% reported in peer-reviewed literature and 15.8% targeted by an AHA ECC 2020 Impact Goal.ConclusionIn movies, defibrillation and cardiac arrest survival outcomes are often portrayed inaccurately, representing missed opportunities for public health education.     

The resuscitation blanket: A useful tool for “hands-on” defibrillation

Aim of study

We investigated the safety, feasibility and efficacy of a resuscitation blanket designed with the intent to protecting the rescuer from the risk of receiving electrical current during defibrillation which, would allow for uninterrupted chest compressions.

Methods

Fifteen pigs weighing between 22 and 40 kg were investigated with an established model of cardiac arrest and CPR. CPR was performed with the interposition of the blanket between the rescuer's hands and the chest of the animal. Defibrillation voltage and current over the blanket were measured. Hemodynamics, including coronary perfusion pressure (CPP), end-tidal CO₂ (EtCO₂) and 50% successful defibrillation threshold (DFT50) were measured and compared during CPR with and without the blanket.

Results

Leakage through the blanket was nominal. Voltages of 42.0, 56.6 and 105 V and mean leakage currents of 1.1, 1.4 and 3.3 μA were measured above the blanket for 150, 200 and 360 J defibrillation shocks. CPP and EtCO₂ in the animals during chest compression with the resuscitation blanket were not significantly different compared to those measured without the blanket. However, when the blanket was not utilized, CPP decreased (P < 0.05) during the 15-s hands-off interruption prior to defibrillation. Defibrillation threshold was significantly lower when the blanket was used.

Conclusion

The resuscitation blanket is a safe and useful tool which protects the rescuer from hands-on defibrillation shocks, allowing for uninterrupted chest compressions, and therefore improving defibrillation success.     

Automated external defibrillators and in-hospital cardiac arrest: patient survival and device performance at an Australian teaching hospital

Aims

To evaluate the effect of automated external defibrillators (AEDs) on patient survival and to describe the performance of AEDs after in-hospital cardiac arrest.

Methods

Prospectively collected data were analysed for cardiac arrests in the general patient care areas of a teaching hospital during the 3 years before and the 3 years after the deployment of AEDs. The association between availability of an AED and survival to hospital discharge was assessed using multivariate logistic regression. AED performance during automated management of the initial rhythms was assessed using information captured by the AEDs.

Results

There were 84 cardiac arrests in the AED period and 82 in the pre-AED period. Patient and event characteristics were similar in each period. The initial rhythm was shockable in 16% of cases. Return of spontaneous circulation was higher in the AED period (54% vs. 35%, P = 0.02) but the proportion of hospital survivors in each period was similar (22% vs. 19%, P = 0.56). The adjusted odds ratio for hospital survival when an AED was available was 1.22 (95% CI 0.53-2.84, P = 0.64). An AED was applied in 77/84 (92%) possible cases. Median interruption to chest compressions was 12 s (inter-quartile range 12-13). An automated shock was delivered in 8/13 (62%) possible cases.

Conclusions

Availability of AEDs was not independently associated with hospital survival. Shockable presenting rhythms were not common and, in keeping with the manufacturer's specifications, the AEDs did not shock all potentially shockable rhythms. The hands-off time associated with automated rhythm management was considerable.