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Introduction: Pediatric sudden cardiac arrest may require the delivery of a defibrillating shock to promote return of spontaneous circulation (ROSC). Fear of harm is a barrier for the use of automated external defibrillators by lay personnel, particularly when the patient is a child. The aim of this study was to observe the effects of delivering pediatric defibrillation shocks to pediatric weight swine who are in a perfusing rhythm or ventricular fibrillation (VF). Methods: Eight swine (10.3-26.8 kg) were studied under anesthesia. Up to 30 shocks were applied using modified samaritan AEDs (HeartSine, UK) to animals either in sinus rhythm or after 30 seconds of VF. Shocks delivered in sinus rhythm were unsynchronized. Four different shock types were applied, utilizing two different waveforms (Waveform-A at 50 J, Waveform-A at 75 J, Waveform-A at 90J and Waveform-B at 50 J). Left ventricular (LV) pressures were recorded invasively (Millar, USA). If the shock was successful, the animal entered a rest period of approximately 5 minutes, after which the next shock was applied. Results: Data presented in Table 1. Out of a total of 77 shocks delivered in sinus rhythm, 2 (2.6%) resulted in conversion to a cardiac arrest rhythm. Analysis of LV pressures demonstrated no significant differences in the change of LV dP/dt from baseline at 1, 10 and 60 seconds post-shock. There was no significant difference in shock success or ROSC between the shock types for defibrillation of VF. Analysis of LV pressures demonstrated no significant differences in the change of LV dP/dt from baseline at at 1, 10 and 60 seconds post-shock between the groups. Conclusions: The results of this study indicate defibrillation shocks applied to swine in sinus rhythm rarely result in conversion to an arrhythmia. Additionally, the variety of shock types demonstrated similar levels of safety and efficacy in this porcine model.

BackgroundPublic access defibrillators (PADs) represent unique life-saving medical devices as they may be used by untrained lay rescuers. Collecting representative clinical data on these devices can be challenging. Here, we present results from a retrospective observational cohort study, describing real-world PAD utilisation over a 5-year period.MethodsData were collected between October 2012 and October 2017. Responders voluntarily submitted electronic data downloaded from HeartSine PADs, and patient demographics and other details using a case report form in exchange for a replacement battery and electrode pack.ResultsData were collected for 977 patients (692 males, 70.8%; 255 females, 26.1%; 30 unknown, 3.1%). The mean age (SD) was 59 (18) years (range ConclusionThis is the first study to report global PAD usage in voluntarily submitted, unselected real-world cases and demonstrates the real-world effectiveness of PADs, as confirmed by first shock success.

Introduction: The AHA Get With the Guidelines Resuscitation Investigators recently identified that in-hospital cardiac arrest patients admitted during nights and weekends are less likely to survive to discharge. Our analysis aimed to determine if a similar relationship applied to out-of-hospital cardiac arrest (OHCA) patients. Methods: Worldwide data collection began in Oct 2012. Users of HeartSine SAM PAD public access defibrillators submitted electronic event data (comprising time/date of event and electrocardiogram traces) and an event report form (comprising patient demographics, location of arrest and survival to hospital outcome). First shock success was defined as termination of shockable rhythm for 5 seconds post-shock. Data was analysed using R. Results: A total of 3400 OHCA cases were collected. Median (IQR) age was 63 (50, 75) and males accounted for 72.4% of the dataset. A total of 1127 first shocks were delivered, and first shock success was 87.2% (983 shocks). Survival outcomes were reported in 2942 cases, and 783 (26.6%) patients survived to hospital admission. First shock success as a response to day of the week (weekday versus weekend [12am Saturday-11.59pm Sunday]) adjusted for patient age, gender and location of arrest, was assessed and there was no association found. When the same model was fitted with survival to hospital admission as a response to day of the week, it was determined that patients are approximately 20% less likely to survive to hospital admission at the weekend (OR=0.81, 95%CI [0.68, 0.95], p=0.01). There was a negative association between survival and OHCA occurring at home (OR=0.32, 95%CI [0.10, 0.94], p=0.03) and increasing age (per 1-year increase, OR=0.99, 95%CI [0.98, 1.00], p Conclusions: OHCA patients are significantly less likely to survive to hospital admission at weekends compared to weekdays. Further analysis on the availability of PADs at professional and recreational locations and availability of trained medical rescuers at the weekend versus weekdays could account for the differences observed.

Introduction: It is reported that quality of chest compressions (CC) during cardiopulmonary resuscitation (CPR) for both professional and non-professional rescuers often do not meet guideline requirements. Devices which provide feedback on the quality of CCs are designed to reduce the incidence of suboptimal compressions and promote the administration of effective CCs. Objective: This analysis investigates the effect of CPR duration on the performance of continuous CCs delivered by professional rescuers. Methods: Data were collected from a first responder group based in Texas, USA. Responders were instructed to use a CPR depth feedback device (Laerdal CPRmeter) and an automatic external defibrillator (AED; HeartSine SAM 350P) when attending sudden cardiac arrest events. The AED was configured with a shock protocol separated by 2-minute episodes of CPR and rescuer CC depth and rate were guided by the CPR depth feedback device. CC depth and rate data were processed for 174 patient events. Each CPR episode was divided into 4-analysis windows, 30-seconds in duration. Mean CC depth and rate data was calculated for each window. There were 1433 observations of CC depth and rate available for analysis across 414 CPR episodes. The data was fitted by a multiple linear regression model to assess the effect of CPR duration on CC performance. Results: The mean CC depth at the beginning of an event was 49.01 +/-0.51 mm. CC depth decreased by 0.82 mm, for each passing 30-second interval (p < 0.001). The mean CC rate at the beginning of an event was 111.17 +/- 0.33 compression per minute (CPM). No significant difference was observed between CC rate and duration of continuous CCs (p = 0.896) however there was a significant increase in CC rate observed of 0.408 CPM for each elapsed 2-minute CPR episode (p = 0.011). Conclusion: A reduction in CC depth was observed within each CPR episode, which may be indicative of fatigue during continuous CCs. Although a reduction of 3.28 mm throughout a 2-minute period of CPR may be clinically insignificant, this effect was observed within a trained rescuer group with CPR feedback. Further research is required to assess the effect of fatigue in non-professional responders.

A twelve-animal porcine study dataset was retrospectively analyzed to assess associations between chest compression (CC) depth, systolic blood pressure (SBP) and end-tidal carbon dioxide (EtCO 2 ). Manual CCs were applied for 7 two-minute episodes, at CC depths between 10mm−55mm. A rolling 15s analysis window was applied to the continuous signals. Mean peak values were calculated for each window. Correlation analysis was applied to assess strength of association. Optimal CC depth to achieve physiological targets was determined via cut-off analysis. A total of 672 observations for each variable were available for analysis. Pearson correlations (95% confidence interval; p-value) between CC depth and both SBP and ETCO 2 were 0.84 $(0.82, 0.86; p and 0.75 $(0.71, 0.78; p respectively. Optimal CC depth cutoff (sensitivity, specificity) to achieve $SBP \ge 100mmHg$ and $EtCO_{2}\ge 10mmHg$ was 33 mm (98.29%, 88.94%)and 20 mm (95.08%, 78.30%) respectively. A reasonable relationship between CC depth and physiological response was observed. Optimal SBP and EtCO 2 cut-offs were achieved significantly below guideline depths. Furthermore, cut-off analysis suggests a disparity between CC depth and physiological targets.

Introduction: As outlined by the Chain of Survival, effective cardiopulmonary resuscitation (CPR) and rapid defibrillation are vital to improve survival from sudden cardiac arrest (SCA). Placement of public access defibrillators (PADs) is becoming more common in public spaces, and they are more frequently used by untrained lay-users. The objective of this analysis was to assess the effect of CPR prior to defibrillation, and the success of PAD usage in terms of first shock success and survival to hospital admission. Methods: This dataset was composed of voluntarily submitted demographic information and electronic PAD files collected from October 2012 - June 2018. Summary statistics were calculated, and proportions were determined with 95% confidence intervals (CI) where appropriate. The association between CPR prior to defibrillation and survival was investigated by fitting a logistical model with survival as the dependent variable and CPR as covariate. Results: A total of 2812 PAD events were analyzed. Mean (SD) patient age was 61 (19) years and males comprised 72.5% (1922 of 2650 events where gender was known) of the events reported. The most common locations of SCA were the home (1039, 36.9%), public (719, 25.6%) and medical facility (328, 11.7%). Median (IQR) time to PAD delivery was 5 (3, 11) minutes. Ventricular fibrillation or tachycardia was present in 1010 (35.9%) patients, and 979 received a shock, with 87.2% (95%CI [85.0%, 89.3%]) achieving first shock success. Of the 849 shockable patients for whom survival was known, 565 (66.5%, (95%CI [63.3%, 69.7%]) survived to hospital admission. Survival outcome was known for 2150 patients, and 681 (31.7%, 95%CI [29.7%, 33.69%]) survived to hospital admission. A total of 1649 (58.6%) SCAs were witnessed and 1293 (78.4%) patients received bystander CPR prior to defibrillation. Bystander CPR prior to defibrillation was significantly associated with survival to hospital admission (OR = 2.17, 95%CI [1.69, 2.81], p Conclusion: These results suggest that CPR application prior to application of a PAD significantly increases a patient’s chances of surviving to hospital admission. This study did not assess CPR quality, but it is intuitive that good quality CPR would align with higher survival outcomes.

Objective: When attempting defibrillation in an out-of-hospital pediatric patient, the use of a reduced energy is recommended by the resuscitation guidelines due to concerns surrounding potential myocardial damage. This study investigated the effectiveness (first shock success) and safety (myocardial damage) of using adult defibrillation energies in a pediatric model of cardiac arrest. Methods: Twelve piglets (9.5-25.5 kg; typical weight range of 1 to 8 year old children) were anaesthetized and VF was electrically induced. After 15 seconds of untreated VF, defibrillation was delivered using either Protocol A (adult energies; 150J) or Protocol B (pediatric energies; 75J). Following successful defibrillation, a 3 minute rest period was allowed for the heart to recover before VF was again induced. Blood samples were collected and analyzed for cardiac troponin I (cTnI). After 20 shocks were delivered, each animal remained anaesthetized and monitored for 6 hours. Results: A total of 240 shocks were delivered across both protocols with adult and pediatric energies providing comparable first shock success rates of 98.3% (116/118) and 96.6% (112/116). Prior to the induction of VF, Protocols A and B presented with equivalent median (IQR) levels of cardiac damage marker cTnI; 0.04 (0.02, 0.07) ng/ml ( n =6) and 0.05 (0.03, 0.08) ng/ml ( n =6), respectively. Comparable cTnI results were also observed upon completion of the defibrillation phase: Protocol A – 0.23 (0.12, 0.32) ng/ml; Protocol B – 0.20 (0.12, 0.27) ng/ml. There was 100% (12/12) survival after the 6 hour monitoring period with both protocols presenting similar cTnI: Protocol A – 0.32 (0.27, 0.55) ng/ml; Protocol B – 0.28 (0.20, 0.46) ng/ml. There were no clinically significant differences observed between the adult and pediatric defibrillation energy groups. Furthermore, histopathological evaluation revealed no discernible difference in cardiac damage between energy protocols. Conclusion: This study demonstrates that adult defibrillation energies are as effective in terminating VF and do not produce statistically higher levels of cTnI than pediatric defibrillation energies. These results suggest that adult defibrillation energies are appropriate for the treatment of pediatric cardiac arrest.

Objective Optimising 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 CO 2 (ETCO 2 ). Methods Two experiments were performed using 24 swine (12 per experiment). For experiment 1, ventricular fibrillation (VF) was induced and mechanical CPR commenced at varying thrusts (0–60kg) for 2min 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 (0–5cm) for 2min 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 ETCO 2 were recorded during each cycle. In both experiments the within-animal correlation between the measured parameters was assessed using a mixed effect model. Results In 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 ETCO 2 ( r =0.85, r =0.64). Conclusion In 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 ETCO 2 suggesting its potential utility to provide CPR feedback in the out of hospital setting to improve performance.

High quality chest compressions (CCs) have been proven to increase patient survival, during cardiac arrest. The impedance cardiogram (ICG) may provide a simple and non-invasive CPR coaching system to improve CC efficacy of minimally trained users. Cardiac arrest was induced in eleven swine. Manual CCs were applied at a fixed depth for two-minute episodes, increasing for each successive episode. Physiological data was recorded at 30s intervals. The primary analysis assessed the relationship between ICG amplitude and CC depth using a 5s analysis window. The secondary analysis compared the ICG amplitude against captured physiological data and CC depth, using a 30s window. The primary analysis yielded a strong Pearson correlation coefficient (95% confidence interval) of 0.90 (0.89, 0.91) between ICG amplitude and CC depth. The secondary analysis produced an overall correlation of 0.92 (0.90, 0.94) between ICG amplitude and CC depth. The within-animal correlation for ICG amplitude and both end-tidal carbon dioxide and systolic blood pressure was 0.94 (0.93, 0.95) and 0.90 (0.88, 0.92) respectively. Our data suggests that the amplitude of ICG is a good predictor of CC efficacy in a porcine model of cardiac arrest, when manual CCs are applied.

Objective: It is widely known that CPR administered in all settings may be sub-optimal. CPR feedback tools can provide reliable feedback to operators to improve compression rate, depth and fraction. The purpose of this study was to evaluate the use of a CPR rate feedback algorithm incorporated into an automated external defibrillator by comparing the CPR compression rate measured by an Impedance Cardiogram based feedback device, a video recording of real-time CPR and using a commercially available accelerometer Hypothesis: ICG based CPR feedback is as effective as accelerometer based feedback. Methods: A total of twelve porcine models were used each weighing 29.62±4.2kg. Rate (CPM), End-tidal CO 2 (ETCO 2 ), Blood Pressure (BP), SpO2 (%) and Depth (mm) was measured for each model. The Impedance Cardiogram (ICG)/Thoracic Impedance was recorded via 2 standard defibrillation electrodes and as a method of detecting the presence of CPR. Ethical approval was granted by the Northern Ireland Home Office and the Home Office in Scotland. Models were anaesthetised using Propofol and Isoflurane and connected to a Datex Ohmeda ® monitor for anaesthesia monitoring. A number of physiological measurements were taken every 2 minutes via the carotid and jugular. Rate and depth were measured continuously using Q-CPR ® , Philips. Recordings from each experiment were acquired using Datex Ohmeda review software for further statistical analysis using SAS 9.2 ® . Findings: The proportion of correct audio and visual feedback of the Impedance Cardiogram based feedback device versus the actual CPR compression rate as demonstrated in video recordings was 95.2%. The study also showed that the proportion of “correct” audio and visual feedback of the SAM 450P CPR Rate Feedback algorithm versus the accelerometer rate (CPM) was 87.5% due to underestimation of some measures in the non-ICG based device. Conclusions: Therefore it could be concluded that an Impedance Cardiogram based feedback device is highly sensitive to end user chest compression rate over a wide range of rates (40 to 180 compressions-per-minute).

Introduction: Studies were conducted to evaluate cardiopulmonary resuscitation (CPR) in a simulated low gravitational field, such as Mars (hypoG), aimed at providing an insight into the performance of terrestrial CPR. Methods: Two studies were conducted to evaluate external chest compressions (ECC) depth and rate, as well as perceived exertion (RPE) and the physiological cost, when 4 sets of 30 ECCs were performed on a standard CPR mannequin for 1.5min during Mars simulation, using terrestrial (1Gz) as control. The first study (n=20; 2005 guidelines) also evaluated the electromyographic (EMG) activity of four muscles (triceps brachii, erector spinae, upper rectus abdominis, pectoralis major). The second study (n=30; 2010 guidelines) included range of elbow flexion, minute ventilation (VE) and peak oxygen consumption (VO2 peak) measurements. HypoG simulation was achieved using a body suspension device (BSD) and a counterweight system. Results: In both studies, subjects successfully performed ECCs at 1Gz and hypoG. In the first study, therewere increases from 1Gz values of 32% (p