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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.

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.

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: 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).