Background: Quality of chest compressions (CC) during cardiopulmonary resuscitation (CPR) often do not meet guideline recommendations for rate and depth. This may be due to the fatiguing nature of physically compressing a patient's chest, meaning that CPR quality reduces over time.Objective: This analysis investigates the effect of CPR duration on the performance of continuous CCs delivered by firefighters equipped with CPRMethods: Data were collected from a first responder group which used CPR feedback and automatic external defibrillator devices when attending out-of-hospital cardiac arrest events. Depth and rate of CC were analysed for 134 patients. Mean CC depth and rate were calculated every 5 s during two-minute episodes of CPR. Regression models were created to evaluate the relationship between applied CC depth and rate as a function of time.Results: Mean (SD) CC depth during the investigation was 48 (9) mm. An inverse relationship was observed between CC depth and CPR duration, where CC depth decreased by 3.39 mm, over two-minutes of CPR (p < 0.001). Mean (SD) CC rate was 112.06 (5.87) compressions per minute. No significant relationship was observed between CC rate and CPR duration (p = 0.077). Mean depth was within guideline range for 33.58% of patient events, while guideline rate was observed in 92.54% of cases.Conclusions: A reduction in CC depth was observed during two-minutes of continuous CCs while CC rate was not affected. One third of patients received a mean CC depth within guideline range (50 to 60 mm).

Incidence of initial non-shockable rhythm during cardiac arrest is increasing and is associated with poorer outcomes. The aim of this analysis was to study non-shockable to shockable rhythm conversion treated using a public access defibrillator (PAD) and to study survival rates related to initial shockable rhythm. HeartSine PAD data were collected between October 2012 to May 2023. The dataset consisted of data downloaded from PADs, and data recorded in case report forms. Initial rhythm and conversion to shockable rhythm were determined. First shock success (FSS) was defined as the termination of the shockable rhythm for at least 5 seconds. Chi-squared test was applied to determine if there was difference in outcomes between those patients with: a shockable rhythm, non-shockable rhythm that converted to shockable, and non-shockable rhythm that did not convert to a shockable rhythm. Of the 6877 cases submitted initial shockable rhythm could be determined for 6736 cases. For the 30.5% (2053/6736) of cases with an initial shockable rhythm, patient outcome was reported for 1923, and 62.9% (1209/1923) survived to hospital admission. Incidence of initial non-shockable rhythm was 69.5% (4683/6736). Change to a shockable rhythm could be determined for 4664 cases and occurred in 5.0% (233/4664). A shock was delivered in 94.8% (221/233) of these cases. FSS could be determined for 165 cases. FSS was 85.5% (141/165). Patient outcome was reported for 87.6% (204/233) where 22.5% (46/204) resulted in survival to hospital admission. For the 95% (4431/4664) of non-shockable cases that did not convert to a shockable rhythm, patient outcome was reported for 82.2% (3644/4431), where 10.8% (395/3644) of patients survived to hospital admission.Thus, conversion from non-shockable to shockable rhythm had improved survival compared to patients who did not convert. Furthermore, when initial rhythm was shockable significantly higher survival to hospital admission was recorded.

Introduction: Refractory VF, which is defined as fibrillation that persists after three or more shocks, has been reported to occur in 20% of VF presenting cardiac arrest patients. This analysis was conducted to assess the frequency of shock resistant VF, during OHCA treated with a public access defibrillator (PAD). Methods: Heartsine Samaritan PAD post-market data collected between October 2012 to January 2021 were analyzed; electrocardiography (ECG) is recorded by the PAD and is assessed for shockability immediately after detecting patient impedance and then following each 2-minute period of CPR. Shock success (SS) was determined for each shock. SS was defined as one in which the initial shockable arrhythmia was terminated for at least five seconds. A consecutive shock was defined as a shock delivered after the first analysis mode following a previous shock. Results: Data was analyzed for 1082 patients who received at least one shock during OHCA. First shock success (FSS) was 88.2% (862/977 assessable shocks). At least three consecutive shocks were delivered in 207/1082 (19.1%) patients. Three patients (3/207, 1.4%) had two unsuccessful shocks followed by termination of VF on the third shock. A further thirteen (13/204, 6.4%) patients had VF which was resistant to defibrillation (i.e., three or more consecutive failed shocks with no observed successful shock). In the remaining 191 patients at least one of the three consecutive shocks was successful, or shock success could not be determined. Conclusion: The prevalence of shock resistant VF for OHCA treated with a PAD is much lower (6.4%) than published data. This low prevalence is in part due to the high FSS observed resulting in reduction in the number of possible shock resistant cases.

Introduction: Previous analysis of emergency medical services manual defibrillator recordings suggests that the proportion of patients with initial shockable rhythms during out-of-hospital cardiac arrest is decreasing over time. This analysis aims to determine if this decline also occurs in public access defibrillator data. Methods: Worldwide post-market data from HeartSine SAM PAD public access defibrillators was collected between 2012 and 2022. Presence of an initial shockable rhythm (ventricular fibrillation or ventricular tachycardia) was determined by the device algorithm decision and clinical overread. The proportion of patients who presented an initial shockable rhythm each year was calculated. Data was analysed using Minitab. Summary statistics were calculated for patient age and gender, and a logistic regression model was used to examine the proportion of initial shockable rhythm over time. Results: A total of 5404 patient events were collected. Seventy-four percent were male, and mean (SD) age was 61.2 (18.2) years. Proportion of initial shockable rhythm as a response to year was assessed, and occurrence of shockable rhythms decreased by approximately 6% per year [OR: 0.94, 95%CI (0.91, 0.96), p<0.001]. Conclusion: In line with findings from emergency service resuscitation attempts, the proportion of initial shockable rhythms in patients treated with a public access defibrillator declined over a ten-year period.

Thoracic impedance (TI) is used in defibrillation to alter shock characteristics to ensure patients receive a standard energy dose.Pulse duration, peak voltage and current are dependent on patient TI where increased TI typically results in a longer shock duration and a higher peak voltage.Some reports suggest that higher impedance patients experience lower rates of shock success.The aim of this analysis was to identify the effect of patient TI on shock outcome.Electronic event data, recorded via HeartSine defibrillators and submitted on a voluntary basis between October 2012 and December 2018 were analysed.Patient TI logged prior to the delivery of the first shock in events with at least one defibrillation attempt were extracted.The first shock was subsequently annotated to determine shock success, defined as the termination of ventricular fibrillation or ventricular tachycardia for at least 5 seconds after shock delivery.Mean TI was compared between successful and unsuccessful defibrillation attempts by a 2-sample t-test.A total of 467 patient events where defibrillation was attempted and had a determinable first shock outcome were analysed.The first shock success rate was 86.08% (n = 402) and mean (standard deviation) patient TI was 89.78 (22.37)Ω, ranging from 37 to 211 Ω.There was no significant difference ( p = 0.989) in patient TI between successful (89.8 Ω) and unsuccessful (89.7 Ω) defibrillation attempts.This analysis demonstrates that there is no association between patient TI and shock outcome.Modifying pulse duration and peak voltage based on TI to deliver a set energy to each patient was effective at abolishing shockable rhythms.

BACKGROUND:Public 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.METHODS:Data 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.RESULTS:Data 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 <1 year to 101 years). PAD usage occurred most commonly in homes (n=328, 33.6%), followed by public places (n=307, 31.4%) and medical facilities (n=128, 13.1%). Location was unknown in 40 (4.09%) events. Shocks were delivered to 354 patients. First shock success was 312 of 350 patients where it could be determined (89.1%, 95% CI 85.4% to 92.2%). Patients with reported response times ≤5 min were more likely to survive to hospital admission (89/296 (30.1%) vs 40/250 (16.0%), p<0.001). Response time was unknown for 431 events.CONCLUSION:This 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.

Background Left circumflex culprit is often missed by the standard 12‐lead ECG. Extended lead systems (body surface potential map [BSPM]) should improve the diagnosis of culprit left circumflex stenosis with myocardial infarction. Methods and Results Retrospective analysis of a hospital research registry (August 2000–August 2010) comprising consecutive patients with (1) ischemic‐type chest pain at rest; (2) 12‐lead ECG and 80‐lead BSPM at first medical contact; and (3) cardiac troponin‐T 12 hours after symptom onset and/or creatine kinase MB fraction, were undertaken. Enrolled in the cohort were patients with culprit left circumflex stenosis (thrombolysis in myocardial infarction flow grade 0/1) at angiography. Acute myocardial infarction AMI was defined as cardiac troponin‐T ≥0.1 μg/L and/or creatine kinase MB fraction >2 upper limits of normal. Enrolled were 482 patients: 168 had exclusion criteria. Of the remaining 314 (age 64±11 years; 62% male), 254 (81%) had AMI: of these, 231 had BSPM STE—sensitivity 0.91, specificity 0.72, positive predictive value 0.93, negative predictive value 0.65, and c‐statistic 0.803 for AMI (P<0.001). Of those with BSPM STE and AMI (n=231), STE was most frequently detected in the posterior (n=111, 48%), lateral (n=53, 23%), inferior (n=39, 17%), and right ventricular (n=21, 9%) territories. Conclusions Among patients with 12‐lead ECG non‐ST‐segment–elevation myocardial infarction and culprit left circumflex stenosis, initial BSPM identifies ST‐segment elevation beyond the territory of the 12‐lead ECG. Greater use of the BSPM may result in earlier identification of AMI, which may lead to more rapid reperfusion.

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<0.001). Adjusting the model for time of day (morning [6am-11.59am], afternoon [12pm-5.59pm], evening [6pm-11.59pm] and night [12am-5.59am]) did not highlight an association with any particular time of day. 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: Survival from sudden cardiac arrest (SCA) relies on prompt defibrillation and effective cardiopulmonary resuscitation (CPR). The effect of SCA patient gender has been assessed, but there has been little research into the effect of rescuer gender. An update to the resuscitation guidelines recommends lay-rescuers perform chest compression (CC) only CPR. This study was conducted to assess quality of CCs performed by male and female lay-rescuers.

Introduction A recent analysis demonstrated that 4.2% of public access defibrillator (PAD) shock decisions were incorrect and that in 5% of instances where a PAD recommended a shock, the user did not press the shock button [1]. Some PADs are fully-automated, where the devices determine if shocks are required, and administer shocks without user input. This reduces possibility that a

Introduction: The home is often reported as the most common location for out-of-hospital sudden cardiac arrests (SCA), and survival outcomes are very low. There has been limited recent research into modern public access defibrillator (PAD) use in the home. The purpose of this analysis was to gain deeper understanding of survival outcomes in the home compared to public locations.

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<0.001). 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.

Purpose When attempting defibrillation in an out-of-hospital paediatric patient, the use of a reduced energy is currently recommended in the resuscitation guidelines due to concerns surrounding potential myocardial damage. The purpose of this pilot study was to investigate the 1st shock success of two different automated external defibrillator (AED) energy protocols and observe the resulting levels of myocardial damage in a paediatric model of cardiac arrest. Method A total of six piglets (10–25 kg) were anaesthetised, instrumented and ventricular fibrillation (VF) was electrically induced. After approximately 15 s of untreated VF, a defibrillation shock was delivered using the selected device in line with Protocol A (adult energy doses of 150J) or Protocol B (paediatric energy doses of 75J). Following successful defibrillation, a 3 min recovery period was allowed for the heart to recover before VF was again induced with a maximum of 20 shocks administered. Blood samples were collected at pre-defined time-points whilst the animal was under anaesthesia and analysed for cardiac troponin I (cTnI). After the defibrillation phase of the protocol, the animals remained anaesthetised and vital signs monitored for a period of 6 hours with blood samples collected hourly for further analysis. Results A total of 120 shocks were delivered across both protocols with a 100% shockable rhythm detection and 100% first shock success observed in both Protocol A and B. Prior to the induction of VF, Protocol A and B presented with similar initial mean (±SD) levels of cTnI; 0.04 (±0.03) ng/ml (n=3) and 0.03 (±0.02) ng/ml (n=3), respectively. Comparable results of cTnI were also observed upon completion of the defibrillation phase (Shock 20); Protocol A – 0.12 (±0.05) ng/ml and Protocol B – 0.14 (±0.07) ng/ml. An increase in mean cTnI was detected into the rest period, peaking by 5 hours for both energy protocols. At the 6 hour endpoint of this study, the mean value of cTnI in the blood was reducing for both energy protocols with no statistically significant difference observed between the high and low defibrillation energy groups. Conclusion There was no statistical evidence to suggest that treating the paediatric animals with a higher adult shock energy caused more myocardial damage than a paediatric shock energy. Further investigations are warranted to determine the long term impact on myocardial tissues in a paediatric patient.

Introduction: Patients with acute left circumflex artery (LCx) occlusion may present with inferior or lateral ST-elevation myocardial infarction (STEMI) or non-STEMI on 12-lead ECG. Non-STEMI patie...