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Objective: We aimed to quantify the number of prehospital randomized controlled trials (RCTs) published in the 25 years since the Callaham editorial and review his perception of prehospital emergency care as "scanty" science., Methods: We replicated Callaham's methods to retrieve publications related to prehospital randomized controlled trials (RCTs). This study systematically searched over 35 million citations cataloged by the National Library of Medicine in the PubMed Database between January 1, 1998, and December 31, 2022. Two independent reviewers screened titles, abstracts, and full manuscripts in two rounds, and key terms that indicated RCTs, such as randomized and controlled, standard, or placebo-controlled were identified., Results: The final study group of prehospital RCTs published between 1998 and 2022 included 141 papers. Of the 141 RCTs, 48.2% concluded no significant difference between the intervention and control groups. The average number of RCTs per year was 5.6. Trials during the study period were conducted in 19 different countries, and multinationally., Conclusion: In the time period reported by Callaham, the average number of prehospital RCTs was 4.5 per year. The number of prehospital RCTs published per year has increased only slightly, to 5.6 per year, in the 25 years since Callaham described prehospital emergency care as a "scanty science."

Background: Cerebral blood flow (CBF) decreases in the first few hours or days following resuscitation from cardiac arrest, increasing the risk of secondary cerebral injury. Using data from experimental studies performed in minipigs, we investigated the relationships of parameters derived from arterial and jugular bulb blood gas analyses and lactate levels (jugular bulb parameters), which have been used as indicators of cerebral perfusion and metabolism, with CBF and the cerebral lactate to creatine ratio measured with dynamic susceptibility contrast magnetic resonance imaging and proton magnetic resonance spectroscopy, respectively., Methods: We retrospectively analyzed 36 sets of the following data obtained during the initial hours following resuscitation from cardiac arrest: percent of measured CBF relative to that at the prearrest baseline (%CBF), cerebral lactate to creatine ratio, and jugular bulb parameters, including jugular bulb oxygen saturation, jugular bulb lactate, arterial-jugular bulb oxygen content difference, cerebral extraction of oxygen, jugular bulb-arterial lactate content difference, lactate oxygen index, estimated respiratory quotient, and arterial-jugular bulb hydrogen ion content difference. Linear mixed-effects models were constructed to examine the effects of each jugular bulb parameter on the %CBF and cerebral lactate to creatine ratio., Results: The arterial-jugular bulb oxygen content difference (P = 0.047) and cerebral extraction of oxygen (P = 0.030) had a significant linear relationship with %CBF, but they explained only 12.0% (95% confidence interval [CI] 0.002-0.371) and 14.2% (95% CI 0.005-0.396) of the total %CBF variance, respectively. The arterial-jugular bulb hydrogen ion content difference had a significant linear relationship with cerebral lactate to creatine ratio (P = 0.037) but explained only 13.8% (95% CI 0.003-0.412) of the total variance in the cerebral lactate to creatine ratio. None of the other jugular bulb parameters were related to the %CBF or cerebral lactate to creatine ratio., Conclusions: In conclusion, none of the jugular bulb parameters appeared to provide sufficient information on cerebral perfusion and metabolism in this setting., (© 2024. Springer Science+Business Media, LLC, part of Springer Nature and Neurocritical Care Society.)

Objective: The epidemiology accompanying helicopter emergency medical services (HEMS) transport has evolved as agencies have matured and become integrated into regionalized health systems, as evidenced primarily by nationwide systems in Europe. System-level congruence between Europe and the United States, where HEMS is geographically fragmentary, is unclear. In this study, we provide a temporal, epidemiologic characterization of the largest standardized private, nonprofit HEMS system in the United States, STAT MedEvac., Methods: We obtained comprehensive timing, procedure, and vital signs data from STAT MedEvac prehospital electronic patient care records for all adult patients transported to UPMC Health System hospitals in the period of January 2012 through October 2021. We linked these data with hospital electronic health records available through June 2018 to establish length of stay and vital status at discharge., Results: We studied 90,960 transports and matched 62.8% (n = 57,128) to the electronic health record. The average patient age was 58.6 years ( 19 years), and most were male (57.9%). The majority of cases were interfacility transports (77.6%), and the most common general medical category was nontrauma (72.7%). Sixty-one percent of all patients received a prehospital intervention. Overall, hospital mortality was 15%, and the average hospital length of stay (LOS) was 8.8 days ( 10.0 days). Observed trends over time included increases in nontrauma transports, level of severity, and in-hospital mortality. In multivariable models, case severity and medical category correlated with the outcomes of mortality and LOS., Conclusion: In the largest standardized nonprofit HEMS system in the United States, patient mortality and hospital LOS increased over time, whereas the proportion of trauma patients and scene runs decreased., Competing Interests: Declaration of Competing Interest The author(s) have no relevant disclosures. There was no grant funding or financial support for this manuscript., (Copyright © 2023 Air Medical Journal Associates. Published by Elsevier Inc. All rights reserved.)

Introduction: Following initial resuscitation from out-of-hospital cardiac arrest, rearrest frequently occurs and has been associated with adverse outcomes. We aimed to identify clinical, treatment, and demographic characteristics associated with prehospital rearrest at the encounter and agency levels., Methods: Adult non-traumatic cardiac arrest patients who achieved ROSC following EMS resuscitation in the 2018-2021 ESO annual datasets were included in this study. Patients were excluded if they had a documented DNR/POLST or achieved ROSC after bystander CPR only. Rearrest was defined as post-ROSC CPR initiation, administration of ≥ 1 milligram of adrenaline, defibrillation, or a documented non-perfusing rhythm on arrival at the receiving hospital. Multivariable logistic regression modeling was used to evaluate the association between rearrest and case characteristics. Linear regression modeling was used to evaluate the association between agency-level factors (ROSC rate, scene time, and scene termination rate), and rearrest rate., Results: Among the 53,027 cases included, 16,116 (30.4%) experienced rearrest. Factors including longer response intervals, longer 'low-flow' intervals, unwitnessed OHCA, and a lack of bystander CPR were associated with rearrest. Among agencies that treated ≥ 30 patients with outcome data, the agency-level rate of rearrest was inversely associated with agency-level rate of survival to discharge to home (R 2  = -0.393, p < 0.001)., Conclusions: This multiagency retrospective study found that factors associated with increased ischaemic burden following OHCA were associated with rearrest. Agency-level rearrest frequency was inversely associated with agency-level survival to home. Interventions that decrease the burden of ischemia sustained by OHCA patients may decrease the rate of rearrest and increase survival., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Standardized reporting of data is crucial for out-of-hospital cardiac arrest (OHCA) research. While the implementation of first responder systems dispatching volunteers to OHCA is encouraged, there is currently no uniform reporting standard for describing these systems. A steering committee established a literature search to identify experts in smartphone alerting systems. These international experts were invited to a conference held in Hinterzarten, Germany, with 40 researchers from 13 countries in attendance. Prior to the conference, participants submitted proposals for parameters to be included in the reporting standard. The conference comprised five workshops covering different aspects of smartphone alerting systems. Proposed parameters were discussed, clarified, and consensus was achieved using the Nominal Group Technique. Participants voted in a modified Delphi approach on including each category as a core or supplementary element in the reporting standard. Results were presented, and a writing group developed definitions for all categories and items, which were sent to participants for revision and final voting using LimeSurvey web-based software. The resulting reporting standard consists of 68 core items and 21 supplementary items grouped into five topics (first responder system, first responder network, technology/algorithm/strategies, reporting data, and automated external defibrillators (AED)). This proposed reporting standard generated by an expert opinion group fills the gap in describing first responder systems. Its adoption in future research will facilitate comparison of systems and research outcomes, enhancing the transfer of scientific findings to clinical practice., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: ‘MPM is chair of Region of Lifesavers, shareholder of SmartResQ ApS, and received speaker honoraria from Stryker. RG is Board Director of Guidelines, European Resuscitation Council, and chair of the Task Force Education, Implementation and Teams, International Liaison Committee on Resuscitation. TS is member of the editorial board, Resuscitation and Resuscitation Plus, member of the science and education committee BLS of the ERC, and member of the ILCOR social media working group. CDD is member of the editorial board of the journal Resuscitation, treasurer of the UK Resuscitation Council and ALS working group member of ILCOR. AA is a consultant with Boston Scientific, Backbeat, Biosense Webster, Cairdac, Corvia, Daiichi-Sankyo, Medtronic, Merit, Microport CRM, and Philips; received speaker fees from Daiichi-Sankyo, Boston Scientific, Biosense Webster, Medtronic, Microport CRM, and Philips; participates in clinical trials sponsored by Boston Scientific, Medtronic, Microport CRM, and Zoll Medical; and has intellectual properties assigned to Boston Scientific, Biosense Webster, and Microport CRM. TB has research, clinical and educational roles in resuscitation care, including in first responder systems. He is a member of the Pre-Hospital Emergency Care Council (Ireland). EB is working group member in ESCAPE-NET and PARQ COST action. BB is treasurer of the European Resuscitation Council (ERC), Chairman of the German Resuscitation Council (GRC), Member of the Advanced Life Support (ALS) Task Force of the International Liaison Committee on Resuscitation (ILCOR), Member of the Executive Committee of the German Interdisciplinary Association for Intensive Care and Emergency Medicine (DIVI), Founder of the “Deutsche Stiftung Wiederbelebung”, Federal Medical Advisor of the German Red Cross (DRK), Co-Editor of “Resuscitation”, Editor of the Journal “Notfall + Rettungsmedizin”, Co-Editor of the Brazilian Journal of Anesthesiology. He received fees for lectures from the following companies: Forum für medizinische Fortbildung (FomF), Baxalta Deutschland GmbH, ZOLL Medical Deutschland GmbH, C.R. Bard GmbH, GS Elektromedizinische Geräte G. Stemple GmbH, Novartis Pharma GmbH, Philips GmbH Market DACH, Bioscience Valuation BSV GmbH. HJB is member of the executive committee of the German Resuscitation Council and vice chair of Region of Lifesavers. SC is member of the editorial board of the journal Resuscitation, member of the advisory board drone delivery Canada and received speaker honoraria from Zoll Medical. ED is shareholder of EVapp VZW, Belgium. DF is co-founder and operations manager of the Heartrunner Citizen Responder System, Sweden and member of the tech&ops committee of EENA (European Emergency Number Association). FLH is shareholder of FirstAED ApS, Denmark. MJ is a working group leader in the EU-funded network PARQ-COST, focusing on cardiac arrest research. JJ is CEO of the non-profit organisation Region der Lebensretter e.V. TAK is employed at Stan B.V. running the national citizen responder network HartSlagNu in the Netherlands. MK is chief medical director, Vienna Emergency Medical Service, and executive president PULS – Austrian Cardiac Arrest Association. KM is member of the editorial board of the journal Resuscitation. SO is employed at the German Red Cross and is board member of the GRC. DDS provided unpaid scientific consulting to CPRSave, a company developing a novel SAS system, and his department received a small grant from the PulsePoint Foundation to increase SAS participation in Allegheny County, PA, US. AS is vice president of the Italian Resuscitation Council (IRC). JSchwietring is chief medical director, ADAC (air rescue) LRG gGmbH. FS is chair elect, European Resuscitation Council and chair, ILCOR Social Media Working Group. PS is chair of the medical committee, Ontario Para & Summer Games and board member, Peel Paramedic Association. HLT is co-founder of PacingCure. He has received funding from the European Union's Horizon 2020 research and innovation programme under acronym ESCAPE-NET, registered under grant agreement No 733381, and the COST Action PARQ (grant agreement No CA19137) supported by COST (European Cooperation in Science and Technology). GT is employed at Resuscitec GmbH, shareholder of Resuscitec GmbH, and board member of the GRC and Region der Lebensretter. JGanter is board member of Region of Lifesavers. SV is president of EVapp NGO, and shareholder Prior-IT BV. CM, KCT, RB, MLC, RC, DD, MME, DE, MCTG, JGronewald, MH, LH, TM, KM, WMN, JSowa, RS, JU, WAW have no conflicts of interest.’., (Copyright © 2023 The Author(s). Published by Elsevier B.V. All rights reserved.)

Background: Prehospital post-resuscitation hypotension and hypoxia have been associated with adverse outcomes in the context of out-of-hospital cardiac arrest (OHCA). We aimed to investigate the association between clinical outcomes and post-resuscitation hypoxia alone, hypotension alone, and combined hypoxia and hypotension., Methods: We used the 2018-2021 ESO annual datasets to conduct this study. All EMS-treated non-traumatic OHCA patients who had a documented prehospital return of spontaneous circulation (ROSC) and two or more SpO 2 readings and systolic blood pressures recorded were evaluated for inclusion. Patients who were less than 18 years of age, pregnant, had a do-not-resuscitate order or similar, achieved ROSC after bystander CPR only, or had an EMS-witnessed cardiac arrest were excluded. Multivariable logistic regression adjusted for standard Utstein factors and highest prehospital Glasgow Coma Scale (GCS) score was used to investigate the association between hypoxia, hypotension, and outcomes., Results: We analyzed data for 17,943 patients, of whom 3,979 had hospital disposition data. Hypotension and hypoxia were not documented in 1,343 (33.8%) patients, 1,144 (28.8%) had only hypoxia documented, 507 (12.7%) had only hypotension documented, and 985 (24.8%) had both hypoxia and hypotension documented. In comparison to patients who did not have documented hypotension or hypoxia, patients who had documented hypoxia (aOR: 1.76 [1.38, 2.24]), documented hypotension (aOR: 3.00 [2.15, 4.18]), and documented hypoxia and hypotension combined (aOR: 4.87 [3.63, 6.53]) had significantly increased mortality. The relationship between mortality and vital sign abnormalities (hypoxia and hypotension > hypotension > hypoxia) was observed in every evaluated subgroup., Conclusions: In this large dataset, hypotension and hypoxia were independently associated with mortality both alone and in combination. Compared to patients without documented hypotension and hypoxia, patients with documented hypotension and hypoxia had nearly five-fold greater odds of mortality.

Background: Observation of the electrocardiogram (ECG) immediately following return of spontaneous circulation (ROSC) in resuscitated swine has revealed the interesting phenomenon of sudden ECG rhythm changes (SERC) that occur in the absence of pharmacological, surgical, or other medical interventions., Objective: We sought to identify, quantify, and characterize post-ROSC SERC in successfully resuscitated swine., Methods: We reviewed all LabChart data from resuscitated approximately 4- to 6-month-old swine used for various experimental protocols from 2006 to 2019. We identified those that achieved sustained ROSC and analyzed their entire post-ROSC periods for evidence of SERC in the ECG, and arterial and venous pressure tracings. Presence or absence of SERC was confirmed independently by two reviewers (ACK, DDS). We measured the interval from ROSC to first SERC, analyzed the following metrics, and calculated the change from 60 sec pre-SERC (or from ROSC if less than 60 sec) to 60 sec post-SERC: heart rate, central arterial pressure (CAP), and central venous pressure (CVP)., Results: A total of 52 pigs achieved and sustained ROSC. Of these, we confirmed at least one SERC in 25 (48.1%). Two pigs (8%) each had two unique SERC events. Median interval from ROSC to first SERC was 3.8 min (inter-quartile range 1.0-6.9 min; range 16 sec to 67.5 min). We observed two distinct types of SERC: type 1) the post-SERC heart rate and arterial pressure increased (72% of cases); and type 2) the post-SERC heart rate and arterial pressure decreased (28% of cases). For type 1 cases, the mean (standard deviation [SD]) heart rate increased by 33.6 (45.7) beats per minute (bpm). The mean (SD) CAP increased by 20.6 (19.2) mmHg. For type 2 cases, the mean (SD) heart rate decreased by 39.7 (62.3) bpm. The mean (SD) CAP decreased by 21.9 (15.6) mmHg., Conclusions: SERC occurred in nearly half of all cases with sustained ROSC and can occur multiple times per case. First SERC most often occurred within the first 4 minutes following ROSC. Heart rate, CAP, and CVP changed at the moment of SERC. We are proceeding to examine whether this phenomenon occurs in humans post-cardiac arrest and ROSC.

Objective: End tidal carbon dioxide (ETCO 2 ) is often used to assess ventilation and perfusion during cardiac arrest resuscitation. However, few data exist evaluating the relationship between ETCO 2 values and mortality in the context of contemporary resuscitation practices. We aimed to explore the association between ETCO 2 and mortality following out-of-hospital cardiac arrest (OHCA)., Methods: We used the 2018-2021 ESO annual datasets to query all non-traumatic OHCA patients with attempted resuscitation. Patients with documented DNR/POLST, EMS-witnessed arrest, ROSC after bystander CPR only, or < 2 documented ETCO 2 values were excluded. The lowest and highest ETCO 2 values recorded during the total prehospital interval, in addition to the pre- and post-ROSC intervals for resuscitated patients, were calculated. Multivariable logistic regression models adjusted for age, sex, initial rhythm, witnessed status, bystander CPR, etiology, OHCA location, sodium bicarbonate administration, number of milligrams of epinephrine administered, and response interval were used to evaluate the association between measures of ETCO 2 and mortality., Results: Hospital outcome data were available for 14,122 patients, and 2,209 (15.6%) were classified as surviving to discharge. Compared to patients with maximum prehospital ETCO 2 values of 30-40 mmHg, odds of mortality were increased for patients with maximum prehospital ETCO 2 values of <20 mmHg (aOR: 3.5 [2.1, 5,9]), 20-29 mmHg (aOR: 1.5 [1.1, 2.1]), and >50 mmHg (aOR: 1.5 [1.2, 1.8]). After 20 minutes of ETCO 2 monitoring, <12% of patients had ETCO 2 values <10 mmHg. This cutpoint was 96.7% specific and 6.9% sensitive for mortality., Conclusion: In this dataset, both high and low ETCO 2 values were associated with increased mortality. Contemporary resuscitation practices may make low ETCO 2 values uncommon, and field termination decision algorithms should not use ETCO 2 values in isolation.

Background Cerebral blood flow (CBF) is impaired in the early phase after return of spontaneous circulation. Sodium nitroprusside (SNP) administration via intracranial subdural catheters improves cerebral cortical microcirculation. We determined whether the SNP treatment improves CBF in the subcortical tissue and evaluated the effects of this treatment on cerebral lactate. Methods and Results Sixty minutes after return of spontaneous circulation following 14 minutes of untreated cardiac arrest, 14 minipigs randomly received 4 mg SNP or saline via intracranial subdural catheters. CBF was measured in regions of interest within the cerebrum and thalamus using dynamic susceptibility contrast-magnetic resonance imaging. After return of spontaneous circulation, CBF was expressed as a percentage of the baseline value. In the saline group, the %CBF in the regions of interest within the cerebrum remained at approximately 50% until 3.5 hours after return of spontaneous circulation, whereas %CBF in the thalamic regions of interest recovered to approximately 73% at this time point. The percentages of the baseline values in the cortical gray matter and subcortical white matter were higher in the SNP group (group effect P =0.026 and 0.025, respectively) but not in the thalamus. The cerebral lactate/creatine ratio measured using magnetic resonance spectroscopy increased over time in the saline group but not in the SNP group (group-time interaction P =0.035). The thalamic lactate/creatine ratio was similar in the 2 groups. Conclusions SNP administered via intracranial subdural catheters improved CBF not only in the cortical gray matter but also in the subcortical white matter. The CBF improvement by SNP was accompanied by a decrease in cerebral lactate.

The application of venoarterial extracorporeal membrane oxygenation (ECMO) in patients unresponsive to conventional cardiopulmonary resuscitation (CPR) has significantly increased in recent years. To date, three published randomized trials have investigated the use of extracorporeal CPR (ECPR) in adults with refractory out-of-hospital cardiac arrest. Although these trials reported inconsistent results, they suggest that ECPR may have a significant survival benefit over conventional CPR in selected patients only when performed with strict protocol adherence in experienced emergency medical services-hospital systems. Several studies suggest that identifying suitable ECPR candidates and reducing the time from cardiac arrest to ECMO initiation are key to successful outcomes. Prehospital ECPR or the rendezvous approach may allow more patients to receive ECPR within acceptable timeframes than ECPR initiation on arrival at a capable hospital. ECPR is only one part of the system of care for resuscitation of cardiac arrest victims. Optimizing the chain of survival is critical to improving outcomes of patients receiving ECPR. Further studies are needed to find the optimal strategy for the use of ECPR.

Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Background: Previous studies comparing the treatment of males and females during out-of-hospital cardiac arrests (OHCA) have been contradictory. Understanding differences in treatment and outcomes is important to assuring appropriate care to both sexes. Hypothesis: Females with OHCA receive fewer interventions and have lower rates of survival to hospital discharge when compared to males with OHCA. Methods: We conducted a secondary analysis of the Resuscitation Outcomes Consortium (ROC) Cardiac Arrest Epistry 3 data collected from April 2011 to June 2015. We included all OHCA cases treated by emergency medical services (EMS) who had sex recorded. We analyzed 36 treatment and outcome variables. We calculated descriptive statistics and compared treatment and outcomes between males and females using chi-square and t-tests. We performed multivariate regressions adjusting for baseline characteristics. Results: Of 120,306 total subjects, 65,241 were included (23,924 female, 41,317 male). Females were 9.9% less likely to have OHCA in public, 10.9% less likely to have a shockable rhythm, and were a median of 5 years older. In the unadjusted analysis, females were defibrillated by EMS less often (OR 1.81, 95% CI [1.74, 1.88]), received epinephrine less often (OR 1.15, 95% CI [1.10, 1.19]), took an average of 67 seconds longer to achieve first return of spontaneous circulation (ROSC) (coefficient -66.75, 95% CI [-83.98, -49.52]), and had 2.2% lower survival to emergency department (ED) arrival (OR 1.09, 95% CI [1.06, 1.13]). After adjusting for age, bystander CPR, witness status, episode location, and initial rhythm, the odds of surviving to hospital discharge were higher in males (OR 1.12, 95% CI [1.05, 1.21]), and the odds of surviving to ED arrival favored females (OR 0.87, 95% CI [0.84-0.90]). Additionally, odds of receiving epinephrine (OR 1.22, 95% CI [1.16, 1.27]) and odds of receiving defibrillation (OR 1.36, 95% CI [1.29, 1.44]) were both higher in males, and time to achieve first ROSC was no longer associated with sex ( p  = 0.114, 95% CI [-3.32, 31.11]). Conclusions: After adjusting for case characteristics, females were less likely to receive some key treatments, including epinephrine and defibrillation. Females also had poorer survival to hospital discharge but had higher odds of surviving to ED arrival.

Background: Sodium bicarbonate ("bicarb") administration in out-of-hospital cardiac arrest (OHCA) is intended to counteract acidosis, although there is limited clinical evidence to support its routine administration. We sought to analyze the association of bicarb with resuscitation outcomes in non-traumatic OHCA., Methods: Records were obtained from the 2019-2020 ESO Data Collaborative prehospital electronic health record database, spanning 1,322 agencies in 50 states. OHCAs with resuscitations lasting 5-40 minutes were stratified by presenting ECG rhythm (VF/VT, pulseless electrical activity (PEA), asystole) for analysis. The outcomes of any prehospital ROSC and survival to discharge were compared by bicarb status using propensity score matching and logistic regressions with/without adjustment., Results: We analyzed 23,567 records, 6,663 (28.3 %) of which included bicarb administration. Most patients presented in asystole (67.4 %), followed by PEA (16.6 %), and VF/VT (15.1 %). In the propensity-matched cohort, ROSC was higher in the bicarb group for the asystole group (bicarb 10.6 % vs control 8.8 %; p = 0.013), without differences in the PEA or VF/VT groups. Survival was higher in the bicarb group for asystole (bicarb 3.3 % vs control 2.4 %; p = 0.020) and for PEA (bicarb 8.1 % vs control 5.4 %; p = 0.034), without differences in the VF/VT group. These results were consistent across adjusted/unadjusted logistic regression analyses: bicarb was associated with ROSC and survival in asystole [uOR (95 % CI): ROSC 1.23 (1.04-1.44), survival 1.40 (1.05-1.87)] and with survival in PEA (1.54 (1.03-2.31)., Conclusions: Bicarb was associated with survival in non-shockable rhythms and ROSC in asystole. Findings from this observational study should be corroborated with prospective randomized work., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Background: Hypoxia and hyperoxia following resuscitation from out-of-hospital cardiac arrest (OHCA)may cause harm by exacerbating secondary brain injury. Our objective was to retrospectively examine theassociationof prehospital post-ROSC hypoxia and hyperoxia with the primary outcome of survival to discharge home., Methods: We utilized the 2019-2021 ESO Data Collaborative public use research datasets for this study (ESO, Austin, TX). Average prehospital SpO 2 , lowest recorded prehospital SpO 2 , and hypoxia dose were calculated for each patient. Theassociationof these measures with survival was explored using multivariable logistic regression. We also evaluated theassociationof American Heart Association (AHA) and European Resuscitation Council (ERC) recommended post-ROSC SpO 2 target ranges with outcome., Results: After application of exclusion criteria, 19,023 patients were included in this study. Of these, 52.3% experienced at least one episode of post-ROSC hypoxia (lowest SpO 2  < 90%) and 19.6% experienced hyperoxia (average SpO 2  > 98%). In comparison to normoxic patients, patients who were hypoxic on average (AHA aOR: 0.31 [0.25, 0.38]; ERC aOR: 0.34 [0.28, 0.42]) and patients who had a hypoxic lowest recorded SpO 2 (AHA aOR: 0.48 [0.39, 0.59]; ERC aOR: 0.52 [0.42, 0.64]) had lower adjusted odds of survival. Patients who had a hyperoxic average SpO 2 (AHA aOR: 0.75 [0.59, 0.96]; ERC aOR: 0.68 [0.53, 0.88]) and patients who had a hyperoxic lowest recorded SpO 2 (AHA aOR: 0.66 [0.48, 0.92]; ERC aOR: 0.65 [0.46, 0.92]) also had lower adjusted odds of survival., Conclusion: Prehospital post-ROSC hypoxia and hyperoxia were associated with worse outcomes in this dataset., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Introduction: Hypotension following resuscitation from out-of-hospital cardiac arrest (OHCA) may cause harm by exacerbating secondary brain injury; however, limited research has explored this relationship. Our objective was to examine the association between duration and depth of prehospital post return of spontaneous circulation (ROSC) hypotension and survival., Methods: We utilized the 2019 and 2020 ESO Data Collaborative public use research data sets for this study (ESO, Austin, TX). Hypotension dose (mmHg*min.), average prehospital systolic blood pressure (SBP), and lowest recorded prehospital SBP were calculated. The association of these measures with survival to home (STH) and rearrest were explored using multivariable logistic regression. Time to hypotension resolution analyses by hypotension management strategy (push dose vasopressors, vasopressor infusion, or fluid only) were conducted using adjusted Cox proportional hazards models., Results: 17,280 OHCA patients met inclusion criteria, of which 3,345 had associated hospital outcome data. Over one-third (37.8%; 6,526/17,280) of all patients had at least one recorded SBP below 90 mmHg. When modeled continuously, average prehospital SBP (1.19 [1.15, 1.23] per 10 mmHg), lowest prehospital SBP (1.20 [1.17, 1.24] per 10 mmHg), and hypotension dose (0.995 [0.993, 0.996] per mmHg*min.) were independently associated with STH. Differences in hypotension management were not associated with differences in survival or time to hypotension resolution., Conclusion: Severity and duration of hypotension were significantly associated with worse outcomes in this dataset. Defining a threshold for hypotension requiring treatment above the classical SBP threshold of 90 mmHg may be warranted in the setting of prehospital post-resuscitation care., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Background: Large animal studies are an important step in the translation pathway, but single laboratory experiments do not replicate the variability in patient populations. Our objective was to demonstrate the feasibility of performing a multicenter, preclinical, randomized, double-blinded, placebo-controlled cardiac arrest trial. We evaluated the effect of epinephrine on coronary perfusion pressure (CPP) as previous single laboratory studies have reported mixed results., Methods: Forty-five swine from 5 different laboratories (Ann Arbor, MI; Baltimore, MD; Los Angeles, CA; Pittsburgh, PA; Toronto, ON) using a standard treatment protocol. Ventricular fibrillation was induced and left untreated for 6 min before starting continuous cardiopulmonary resuscitation (CPR). After 2 min of CPR, 9 animals from each lab were randomized to 1 of 3 interventions given over 12 minutes: (1) Continuous IV epinephrine infusion (0.00375 mg/kg/min) with placebo IV normal saline (NS) boluses every 4 min, (2) Continuous placebo IV NS infusion with IV epinephrine boluses (0.015 mg/kg) every 4 min or (3) Placebo IV NS for both infusion and boluses. The primary outcome was mean CPP during the 12 mins of drug therapy., Results: There were no significant differences in mean CPP between the three groups: 14.4 ± 6.8 mmHg (epinephrine Infusion), 16.9 ± 5.9 mmHg (epinephrine bolus), and 14.4 ± 5.5 mmHg (placebo) (p = NS). Sensitivity analysis demonstrated inter-laboratory variability in the magnitude of the treatment effect (p = 0.004)., Conclusion: This study demonstrated the feasibility of performing a multicenter, preclinical, randomized, double-blinded cardiac arrest trials. Standard dose epinephrine by bolus or continuous infusion did not increase coronary perfusion pressure during CPR when compared to placebo., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Background: Guidelines for depth of chest compressions in pediatric cardiopulmonary resuscitation (CPR) are based on sparse evidence., Objective: We sought to evaluate the performance of the two most widely recommended chest compression depth levels for pediatric CPR (1.5 in. and 1/3 the anterior-posterior diameter- APd) in a controlled swine model of asphyxial cardiac arrest., Methods: We executed a 2-group, randomized laboratory study with an adaptive design allowing early termination for overwhelming injury or benefit. Forty mixed-breed domestic swine (mean weight = 26 kg) were sedated, anesthetized and paralyzed along with endotracheal intubation and mechanical ventilation. Asphyxial cardiac arrest was induced with fentanyl overdose. Animals were untreated for 9 min followed by mechanical CPR with a target depth of 1.5 in. or 1/3 the APd. Advanced life support drugs were administered IV after 4 min of basic resuscitation followed by defibrillation at 14 min. The primary outcomes were return of spontaneous circulation (ROSC), hemodynamics and CPR-related injury severity., Results: Enrollment in the 1/3 APd group was stopped early due to overwhelming differences in injury. Twenty-three animals were assigned to the 1.5 in. group and 15 assigned to the 1/3 APd group, per an adaptive group design. The 1/3 APd group had increased frequency of rib fracture (6.7 vs 1.7, p < 0.001) and higher proportions of several anatomic injury markers than the 1.5 in. group, including sternal fracture, hemothorax and blood in the endotracheal tube (p < 0.001). ROSC and hemodynamic measures were similar between groups., Conclusion: In this pediatric model of cardiac arrest, chest compressions to 1/3APd were more harmful without a concurrent benefit for resuscitation outcomes compared to the 1.5 in. compression group., Competing Interests: Declaration of Competing Interest Dr. Salcido performs fee-for-service work for ZOLL Medical. Drs. Salcido and Menegazzi hold a patent on a system for cardiopulmonary resuscitation., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Background: Mobile phone-based dispatch of volunteers to out-of-hospital cardiac arrests (OHCA) has been shown to increase the likelihood of early CPR and AED application. In the United States, limited characterization of patients encountered as a result of such systems exists., Aims: Examine prehospital case characteristics and outcomes from a multi-year deployment of PulsePoint Respond in Pittsburgh, Pennsylvania., Methods: PulsePoint event timing, location, and associated prehospital electronic health records (ePCRs) were obtained for EMS-encountered OHCA cases that did and did not generate PulsePoint alerts within the service area of Pittsburgh EMS from July 2016 to October 2020. ePCRs were reviewed and OHCA case characteristics were extracted according to the Utstein template. PulsePoint-associated OHCA and non-PulsePoint-associated OHCA were compared., Results: Of 840 total PulsePoint dispatches, 64 (7.6%) were for OHCA associated with a resuscitation attempt. Forty-one (64.1%) were witnessed, 38 (59.4%) received bystander CPR, and 13 (20.0%) of these patients had an AED applied prior to EMS arrival. Twenty-seven (39.7%) had an initial shockable rhythm, and 31 (48.4%) patients achieved ROSC in the field. In the city of Pittsburgh, there were 1229 total OHCA during the study period, with an estimated 29.6% occurring in public. When PulsePoint-associated and publicly occurring non-PulsePoint-associated OHCA were compared, baseline characteristics (age, sex, witnessed status) were similar, but PulsePoint-associated OHCA received more bystander CPR (p = 0.008)., Conclusions: A minority of PulsePoint dispatches in Pittsburgh were triggered by true OHCA. The majority of OHCA during the study period occurred within private residences where PulsePoint responders are not currently dispatched. PulsePoint dispatches were associated with prognostically favorable OHCA characteristics and increased bystander CPR performance., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Objective: To develop and internally validate a metalearner algorithm to predict the hourly rate of emergency medical services (EMS) dispatches in an urban setting., Methods: We performed an analysis of EMS data from New York City between years 2015-2019. Our outcome was hourly EMS dispatches, expressed as continuous data. Hours were split into derivation (75%) and validation (25%) datasets. Candidate variables included averages of prior rates, temporal and weather characteristics. We used a metalearner to evaluate and aggregate individual learners (generalized linear model, generalized additive model, random forest, multivariable adaptive regression splines, and extreme gradient boost). Four models were investigated: 1) temporal variables, 2) weather and temporal variables, and datasets in which weather data were lagged by 3) six and 4) twelve hours. In exploratory analyses, we constructed learners for high acuity and trauma encounters., Results: 7,364,275 EMS dispatches occurred during the 43,823-hour period. When using temporal variables, the mean absolute error (MAE) rate was 11.5 dispatches in the validation dataset. These were slightly improved following incorporation of weather variables (MAE 11.3). When using 6- and 12-hour lagged weather variables, learners demonstrated lower accuracy (MAE 11.8 in 6-hour lagged datasets; 12.2 in 12-hour lagged dataset). All models had a coefficient of determination (R 2 ) ≥0.91. The extreme gradient boosting and random forest learners were assigned the highest coefficients. In an investigation of variable importance, hour of day and average EMS dispatches over the previous six hours were the most important variables in both the extreme gradient boosting and random forest learners. The algorithm performed well at predicting frequently occurring peaks, with greater challenges at both extremes. Learners created high-acuity and for trauma-related encounters demonstrated superior MAE, but with lower R 2 in the validation cohort (MAE 6.9 and R 2 0.84 for high acuity encounters; MAE 5.3 and R 2 0.79 for trauma in learners using time and weather variables)., Conclusion: We developed an ensemble machine learning algorithm to predict EMS dispatches in an urban setting. These models demonstrated high accuracy, with MAEs <12 per hour in all. These algorithms may carry benefit in the real-time prediction of EMS responses, allowing for improved resource utilization., Competing Interests: Declaration of Competing Interest All authors report no conflicts of interest., (Copyright © 2021. Published by Elsevier B.V.)

Background: Emergency medical services (EMS) response volume has been linked to weather and temporal factors in a regional EMS system. We aimed to identify if models of EMS utilization incorporating these data are generalizable through geographically disparate areas in the United States., Methods: We performed a retrospective analysis of EMS dispatch data from four regions: New York City, San Francisco, Cincinnati, and Marin County for years 2016-2019. For each model, we used local weather data summarized from the prior 6 h into hourly bins. Our outcome for each model was EMS dispatches as count data. We fit and optimized a negative binomial regression model for each region, to estimate incidence rate ratios. We compared findings to a prior study performed in Western Pennsylvania., Results: We included 5,940,637 EMS dispatches from New York City, 809,405 from San Francisco, 260,412 from Cincinnati, and 77,461 from Marin County. Models demonstrated consistency with the Western Pennsylvania model with respect to temperature, season, wind speed, dew point, and time of day; both in terms of direction and effect size when expressed as incidence rate ratios. Precipitation was associated with increasing dispatches in the New York City, Cincinnati, and Marin County models, but not the San Francisco model., Conclusion: With minor differences, regional models demonstrated consistent associations between dispatches and time and weather variables. Findings demonstrate the generalizability of associations between these variables with respect to EMS use. Weather and temporal factors should be considered in predictive modeling to optimize EMS staffing and resource allocation., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Background: The electroencephalograph (EEG) pattern of burst suppression with identical bursts (BSIB), with or without myoclonus, occurs often after resuscitation from cardiac arrest. These patterns are associated with severe brain injury but their neuropathological basis is unknown. Using EEG source localization, we tested whether post-cardiac arrest myoclonus was associated with specific anatomical distribution of BSIB., Methods: We performed a single center, case-control study of EEG-monitored post-cardiac arrest patients with BSIB. We determined the presence of myoclonus from clinical notes and video recordings. We generated normalized source density maps (sLORETA) for the first 0.5 s of each burst projected onto a standard anatomic model, and compared proportion of EEG power in the precentral gyrus (motor cortex) to the rest of the brain., Results: We included 20 patients, 10 with and 10 without myoclonus. Patients with myoclonus had greater electrical activation localized to the precentral gyrus compared to those without (median 3.25 [IQR 2.74-3.59] vs 2.68 [IQR 2.66-2.71], P = 0.04). There was no difference between groups in region of burst origin., Conclusion: Among patients with BSIB after cardiac arrest, those with clinical myoclonus have more electrocortical activation in the precentral gyrus., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Introduction: Out-of-hospital cardiac arrest (OHCA) is a major cause of morbidity and mortality in the US. Of major concern is a lack of therapies to mitigate associated brain injury. Immune cell infiltration (ICI) into the brain, which may exacerbate injury post-resuscitation, is one possible therapeutic target, although the post-OHCA immune response has not been fully characterized., Objective: In this pilot study, we aimed to detect early post-resuscitation cytotoxic lymphocyte ICI in porcine brain using a model of opioid-mediated asphyxial OHCA., Methods: Ten young, healthy swine (26.7+/-3.4 kg) were sedated, anaesthetized and paralyzed. In eight of the animals, this was followed by induction of asphyxial OHCA via fentanyl bolus and concurrent airway occlusion. The remaining two 'sham' animals were instrumented but did not undergo asphyxia. After nine minutes of asphyxia, mechanical CPR and manual ventilations were started, in an initial BLS followed by ALS configuration. At termination of resuscitation or euthanasia, the whole brain was removed. Immune cells were extracted and analyzed via flow cytometry., Results: 304 +/- 62.2 cells/g were discovered to be CD8 single positive cells in animals that achieved ROSC, 481 +/- 274.4 cells/g in animals that did not achieve ROSC, and 40 +/- 11.31 cells/g in sham animals. CD8 single positive cells made up 0.473 +/- 0.24% of detected cells in animals that achieved ROSC, 0.395 +/- 0.062% in animals that did not achieve ROSC, and 0.19 +/- 0.014% in sham animals (No ROSC vs Sham, p = 0.012)., Conclusions: These data suggest that cytotoxic lymphocytes may be localizing to the brain during cardiac arrest resuscitation., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2021 The Author(s).)

Background: There is an emerging body of evidence that links exposure to shift work to cardiovascular disease (CVD). The risk of coronary events, such as myocardial infarction, is greater among night shift workers compared to day workers. There is reason to believe that repeated exposure to shift work, especially night shift work, creates alterations in normal circadian patterns of blood pressure (BP) and heart rate variability (HRV) and that these alterations contribute to increased risk of CVD. Recent data suggest that allowing shift workers to nap during night shifts may help to normalize BP and HRV patterns and, over time, reduce the risk of CVD. The risk of CVD related to shift work is elevated for emergency medical services (EMS) shift workers due in part to long-duration shifts, frequent use of night shifts, and a high prevalence of multiple jobs., Methods: We will use a randomized crossover trial study design with three study conditions. The targeted population is comprised of EMS clinician shift workers, and our goal enrollment is 35 total participants with an estimated 10 of the 35 enrolled not completing the study protocol or classified as lost to attrition. All three conditions will involve continuous monitoring over 72 h and will begin with a 36-h at-home period, followed by 24 total hours in the lab (including a 12-h simulated night shift), ending with 12 h at home. The key difference between the three conditions is the intra-shift nap. Condition 1 will involve a simulated 12-h night shift with total sleep deprivation. Condition 2 will involve a simulated 12-h night shift and a 30-min nap opportunity. Condition 3 will involve a simulated 12-h night shift with a 2-h nap opportunity. Our primary outcomes of interest include blunted BP dipping and reduced HRV as measured by the standard deviation of the inter-beat intervals of normal sinus beats. Non-dipping status will be defined as sleep hours BP dip of less than 10%., Discussion: Our study will address two indicators of cardiovascular health and determine if shorter or longer duration naps during night shifts have a clinically meaningful impact., Trial Registration: ClinicalTrials.gov NCT04469803 . Registered on 9 July 2020.

Objective: The two objectives of this report are: first, to describe a comparison of chest compressions unsynchronized or synchronized to native cardiac activity in a porcine model of hypotension, and second, to develop an algorithm to provide synchronized chest compressions throughout a range of native heart rates likely to be encountered when treating PEA cardiac arrest. Methods: We adapted our previously developed signal-guided CPR system to provide compressions synchronized to native electrical activity in a porcine model of hypotension as a surrogate of PEA arrest. We describe the first comparison of unsynchronized to synchronized compressions in a single animal as a proof-of-concept. We developed an algorithm to provide optimal synchronized chest compressions regardless of intrinsic PEA heart rate while simultaneously maintaining the chest compression rate within a desired range. We tested the algorithm with computer simulations measuring the proportion of intrinsic and compression beats that were synchronized, and the compression rate and its standard deviation, as a function of intrinsic heart rate and heart rate jitter. Results: We demonstrate and compare unsynchronized versus synchronized chest compressions in a single porcine model with an intrinsic rhythm and hypotension. Synchronized, but not unsynchronized, chest compressions were associated with increased blood pressure and coronary perfusion pressure. Our synchronized chest compression algorithm is able to provide synchronized chest compressions to over 90% of intrinsic beats for most heart rates while maintaining an average compression rate between 90 and 140 compressions per minute with relatively low variability. Conclusions: Synchronized chest compression therapy for pulseless electrical rhythms is feasible. A high degree of synchronization can be maintained over a broad range of intrinsic heart rates while maintaining the compression rate within a satisfactory range. Further investigation to assess benefit for treatment of PEA is warranted.

Background: Ventricular fibrillation (VF) waveform analyses are considered a reliable proxy for OHCA characteristics in out-of-hospital cardiac arrest (OHCA), but patient characteristics such as cardiovascular medication use might also be associated with changes in VF waveform measures., Objectives: To assess associations between cardiovascular medication use and amplitude spectrum area (AMSA) of VF, while correcting for the presence of cardiovascular disease (CVD), CVD risk factors, and OHCA characteristics., Methods: We included 990 VF patients from an OHCA registry in the Netherlands, with available information on medical history and cardiovascular medication use. Associations between cardiovascular medication use and AMSA were tested in a multivariate linear regression model, adjusting for CVD, CVD risk factors, and OHCA characteristics. Model performance was shown using R-square and R-change. We also calculated whether medication use was associated with faster dissolution of AMSA to lower values with increasing time delay., Results: In the multivariate analysis, when corrected for CVD, CVD risk factors and OHCA characteristics, only potassium-sparing agents were associated with a lower AMSA when compared to patients using other cardiovascular medications (OR 0.46 [95% CI 0.10-0.81]; P < 0.012). The decrease in AMSA with increasing EMS-call-to-ECG delay was the same for patients with and without cardiovascular medication use (all P > 0.05). Only a small part of the variance in AMSA could be explained by medication use (R-square 0.003- 0.026). Adding OHCA characteristics to the model resulted in the largest R square change (0.09-0.15)., Conclusions: It is unlikely that there is a strong and clinically relevant independent pharmacologic effect of cardiovascular medication use on AMSA. In OHCA, AMSA might be used as patient management tool without considering cardiovascular medication use., (Copyright © 2020 The Authors. Published by Elsevier B.V. All rights reserved.)

Purpose of Review: The current review will give an overview of different possibilities to monitor quality of cardiopulmonary resuscitation (CPR) from a physiologic and a process point of view and how these two approaches can/should overlap., Recent Findings: Technology is evolving fast with a lot of opportunities to improve the CPR quality. The role of smartphones and wearables are step-by-step identified as also the possibilities to perform patient tailored CPR based on physiologic parameters. The first steps have been taken, but more are to be expected. In this context, the limits of what is possible with human providers will become more and more clear., Summary: To perform high-quality CPR, at first, one should optimize rate, depth and pause duration supported by process monitoring tools. Second, the evolving technological evolution gives opportunities to measure physiologic parameters in real-time which will open the way for patient-tailored CPR. The role of ultrasound, cerebral saturation and end-tidal CO2 in measuring the quality of CPR needs to be further investigated as well as the possible ways of influencing these measured parameters to improve neurological outcome and survival.

Background: Bystander CPR before the arrival of EMS is a major factor in out of hospital cardiac arrest (OHCA) survival. To recruit trained bystanders, mobile phone-based alert systems have been developed, but their limitations are not well understood., Objective: We investigated the effects of landscape features on the capabilities of the PulsePoint CPR dispatch platform in Allegheny County, Pennsylvania. We hypothesized that landscape features would reduce walkable area within dispatch zones and that larger alert radii could mitigate these effects., Methods: CPR alert location data were obtained from the Allegheny County 911 PulsePoint deployment from July 2016-2019 (n = 1100). PulsePoint, a smartphone-based citizen CPR dispatch platform, alerts volunteers to public OHCAs within 400 m. Digital maps of alerts were generated for walkability analysis using the image Labeler MATLAB polygon tool. Unwalkable areas were labeled, classified into five categories, and quantified., Results: Of the 1100 events analyzed, encompassing 212 mi 2 , 357 (32.45%) had no impediments to walkability. Within a 400 m radius of partially impeded events, the median proportion of obstructed area was 0.2250 (Min: 0.0005, Max: 0.8338, IQR: 0.3004, S x : 0.1923). When the alert radius was expanded to 468 m, the median increased to 0.2336 (Min: 0.0016, Max: 0.8597, IQR: 0.3064, S x : 0.1950). The percentages of total unwalkable area by each category were: terrain (54.286%), water (24.674%), road w/o crosswalk (11.3197%), railroad (7.4100%), private property (2.3102%)., Conclusions: In this region, most PulsePoint alerts had unwalkable areas, mostly from terrain and water. Contrary to our initial hypotheses, moderately increasing dispatch radius did not improve walkability., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Introduction: Public access defibrillation (PAD) programs seek to optimize locations of automated external defibrillators (AEDs) to minimize the time from out-of-hospital cardiac arrest (OHCA) recognition to defibrillation. Most PAD programs have focused on static AED (S-AED) locations in high traffic areas; pervasive electronic data infrastructure incorporating real-time geospatial data opens the possibility for AED deployment on mobile infrastructure for retrieval by nearby non-passengers. Performance characteristics of such systems are not known. Hypothesis: We hypothesized that publicly accessible AEDs located on buses would increase publicly accessible AED coverage and reduce AED retrieval time relative to statically located AEDs. Methods: S-AED sites in Pittsburgh, PA were identified and consolidated to 1 AED per building for analysis ( n  = 582). Public bus routes and schedules were obtained from the Port Authority of Allegheny County. OHCA locations and times were obtained from the Pittsburgh site of the Resuscitation Outcomes Consortium. Two simulations were conducted to assess the characteristics and impact of AEDs located on buses. In Simulation #1, geographic coverage area of AEDs located on buses (B-AEDs) was estimated using a 1/8th mile (201 m) retrieval radius during weekday, Saturday and Sunday periods. Cumulative geographic coverage across each period of the week was compared to S-AED coverage and the added coverage provided by B-AEDs was calculated. In Simulation #2, spatiotemporal event coverage was estimated for historical OHCA events, assuming constraints designed to reflect real world AED retrieval scenarios. Event coverage and AED retrieval time were compared between B-AEDs and S-AEDs across periods of the week and residential/nonresidential spatial areas. Results: Cumulative geographic coverage by S-AEDs was 23% across all periods, assuming uniform access hours. B-AEDs alone versus B-AEDs + S-AEDs covered 20% vs. 34% (weekday), 14% + 30% (Saturday), and 10% + 28% (Sunday). There was no statistically significant difference in 3-minute historical AED accessibility between only B-AEDs and only S-AEDs in standalone deployments (12% vs. 14%). However, when allowing for retrieval of either type of AED in the same scenario, event coverage was improved to 22% ( p  < 0.001). Conclusion: Deployment of B-AEDs may improve AED coverage but not as a standalone deployment strategy.

Introduction: We previously found potassium cardioplegia followed by rapid calcium reversal (Kplegia) can achieve defibrillation in a swine model of electrical phase of ventricular fibrillation (VF) comparable to standard care., Hypothesis: Exploring 3 possible potassium dose and timing protocols, we hypothesize Kplegia may benefit resuscitation of longer duration untreated VF., Methods: Three separate blinded randomized placebo-controlled trials were performed with electrically-induced VF untreated for durations of 6, 9, and 12min in a swine model. Experimental groups received infusion of 1 or 2 boluses of intravenous (IV) potassium followed by a single calcium reversal bolus. Potassium was replaced by saline in the control groups. Outcomes included: amplitude spectrum area (AMSA) during VF, resulting rhythms, number of defibrillations, return of spontaneous circulation (ROSC), and hemodynamics for 1h post ROSC. Binomial and interval data outcomes were compared with exact statistics. Serial interval data were assessed with mixed regression models., Results: Twelve, 12, and 8 animals were included at 6, 9, and 12min VF durations for a total of 32. ROSC was achieved in: 4/6 Kplegia and 3/6 control animals in the 6min protocol, (p=1.00), 4/6 Kplegia and 2/6 control animals in the 9min protocol,(p=0.57), and 0/5 Kplegia and 1/3 control animals in the 12min protocol,(p=0.38). Two of 8 Kplegia animals achieved ROSC with chemical defibrillation alone., Conclusions: The majority of animals achieved ROSC after up to 9min of untreated VF arrest using K plegia protocols. K plegia requires further optimization for both peripheral IV and intraosseous infusion, and to assess for superiority over standard care. Institutional Animal Care and Use Committee protocol #15127224., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Background: Fluctuations in emergency medical services (EMS) responses can have a substantial impact on the ability of agencies to meet resource needs within an EMS system. We aimed to identify weather characteristics as potentially predictable factors associated with EMS responses. Methods: We reviewed hourly counts of scene responses documented by 24 EMS agencies in Western Pennsylvania from January 1, 2014 to December 31, 2017 and compared rates of responses to weather characteristics. Responses to counties nonadjacent to the studied weather reporting station and interfacility/scheduled transports were excluded. We identified the mean temperature, meters visibility, dew point, wind speed, total millimeters of precipitation, and presence of rain or snow in 6-hour windows prior to dispatch, in addition to temporal factors of time of day and weekend vs. weekday. Analysis was performed using multivariable linear regression of a negative binomial distribution, reporting incidence rate ratios (IRR) with 95% confidence intervals (CI). Secondary analyses were performed for transports to the hospital and cases involving transports for traumatic complaints and pediatric patients (age <18 years). Results: We included 529,058 responses (54.8% female, mean age 57.2 ± SD 24.7 years). In our multivariable model, responses were associated with (IRR, 95% CI) rain (1.10, 1.08-1.11) snow (1.07, 1.05-1.09), and both rain and snow (1.15, 1.11-1.19). A lower incidence of responses occurred on weekends (0.84, 0.83-0.85) and at night (0.62, 0.61-0.62). Increasing temperature in 5 °C increments was associated with an increase in responses across seasons with an effect that varied between 1.16 (1.15-1.17) in winter to 1.31 (1.28-1.33) in summer. Windy weather was associated with increased responses from light breeze (1.10, 1.09-1.11) to fresh breeze or greater (1.23, 1.16-1.30). Transports occurred in a similar pattern to responses. Trauma transports ( n  = 64,235) occurred more during weekends (1.04, 1.02-1.06). Pediatric transports ( n  = 21,880) were not significantly associated with precipitation or season. Conclusion: EMS responses increased with rising temperature and following rain and snow. These findings may assist in planning by EMS agencies and emergency departments to identify periods of greatest resource utilization.

Background: The early use of automated external defibrillators (AEDs) can save lives by correcting lethal ventricular arrhythmias with minimal operator intervention. AED shock advisements also play a role in termination of resuscitation strategies. AED function is dependent on the accuracy of their shock advisement algorithms, which may differ between manufacturers. We sought to compare the shock advisement performance characteristics of several AEDs. Methods: We conducted a prospective, laboratory-based simulation study evaluating five commercially available AEDs from Cardiac Science, Defibtech, Medtronic, Philips, and Zoll. Shock advisement performance was evaluated for eight ECG rhythms {ventricular fibrillation (VF), ventricular tachycardia (VT), toursades de pointes (TdP), sinus rhythm (SR), atrial fibrillation (AF), atrial flutter (AFL), idioventricular rhythm (IDV), and asystole} that were generated using the SimMan Classic Manikin and the LLEAP Simulator software (Laerdal Medical Inc., Norway). We recorded shock advisement decisions for each of the ECG rhythms three times per device. Shock advisements were coded as discordant if a shock was advised for a non-shockable rhythm or not advised for a shockable rhythm. Results: We analyzed 330 rhythm trials in total (66 per device), finding 28 (8.5%) discordant shock advisements overall. Discordance ranged from 6% to 11% among the five AED models. VF rhythm variants were the most frequent (43%) source of discordant advisements. No shocks were advised for any of the sinus rhythms, AFL, AF with QRS > 40, IDV, or asystole. Conclusions: Discordant shock advisements were observed for each AED and varied between manufacturers, most often involving VF. There may be implications for termination of resuscitation decision making.

Objective: To determine whether the administration of intra-arrest cyclosporine (CCY) and methylprednisolone (MP) preserves left ventricular ejection fraction (LVEF) and cardiac output (CO) after return of spontaneous circulation (ROSC)., Methods: Eleven, 25-30kg female swine were randomized to receive 10mg/kg CCY + 40mg MP or placebo, anesthetized and given a transthoracic shock to induce ventricular fibrillation. After 8 minutes, standard CPR was started. After two additional minutes, the experimental agent was administered. Animals with ROSC were supported for up to 12h with norepinephrine as needed. Echocardiography was performed at baseline, and 1, 2, 6 and 12h post-ROSC. Analysis was performed using generalized estimating equations (GEE) after downsampling continuously sampled data to 5 minute epochs., Results: Eight animals (64%) achieved ROSC after a median of 7 [IQR 5-13] min of CPR, 2 [ IQR 1-3] doses of epinephrine and 2 [IQR 1-5] defibrillation shocks. Animals receiving CCY+MP had higher post ROSC MAP (GEE coefficient -10.2, P = <0.01), but reduced cardiac output (GEE coefficient 0.8, P = <0.01) compared to placebo. There was no difference in LVEF or vasopressor use between arms., Conclusions: Intra-arrest cyclosporine and methylprednisolone decreased post-arrest cardiac output and increased mean arterial pressure without affecting left ventricular ejection fraction.

Introduction: Hemodynamic-guided cardiopulmonary resuscitation (HGCPR) achieves better outcomes than standard resuscitation. Currently, HGCPR requires an invasive procedure, infeasible during resuscitation. Non-invasive measures of blood flow could provide useful hemodynamic guidance to rescuers., Objective: We describe initial efforts to develop a device that detects, analyzes, and measures the velocity of carotid artery blood flow (CABF) towards the brain at pre-arrest baseline ('baseline') and during cardiopulmonary resuscitation, here tested in a swine model of cardiac arrest (CA). A key element of that device consists of non-imaging diagnostic ultrasound, due to its simplicity and small form factor, hence potential for deployment during HGCPR in a bandage placed on the neck., Methods: Sixteen mixed-breed domestic swine were sedated, anesthetized and paralyzed, followed by endotracheal intubation and mechanical ventilation. Cardiac arrest was induced with a 3-s 100 mA transthoracic shock or bolus of fentanyl, after which all animals received mechanical CPR. A non-imaging ultrasound probe was manually applied to the neck over the carotid artery to capture CABF during baseline, as verified with diagnostic ultrasound imaging, and during mechanical resuscitation., Results: We successfully collected CABF measurements at baseline in 14/16 swine and during attempted resuscitation with mechanical chest compression in 5/16 swine. Signal characteristics include peak blood flow both towards (90.4 +/-20.4 cm/s) and away from the brain (-44.2 +/-31.8 cm/s) during resuscitation, each larger than flow towards (41.7+/-14.8 cm/s) and away from brain (-3.0 +/-7.8 cm/s) during baseline., Conclusion: Measurement of CABF before and during CPR in swine with a non-imaging ultrasound probe is feasible before CA and informative when achieved during CPR. For example, observations of reverse flow within the carotid artery during CPR merits further study for its prevalence and effect on resuscitation outcomes. Also, tissue motion represents a significant obstacle for CABF measurement during CPR. Additional work will determine the feasibility and utility of non-imaging ultrasound measurements of CABF during resuscitation., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Introduction: Opioid-related overdoses have been steadily increasing over the past decade in the United States. Naloxone is used by first responders to revive overdose victims, but results may be improved by increasing access to and usage of naloxone by bystanders. Automated External Defibrillators (AEDs) are pervasive, recognizable, and publicly accessible. Co-locating naloxone kits with AEDs could increase public naloxone access and usage. However, the impact of co-locating naloxone kits with AEDs is not known., Objectives: We sought to evaluate the impact of co-locating naloxone kits with AEDs in a simulation study centered on Allegheny County, Pennsylvania., Methods: Naloxone administration frequency (N = 3,650) at the zip-code level from March 2016 to March 2017 was provided by the Allegheny County Health Department. AED point locations (N = 1,653) were obtained from the University of Pittsburgh's Resuscitation Logistics and Informatics Venture. Zip-code level geospatial analyses were conducted using QGIS and STATA to determine the correlation between AED count and naloxone administrations. AED naloxone kit (N-AED) coverage, based on a maximum "walking-distance" radius of 200 m, was estimated at a zip-code level using the QGIS buffer tool and a custom MATLAB script. Potential impact of N-AEDs was estimated assuming uniform spatial distribution of naloxone administrations., Results: The median (IQR) AED coverage based on a 200 m access radius per zip code was 4% (0-7). The median (IQR) number of naloxone administrations per zip code was 27(7-55). A total of 82 zip codes had data for both AED locations and naloxone administrations. The correlation between number of AEDs and naloxone administrations per zip code was 0.20. Overall, 16% of naloxone administrations were estimated to be covered by an N-AED., Conclusion: Using these limited methods, co-locating naloxone with AEDs is not likely to have a standalone impact on preventing overdose fatalities.

Background: Intra-resuscitation antiarrhythmic drugs may improve resuscitation outcomes, in part by avoiding rearrest, a condition associated with poor out-of-hospital cardiac arrest (OHCA) outcomes. However, antiarrhythmics may also alter defibrillation threshold. The objective of this study was to investigate the relationship between rearrest and intra-resuscitation antiarrhythmic drugs in the context of the Resuscitation Outcomes Consortium (ROC) amiodarone, lidocaine, and placebo (ALPS) trial., Hypothesis: Rearrest rates would be lower in cases treated with amiodarone or lidocaine, versus saline placebo, prior to first return of spontaneous circulation (ROSC). We also hypothesized antiarrhythmic effects would be quantifiable through analysis of the prehospital electrocardiogram., Methods: We conducted a secondary analysis of the ROC ALPS trial. Cases that first achieved prehospital ROSC after randomized administration of study drug were included in the analysis. Rearrest, defined as loss of pulses following ROSC, was ascertained from emergency medical services records. Rearrest rate was calculated overall, as well as by ALPS treatment group. Multivariable logistic regression models were constructed to assess the association between treatment group and rearrest, as well as rearrest and both survival to hospital discharge and survival with neurologic function. Amplitude spectrum area, median slope, and centroid frequency of the ventricular fibrillation (VF) ECG were calculated and compared across treatment groups., Results: A total of 1144 (40.4%) cases with study drug prior to first ROSC were included. Rearrest rate was 44.0% overall; 42.9% for placebo, 45.7% for lidocaine, and 43.0% for amiodarone. In multivariable logistic regression models, ALPS treatment group was not associated with rearrest, though rearrest was associated with poor survival and neurologic outcomes. AMSA and median slope measures of the first available VF were associated with rearrest case status, while median slope and centroid frequency were associated with ALPS treatment group., Conclusion: Rearrest rates did not differ between antiarrhythmic and placebo treatment groups. ECG waveform characteristics were correlated with treatment group and rearrest. Rearrest was inversely associated with survival and neurologic outcomes., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Introduction: Brain tissue hypoxia may contribute to preventable secondary brain injury after cardiac arrest. We developed a porcine model of opioid overdose cardiac arrest and post-arrest care including invasive, multimodal neurological monitoring of regional brain physiology. We hypothesized brain tissue hypoxia is common with usual post-arrest care and can be prevented by modifying mean arterial pressure (MAP) and arterial oxygen concentration (PaO 2 )., Methods: We induced opioid overdose and cardiac arrest in sixteen swine, attempted resuscitation after 9 min of apnea, and randomized resuscitated animals to three alternating 6-h blocks of standard or titrated care. We invasively monitored physiological parameters including brain tissue oxygen (PbtO 2 ). During standard care blocks, we maintained MAP > 65 mmHg and oxygen saturation 94-98%. During titrated care, we targeted PbtO2 > 20 mmHg., Results: Overall, 10 animals (63%) achieved ROSC after a median of 12.4 min (range 10.8-21.5 min). PbtO 2 was higher during titrated care than standard care blocks (unadjusted β = 0.60, 95% confidence interval (CI) 0.42-0.78, P < 0.001). In an adjusted model controlling for MAP, vasopressors, sedation, and block sequence, PbtO 2 remained higher during titrated care (adjusted β = 0.75, 95%CI 0.43-1.06, P < 0.001). At three predetermined thresholds, brain tissue hypoxia was significantly less common during titrated care blocks (44 vs 2% of the block duration spent below 20 mmHg, P < 0.001; 21 vs 0% below 15 mmHg, P < 0.001; and, 7 vs 0% below 10 mmHg, P = .01)., Conclusions: In this model of opioid overdose cardiac arrest, brain tissue hypoxia is common and treatable. Further work will elucidate best strategies and impact of titrated care on functional outcomes., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Background: Amplitude spectrum area (AMSA) of ventricular fibrillation (VF) has been associated with survival from out-of-hospital cardiac arrest (OHCA). Ischemic heart disease has been shown to change AMSA. We studied whether the association between AMSA and survival changes with acute ST-elevation myocardial infarction (STEMI) as cause of the OHCA and/or previous MI., Methods: Multivariate logistic regression with log-transformed AMSA of first artifact-free VF segment was used to assess the association between AMSA and survival, according to presence of STEMI or previous MI, adjusting for resuscitation characteristics, medication use and comorbidities., Results: Of 716 VF-patients included from an OHCA-registry in the Netherlands, 328 (46%) had STEMI as cause of OHCA. Previous MI was present in 186 (26%) patients. Survival was 66%; neither previous MI (P=0.11) nor STEMI (P=0.78) altered survival. AMSA was a predictor of survival (ORadj: 1.52, 95%-CI: 1.28-1.82). STEMI was associated with lower AMSA (8.4mV-Hz [3.7-16.5] vs. 12.3mV-Hz [5.6-23.0]; P<0.001), but previous MI was not (9.5mV-Hz [3.9-18.0] vs 10.6mV-Hz [4.6-19.3]; P=0.27). When predicting survival, there was no interaction between previous MI and AMSA (P=0.14). STEMI and AMSA had a significant interaction (P=0.002), whereby AMSA was no longer a predictor of survival (ORadj: 1.03, 95%-CI: 0.77-1.37) in STEMI-patients. In patients without STEMI, higher AMSA was associated with higher survival rates (ORadj: 1.80, 95%-CI: 1.39-2.35)., Conclusions: The prognostic value of AMSA is altered by the presence of STEMI: while AMSA has strong predictive value in patients without STEMI, AMSA is not a predictor of survival in STEMI-patients., (Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.)

Introduction: Optimizing placement of Automated External Defibrillators (AED) can increase survival after an out-of-hospital cardiac arrest (OHCA). Using postal collection boxes (PCB) as locations for AEDs could potentially enhance accessibility and streamline maintenance. In this study, we modeled the hypothetical effects of deploying AEDs at PCB locations., Hypothesis: We hypothesized that PCB-AEDs would increase AED coverage overall and in residential areas, and reduce the distance from OHCA to an AED., Methods: AEDs in Pittsburgh, PA were identified by the University of Pittsburgh Resuscitation Logistics and Informatics Venture (n=747). PCB locations were obtained from the United States Postal Service (n=479). OHCA locations from 2009 to 2014 were obtained from the Pittsburgh site of the Resuscitation Outcomes Consortium. AED coverage assuming a ¼ mile radius around each AED was estimated for known AEDs, PCB-AEDs (hypothetical AED locations), and known AEDs augmented by PCB-AEDs, both overall and for residential and non-residential zones. Linear distance from each OHCA to the nearest AED was calculated and compared between the sets., Results: The set of known AEDs augmented with PCB-AEDs covered more of the city overall (55% vs 30%), as well as greater proportions of residential (62% vs 27%) and non-residential areas (45% vs 30%). The median distance from OHCA to AED was significantly shorter when known AEDs were augmented with PCB-AEDs (0.12mi vs 0.32mi; p=0.001)., Conclusion: Augmenting existing publicly accessible AEDs with AEDs deployed at PCBs can increase AED spatial coverage in both residential and non-residential areas, and reduce the distance from AED to OHCA., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Background: Previous work has demonstrated that when out-of-hospital cardiac arrest (OHCA) patients achieve return of spontaneous circulation (ROSC), but subsequently have another cardiac arrest prior to hospital arrival (rearrest), the probability of survival to hospital discharge is significantly decreased. Additionally, few modifiable factors for rearrest are known. We sought to examine the association between rearrest and compression-to-ventilation ratio during cardiopulmonary resuscitation (CPR) and to confirm the association between rearrest and outcomes., Hypothesis: Rearrest incidence would be similar between cases treated with 30:2 or continuous chest compression (CCC) CPR, but inversely related to survival and good neurological outcome., Methods: We conducted a secondary analysis of a large randomized-controlled trial of CCC versus 30:2 CPR for the treatment of OHCA between 2011 and 2015 among 8 sites of the Resuscitation OUTCOMES: Consortium (ROC). Patients were randomized through an emergency medical services (EMS) agency-level cluster randomization design to receive either 30:2 or CCC CPR. Case data were derived from prehospital patient care reports, digital defibrillator files, and hospital records. The primary analysis was an as-treated comparison of the proportion of patients with a rearrest for patients who received 30:2 versus those who received CCC. In addition, we assessed the association between rearrest and both survival to hospital discharge and favorable neurological outcome (Modified Rankin Score≤3) in patients with and without ROSC upon ED arrival using multivariable logistic regression adjusting for age, sex, initial rhythm and measures of CPR quality., Results: There were 14,109 analyzable cases that were determined to have definitively received either CCC or 30:2 CPR. Of these, 4713 had prehospital ROSC and 2040 (43.2%) had at least one rearrest. Incidence of rearrest was not significantly different between patients receiving CCC and 30:2 (44.1% vs 41.8%; adjusted OR: 1.01; 95% CI: 0.88, 1.16). Rearrest was significantly associated with lower survival (23.3% vs 36.9%; adjusted OR: 0.46; 95%CI: 0.36-0.51) and worse neurological outcome (19.4% vs 30.2%; adjusted OR: 0.46; 95%CI: 0.38, 0.55)., Conclusion: Rearrest occurrence was not significantly different between patients receiving CCC and 30:2, and was inversely associated with survival to hospital discharge and MRS., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Objectives: Potassium cardioplegia-induced transient asystole may conserve myocardial energy, foster chemical defribrillation, and improve VF arrest outcome. A trial of potassium infusion with or without calcium reversal was conducted to test for improvement in intra-arrest VF waveform and post-ROSC hemodynamics., Methods: Eighteen swine were randomized to three treatment arms in two phases. VF was electrically induced and untreated for 4min. The animals then received 6min of mechanical CPR. Blinded investigators infused two study medicines peripherally during this interval. One group received 1.5mEq/kg KCl with CPR initiation followed 3min later by CaCl 10% infusion 0.12cm(3)/kg, the second group received 1.5mEq/kg KCl without CaCl, and the third group received placebo infusions. Ten minutes post VF initiation, defibrillation was performed, as appropriate, followed by ACLS for continued arrest or observation for 30min if ROSC. AMSA change from before to 5min post study drug infusion was compared with nonparametric statistics. MAP post ROSC was compared using mixed linear regression analysis., Results: Average normalized AMSA change was -0.15, -0.63, and +0.27 in the KCl, KCl+CaCl, and placebo groups, respectively (p=0.01). Three KCl+CaCl animals developed on organized rhythm chemically without electrical defibrillation. One, 3, and 4 animals in the KCl, KCl+CaCl, and placebo groups, respectively, survived post ROSC. Post ROSC, MAP decreased 1.8mmHg (95% CI -1.4 to 5.1) min(-1) less in the KCl+CaCl group compared to placebo., Conclusions: Chemical defibrillation and ROSC are possible post potassium-induced asystole. Potassium followed by calcium reversal, but not potassium alone, led to ROSC and post-ROSC hemodynamics comparable to recommended therapy., (Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.)

Background: The frequency of lethal overdose due to prescription and non-prescription drugs is increasing in North America. The aim of this study was to estimate overall and regional variation in incidence and outcomes of out-of-hospital cardiac arrest due to overdose across North America., Methods: We conducted a retrospective cohort study using case data for the period 2006-2010 from the Resuscitation Outcomes Consortium, a clinical research network with 10 regional clinical centers in United States and Canada. Cases of out-of-hospital cardiac arrest due to drug overdose were identified through review of data derived from prehospital clinical records. We calculated incidence of out-of-hospital cardiac arrest due to overdose per 100,000 person-years and proportion of the same among all out-of-hospital cardiac arrests. We analyzed the association between overdose cardiac arrest etiology and resuscitation outcomes., Results: Included were 56,272 cases, of which 1351 were due to overdose. Regional incidence of out-of-hospital cardiac arrest due to overdose varied between 0.5 and 2.7 per 100,000 person years (p<0.001), and proportion of the same among all treated out-of-hospital cardiac arrests ranged from 0.8% to 4.0%. Overdose cases were younger, less likely to be witnessed, and less likely to present with a shockable rhythm. Compared to non-overdose, overdose was directly associated with return of spontaneous circulation (OR: 1.55; 95% CI: 1.35-1.78) and survival (OR: 2.14; 95% CI: 1.72-2.65)., Conclusions: Overdose made up 2.4% of all out-of-hospital cardiac arrest, although incidence varied up to 5-fold across regions. Overdose cases were more likely to survive than non-overdose cases., (Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.)

Background: The loss of pulses after successful return of spontaneous circulation (ROSC) in out-of-hospital cardiac arrest (OHCA) is known as rearrest (RA). The causes of RA are not well understood., Objectives: To investigate the association between shock pause intervals and RA., Methods: Data from treated OHCA with ROSC and one or more defibrillation attempts were obtained from one site of the Resuscitation Outcomes Consortium. All analyses were conducted internally. Data available for analysis included cases spanning 2006-2008 and 2010-2011. Defibrillator tracings were used to calculate both components of the perishock pause (PSP) interval: the pre- (preSP) and the postshock pauses (postSP). RA and no-RA shock pauses were compared and independent associations between shock pause intervals, patient characteristics, and RA were assessed with the appropriate statistical tests., Results: Analysis included 241 shocks from 101 cases. Forty-one cases (41%) had RA. RA vs. no-RA median (interquartile range) shock pauses in seconds were: preSP 13.5 (6.0-18.0) vs. 15.0 (10.9-21.5) (p = 0.121); postSP 6.0 (3.5-8.2) vs. 8.7 (4.5-13.9) (p = 0.053); and PSP 18.0 (12.3-24.0) vs. 24.0 (16.7-30.2) (p = 0.022). Considering all possible shock pause durations, shock pause lengths and various patient characteristics were not associated with RA. If 30 s or shorter, the preSP (odds ratio [OR] 0.90, 955 confidence interval [CI] 0.82-0.98) and postSP (OR 0.89, 95% CI 0.79-0.99) were related to RA., Conclusion: Shock pause length was inversely associated with RA when shock pause intervals were limited to 30 s or less. Shock pauses and RA were not associated when all durations of shock pauses were considered., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Objectives: Cardiac arrest is one of the leading causes of death in the United States and is treated by cardiopulmonary resuscitation (CPR). CPR involves both chest compressions and positive pressure ventilations when given by medical providers. Mechanical chest compression devices automate chest compressions and are beginning to be adopted by emergency medical services with the intent of providing high-quality, consistent chest compressions that are not limited by human providers who can become fatigued. Biosignals acquired from cardiac arrest patients have been characterized in their ability to track the effect of CPR on the patient. The authors investigated the feasibility and appropriate response of a biosignal-guided mechanical chest compression device in a swine model of cardiac arrest., Methods: After a custom signal-guided chest compression device was engineered, its ability to respond to biosignal changes in a swine model of cardiac arrest was tested. In a preliminary series of six swine, two biosignals were used: mean arterial pressure (MAP) and a mathematical derivative of the electrocardiogram waveform, median slope (MS). How these biosignals changed was observed when chest compression rate and depth were adjusted by the signal-guided chest compression device, independent of the user. Chest compression rate and depth were adjusted by the signal-guided chest compression device according to a preset threshold algorithm until either of the biosignals improved to satisfy a set "threshold" or until the chest compression rate and depth achieved maximum values. Defibrillation was attempted at the end of each resuscitation in an effort to achieve return of spontaneous circulation (ROSC)., Results: The signal-guided chest compression device responded appropriately to biosignals by changing its rate and depth. All animals exhibited positive improvements in their biosignals. During the course of the resuscitation, three of the six animals improved their MS biosignal to reach the MS threshold, while two of the six animals improved their MAP biosignal to reach the MAP threshold. In the six experiments conducted, defibrillation was attempted on five animals, and two animals achieved ROSC., Conclusions: In this proof-of-concept study, a signal-guided chest compression device was demonstrated to be capable of responding to biosignal input and delivering chest compressions with a broad range of rates and depths., (© 2015 by the Society for Academic Emergency Medicine.)

Introduction: Rearrest occurs when a patient experiences cardiac arrest after successful resuscitation. The incidence and outcomes of rearrest following out-of-hospital cardiac arrest have been estimated in limited local studies. We sought provide a large-scale estimate of rearrest incidence and its effect on survival., Methods: We obtained case data from emergency medical services-treated, out-of-hospital cardiac arrest from the Resuscitation Outcomes Consortium, a multi-site clinical research network with clinical centers in 11 regions in the US and Canada. The cohort comprised all cases captured between 2006 and 2008 at 10 of 11 regions with prehospital return of spontaneous circulation. We used three methods to ascertain rearrest via direct signal analysis, indirect signal analysis, and emergency department arrival vital status. Rearrest incidence was estimated as the proportion of cases with return of spontaneous circulation that experience rearrest. Regional rearrest incidence estimates were compared with the χ(2)-squared test. Multivariable logistic regression was used to assess the relationship between rearrest and survival to hospital discharge., Results: Out of 18,937 emergency medical services-assessed cases captured between 2006 and 2008, 11,456 (60.5%) cases were treated by emergency medical services and 4396 (38.4%) had prehospital return of spontaneous circulation. Of these, rearrest ascertainment data was available in 3253 cases, with 568 (17.5%) experiencing rearrest. Rearrest differed by region (10.2% to 21.2%, p < 0.001). Rearrest was inversely associated with survival (OR: 0.19, 95% CI: 0.14-0.26)., Conclusions: Rearrest was found to occur frequently after resuscitation and was inversely related to survival., (Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.)