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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: 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.)

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: 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: 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.)

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: 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: 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.)

Objective: Out-of-hospital cardiac arrest (OHCA) is a leading cause of mortality in the United States. We sought to evaluate the accuracy of the patient care report (PCR) for detection of 2 clinically important events: return of spontaneous circulation (ROSC) and rearrest (RA)., Methods: We used defibrillator recordings and PCRs for Emergency Medical Services-treated OHCA collected by the Resuscitation Outcomes Consortium's Pittsburgh site from 2006 to 2008 and 2011 to 2012. Defibrillator data included electrocardiogram rhythm tracing, chest compression measurement, and audio voice recording. Sensitivity analysis was performed by comparing the accuracy of the PCR to detect the presence and number of ROSC and RA events to integrated defibrillator data., Results: In the 158 OHCA cases, there were 163 ROSC events and 53 RA events. The sensitivity of PCRs to identify all ROSC events was 85% (confidence interval [CI], .795-.905); to identify primary ROSC events, it was 85% (CI, .793-.907); and to identify secondary ROSC events, it was 78% (CI, .565-.995). The sensitivity of PCRs to identify the presence of all RA events was .60 (CI, .469-.731); to identify primary RA events, it was 71% (CI, .578-.842); and to identify secondary RA events, it was 0. Of the 32 RA incidents captured by the PCR, only 15 (47%) correctly identified the correct lethal arrhythmia., Conclusions: We found that PCRs are not a reliable source of information for assessing the presence of ROSC and post-RA electrocardiogram rhythm. For quality control and research purposes, medical providers should consider augmenting data collection with continuous defibrillator recordings before making any conclusions about the occurrence of critical resuscitation events., (Copyright © 2014 Elsevier Inc. All rights reserved.)

Introduction: In the United States, out-of-hospital cardiac arrest from drug overdose (OD-OHCA) caused over 38,000 deaths in 2010. A study in Pittsburgh found that OD-OHCA patients differed demographically and in the resuscitation treatments they received, despite identical AHA resuscitation guidelines. We hypothesized that health-care provider perceptions affect decision-making in the treatment of OD-OHCA versus non-OD OHCA., Methods: We conducted this survey at the National Association of EMS Physicians 2013 Scientific Assembly. Physicians and non-physician health-care providers were given one of two surveys containing 19 questions pertaining to the respondents' affiliated EMS agencies, the estimated proportion of OD-OHCA as well as the drugs involved, and the respondents' belief about the treatments for OD versus non-OD OHCA., Results: One hundred ninety-three respondents participated in this survey. Of the 193, 144 (75%) were physicians and 49 (25%) were nonphysicians. Seventy-nine percent of physicians identified current status as a medical director and 76% of nonphysicians identified as a paramedic. Participants estimated the average monthly proportion of all OHCA due to OD to be 9.4%. Participants ranked opioids, alcohol, antidepressants, and benzodiazepines as the most commonly utilized agents in OD-OHCA. The majority of physicians (42%) felt that the incidence of OD-OHCA was not changing while the majority of nonphysicians (53%) felt the incidence was increasing. Eighty-four percent of all respondents reported the use of naloxone during OD-OHCA resuscitation, while 13% reported administering naloxone during non-OD OHCA resuscitation. Eighty-nine percent of physicians and 67% of nonphysicians indicated that OD-OHCA patients had different demographics than non-OD OHCA, with primary reported differences being age, comorbidities, and socioeconomic status. Sixty-three percent of physicians and 71% of nonphysicians felt that OD-OHCA patients should be treated differently, with primary differences being the incorporation of etiology-specific treatments, performing different CPR with a focus on airway support, and transporting earlier., Conclusions: When surveyed, physicians and nonphysician providers report perceiving OD-OHCA treatment, outcomes, and patient demographics differently than non-OD OHCA and making different treatment decisions based on these perceptions. This may result in etiology-oriented resuscitation in the out-of-hospital setting, despite the lack of OD-specific resuscitation guidelines.

Objective: Pulmonary aspiration of gastric contents occurs 20 to 30% of the time during cardiopulmonary resuscitation (CPR) of cardiac arrest due to loss of protective airway reflexes, pressure changes generated during CPR, and positive pressure ventilation (PPV). Although the American Heart Association has recommended the laryngeal mask airway (LMA) as an acceptable alternative airway for use by emergency medical service personnel, concerns over the capacity of the device to protect from pulmonary aspiration remain. We sought to determine the occurrence of aspiration after LMA placement, CPR, and PPV., Methods: We inserted a size 4 LMA, modified so that a vacuum catheter could be advanced past the LMA diaphragm, into the hypopharynx of 16 consecutive postexperimental mixed-breed domestic swine. Fifteen millilitres of heparinized blood was instilled into the oropharynx. Chest compressions were performed for 60 seconds with asynchronous ventilation via a mechanical ventilator. We then suctioned through the LMA for 1 minute. The catheter was removed and inspected for signs of blood. The LMA cuff was deflated, removed, and inspected for signs of blood., Results: None of 16 animals (95% CI 0-17%) had a positive test for the presence of blood in both the vacuum catheter and the intima of the LMA diaphragm., Conclusions: In this swine model of regurgitation after LMA placement, there were no cases with evidence of blood beyond the seal created by the LMA cuff. Future studies are needed to determine the frequency of pulmonary aspiration after LMA placement during CPR and PPV in the clinical setting.

Background: Previous research has demonstrated significant relationships between peri-shock pause and survival to discharge from out-of-hospital shockable cardiac arrest (OHCA)., Objective: To determine the impact of peri-shock pause on survival from OHCA during the ROC PRIMED randomized controlled trial., Methods: We included patients in the ROC PRIMED trial who suffered OHCA between June 2007 and November 2009, presented with a shockable rhythm and had CPR process data for at least one shock. We used multivariable logistic regression to determine the association between peri-shock pause duration and survival to hospital discharge., Results: Among 2006 patients studied, the median (IQR) shock pause duration was: pre-shock pause 15s (8, 22); post-shock pause 6s (4, 9); and peri-shock pause 22.0 s (14, 31). After adjusting for Utstein predictors of survival as well as CPR quality measures, the odds of survival to hospital discharge were significantly higher for patients with pre-shock pause <10s (OR: 1.52, 95% CI: 1.09, 2.11) and peri-shock pause <20s (OR: 1.82, 95% CI: 1.17, 2.85) when compared to patients with pre-shock pause ≥ 20s and peri-shock pause ≥ 40s. Post-shock pause was not significantly associated with survival to hospital discharge. Results for neurologically intact survival (Modified Rankin Score ≤ 3) were similar to our primary outcome., Conclusions: In patients with cardiac arrest presenting in a shockable rhythm during the ROC PRIMED trial, shorter pre- and peri-shock pauses were significantly associated with higher odds of survival. Future cardiopulmonary education and technology should focus on minimizing all peri-shock pauses., (Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.)

Implementation barriers for extracorporeal life support in out-of-hospital cardiac arrest (OHCA) include initiation delay and candidate selection. We explored ischemia duration, cardiopulmonary resuscitation (CPR) duration, and physiologic variables that discriminated animals with return of spontaneous circulation (ROSC). We instrumented eight female swine (31.9 +/- 9.8 kg) with femoral artery and external jugular vein cannula. After 8 (n = 4) or 15 (n = 4) minutes ventricular fibrillation (VF), animals received 30, 40, 50, or 60 minutes of CPR and then drugs (.6 U/kg vasopressin, .1 mg/kg epinephrine, .1 mg/kg propranolol, sodium bicarbonate as indicated) after 5 minutes of CPR. Extracorporeal membrane oxygenation (ECMO) flow rate was 3 L/min < or =2 hours and then 1.5 L/min < or =2 hours before weaning. Animals were defibrillated (150 J biphasic) > or =15 minutes ECMO. Primary outcome for successful resuscitation was ROSC (organized rhythm with systolic blood pressure >80 mmHg). We measured arterial blood gas, electrolytes, mean arterial pressure (MAP), coronary perfusion pressure (CPP), and five quantitative VF waveform measures at key intervals. Continuous variables were compared with two-sample t test. All 8-minute VF animals were successfully resuscitated and had ROSC. MAP was higher at the beginning (27.0 +/- 7.1 vs. 15.0 +/- 4.4; p = .03) and end (31.3 +/- 12.8 vs. 11.5 +/- 7.3; p = .03) of CPR in animals successfully resuscitated. CPP was higher at the beginning of CPR (11.9 +/- 4.6 vs. 3.3 +/- 2.2;p = .01) and the end of CPR (18.5 + 12.1 vs..9 +/- 1.4; p = .03) among animals with ROSC. Amplitude spectrum area (AMSA) was superior at the end of CPR (-2.0 +/- 1.8 vs. -5.0 +/- 1.4; p = .04) in animals successfully resuscitated. In a porcine OHCA model, MAP and CPP at the beginning and end of CPR were higher in animals successfully resuscitated. AMSA was superior at the end of CPR in animals successfully resuscitated.

Introduction: The ventricular fibrillation (VF) waveform is dynamic and predicts defibrillation success. Quantitative waveform measures (QWMs) quantify these changes. Coronary perfusion pressure (CPP), a surrogate for myocardial perfusion, also predicts defibrillation success. The relationship between QWM and CPP has been preliminarily explored. We sought to further delineate this relationship in our porcine model and to determine if it is different between animals with/without ROSC (return of spontaneous circulation)., Hypothesis: A relationship exists between QWM and CPP that is different between animals with/without ROSC., Methods: Utilizing a prior experiment in our porcine model of prolonged out-of-hospital VF cardiac arrest, we calculated mean CPP, cumulative dose CPP, and percent recovery of three QWM during resuscitation before the first defibrillation: amplitude spectrum area (AMSA), median slope (MS), and logarithm of the absolute correlations (LAC). A random effects linear regression model with an interaction term CPP ROSC investigated the association between CPP and percent recovery QWM and how this relationship changes with/without ROSC., Results: For 12 animals, CPP and QWM measures (except LAC) improved during resuscitation. A linear relationship existed between CPP and percent recovery AMSA (coefficient 0.27; 95%CI 0.23, 0.31; p<0.001) and percent recovery MS (coefficient 0.80; 95%CI 0.70, 0.90; p<0.001). A linear relationship existed between cumulative dose CPP and percent recovery AMSA (coefficient 2.29; 95%CI 2.0, 2.56; p<0.001) and percent recovery MS (coefficient 6.68; 95%CI 6.09, 7.26; p<0.001). Animals with ROSC had a significantly "steeper" dose-response relationship., Conclusions: There is a linear relationship between QWM and CPP during chest compressions in our porcine cardiac arrest model that is different between animals with/without ROSC., (Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.)

Background: There are few if any real-time physiologic measures that currently provide feedback during resuscitation from cardiac arrest. Such measures could be used to guide therapy not simply based on process guidelines but on the physiologic response of the patient from moment to moment. To this end, we applied an existing technology - quantitative waveform measures (QWMs) of the ventricular fibrillation (VF) electrocardiogram (ECG) - as a continuous measure of myocardial response to reperfusion with cardiopulmonary bypass (CPB) after prolonged cardiac arrest., Methods: Sixteen domestic, mixed-breed swine were sedated, anesthetized and paralyzed. Mechanical ventilation with room air was provided. Large diameter bypass catheters were placed in the right external jugular vein and right femoral artery for cardiopulmonary bypass (CPB). VF was induced with a 3-s 100mA transthoracic shock and left untreated for 15, 20, 25, or 30min, followed by 10min of centrifugal pump CPB (Bard CPS). Continuous Lead II ECG was recorded with an electronic data acquisition system (Power Lab, ADInstruments). Four QWMs representing 4 signal characteristics of the VF ECG were calculated in 5-s windows throughout the course of untreated VF and resuscitation with CPB., Results: Four animals were assigned to each VF duration group. QWM recovery was inversely correlated with untreated VF duration, and was drastically reduced above 20min of untreated VF. Return of spontaneous circulation (ROSC) was highly unlikely after 20min of untreated VF., Conclusion: QWMs of the VF ECG provided a real-time metric of myocardial electrophysiologic response to reperfusion with CPB. Resuscitation from greater than 20min of untreated cardiac arrest was unlikely. QWMs may be useful for titrating CPB duration before defibrillation and assessing CPR quality independently of process guidelines., (Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.)

Background: Recently, portable extracorporeal membrane oxygenation (ECMO) machines have become commercially available. This creates the potential to utilize extracorporeal life support (ECLS) for the treatment of sudden cardiac arrest in the emergency department, and potentially in the out-of-hospital setting., Objective: We sought to determine the feasibility of installing the ECMO circuit during delivery of mechanical chest compression CPR., Methods: We used 5 mixed-breed domestic swine with a mean mass of 26.0 kg. After induction of anesthesia, animals were instrumented with micromanometer-tipped transducers placed in the aorta and right atrium via the left femoral artery and vein. Ventricular fibrillation (VF) was induced electrically with a transthoracic shock and left untreated for 8 min. Then, mechanical chest compressions were begun (LUCAS, Jolife, Lund, Sweden) and manual ventilations were performed to maintain ETCO(2) between 35 and 45Torr. Compressions continued until ECMO flow was started. Ten minutes after induction of VF, drugs were given (epinephrine, vasopressin, and propranolol). ECMO installation was started via cutdown on the right external jugular vein and right femoral artery for placement of venous and arterial catheters while chest compressions continued. ECMO installation start time varied from 17 to 30 min after start of compressions and continued until ECG indicated a shockable rhythm. First rescue shocks were given at 22, 32, 35, 44, and 65 min., Results: ECMO was successfully installed in all five animals without incident. It was necessary to briefly discontinue chest compressions during the most delicate part of inserting the catheters into the vessels. ECMO also allowed for very rapid cooling of the animals and facilitated post-resuscitation hemodynamic support. Only the 65-min animal did not attain return of spontaneous circulation (ROSC)., Conclusion: Mechanical chest compression may be a suitable therapeutic bridge to the installation of ECMO and does not interfere with ECMO catheter placement., (Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.)

Background: Perishock pauses are pauses in chest compressions before and after defibrillatory shock. We examined the relationship between perishock pauses and survival to hospital discharge., Methods and Results: We included out-of-hospital cardiac arrest patients in the Resuscitation Outcomes Consortium Epistry-Cardiac Arrest who suffered arrest between December 2005 and June 2007, presented with a shockable rhythm (ventricular fibrillation or pulseless ventricular tachycardia), and had cardiopulmonary resuscitation process data for at least 1 shock (n=815). We used multivariable logistic regression to determine the association between survival and perishock pauses. In an analysis adjusted for Utstein predictors of survival, the odds of survival were significantly lower for patients with preshock pause ≥20 seconds (odds ratio, 0.47; 95% confidence interval, 0.27 to 0.82) and perishock pause ≥40 seconds (odds ratio, 0.54; 95% confidence interval, 0.31 to 0.97) compared with patients with preshock pause <10 seconds and perishock pause <20 seconds. Postshock pause was not independently associated with a significant change in the odds of survival. Log-linear modeling depicted a decrease in survival to hospital discharge of 18% and 14% for every 5-second increase in both preshock and perishock pause interval (up to 40 and 50 seconds, respectively), with no significant association noted with changes in the postshock pause interval., Conclusions: In patients with cardiac arrest presenting in a shockable rhythm, longer perishock and preshock pauses were independently associated with a decrease in survival to hospital discharge. The impact of preshock pause on survival suggests that refinement of automatic defibrillator software and paramedic education to minimize preshock pause delays may have a significant impact on survival.

Aims: As the duration of untreated cardiac arrest increases, the effectiveness of standard therapies declines, and may be more harmful than helpful. We investigated the hemodynamic, metabolic and anti-inflammatory effects of Ringer's ethyl pyruvate solution (REPS) versus Ringer's solution (RS) in the acute model of prolonged porcine arrest., Methods: Seventeen mixed-breed swine were induced into ventricular fibrillation (VF) and left untreated for 8min. CPR was begun using a mechanical chest compression device at a rate of 100 per minute. At the onset of CPR, animals were randomly assigned to treatment with either 25mL/kg of RS or 25mL/kg of REPS containing 40mg/kg of ethyl pyruvate, infused over 5min in blinded fashion. CPR continued with administration of a drug cocktail at 2min and the first rescue shock was delivered at minute 13 of VF. Animals having ROSC were supported with standardized care for 2h., Results: Both groups had 100% ROSC and 100% 2-h survival. The REPS group exhibited higher median CPP (27.3mmHg) than the control group (16.5mmHg) by 3min of CPR, which continued throughout the duration of CPR (p=0.02). The median time to hypotension following ROSC was 9.64min in the REPS group and 7.25min in controls (p=0.04) and there was a non-significant trend of decreased use of vasopressors for the duration of resuscitation. There was no difference in systemic or cerebral metabolism between groups. There were non-significant trends of decreased IL-6, increased Il-10 and decreased mesenteric bacterial colony growth in those treated with REPS when compared to RS., Conclusions: The administration of REPS with CPR significantly improved intra- and post-resuscitation hemodynamics in this swine model of prolonged cardiac arrest, but did not definitely change the metabolic or inflammatory profile during the acute resuscitation period.

Objective: We sought to determine the effect of the preshock pause (PSP) on coronary perfusion pressure (CPP) decay and subsequent rescue shock (RS) outcome in porcine ventricular fibrillation (VF)., Methods: Retrospective analysis of digitally recorded CPP tracings was performed. Ventricular fibrillation was electrically induced in all animals and resuscitation was standardized in all experiments. The first RS was delivered after an average of 10.8 minutes of VF (7.4 minutes of nontreatment and 3.4 minutes of resuscitation). The continuous CPP tracing segments, during the hands-off period prior to the first two rescue shocks, were imported into a spreadsheet and analyzed using descriptive statistics as well as univariate and multivariate statistical methods. The RS outcome for each animal was recorded as failed or return of spontaneous circulation (ROSC) (a systolic blood pressure of 80 mmHg or greater, sustained continuously for at least 1 minute)., Results: We included 196 rescue shocks (120 first RS [RS1], 76 second RS [RS2]) from 120 swine. The mean CPP following the last compression before RS was 23.4 mmHg (standard error of the mean [SEM]: 1.3). The median PSP duration was 4.1 seconds (interquartile range [IQR]: 3.3, 6.1). The mean CPP just prior to RS was 7.6 mmHg (SEM: 0.6). Overall, the RS was successful (ROSC) in 57 of 120 (0.47 [95% confidence interval (CI): 0.38, 0.56]) attempts. Univariate results showed a counterintuitive positive correlation between PSP and maximum CPP for RS1 (r = 0.548, p < 0.001)., Conclusion: During the resuscitation PSP in these porcine studies of prolonged VF, CPP dropped precipitously, but RS outcome was not adversely affected.

Background: Hypothermia has been shown to improve survival and neurological outcomes for ventricular fibrillation (VF) cardiac arrest. The electrophysiological mechanisms of hypothermia are not well-understood, nor are the effects of beginning cooling during the resuscitation., Methods and Results: We hypothesized that inducing hypothermia prior to the onset of VF would slow the deleterious changes seen in the ECG during VF and that inducing hypothermia at the start of resuscitation would increase the rates of ROSC and short-term survival in a porcine model of prolonged VF. We randomly assigned 42 domestic swine (27.2+/-2.3 kg) to either pretreatment with hypothermia before induction of VF (PRE), normothermic resuscitation (NORM) or intra-resuscitation hypothermia (IRH). During anesthesia, animals were instrumented via femoral cutdown. Lead II ECG was recorded continuously. PRE animals were cooled before the induction of VF, with a rapid infusion of 4 degrees normal saline (30mL/kg). VF was induced electrically, left untreated for 8min, then mechanical CPR began. During CPR the NORM animals got 30mL/kg body-temperature saline and the IRH animals got 30mL/kg 4 degrees saline. In all groups first rescue shocks were delivered after 13min of VF. We calculated the VF scaling exponent (ScE) for the entire 8min period (compared using GEE). ROSC and survival were compared with Fisher's exact test. Mean temperature in degrees C at the onset of VF was PRE=34.7 degrees (+/-0.8), NORM=37.8 (+/-0.9), and IRH=37.9 (+/-0.9). The ScE values over time were significantly lower after 8min in the PRE group (p=0.02). ROSC: PRE=10/14 (71%), NORM=6/14 (43%) and IRH=12/14 (86%); p for IRH vs. NORM=0.02. Survival: PRE=9/14 (64%), NORM=5/14 (36%), IRH 8/14 (57%)., Conclusion: Hypothermia slowed the decay of the ECG waveform during prolonged VF. IRH improved ROSC but not short-term survival compared to NORM. It is possible to rapidly induce mild hypothermia during CPR using an IV infusion of ice-cold saline.

Background: Endogenous adenosine (ADO) is cardioprotective during ischemia and its myocardial concentration increases during untreated ventricular fibrillation (VF). We have previously shown that ADO A1 receptor (ADOA1R) antagonism hastens the time-dependent decay in VF waveform morphology during the circulatory phase of cardiac arrest., Objective: To determine the effect of ADOA1R antagonism on ROSC and short-term survival in prolonged VF., Methods: Thirty-six swine were assigned by block randomization to one of three groups: a group that received only vehicle (CONTROL), an ADOA1R antagonist pretreatment group (PRE), and a group that was given ADOA1R antagonist during resuscitation (DURING). The animals were instrumented under anesthesia, and ADOA1R antagonist or vehicle, per group assignment, was infused 5 minutes prior to VF induction. At minute 8 of untreated VF, chest compression with ventilation was initiated and a standard drug cocktail, with ADOA1R antagonist or vehicle, was given. The first rescue shock (150 J biphasic) was delivered after 11 minutes of VF. Proportions with 95% confidence intervals (CIs) were calculated for the two outcome measures., Results: The baseline characteristics and chemistry values for the three groups were mathematically the same. The DURING group had a greater proportion of female animals (seven of 12) in comparison with the CONTROL group (two of 12) (p=0.03). ADOA1R antagonism hastened the decay of VF as previously demonstrated, but the rate of ROSC was the same for all groups: CONTROL=seven of 12, PRE=six of 12, and DURING=seven of 12. There were also no differences in short-term survival: CONTROL=four of 12, PRE=five of 12, and DURING=seven of 12., Conclusions: In this study, ADOA1R antagonism had no effect on outcome whether given before induction of VF or upon resuscitation after 8 minutes of untreated VF. The role of endogenous ADO in prolonged VF remains unclear.

Background: An impedance threshold device (ITD) has been designed to enhance circulation during CPR by creating a negative intrathoracic pressure during the relaxation phase of chest compression., Hypothesis: We sought to determine the effects of the ITD on coronary perfusion pressure (CPP), return of spontaneous circulation (ROSC), and short-term survival (20 minutes after ROSC). We hypothesized that the ITD would improve all 3 variables when compared to standard CPR., Methods: Using a case-control design nested within a randomized primary study, we compared CPR with the ITD (ITD-CPR) to standard CPR without the device (S-CPR). We systematically assigned 36 domestic swine, weighing 23-29 kg, (18 per group) to resuscitation with either ITD-CPR or S-CPR after 8 minutes of untreated ventricular fibrillation (VF). At minute 8, mechanical chest compression and ventilation began, and drugs (0.1 mg/kg epinephrine, 40U vasopressin, 1.0 mg propranolol, 1 mEq/kg sodium bicarbonate) were given. The first rescue shock (150J biphasic) was delivered at minute 11 of VF. We recorded CPP, ROSC (systolic pressure > 80 mmHg sustained for 60 s continuously), and survival. Data were analyzed with Fisher's exact test and generalized estimating equations (GEE), with alpha = 0.05., Results: We analyzed 3,150 compressions. CPP for the ITD-CPR group (28.1 mmHg [95% CI 27-29.3 mmHg]), did not differ from the S-CPR group (32.3 mmHg [95% CI 31.2-33.4 mmHg]). ROSC occurred in 6/18 (33%) animals in the ITD-CPR, and 14/18 (78%) in the S-CPR group (p = 0.02). Survival occurred in 3/18 (17%) ITD-CPR and 13/18 (72%) S-CPR group (p = 0.003)., Conclusions: ITD-CPR did not improve CPP compared to S-CPR. ROSC and survival were significantly lower with ITD-CPR.