Association between a Post-Resuscitation Care Bundle and the Odds of Field Rearrest after Successful Resuscitation from Out-of-Hospital Cardiac Arrest: A Pre/Post Study.

OBJECTIVES: Rearrest after successful resuscitation from out-of-hospital cardiac arrest (OHCA) is common and is associated with worse patient outcomes. However, little is known about the effect of interventions designed to prevent rearrest. We assessed the association between a prehospital care protocol for immediate management after return of spontaneous circulation (ROSC) and rates of field rearrest and survival to discharge in patients with prehospital ROSC. METHODS: This was a retrospective study of adult patients with OHCA and field ROSC within a large EMS system before (April 2017-August 2018) and after (April 2019-February 2020) implementation of a structured prehospital post-ROSC care protocol. The protocol was introduced in September 2018 and provided on-scene stabilization direction including guidance on ventilation and blood pressure support. Field data and hospital outcomes were used to compare the frequency of field rearrest, hospital survival, and survival with good neurologic outcome before and after protocol implementation. Logistic regression was used to assess the association between the post-implementation period and these outcomes, and odds ratios were reported. The association between individual interventions on these outcomes was also explored. RESULTS: There were 2,706 patients with ROSC after OHCA in the pre-implementation period and 1,780 patients in the post-implementation period. The rate of prehospital rearrest was 43% pre-implementation vs 45% post-implementation (RD 2%, 95% CI -1, 4%). In the adjusted analysis, introduction of the protocol was not associated with decreased odds of rearrest (OR 0.87, 95% CI 0.73, 1.04), survival to hospital discharge (OR 1.01, 95% CI 0.81, 1.24), or survival with good neurologic outcome (OR 0.81, 95% CI 0.61, 1.06). Post-implementation, post-ROSC administration of saline and push-dose epinephrine increased from 11% to 25% (RD 14%, 95% CI 11, 17%) and from 3% to 12% (RD 9% 95% CI 7, 11%), respectively. In an exploratory analysis, push-dose epinephrine was associated with a decreased odds of rearrest (OR 0.68, 95% CI 0.50, 0.94). CONCLUSIONS: Introduction of a post-ROSC care protocol for patients with prehospital ROSC after OHCA was not associated with reduced odds of field rearrest. When elements of the care bundle were considered individually, push-dose epinephrine was associated with decreased odds of rearrest.

Process and Impact of Development of an Adolescent Emergency Psychiatry Unit at a Large Urban Hospital.

OBJECTIVES: Boarding of adolescent patients with mental health concerns requiring ongoing observation and treatment is of increasing concern across US emergency departments. The objective was a proof of concept of developing an adolescent psychiatric emergency unit and assessment of the impact of this unit on lengths of stay (LOS). METHODS: We describe the creation of the unit designed to allow safe assessment and boarding of patients, and appropriate interventions and services, while arranging transfer to inpatient facility or safe discharge home. Using a precreation and postcreation analysis and comparison with a similar facility that did not create such a unit, we utilized linear regression to investigate the primary outcome of total length of stay and secondary outcomes of psychiatric emergency department and pediatric emergency department length of stay for both unit-eligible patients and all patients. RESULTS: The overall length of stay was not associated with a statistically significant change for unit-eligible patients; however, there was a significant decrease in the pediatric emergency department LOS for unit-eligible patients. This was associated with a decrease in beds lost to boarding in the pediatric emergency department of 544 hours per month. CONCLUSIONS: Creation of an adolescent psychiatric emergency unit without allotment of significant additional resources is an option to decrease pediatric emergency department boarding times for adolescent patients requiring ongoing emergent therapy for mental health concerns.

Equitable Allocation of Remdesivir for the COVID-19 Pandemic in Los Angeles County.

OBJECTIVE: Subsequent to the Emergency Use Authorization (EUA) by the Food and Drug Administration, Gilead Sciences Inc. donated a supply of remdesivir to the United States government for immediate treatment of patients with COVID-19. The Los Angeles County Emergency Medical Services Agency (LAC-EMS) was tasked with the allocation. The objective of this study was to describe the process for allocation and the patients who were treated with the donated remdesivir in LAC. METHODS: LAC-EMS developed a strategic plan to distribute federal allocations of remdesivir to LAC hospitals based on the proportion of patients admitted with COVID-19 at each hospital. Criteria for treatment and its duration were based on the EUA at local hospital discretion. Data were collected on patients treated from May to December 2020. Variables included characteristics (age, sex, race/ethnicity), hospital care (level of care and respiratory support at start of treatment, ventilator support, total ventilator days), and outcomes (length of intensive care (ICU) and hospital stay, survival to discharge, disposition). We compared demographics of treated patients to the overall population of hospitalized patients in LAC. RESULTS: LAC-EMS distributed 34,250 vials of remdesivir in 7 allocations, which treated 5,376 patients. The median age was 60 (IQR 48-70); 62% were male, 59% Hispanic, 17% White, 6% Asian, 5% Black. Prior to remdesivir, 96% of patients required respiratory support including 49% supplemental oxygen, 35% high-flow nasal cannula, 3% continuous or bilevel positive airway pressure and 9% mechanical ventilation, with one quarter of patients in the ICU. Overall, 26% of patients were mechanically ventilated during the hospitalization, median 11 days (IQR 8-23), while 41% required ICU care, median 10 days (IQR 5-19). Median length of stay for all patients was 10 days (IQR 7-18) with 4,218 patients (74%) surviving to discharge and 80% of survivors discharged home. Compared with overall hospitalized patients with COVID-19, treated patients more likely to be male and middle-aged, and less likely to be Black. CONCLUSION: LAC-EMS's strategic plan to distribute donated remdesivir to hospitals based on the number of inpatients with COVID-19 resulted in the treatment of 5,376 patients of whom 74% survived to hospital discharge.

Blood Pressure Management After Endovascular Therapy for Acute Ischemic Stroke: The BEST-II Randomized Clinical Trial.

Importance: The effects of moderate systolic blood pressure (SBP) lowering after successful recanalization with endovascular therapy for acute ischemic stroke are uncertain. Objective: To determine the futility of lower SBP targets after endovascular therapy (<140 mm Hg or 160 mm Hg) compared with a higher target (≤180 mm Hg). Design, Setting, and Participants: Randomized, open-label, blinded end point, phase 2, futility clinical trial that enrolled 120 patients with acute ischemic stroke who had undergone successful endovascular therapy at 3 US comprehensive stroke centers from January 2020 to March 2022 (final follow-up, June 2022). Intervention: After undergoing endovascular therapy, participants were randomized to 1 of 3 SBP targets: 40 to less than 140 mm Hg, 40 to less than 160 mm Hg, and 40 to 180 mm Hg or less (guideline recommended) group, initiated within 60 minutes of recanalization and maintained for 24 hours. Main Outcomes and Measures: Prespecified multiple primary outcomes for the primary futility analysis were follow-up infarct volume measured at 36 (±12) hours and utility-weighted modified Rankin Scale (mRS) score (range, 0 [worst] to 1 [best]) at 90 (±14) days. Linear regression models were used to test the harm-futility boundaries of a 10-mL increase (slope of 0.5) in the follow-up infarct volume or a 0.10 decrease (slope of -0.005) in the utility-weighted mRS score with each 20-mm Hg SBP target reduction after endovascular therapy (1-sided α = .05). Additional prespecified futility criterion was a less than 25% predicted probability of success for a future 2-group, superiority trial comparing SBP targets of the low- and mid-thresholds with the high-threshold (maximum sample size, 1500 with respect to the utility-weighted mRS score outcome). Results: Among 120 patients randomized (mean [SD] age, 69.6 [14.5] years; 69 females [58%]), 113 (94.2%) completed the trial. The mean follow-up infarct volume was 32.4 mL (95% CI, 18.0 to 46.7 mL) for the less than 140-mm Hg group, 50.7 mL (95% CI, 33.7 to 67.7 mL), for the less than 160-mm Hg group, and 46.4 mL (95% CI, 24.5 to 68.2 mL) for the 180-mm Hg or less group. The mean utility-weighted mRS score was 0.51 (95% CI, 0.38 to 0.63) for the less than 140-mm Hg group, 0.47 (95% CI, 0.35 to 0.60) for the less than 160-mm Hg group, and 0.58 (95% CI, 0.46 to 0.71) for the high-target group. The slope of the follow-up infarct volume for each mm Hg decrease in the SBP target, adjusted for the baseline Alberta Stroke Program Early CT score, was -0.29 (95% CI, -0.81 to ∞; futility P = .99). The slope of the utility-weighted mRS score for each mm Hg decrease in the SBP target after endovascular therapy, adjusted for baseline utility-weighted mRS score, was -0.0019 (95% CI, -∞ to 0.0017; futility P = .93). Comparing the high-target SBP group with the lower-target groups, the predicted probability of success for a future trial was 25% for the less than 140-mm Hg group and 14% for the 160-mm Hg group. Conclusions and Relevance: Among patients with acute ischemic stroke, lower SBP targets less than either 140 mm Hg or 160 mm Hg after successful endovascular therapy did not meet prespecified criteria for futility compared with an SBP target of 180 mm Hg or less. However, the findings suggested a low probability of benefit from lower SBP targets after endovascular therapy if tested in a future larger trial. Trial Registration: ClinicalTrials.gov Identifier: NCT04116112.

Organ donor management goals and delayed graft function in adult kidney transplant recipients.

BACKGROUND: Delayed graft function (DGF) after kidney transplantation is a common occurrence and correlates with poor graft and patient outcomes. Donor characteristics and care are known to impact DGF. We attempted to show the relationship between achievement of specific donor management goals (DMG) and DGF. METHODS: This is a retrospective case-control study using data from 14 046 adult kidney donations after brain death from hospitals in 18 organ procurement organizations (OPOs) which were transplanted to adult recipients between 2012 and 2018. Data on DMG compliance and donor, recipient, and ischemia-related factors were used to create multivariable logistic regression models. RESULTS: The overall rate of DGF was 29.4%. Meeting DMGs for urine output and vasopressor use were associated with decreased risk of DGF. Sensitivity analyses performed with different imputation methods, omitting recipient factors, and analyzing multiple time points yielded largely consistent results. CONCLUSIONS: The development of DMGs continues to show promise in improving outcomes in the kidney transplant recipient population. Studies have already shown increased kidney utilization in smaller cohorts, as well as other organs, and shown decreased rates of DGF. Additional research and analysis are required to assess interactions between meeting DMGs and correlation versus causality in DMGs and DGF.

Variation in Post-Cardiac Arrest Care Within a Regional EMS System.

Objective: Within Emergency Medical Systems (EMS) regional systems, there may be significant differences in the approach to patient care despite efforts to promote standardization. Identifying hospital-level factors that contribute to variations in care can provide opportunities to improve patient outcomes. The purpose of this analysis was to evaluate variation in post-cardiac arrest care within a large EMS system and explore the contribution of hospital-level factors. Methods: This was a retrospective analysis from a regional cardiac system serving over 10 million persons. Patients with out-of-hospital cardiac arrest (OHCA) with return of spontaneous circulation (ROSC) are transported to 36 cardiac arrest centers with 24/7 emergent coronary angiography (CAG) capabilities and targeted temperature management (TTM) policies based on regional guidelines. We included adult patients ≥18 years with non-traumatic OHCA from 2016-2018. Patients with a Do-Not-Resuscitate order and those who died in the emergency department (ED) were excluded. For the TTM analysis, we also excluded patients who were alert in the ED. The primary outcome was receiving CAG or TTM after cardiac arrest. The secondary outcome was neurologic recovery (dichotomized to define a "good" outcome as cerebral performance category (CPC) 1 or 2). We used generalized estimating equations including patient-level factors (age, sex, witnessed arrest, initial rhythm) and hospital-level factors (academic status, hospital size based on licensed beds, annual OHCA patient volume) to estimate the odds ratios associated with these variables. Results: There were 7831 patients with OHCA during the study period; 4694 were analyzed for CAG and 3903 for TTM. The median and range for treatment with CAG and TTM after OHCA was 23% (12-49%) and 58% (17-92%) respectively. Hospital size was associated with increased likelihood of CAG, adjusted odds ratio 1.71, 95% CI 1.05-2.86, p = 0.03. Academic status approached significance in its association with TTM, adjusted odds ratio 1.69, 95% CI 0.98-2.91, p = 0.06. Overall, 28% of patients survived with good neurologic outcome, ranging from 17 to 43% across hospitals. Conclusion: Within this regional cardiac system, there was significant variation in use of CAG and TTM after OHCA, which was not fully explained by patient-level factors. Hospital size was associated with increased CAG.

A novel, reverse-phase-shifting, thermoreversible foaming hydrogel containing antibiotics for the treatment of thermal burns in a swine model - A pilot study.

BACKGROUND: This study compared a novel topical hydrogel burn dressing (CI-PRJ012) to standard of care (silver sulfadiazine) and to untreated control in a swine thermal burn model, to assess for wound healing properties both in the presence and absence of concomitant bacterial inoculation. METHODS: Eight equal burn wounds were created on six Yorkshire swine. Half the wounds were randomized to post-burn bacterial inoculation. Wounds were subsequently randomized to three treatments groups: no intervention, CI-PRJ012, or silver sulfadiazine cream. At study end, a blinded pathologist evaluated wounds for necrosis and bacterial colonization. RESULTS: When comparing CI-PRJ012 and silver sulfadiazine cream to no treatment, both agents significantly reduced the amount of necrosis and bacteria at 7 days after wound creation (p < 0.01, independently for both). Further, CI-PRJ012 was found to be significantly better than silver sulfadiazine (p < 0.02) in reducing bacterial colonization. For wound necrosis, no significant difference was found between silver sulfadiazine cream and CI-PRJ012 (p = 0.33). CONCLUSIONS: CI-PRJ012 decreases necrosis and bacterial colonization compared to no treatment in a swine model. CI-PRJ012 appeared to perform comparably to silver sulfadiazine. CI-PRJ012, which is easily removed with the application of room-temperature water, may provide clinical advantages over silver sulfadiazine.

Association of Residency Applicants' Hobbies and Subsequent Technical Proficiency Ratings as General Surgery Chief Residents: A Multi-Institutional Study.

OBJECTIVE: To determine whether participation in certain hobbies (e.g., participation in sports, playing musical instruments, or other hobbies requiring fine motor skills), preresidency, are associated with higher technical skills ratings at the time of residency graduation. DESIGN: Faculty members from 14 general surgery residency programs scored individual graduates from 2017 to 2020 on their technical skills using a 5-point Likert scale. Hobbies for these residents were collected from their Electronic Residency Application Service (ERAS) data. A single reviewer classified each ERAS hobby into predefined categories including musical instruments, sports requiring hand-eye coordination, team sports, and activities necessitating hand-eye coordination. Spearman correlation coefficients were calculated for the relationship between each category of hobby-as well as the total number of hobbies in each category-and the outcome of surgical faculty ratings of residents' technical surgical skills during their last year of residency. A proportional odds model including the above predictive variables was also fit to the data. SETTING: Fourteen general surgery residency programs. PARTICIPANTS: General surgery residency graduates from 14 different programs from 2017 to 2020. RESULTS: There were 296 residents across 14 institutions. The average ranking of residents' technical skills was 3.24 (SD 1.1). A total of 40% of residents played sports involving hand-eye coordination, 31% played team sports, 28% participated in nonsport hobbies that require eye-hand coordination, and 20% played musical instruments. Correlation coefficients were not statistically significant for any of the categories. In the proportional odds model, none of the variables were associated with statistically significant increased odds of a higher technical skills rating. CONCLUSIONS: There was no correlation between general surgery chief residents' technical skills as rated by faculty, and self-reported pre-residency hobbies on the ERAS application. These findings suggest such hobbies prior to residency are unlikely to predict future technical skills prowess.

Characteristics Associated With Outstanding General Surgery Residency Graduate Performance, as Rated by Surgical Educators.

Importance: Characteristics of outstanding graduating surgical residents are currently undefined. Identifying these qualities may be important in guiding resident selection and resident education. Objective: To determine characteristics that are most strongly associated with being rated as an outstanding graduating surgical resident. Design, Setting, and Participants: The multi-institutional study had 3 phases. First, an expert panel developed a list of characteristics embodied by top graduating surgical residents. Second, groups of faculty from 14 US general-surgery residency programs ranked 2017 through 2020 graduates into quartiles of overall performance. Third, faculty evaluated their graduates on each characteristic using a 5-point Likert scale. Data were analyzed using Spearman rank-order correlation to identify which individual characteristics were associated with overall graduate performance. A least absolute shrinkage and selection operator (LASSO) ordinal regression was performed to select a parsimonious model to predict the outcome of overall performance rating from individual characteristic scores. Main Outcome and Measures: Surgical educators' rankings of general surgery residency graduates' overall performance. Results: Fifty faculty from 14 US residency programs with a median of 13 (range, 5-30) years of surgical education experience evaluated 297 general surgery residency graduates. Surgical educators identified 21 characteristics that they believed outstanding graduating surgical residents possessed. Two hundred ninety-seven surgical residency graduates were evaluated. Higher scores in every characteristic correlated with better overall performance. Characteristics most strongly associated with higher overall performance scores were surgical judgment (r = 0.728; P < .001), leadership (r = 0.726; P < .001), postoperative clinical skills (r = 0.715; P < .001), and preoperative clinical skills (r = 0.707; P < .001). The remainder of the characteristics were moderately associated with overall performance. The LASSO regression model identified 3 characteristics from which overall resident performance could be accurately predicted without measuring other qualities: surgical judgment (odds ratio [OR] per 1 level of 5-level Likert scale OR, 1.27; 95% CI, 1.03-1.51), leadership (OR, 1.27; 95% CI, 1.06-1.48), and medical knowledge (OR, 1.16; 95% CI, 1.01-1.33). Conclusions and Relevance: All individual characteristics identified by surgical educators as being qualities of outstanding graduating surgical residents were positively associated with overall graduate performance. Surgical judgment and leadership skills had the strongest individual associations. Assessment of only 3 qualities (surgical judgment, leadership, and medical knowledge) were required to predict overall resident performance ratings. These findings highlight the importance of developing specific surgical judgment and leadership skills curricula and assessments during surgical residency.

Optimal tumor sampling for immunostaining of biomarkers in breast carcinoma.

INTRODUCTION: Biomarkers, such as Estrogen Receptor, are used to determine therapy and prognosis in breast carcinoma. Immunostaining assays of biomarker expression have a high rate of inaccuracy; for example, estimates are as high as 20% for Estrogen Receptor. Biomarkers have been shown to be heterogeneously expressed in breast tumors and this heterogeneity may contribute to the inaccuracy of immunostaining assays. Currently, no evidence-based standards exist for the amount of tumor that must be sampled in order to correct for biomarker heterogeneity. The aim of this study was to determine the optimal number of 20X fields that are necessary to estimate a representative measurement of expression in a whole tissue section for selected biomarkers: ER, HER-2, AKT, ERK, S6K1, GAPDH, Cytokeratin, and MAP-Tau. METHODS: Two collections of whole tissue sections of breast carcinoma were immunostained for biomarkers. Expression was quantified using the Automated Quantitative Analysis (AQUA) method of quantitative immunofluorescence. Simulated sampling of various numbers of fields (ranging from one to thirty five) was performed for each marker. The optimal number was selected for each marker via resampling techniques and minimization of prediction error over an independent test set. RESULTS: The optimal number of 20X fields varied by biomarker, ranging between three to fourteen fields. More heterogeneous markers, such as MAP-Tau protein, required a larger sample of 20X fields to produce representative measurement. CONCLUSIONS: The optimal number of 20X fields that must be sampled to produce a representative measurement of biomarker expression varies by marker with more heterogeneous markers requiring a larger number. The clinical implication of these findings is that breast biopsies consisting of a small number of fields may be inadequate to represent whole tumor biomarker expression for many markers. Additionally, for biomarkers newly introduced into clinical use, especially if therapeutic response is dictated by level of expression, the optimal size of tissue sample must be determined on a marker-by-marker basis.

Quantitative assessment shows loss of antigenic epitopes as a function of pre-analytic variables.

Pre-analytic variables, specifically cold ischemic time, have been implicated as key variables in the measurement of proteins by immunohistochemistry. To determine the significance and magnitude of antigenic loss due to pre-analytic variables, we have compared protein antigenicity in core needle biopsies, with essentially no cold ischemic time, with that in routinely processed tumor resection specimens. Two cohorts of matched core needle biopsies and tumor resections were collected with 20 matched pairs and 14 matched pairs, respectively. Both series were analyzed by quantitative immunofluorescence using the AQUA® method. Epitopes phospho-ERK, total ERK, phospho-AKT, total AKT, phospho-S6K1, total S6K1, estrogen receptor (ER), Ki67, cytokeratin and GAPDH were assessed. Detection levels for all phospho-epitopes were significantly decreased in tumor resections compared with biopsies while no significant change was seen in the corresponding total proteins. Of the other four proteins examined, ER and cytokeratin showed significant loss of antigenicity. This data suggest that measurement of phospho-protein antigenicity in formalin-fixed tissue by immunological methods is dramatically affected by pre-analytic variables. This study suggests that core needle biopsies are more accurate for assessment of tissue biomarkers.

Comparison of Active Learning Techniques: Audience Response Questions Versus Small Group Discussion on Immediate- and Long-term Knowledge Gain.

OBJECTIVES: Active learning techniques help with motivation, involvement, and retention during didactics. There are few studies comparing different active learning methods, and these have yielded mixed results. The objective of this study was to compare the effect of two active learning methods-small-group discussion and audience response system (ARS)-on immediate- and long-term knowledge gain. METHODS: This was a prospective experimental study of emergency medicine (EM) subinterns and residents. Participants were randomized into two groups, and baseline knowledge was assessed with a multiple-choice pretest. Didactic sessions on salicylate toxicity and ocular trauma were given to both groups utilizing either small-group discussion or ARS. A crossover design was utilized to ensure that both groups received instruction by each method. A multiple-choice posttest was administered following the didactics and again 2 months later. Pre- and posttests were identical. All test items were written by an academic faculty member with advanced training in medical education and item writing and were based on the goals and objectives of the session. Test items were piloted with a reference group of learners. Didactic instructors were blinded to test items. Data were analyzed using a linear mixed-effects model. RESULTS: Thirty-eight subinterns and residents participated in the study. Both instructional methods showed immediate- and long-term knowledge gain. The linear mixed-effects model did not demonstrate any significant difference between instructional methods on immediate knowledge gain (mean difference = 0.18, p = 0.62, 95% confidence interval [CI] = -0.52 to 0.88) or long-term knowledge gain (mean difference = -0.42, p = 0.36, 95% CI = -1.32 to 0.47). CONCLUSION: In this small study, there was no significant difference between instructional methods on immediate- and long-term knowledge gain in EM subinterns and residents.

Outcome assessment of medical education fellowships in emergency medicine.

OBJECTIVES: Medical education fellowships in emergency medicine (EM) provide training in teaching, assessment, educational program administration, and scholarship. The longitudinal impact of this training is unknown. Our objective was to characterize the career outcomes of medical education fellowship graduates. METHODS: We solicited curriculum vitae (CV) from graduates of U.S. EM education fellowships by email. We abstracted data from CVs with a standard instrument that included program characteristics, employment history, leadership positions, awards, and scholarly productivity. We calculated and reported descriptive statistics. RESULTS: A total of 71 of 91 (78%) graduates participated. Thirty-three completed a 1-year fellowship and 38 completed a 2-year fellowship. Nineteen (27%) completed an advanced degree during fellowship. Median (range) graduation year was 2016 (1997-2020). The majority, 63 of 71 (89%), work in an academic setting. Graduates held leadership positions in continuing medical education, graduate medical education, and undergraduate medical education. Forty-eight (68%) served on national medical education committees. The mean ± SD number of national medical education awards was 1.27 ± 2.03. The mean ± SD number of national medical education presentations was 7.63 ± 10.83. Graduates authored a mean ± SD of 3.63 ± 5.81 book chapters and a mean ± SD of 4.99 ± 6.17 peer-reviewed medical education research publications. Ten (14%) served on journal editorial boards, 34 (48%) were journal reviewers, and 31 (44%) had received a medical education grant. CONCLUSION: EM medical education fellowship graduates are academically productive and hold education leadership positions.

The Design of an Adaptive Clinical Trial to Evaluate the Efficacy of Extra-Corporeal Membrane Oxygenation for Out-of-Hospital Cardiac Arrest.

BACKGROUND: Extracorporeal cardiopulmonary resuscitation (ECPR) is a promising therapy for out-of-hospital cardiac arrest (OHCA) that is refractory to standard therapy, but no multicenter randomized clinical trials have been conducted to establish its efficacy. We report the design and operating characteristics of a proposed randomized Bayesian adaptive "enrichment" clinical trial designed to determine whether ECPR is effective for refractory OHCA and, if effective, to define the interval after arrest during which patients derive benefit. METHODS: Through iterative trial simulation and trial design modification, we developed a Bayesian adaptive trial of ECPR for adults who experience non-traumatic out-of-hospital cardiac arrest. Our proposed trial design addresses the threats to trial success identified during the design process, which were (1) the uncertainty surrounding the cardiac arrest (CA)-to-ECPR interval within which clinical benefit might be preserved (2) the difference in prognosis between patients with an initial rhythm that is non-shockable vs. shockable. Trial subjects will be randomized 1:1 to receive either standard care or expedited transport to a hospital for potential ECPR. The CA-to-ECPR interval will be estimated in real time based on the sum of the estimated paramedic response time (911 call to scene arrival), paramedic scene time, and transport time to hospital. A Bayesian decreasing step function will be used to estimate the efficacy of the treatment with an outcome of the 90-day utility-weighted Modified Rankin Scale (uwmRS) for each rhythm subgroup and estimated CA-to-ECPR interval at pre-specified interims. The trial will adaptively lengthen the estimated CA-to-ECPR eligibility window if the treatment appears effective at the upper limit of initial eligibility window. If ECPR appears ineffective at longer estimated CA-to-ECPR intervals, the upper limit of the window for enrollment eligibility will be shortened. The analysis will be stratified by rhythm subgroup. RESULTS: With a maximum total sample size of 400, and a cap on the maximum sample size of 300 for the non-shockable rhythm subgroup, the trial design has power ranging from 91-100% to detect a benefit from ECPR for non-shockable rhythms under the various efficacy scenarios simulated and power ranging from 69-98% for shockable rhythms under the same scenarios. The trial design also has a high probability of correctly identifying the maximum CA-to-ECPR interval within which ECPR produces a clinically significant benefit of 0.2 on the uwMRS. If ECPR is equivalent to standard CA care, the type I error is 2.5% with a 99% probability of stopping enrollment early for futility in the non-shockable subgroup and a 97% probability of stopping enrollment early for futility in the shockable subgroup. CONCLUSION: This proposed adaptive trial design helps to ensure the population of patients who are most likely to benefit from treatment-as defined both by rhythm subgroup and estimated CA-to-ECPR interval-is enrolled. The design promotes early termination of the trial if continuation is likely to be futile.