Out-of-hospital Cardiac Arrest Patients Research Articles

The impact of smartphone-dispatched CPR-trained volunteers on OHCA outcomes is influenced by patient age

The early initiation of cardiopulmonary resuscitation (CPR) measures by non-professionals before the arrival of Emergency Medical Service (EMS) is known to be crucial for improving outcomes after out-of-hospital cardiac arrest (OHCA). We assessed the impact of deploying CPR-trained volunteers via a smartphone-based alerting system on the outcome of OHCA patients. In a retrospective nonrandomized cohort study, all OHCA cases in the city of Aachen over a six-year period were analysed. We compared patient data, CPR metrics, alerting system data as well as outcome data between the intervention and control groups. From June 2017 to May 2023, 101 out of 852 resuscitations were initiated by volunteers alerted via a smartphone-based alerting system in OHCA events. We found no overall rise in the return of spontaneous circulation (ROSC) rate. An age-dependent subgroup analysis indicated an increased incidence of initially shockable rhythms and an increased ROSC rate for patients younger than 60 years in the intervention group, while implying a lower ROSC rate in patients older than 80 years after mobile responder CPR. Although this study was underpowered to yield statistically significant results, our findings suggest the need for an age-sensitive approach when evaluating the effects of first-responder systems on OHCA cases.

Abstract Su605: Return of Spontaneous Circulation after Transport with Ongoing Cardiopulmonary Resuscitation: Is Transport Always Futile?

Introduction: Despite validated Termination of Resuscitation (TOR) rules for Out of Hospital Cardiac Arrest (OHCA) some OHCA patients are transported prior to Return of Spontaneous Circulation (ROSC), sometimes with long transport times. There are certain therapies unavailable in the prehospital setting which could make transport prior to ROSC beneficial for some OHCA patients. Hypothesis: We hypothesized that longer transport times for patients with ongoing Cardiopulmonary Resuscitation (CPR) would be associated with progressively lower probability of achieving ROSC. Aims: To determine if there is a transport time interval beyond which ROSC becomes so unlikely that transport time could be determinant factor for TOR. Methods: We performed a retrospective study of the 2020-2022 NEMSIS national prehospital dataset. We included adult OHCA patients that did not have ROSC prehospital, were transported to the hospital, and had outcome and timestamp data available. We calculated transport time for each encounter and stratified encounters into 5-minute transport time intervals. We defined our outcome as ROSC after transport. We used multivariable logistic regression evaluating the association between 5-minute increases in transport time and ROSC. We performed a secondary analysis of patients that met termination of resuscitation (TOR) criteria (unwitnessed OHCA with no CPR or AED placement prior to EMS arrival). Results: Of 1,409,692 OHCAs, we included 137,957 OHCAs that were transported without prehospital ROSC. The median transport time was 8.9 minutes (IQR 5.4-13.8), and 17,957 (13.1%) had ROSC after hospital arrival. In 5-minute intervals from 0-30 minutes, ROSC rates were 13.5%, 13.1%, 12.0%, 11.1%, 12.1%, and 13.9%. Odds of ROSC per 5-minute increase in transport time was 1.00 (95% CI 1.00-1.00). For patients that met field TOR criteria, rates of ROSC for each 5-minute interval from 0-30 minutes were 9.2%, 8.7%, 7.6%, 5.9%, 6.1%, 4.2%, 7.5%. Odds of ROSC per 5-minute increase in transport time was 0.93 (95% CI 0.88-0.98). Conclusion: In this dataset we were unable to identify a transport time interval up to 30 mins beyond which transport is futile, even in patients who were transported despite meeting the universal TOR rule. Decision to transport based on case-by-case OHCA characteristics could have influenced results. Further research is needed to identify the subset of patient in whom transport prior to ROSC may be beneficial.

Abstract 4137905: The association between prehospital epinephrine administration and short-term outcomes in patients with shockable out-of-hospital cardiac arrest and extracorporeal cardiopulmonary resuscitation: a propensity matched analysis

Background: In out-of-hospital cardiac arrest (OHCA) patients with an initial shockable rhythm, epinephrine increases the likelihood of return of spontaneous circulation (ROSC), but its effect on neurological outcome remains uncertain. Epinephrine administered before extracorporeal resuscitation (ECPR), which is a non-pharmacological method to obtain ROSC, may have worsened neurological outcome. Aim: To evaluate the impact of prehospital epinephrine administration on the prognosis of OHCA patients undergoing ECPR. Methods: This is a retrospective analysis of a cohort study from a multicenter, prospective registry of 81234 OHCA patients between 2014 and 2021. After the application of exclusion criteria, 1061 OHCA patients with an initial shockable rhythm and who underwent ECPR were eligible for this study. The primary outcome was favorable neurological outcome at 30 days after the OHCA and the secondary outcome was ROSC during transfer. Patients who did and did not receive prehospital epinephrine were propensity score-matched on the basis of age, gender, witness arrest, bystander-initiated CPR, dispatcher-assisted CPR, advanced airway management, call-to-defibrillation interval, year and district. Results: Among 1061 eligible patients, 442 patients received epinephrine and 619 patients did not. Matching was successful in achieving covariate balance as shown by a standardized difference of <10% for all variables (329 matched pairs). The proportion of patients with prehospital ROSC was significantly higher in those who received prehospital epinephrine than those who did not (36 [8%] vs 31 [5%]; adjusted odds ratio [OR] after propensity score-matching, 1.96 [95% CI 1.05-3.67], p=0.03). The proportion of patients with favorable neurological outcome at 30 days was not significantly lower in those who received prehospital epinephrine than those who did not (34 [8%] vs 78 [13%]; adjusted OR after propensity score-matching, 0.78 [95% CI 0.45-1.37], p=0.39). Conclusion: In patients with shockable OHCA and ECPR, prehospital epinephrine administration was significantly associated with increased ROSC before hospital arrival and not significantly with decreased favorable neurological outcome at 30 days.

Abstract Su904: The association between base excess on arrival at the hospital and neurological outcome of adult out-hospital cardiac arrest: observational study

Background: The relationship between base-excess (BE) values, which take into account the time interval from cardiac arrest to blood test, and neurological outcome after out-of-hospital cardiac arrest (OHCA) is not well understood. The purpose of this study was to evaluate the association between BE on arrival at the hospital and neurological outcomes in OHCA patients. Methods: The CRITICAL study, a prospective, multicenter observational study in Osaka, Japan, registered consecutive OHCA patients who were transported to 16 participating critical care centers from 2012 to 2021. We included adult patients aged 18 years with witnessed OHCA whose BE values on hospital arrival was available, and divided patients into quartiles based on BE values of initial blood test on arrival at the hospital: Q1 (BE ≤ −21.1 mmol/L), Q2 (−21.1 < BE ≤ −15.7 mmol/L), Q3 (−15.7 < BE ≤ −10.4 mmol/L), and Q4 (BE > −10.4 mmol/L). The primary outcome was one-month survival with favorable neurological outcome, defined as cerebral performance category scale 1 or 2. Results: A total of 23,854 patients were registered, and 6,066 of them were eligible for analyses. Neurologically favorable outcome was the lowest in the Q1 group (3.2% [49/1,528]), followed by the Q2 (4.7% [70/1,493]), Q3 (9.8% [148/1,515]), and Q4 (23.5% [359/1,530]) group. In the multivariable logistic regression analysis, the adjusted odds ratio of Q1 compared with Q4 for one-month favorable neurological outcome was 0.13 (95% CI 0.090–0.18). The proportion of one-month favorable neurological outcome decreased progressively across decreasing quartiles (p for trend < 0.001). In subgroup analysis, there was an interaction between presence of return of spontaneous circulation (ROSC) before blood test and neurological outcome (p for interaction < 0.001). The neurological outcome worsened as the BE values decreased among those who achieved ROSC before the blood test (p for trend < 0.001), but not in those without ROSC (p for trend = 0.078). There was not a significant interaction between BE values without ROSC before blood test and time from witness to blood test (p for interaction = 0.501). Conclusions: We demonstrated that lower BE values at hospital arrival were associated with worse neurological outcome. The BE values may be one of the effective prognostic indications for neurological outcome, especially in OHCA patients with ROSC before hospital arrival.

Abstract Su304: The Effect of Time to DC Shock on Return of Spontaneous Circulation in Out-of-Hospital Cardiac Arrest with Recurrent Shockable Rhythm

Objective: The optimal timing for defibrillation attempts in out-of-hospital cardiac arrest (OHCA) patients with recurrent shockable rhythms [ventricular fibrillation (VF) or pulseless ventricular tachycardia (VT)] is uncertain. This study examined the association between "time to DC shock" and the return of spontaneous circulation (ROSC) in OHCA patients with recurrent shockable rhythms. Methods: This was a retrospective analysis of data from the Salt Lake City Fire Department (SLCFD) from 2012 to 2023. Rhythm-filtering technology, used since 2012, enabled real-time and accurate interpretation of cardiac rhythms during CPR, with local protocols allowing early defibrillation for recurrent VF/ pulseless VT cases. Patients who experienced four or five episodes of shockable rhythms and received defibrillation were included. Generalized estimating equation (GEE) analysis was used to evaluate the association between time to shock preceding recurrent defibrillation and ROSC. Results: A total of 142 patients were included, with a mean age of 59.7 ± 15 years; 105 (73.9%) were male, 63 (44.4%) arrested in public locations, and 101 (71.1%) had witnessed arrests. Adjusted GEE analysis revealed that longer time to shock was associated with lower odds of achieving ROSC (OR: 0.81, 95% CI: 0.72–0.93, p = 0.005). Every one-minute delay in defibrillation is predicted to decrease the likelihood of achieving ROSC by 19%. Conclusion: In patients with recurrent shockable rhythms, every one-minute delay in delivering a shock was associated with a statistically significant 19% reduction in the chance of achieving ROSC. This finding highlights the importance of reducing the time to defibrillation in managing recurrent shockable rhythms and suggests reevaluating the current recommendation of two-minute intervals for rhythm check and shock delivery.

Abstract 4122309: Prognostic implication and hemodynamic characteristics of modified SCAI class in comatose OHCA patients: data from the BOX trial.

Background: Cardiogenic shock (CS) complicating acute myocardial infarction (AMI) is associated with high mortality. Transient myocardial stunning seen after out-of-hospital cardiac arrest (OHCA) often presents similar clinical characteristics as CS upon hospital arrival. OHCA involves a sudden cessation of circulation followed by a low-flow period during resuscitation, while CS involves prolonged myocardial dysfunction leading to hypoperfusion. The Society for Cardiovascular Angiography and Interventions (SCAI) proposed five distinct shock stages, further refined by the Cardiogenic Shock Working Group (CSWG). OHCA typically places patients in SCAI stage E, but this study abandoned that automatic classification. Methods: This post hoc analysis of the BOX trial data involved comatose OHCA patients with a presumed cardiac cause. Patients were classified using the CSWG-SCAI shock classification upon hospital admission without automatically assigning OHCA patients to stage E. Invasive arterial and pulmonary arterial measurements were taken within the first 72 hours of ICU admission. Cardiac Index (CI), cardiac power output (CPO), and perfusion pressure (mean arterial pressure minus central venous pressure) were calculated. Results: The results demonstrated that 31.6% of the 789 included patients were classified as SCAI class B/C, 29.9% as SCAI class D, and 38.5% as SCAI class E. One-year mortality for SCAI classes was as follows: B/C (21.3%), D (34.3%), and E (48.4%), with a p-value of <0.001 (Figure 1). There was no difference in CI and CPO within the first 72 hours of the ICU stay between SCAI classes. The first recorded perfusion pressure differed between SCAI class B/C and E (63.4±14.3 mmHg vs. 60±14.1 mmHg and 60.9±14.2 mmHg, respectively, p=0.008). This difference was only found at the first measurement. As lactate levels are a variable of SCAI classification, it was anticipated that there would be a significant difference in lactate at arrival. This difference in lactate remained at 36 hours after admission (1.3±0.7 mmol/L vs. 1.6±0.8 mmol/L and 1.9±1.1 mmol/L, respectively, p<0.001), but not thereafter. A higher proportion of patients developed acute kidney injury (AKI) as the SCAI classification increased (20%, 31% and 48%, respectively, p<0.001). Conclusion: One-year mortality increased with increasing SCAI classes but hemodynamic parameters within the first 72 hours of treatment did not differ between groups.

Abstract Sa1104: Head and Pulmonary Artery Chest CT Detect Most but Not All Causes of Sudden Death and Resuscitation Injury Compared to Head to Pelvis CT Angiography in Survivors of Out of Hospital Circulatory Arrest

Introduction: Head-to-pelvis “sudden death computed tomography” angiography (SDCT) has a high diagnostic yield to identify causes and complications of out-of-hospital cardiac arrest (OHCA). The differences in yields of non-contrast head CT (H-CT) and pulmonary embolism chest CT (CT PE) angiography alone or in combination is not clear. Methods: Our prospective observational cohort enrolled patients that survived OHCA resuscitation and had a SDCT (H-CT, ECG-gated chest CT, and non-ECG gated venous phase abdomen/pelvis CT) within 6 hours of arrival (December 2015 – February 2018). For this sub-study, we assessed the same scans for diagnoses obtainable from routine H-CT and CT PE axial coverage alone, excluding any added (SDCT) findings from ECG-gating and abdomen/pelvis assessment. The primary outcome was the difference in diagnostic yield of time-critical and non-time-critical diagnoses by CT PE with or without H-CT compared to SDCT. Results: SDCT identified 86 time-critical diagnoses in 104 enrolled patients, including 39 pneumonias (45% of diagnoses), 13 myocardial infarctions [MI] (15%), 8 pulmonary embolisms (9%), 8 pneumothoraces (9%), 8 abdominal catastrophes (9%), 3 intracranial hemorrhages (3%), and 1 vascular access hemorrhage (1%) [ Table ]. CT PE alone identified 61 of the 86 time-critical diagnoses (71%), missing 25 diagnoses (29%) compared to SDCT. Missing diagnoses included MI (13/13), abdominal catastrophe (8/8), and active vascular access hemorrhage (1/1). H-CT diagnosed all 3 intracranial hemorrhages. Of the 208 non-time-critical diagnoses identified by SDCT, CT PE identified 183 non-time critical diagnoses (88%), missing 25 diagnoses (12%). H-CT did not identify any non-time-critical diagnoses. Conclusions: CT PE imaging with H-CT identifies a majority—but not all—time-critical and non-time-critical diagnoses in OHCA patients, mainly failing to capture coronary and intra-abdominal pathologies. SDCT, which includes ECG-gated chest CT and abdomen/pelvis CT, improves total diagnostic yield, but its incremental utility requires further study.

Abstract Su404: Time difference between pad placement in double versus single external defibrillation: a live patient simulation model

Background: Out-of-hospital cardiac arrest (OHCA) cause significant patient morbidity and mortality. Double sequential external defibrillation (DSED) represents an alternative treatment for OHCA patients, but the use is currently reserved for patients in refractory ventricular fibrillation. However, OHCA patients may achieve return of spontaneous circulation earlier with the use of DSED as the initial treatment. Aims: To compare the necessary times needed to establish pad placement in DSED compared to standard pad placement in a live patient simulation model. Methods: This study was an observational cohort study with ambulance personnel and live patient models. Two-member teams established two defibrillators ready for rhythm analysis. Time spent for standard pad placement and DSED was registered in the same procedure. The procedure was performed on two patient categories, with BMI 20,9 (patient A) and BMI 32,8 (patient B). All team members performed the procedure on both patient categories. Results: In total, 108 procedures were performed on both patient categories. Mean difference in time needed for DSED versus standard pad placement was 13.7 ± 4.8 seconds for patient A, and 13.9 ± 4.6 seconds for patient B. There was no significant difference in time spent between the two patient categories (p=0.725). Conclusion: The necessary time to establish DSED versus standard defibrillation pad placement was short. This may support clinical studies on DSED as initial treatment for OHCA patients without risk of significant increase in time to first defibrillation.

Abstract Su1201: Alteration in cerebrospinal fluid flow in out-of-hospital cardiac arrest patients who underwent target temperature management.

Background: Various parameters of cerebrospinal fluid (CSF) flow measured through magnetic resonance imaging (MRI) flowmetry are utilized to assess the progression of certain diseases. Our study evaluated changes in CSF flow using MRI flowmetry in survivors of out-of-hospital cardiac arrest (OHCA) who underwent target temperature management (TTM). Methods: This prospective observational cohort study was conducted from May 2023 to April 2024 at a single center. We performed Wilcoxon signed-rank tests to compare maximum velocity (V max ), stroke volume (SV), maximum flow (flow max ), and stroke distance measured immediately after return of spontaneous circulation (ROSC) with those measured at 72 h after ROSC. Results: Of the 20 patients enrolled, 7(35.0%), 1(5.0%), 2(10.0%), 5(25.0%) and 5(25.0%) patients had CPC scores of 1, 2, 3, 4, and 5, respectively. V max , SV, flow max , stroke distance measured immediately after ROSC were 3.41 (2.03~4.96), 14.00 (4.00~23.38), 0.09 (0.06~0.22), -0.07 (-0.17~0.05), respectively. V max , SV, flow max , stroke distance measured at 72h after ROSC were 5.26 (2.76~9.28), 24.00 (10.38~42.25), 0.14 (0.08~0.31), -0.07 (-0.18~0.03), respectively. Although V max , SV, and flow max measured at 72 h after ROSC were statistically significantly higher compared to those measured immediately after ROSC (p = 0.002, 0.02, 0.002), there was no significant difference between the stroke distances measured immediately after ROSC and at 72 h after ROSC (p = 0.43). Additionally, the caudocranial direction of CSF flow was observed in 13 (65.0%) patients immediately after ROSC, and in 14 (70.0%) patients 72h after ROSC. Conclusion: This study demonstrated that alterations in cerebrospinal fluid flow were observed in OHCA patients. However, Further studies are needed to determine whether there are differences in alteration in CSF flow based on neurological prognosis.

Abstract Su1206: Reduced Time to Goal Therapeutic Hypothermia With Implementation of a Post Cardiac Arrest Consult Service

Introduction: Critical care after advanced cardiac life support can be pivotal for survival and outcomes in patients with out-of-hospital cardiac arrest (OHCA). Prior studies have demonstrated improvements in survival after OHCA with shorter door-to-therapeutic hypothermia (TH) initiation times. Post-cardiac arrest consult teams (PCACT) can facilitate TH to goal 33°C and other aspects of post-arrest care. However, the effects of such a service on TH have not been consistently quantified. Hypothesis: More OHCA patients would undergo TH and reach goal temperature sooner following implementation of a PCACT. Aims: We aim to evaluate the effectiveness of a PCACT in optimizing TH in survivors of OHCA. Methods: We conducted a retrospective chart review of 305 patients admitted between January 1, 2021 and December 31, 2022. Implementation of a dedicated PCACT, comprised of a neurointensivist and an advanced practice provider or neurocritical care fellow, occurred on January 1, 2022. The PCACT was active on weekdays only. One year before and after this date were designated as “pre-PCACT” and “post-PCACT”, respectively. De-identified patient demographics, clinical features of cardiac arrest, and TH data were collected and compared using Wilcoxon rank-sum and Chi-squared tests for continuous and categorical variables, respectively. Results: Of the 305 patients admitted during the study period, 149 were in the pre-PCACT group and 156 were in the post-PCACT group. Baseline demographics between the two groups were similar except that the post-PCACT group had more patients with non-shockable rhythms (64% vs. 54%, p =0.001). Patients were not cooled to 33°C more frequently (50 vs. 52%) pre- or post-PCACT. TH to 33°C was performed in 156 (51%) patients, 78 patients (50%) pre- and post-PCACT implementation. There were no baseline demographic or temperature differences between the two groups amongst patients undergoing TH to 33°C. Post-PCACT patients were quicker to reach 33°C (1.6 vs. 3 hours, p =0.001). After PCACT implementation, this difference was noted during weekdays but not during weekends (1.3 vs. 2.7 hours, p =0.05).There were no differences in survival or neurologic outcomes pre- and post-PCACT introduction, nor between patients who were or were not cooled to 33C. Conclusion(s): Implementation of a PCACT may streamline care to reduce time to goal temperature during TH. However, further study is required to determine whether a PCACT can improve outcomes.

Abstract 4137065: Efficacy and Safety of Extracorporeal CPR in Out-of-Hospital Cardiac Arrest Survival and Neurological Integrity: a Meta-Analysis of Randomized Controlled Trials

Introduction: Out-of-hospital cardiac arrest (OHCA) remains a significant public health challenge, with conventional cardiopulmonary resuscitation (CPR) often yielding limited success. Extracorporeal CPR (eCPR) has emerged as a potential adjunctive therapy to improve outcomes in OHCA patients. Purpose: To evaluate the efficacy and safety of eCPR compared to conventional CPR in OHCA. Methods: A comprehensive search of Cochrane CENTRAL, PubMed, Ovid Medline, and Web of Science databases was conducted independently until November 10, 2023. Randomized controlled trials (RCTs) comparing eCPR with conventional CPR in OHCA were included. Primary efficacy outcome was defined as survival to hospital discharge, while primary safety outcome was assessed for bleeding events. Summary effect measures of the primary outcomes were obtained by pooling the data with an inverse variance–weighted random-effects model. A sensitivity analysis was performed regarding whether the conclusions reached might differ substantially if a single study was omitted. Statistical analyses were performed with “meta” package in R (version 4.3.2) and Revman 5.4. Results: Four unique RCTs involving 435 patients were included in the analysis. ECCPR was associated with a significantly higher rate of survival at 1 month with good neurological outcome (Risk Ratio [RR] 1.55, 95% Confidence Interval (CI) 1.06 to 2.27, I 2 : 0%) but comparable at survival to hospital discharge (RR 1.10, 95% CI 0.16 to 7.30, I 2 : 47%) compared to conventional CPR. Furthermore, no significant differences were observed between eCPR and conventional CPR groups in survival rates at 3 months (RR 1,33, 95% CI 0.92 to 1.94, I 2 : 64%), survival at 6 months with good neurological outcome (RR 1.39, 95% CI 0.97 to 1.99, I 2 : 0%), and survival at 6 months (RR 2.79, 95% CI 0.33 to 23.28, I 2 : 63%). eCPR demonstrated a statistically significant elevation in bleeding events compared to conventional CPR (RR 4.25, 95% CI 2.37 to 7.64, I 2 : 0%). Sensitivity analysis revealed that none of the studies significantly influenced the pooled risk estimate to any great extent. Conclusion: eCPR shows beneficial results in improving short-term survival and neurological outcomes at 1-month post-OHCA. However, it is associated with an elevated risk of bleeding when compared to conventional CPR. Further investigations are imperative to delineate the specific patient populations that stand to gain the most benefit from ECPR intervention.

Abstract Su906: Patient and Arrest Characteristics Associated with Rearrest and Mortality Following Out of Hospital Cardiac Arrest

Background: Cardiac rearrest post-return of spontaneous circulation (ROSC) is a critical concern in emergency care, as it is associated with worse outcomes. Patient characteristics and arrest factors associated with rearrest remain poorly understood, making predicting rearrest after out of hospital cardiac arrest (OHCA) challenging. Aim: To examine rearrest patterns, identify patient-specific risk factors for rearrest, and assess the impact of rearrest on patient outcomes. Hypothesis: Patients that experience rearrest after OHCA will have greater cardiac comorbidities, unfavorable arrest characteristics, and greater mortality. Methods: We performed an observational single-site clinical trial of consecutive adult EMS OHCA patients with ROSC (1/01/2018 to 3/31/24). EMS reports, continuous EMS ECG recordings, and electronic health records were analyzed to determine rearrest occurrence at any time during EMS and ED care. Patient demographics, comorbidities, and arrest/rearrest characteristics were determined. The primary outcome was survival at 6 months. Statistical significance was determined using Chi-square and logistic regression (LR) analyses. Results: We examined 344 patients with OHCA and ROSC, of whom 173 patients rearrested and 171 did not. Patients experiencing rearrest were older (p<0.003) and more likely to be female (p<0.013). They were also more likely to have ED resuscitation medications and interventions (epinephrine, amiodarone, lidocaine, defibrillation, all p<0.001) and a higher incidence of underlying cardiovascular comorbidities, including HTN and CAD (p<0.03). Notably, PEA and asystole were the most common rearrest rhythms, and time from arrest to ROSC was greater (30±16 vs. 25±15 min, p<0.007) in rearrest patients vs. those who did not rearrest. Patients with rearrest were less likely to receive TTM (p<0.003) and importantly, had higher rates of in-hospital and six-month mortality (both p<0.001). In a LR model, no rearrest (OR 2.4, 1.1-5.2), shockable arrest rhythm (OR 9.3, 4-22), female sex (OR 3.3, 1.6-6.5), and therapeutic hypothermia (OR 3.3, 1.7-6.4), were associated with survival (all p<0.04). Conclusions: Rearrest is independently associated with mortality. Increased age, male sex, and underlying cardiac comorbidities were associated with rearrest. Patient and arrest characteristics may predict rearrest. Improved understanding of why these factors promote rearrest will be important to prevent rearrest to enhance OHCA outcomes.

Abstract Su703: Racial/Ethnic Disparities in Bystander Cardiopulmonary Resuscitation after Witnessed Out-of-Hospital Cardiac Arrest: A NEMSIS Database Study

Introduction: Out of hospital cardiac arrest (OHCA) is a leading cause of death in the United States, with upwards of 360,000 OHCAs annually. Receiving bystander cardiopulmonary resuscitation (CPR) almost doubles an individual’s odds of survival compared to those who don’t receive bystander CPR. Unfortunately, in the US, bystander application of CPR only occurs in 40% of OHCA. Improving the rate of bystander CPR and AED use will improve survival rates for OHCA. Minoritized populations experience worse outcomes from OHCA. Compared to non-Hispanic whites, they are less likely to survive to hospital discharge. A cross-sectional study of witnessed OHCA patients found that Black and Hispanic patients had lower rates of bystander CPR. Less is known about disparities in care for Asian American persons who experience OHCA. Studies using the Resuscitation Outcomes Consortium Epidemiologic Registry (ROC) and the Cardiac Arrest Registry to Enhance Survival (CARES) have concluded discrepant results, with ROC finding that Asian Americans were less likely to receive bystander CPR and CARES finding that they were just as likely to receive bystander CPR compared to non-Hispanic Whites. To that end, we sought to evaluate the association between bystander CPR and Asian race after witnessed OHCA. Objective: To evaluate the association between race/ethnicity and the odds of receiving bystander cardiopulmonary resuscitation (bCPR) after witnessed out-of-hospital cardiac arrest (OHCA). Methods: Data were obtained from the National Emergency Medical Services Information System (NEMSIS) database for adults (≥18 years) with a witnessed non-traumatic OHCA in the year 2022. Patients were separated into two groups: Non-Hispanic White and Asians. The primary outcome was the odds of receiving bCPR. Exclusions included traumatic etiology, do-not-resuscitate orders, and arrests witnessed by healthcare providers. Pearson’s chi-square test was used to test significance. Results: A total of 73,215 witnessed OHCA activations were included in this study. Overall, bystander CPR rates were lower for the Asian group (59.8%) compared to the Non-Hispanic White group (65.0%). Pearson’s chi-square test showed a statistically significant difference between the bCPR rates of the Asian group and Non-Hispanic White group, with a p-value of less than 0.001. Conclusion: Racial/ethnic disparities exist for Asian individuals in the odds of receiving bCPR after a witnessed non-traumatic OHCA.

Abstract Sa1103: Utility of early Computed Tomography after out-of-hospital cardiac arrest resuscitation

Background: Initial care after out-of-hospital cardiac arrest (OHCA) poses major challenges to clinical teams due to diverse arrest etiologies and the potential need for time-sensitive interventions. Emergency department-based evaluation of these patients is crucial for identifying treatable causes of arrest. Recent data from one academic hospital highlights the potential importance of initial broad computed tomography (CT) immediately following resuscitation. Objective: To assess the ability of early post-arrest CT imaging to diagnose potential etiologies and sequelae of OHCA. Methods: We employed a registry of consecutive OHCA cases admitted to 3 hospitals within the University of Pennsylvania Health System between 1/2019-10/2020, collecting demographic, arrest, and post-arrest clinical data. Inclusion criteria included age >18 y, OHCA with return of spontaneous circulation (ROSC). We abstracted CT data including findings, contrast use, and timing, and subsequent clinical notes to assess for interventions performed based on CT findings from the EHR. KDIGO definition was used for acute kidney injury (AKI). SAS software was used for data analysis. Results: A total of 161 OHCA patients were included (mean age 60.8±15.6y; 42% female). Initial shockable rhythms were present in 16%, with 70% witnessed and 39% receiving bystander CPR. 154 patients survived to admission, and 41 survived to discharge. 117 patients underwent CT imaging in the ED: 117 underwent head CT, 87 chest CT, and 64 abdomen/pelvis CT. Median time to any first CT was 2.0h (IQR:1.4,2.8). Intracranial hemorrhage was diagnosed in 5/117 patients (4.3%); 3 received conservative therapy. Cerebral edema was found in 30/117 patients (25.6%), 10 received treatment. Pulmonary embolism was diagnosed in 8/87 cases (9.2%), 7 of which were acute and treated pharmacologically and/or mechanically. Aspiration and/or pneumonia, pneumonitis, bronchitis, bronchiolitis was found on 65/84 cases (74.7%), 30 received antibiotics. Deep venous thrombosis was detected in 3/64 patients (4.7%), 2 received anticoagulation. We found no significant differences in AKI rates with the use of contrast compared to patients receiving no contrast (p=0.93). Conclusion: These results confirm and extend other reports emphasizing the potential value for routine use of CT imaging post-ROSC. Implementing larger scale prospective studies comparing such protocols and standard-of-care is important to determine impact on OHCA outcomes.

Abstract Su701: The Influence of Public Assistance Among Patients Who Received Extracorporeal Cardiopulmonary Resuscitation after Cardiac Arrest in Japan

Background: This study aimed to evaluate the influence of public assistance on patients with out-of-hospital cardiac arrest (OHCA) who received extracorporeal cardiopulmonary resuscitation (ECPR) in Japan. Methods: We conducted a secondary analysis of data from the SAVE-J II study, a retrospective, multicenter registry study involving 36 participating institutions in Japan. Patients with cardiac arrest who received ECPR were divided into two groups depending on whether or not they had received public assistance. The primary outcome was 30-day survival. Secondary outcomes were as follows: 30-day favorable neurological outcomes (cerebral performance category scores 1-2); survival at discharge; favorable neurological outcome at discharge; number of intensive care unit, hospital, ventilator, and extracorporeal membrane oxygenation days; medical expenses; proportion of percutaneous coronary intervention; target temperature management; mechanical circulatory support (MCS) device use; and withdrawal of life-sustaining therapy. Results: Of 2,157 patients registered in the SAVE-J II study, 1,885 patients were enrolled in this study; 99 patients (5.3%) received public assistance and 1,786 patients (94.7%) did not. Multivariable logistic regression analysis did not show a significant difference in 30-day survival (OR 1.22, 95% CI 0.77-1.95, p=0.40). The log-rank test for the Kaplan-Meiercurve on 30-day survival did not demonstrate a significant difference (p=0.46). Except for the use of MCS devices, there were no significant differences in secondary outcomes. Conclusions: The use of public assistance did not influence the prognoses of OHCA patients receiving ECPR. Treatment option during hospitalization may be affected by the use of public assistance.

Abstract Su607: Which would be major? witnessed collapse or bystander resuscitation?

Background: Witnessed collapse and bystander cardiopulmonary resuscitation (CPR) are two variables commonly used to predict outcomes in out-of-hospital cardiac arrest (OHCA). Some published studies have shown that bystander CPR were not significantly associated with outcomes after confounders adjusted. This may imply that witnessed collapse would be a superior prognostic factors beyond bystander CPR. Hypothesis: Witnessed collapse and bystander CPR may not contribute equally to prehospital return of spontaneous circulation (ROSC), and the former may be major. Aims: To investigate four prediction models for prehospital ROSC using stratification of the witnessed collapse and bystander CPR. Methods: The study enrolled OHCA patients treated by the emergency medical service (EMS) from January 2010 to December 2022 in three EMS systems in Taiwan. Data were extracted from the records of each medical service encounter, including patient demographics, dispatch timing, prehospital management, witnessed collapse and bystander CPR. The primary outcome was any prehospital ROSC. Patients were stratified into four groups by witnessed collapse (with/without) and bystander CPR (with/without) status, namely W+B+, W-B+, W+B- and W-B-. Prehospital ROSC prognostication were identified using multivariable logistic regression analysis. Results: The analysis comprised 17,323 patients, among whom 1,165 (6.7%) achieved prehospital ROSC. The W+B+ group demonstrated the highest prehospital ROSC rate at 13.0%, as compared with the other groups significantly (9.0%, 3.4%, and 4.1%, as depicted in Image 1). Stratification of the prehospital ROSC model (Image 2) indicated that the W+B+ group had several common predictors including age, traumatic arrest, no-flow time, public access defibrillation (PAD), and resuscitation events. However, certain predictors in other groups were removed during regression process. Notably, no-flow time significantly influenced prehospital ROSC only in the W+B+ and W+B- groups. Conversely, in the W-B- group, most variables had minimal impact on prehospital ROSC, reflecting the limited effectiveness of traditional predictors within this subgroup. Conclusion: The significance of witnessed collapse as a prognostic factor may be equal to or even greater than that of bystander CPR. Further studies are needed to confirm.

Abstract Su507: Occurrence of Fibrillation in Out-of-hospital Cardiac Arrest Patients Presenting in a Non-shockable Rhythm when Treated with an Automated External Defibrillator

Background: Most out-of-hospital cardiac arrest (OHCA) patients who are initially treated with an automated external defibrillator (AED) and present in a non-shockable rhythm never receive a shock. This analysis reports on patients who presented in a non-shockable rhythm when the AED was initially applied and later transitioned into a shockable rhythm. Methods: Data from a convenience group of OHCA patients treated with a Philips HeartStart Home, Onsite or FRx AED were included. The AEDs were the first defibrillator on scene either in home, in public access or by a BLS team. Application of any medication during AED use was unlikely. Each patient’s heart rhythms were reviewed by an expert. All patients whose initial rhythm was non-shockable but later received at least one shock were identified and the rhythms were analyzed. Results: Out of 876 patients, 322 (36.8%) received at least one shock, of which five patients (1.6%) presented in a non-shockable rhythm and were later shocked. Three patients presented in an organized rhythm. The first patient degraded into Torsade de Pointe as shown in Figure 1; the post-shock rhythm was organized. The second patient received no CPR and A-V pacing was observed in the ECG recording. The pacing stopped when the rhythm transitioned into VF and restarted post shock. The third patient transitioned into VF during chest compressions and the post-shock rhythm was asystole. The remaining two patients presented in asystole and the rhythm evolved to fine VF after receiving chest compressions. After defibrillation, their rhythms returned to asystole. Conclusions: For OHCA patients treated with an AED, presenting in a non-shockable rhythm and later transitioning into a shockable rhythm is rare but possible. Lay-responder CPR may play a role in rhythm evolvement. The impact of rhythm changes on survivability of these patients is unknown.

Abstract Su603: Out-of-hospital cardiac arrest presenting with ST-segment elevation myocardial infarction: Real world assessment and treatment

Background: Coronary artery disease is a common cause of out-of-hospital cardiac arrest (OHCA). Early recognition myocardial infarction (MI) and initiating appropriate therapy has been shown to improve outcomes in OHCA. While early coronary intervention is part of guidelines-based care, the implementation of these recommendation in actual US practice remains poorly described. Objectives: This study aims to characterize patients presenting with OHCA and MI in a cohort from 4 hospitals, to assess care of these patients in actual practice. Methods: We employed a database of OHCA patients admitted to four hospitals within the University of Pennsylvania Hospital System between 01/2019-12/2023. For this study, we included all patients that were diagnosed with STEMI during emergency department evaluation, and collected demographic, arrest, coronary angiographic, and ECG data from electronic health records. SAS was used for statistical analysis. Results: A total of 43 MI cases were included; mean age was 60.6±11.8 y, 65% male, mean BMI 30.0±6.3, 58.1% African American, 27.9% White or Caucasian, and 16.3% had a medical history of myocardial infarction. 74.4% were witnessed, and 44.2% received bystander CPR[BA1]. Initial shockable rhythm was present in 34.9%. 38 survived to hospital admission, and 9 were discharged alive. The first obtained 12-lead ECG (median time to ECG: 13min, (IQR: 3.5-26.5)) found that ST-segment elevations were present in 88.4%, ST-segment depressions in 44.2%, T-wave inversions in 4.7%, QT prolongation in 9.3%, and wide QRS in 18.6%. Sinus rhythm was most common (41.9%), followed by junctional rhythm (9.3%). Left and right bundle branch blocks (4.3% and 7%, respectively) and AV block (7%) were recorded. Coronary angiography (median time to angiography: 1.95hr (IQR: 1.3-4.2)) was performed in 29 patients and revealed that left anterior descending artery (28.6%) was the most common location for a culprit lesion, followed by the right coronary artery (21.4%), and left circumflex artery (10.7%). Notably, in 21.4% of cases, no culprit lesion was identified. 13 patients underwent angioplasty with stent, 4 received balloon angioplasty, and 1 underwent aspiration thrombectomy. Conclusion: This study highlights important attributes of OHCA patients presenting with MI. This paves the way for larger studies comparing ECG and coronary angiography findings between MI and control populations to help identify and improve acute care for OHCA MI patients.

Sex-related differences in the association of obesity described by emergency medical teams on outcomes in out-of-hospital cardiac arrest patients.

Out-of-hospital cardiac arrests (OHCA) are a major global health concern, occurring frequently worldwide. Obesity may impact outcomes in OHCA patients. This study aimed to assess the impact of obesity on the return of spontaneous circulation (ROSC) in OHCA patients, considering sex differences. A retrospective cohort study was conducted, analyzing medical records of patients assisted by the Emergency Medical System (EMS) in Poland from January 2021 to June 2022. The study included 33,636 patients with OHCA. Obesity status was determined using ICD-10 codes (E66) and descriptive diagnoses recorded by EMS teams. Univariate analysis indicated that obesity decreased the odds of ROSC by 25.47% (odds ratio (OR) = 0.75, 95% confidence interval (95% CI): 0.61-0.92) in women and by 19.76% (OR = 0.80, 95% CI: 0.66-0.97) in men. However, multivariate analysis, adjusting for confounding variables, did not confirm a statistically significant impact of obesity on ROSC outcomes. The likelihood of ROSC was significantly higher in individuals with an initial ventricular fibrillation (VF) or pulseless ventricular tachycardia (pVT) rhythm compared to Asystole/pulseless electrical activity (PEA), being 4.204 times higher in women (95% CI: 3.525-5.014) and 3.655 times in men (95% CI: 3.320-4.023). Out-of-hospital cardiac arrest in a public place increased the odds of ROSC more than twofold for both sexes (women: OR = 2.20, 95% CI: 2.00-2.43; men: OR = 2.13, 95% CI: 1.98-2.29). Among women without obesity, hypertension decreased the odds of ROSC by 11.11% (OR = 0.89, 95% CI: 0.81-0.99). Our study demonstrated that obesity was not an independent predictor of ROSC in OHCA patients. Different predictors of ROSC were identified for men and women. Initial VF/pVT rhythm, location of OHCA and age were the significant factors influencing ROSC.

The association between intra-arrest arterial blood pressure and return of spontaneous circulation in out-of-hospital cardiac arrest

BackgroundThe optimal haemodynamic parameter for goal-directed resuscitation in out-of-hospital cardiac arrest (OHCA) remains uncertain. This study aimed to characterise the association between invasive blood pressure (IBP) measurements and return of spontaneous circulation (ROSC) in adult OHCA patients, to identify this parameter. MethodsA retrospective observational study was conducted at East Anglian Air Ambulance (EAAA). Adult (≥18 years) medical OHCA patients attended by EAAA between 01/02/2015 and 01/02/2024, who had arterial IBP measurement during chest compressions were included. The initial, minimum, maximum, average (mean) and Δ (maximum-initial) were calculated for systolic (SBP), diastolic (DBP) and mean arterial (MAP) components of IBP. Logistic regression and receiver operating characteristic curves tested the association between IBP variables and ROSC. ResultsDuring the study period, 4363 OHCA patients were attended and 80 met inclusion criteria. Thirty-four patients (42.5 %) achieved ROSC and 4 (5.0 %) survived to discharge. The maximum, average and Δ DBP; and maximum and average MAP were positively associated with ROSC. Maximum DBP had an AUC of 0.83 (95 % CI 0.74–0.92) with an optimal cut-off of 35 mmHg (sensitivity 94.1 %; specificity 58.7 %) for predicting ROSC. The odds ratio for ROSC was 1.05 (95 % CI 1.03–1.08) for every 1 mmHg increase in maximum DBP. ConclusionsThis study supports the use of arterial DBP as an important haemodynamic parameter for goal-directed resuscitation in adult OHCA. Maximising DBP may increase the chances of ROSC. These data suggest that a DBP threshold of 35 mmHg is optimal for identifying patients who may achieve ROSC with continued resuscitation.