bluuebunny/crossref_metadata_2025 huggingface dataset:
Abstract 161: Impact Of Leukocyte Filtration And Leukocyte Modulation On Myocardial Injury After Prolonged Cardiac Arrest Treated With Extracorporeal Cardiopulmonary Resuscitation In A Swine Model
Authors: Nakashima Takahiro , Liao Jinhui , VanZalen Jensyn , Phillips Annie , Hill Joseph , Harvey Stephen , Longan Keenan , Westover Angela , Lou Liandi , HUMES HARVEY D , Bartlett Robert , Rojas-Pena Alvaro , Neumar Robert W
Published: June 2023

Background:
Post-arrest myocardial dysfunction is one of the major causes of rearrest within early period after return of spontaneous circulation (ROSC). Multiple interacting processes including leukocyte-mediated injury is suspected to contribute to deterioration of cardiac function after cardiac arrest. Unlike the standard leukocyte filter (LF), the leukocyte modulation (L-MOD) device is expected to alter the natural inflammatory process by preferentially binding and inactivating the activated leukocytes. We tested the hypothesis that either a standard LF system or a L-MOD device will decrease myocardial injury during extracorporeal cardiopulmonary resuscitation (ECPR).

Methods:
Total 34 swine (45.5±2.5 kg, male=18, female=16) underwent 8 minutes of untreated ventricular fibrillation cardiac arrest followed by mechanical CPR for 30 minutes. Immediately followed by 8 hours of ECPR with randomly assigned leukocyte treatment protocol; ECPR with standard care (n=10), LF (n=12), and L-MOD (n=12). Left ventricular ejection fraction (LVEF) was evaluated hourly by transthoracic echocardiography. At the end of the study, the heart was removed, fixed and embedded in paraffin. 5- μm sections off the left and right ventricular (RV) free wall were H & E stained for analysis. Five views each of LV and RV under 20хobjective lens were randomly selected with Leica LAS X software. Myofiber degeneration and hemorrhage were graded as 0 (absence) to 3 (severe). Grade was average of 5 views.

Results:
The mean LVEF at baseline was 65±6%. There were no significantly difference in rate of achieving ROSC (70% vs. 75% vs. 58.3%, p=0.671) and LVEF at 8 hours after initiating ECPR (35±27% vs. 36±31% vs. 28±30%, p=0.776) between the group with control, LF, and LMOD respectively. There were no significant difference in myofiber degeneration grade (LV, 1.5±0.5 vs. 1.1±0.6 vs. 1.4±0.4, p=0.334; and RV, 1.6±0.6 vs. 1.8±0.7 vs. 1.5±0.6, p=0.525) and hemorrhage grade (LV, 0.0±0.1 vs. 0.0±0.1 vs. 0.0±0.1, p=0.841; and RV, 0.0±0.0 vs. 0.0±0.0 vs. 0.0±0.0) between control, LF, and L-MOD groups.

Discussion:
In swine model with prolonged cardiac arrest treated with ECPR, a standard LF system and a L-MOD device did not decrease early myocardial injury.
Abstract 163: Lung Inflation Occurs Infrequently In Most Patients During 30:2 CPR With Bag-Valve-Mask Ventilation
Authors: Idris Ahamed H , Aramendi Elisabete , Leroux Brian , Jaureguibeitia Xabier , Shaver Sarah , Kudenchuk Peter J , Rea Thomas , Christenson Jim , Chang Mary , Vaillancourt Christian , Blackwood Jennifer E , Salcido David D , Callaway Clifton W , Owens Pamela , Wang Henry
Published: June 2023

Background:
Few studies have measured ventilation early in cardiopulmonary resuscitation (CPR) before advanced airway placement. In 30:2 CPR, there is a pause to give two ventilations after each round of 30 chest compressions. Recently, we developed a method to identify lung inflation (ventilation) waveforms from thoracic bioimpedance defibrillator recordings measured through defibrillator pads. Early work showed that in 75% of patients receiving bag-valve-mask (BVM) ventilation, lung inflation waveforms occurred in less than half of pauses in chest compressions during 30:2 CPR.

Objective:
To determine the incidence of lung inflation with BVM during 30:2 CPR in a multi-center study.

Methods:
Our study included adult out-of-hospital cardiac arrest patients from five sites of the Resuscitation Outcomes Consortium Trial of Continuous or Interrupted Chest Compressions during CPR. Patients had 30:2 CPR with ≥ two minutes of thoracic bioimpedance signal recorded with a defibrillator (Lifepak, Physio-control, Redmond, WA or MRx, Philips, Andover, MA). Previously, we defined a ventilation waveform as having a bioimpedance amplitude ≥0.5 Ohm (corresponding to ≥ 250 ml Vt) with a duration ≥1 sec. A valid pause was 3 sec to 15 sec. An automated program analyzed the recordings. We describe groups with ventilation waveforms in <50% or ≥50% of pauses.

Results:
We included 1,552 patients; mean age was 66 years, 67% were male, mean (±SD) duration of 30:2 CPR was 9.9 ±5.8 min from the start of chest compressions until advanced airway placement. During this period there was a total of 21,705 pauses in chest compressions, a median of 12 pauses in chest compressions, and a median of 5 ventilations; 56% of patients had ventilation waveforms in <50% of pauses (Group 1, N=868), and 44% had waveforms in
>
50% of pauses (Group 2, N=678). The median (IQR) number of pauses in Group 1 vs. Group 2, was 12 (8, 20) vs. 12 (7, 17) and the median number of ventilations was 3 (1, 6) vs. 13 (7, 21), respectively, during 30:2 CPR. The median duration of pauses for Group 1 vs. Group 2, was 5.8s (5.0, 6.5) vs. 5.7s (5.0, 6.7).

Conclusion:
For most patients, this multi-center study showed that ventilation waveforms were present in less than 50% of pauses in chest compressions during 30:2 CPR with BVM ventilation.
Abstract 171: Correlation Between The Neurological Pupil Index And Blood Brain Barrier Permeability In Out Of Hospital Cardiac Arrest Patients Treated With Target Temperature Management
Authors: You Yeonho , Kang Changshin , Ahn Hong Joon J , Park Jung Soo , Jeong Won-joon , Min Jinhong , In Yong N
Published: June 2023

BBB disruption following OHCA causes poor neurological prognosis and the changes in the prognostic value of biomarkers. However, several tools to evaluate BBB disruption are either invasive or cannot provide a continuous monitoring. Blood retina barrier (BRB) is similar with BBB anatomically and functionally, and BRB disruption influences the pupillary light reflex (PLR). Therefore, we studied on the correlation between BBB permeability and NPi in OHCA patients treated with TTM.This study was prospectively conducted between October 2020 and March 2022 (**** IRB 2019-07-033-09). NPi and Albumin quotientt (Qa) to determine BBB permeability were presented every 2 h until 24 h, and then 48 h and 72 h after ROSC. 25 patients were required after sample size calculation, and partial correlation analysis between NPi and Qa was performed with prognostic control. Changes in NPi and Qa over time were analysed using the generalised estimating equation. Basal characteristics were in table 1 and figure 1. Since this study aimed to elucidate the correlation between NPi and Qa, data on NPi and Qa during seizures were included in this study. Additionally, the drug used in this study was found to have no effect on NPi in previous studies. NPi was lower, and Qa was higher in the group with poor neurological prognosis (Table 2,3, and Fig. 2). There was a moderate negative correlation between NPi and Qa (Fig. 3).This study demonstrated that NPi had a moderate negative correlation with BBB permeability in OHCA patients treated with TTM. Therefore, further studies on prognostic strategies using biomarkers and NPi considering the increase in BBB permeability are needed.

1
Abstract 174: Usefulness Of Cerebrospinalfluid Partial Pressure Of Carbone Dioxide As A Predictor Of Poor Neurological Outcomes In Cardiac Arrest Patients Who Underwent Target Temperature Management.
Authors: JEON SOYOUNG , Ahn Hong Joon , Park Jung Soo , You Yeonho , Yoo Insool , Kim Seung Whan , Lee Jinwoong , Ryu Seung , Jeong Wonjoon , Cho Yongchul , Kang Changshin
Published: June 2023

Aim:
We aimed to predict the six-month neurological outcomes of out-of-hospital cardiac arrest(OHCA) patients who underwent target temperature management(TTM) using cerebrospinal fluid(CSF) partial pressure of carbon dioxide(PCO
2
).

Hypothesis:
We hypothesized that CSF PCO
2
would decrease after cardiac arrest. The buffer system and viscosity of the CSF change when the blood-brain barrier ​​and blood cerebrospinal fluid barrier are disrupted and ions and proteins are released from damaged neurons and cells into the CSF.

Methods:
We performed gas analysis of arterial blood and CSF samples to assess the PCO
2
of OHCA patients who underwent TTM from November 2018 to August 2021. The PCO
2
was assessed immediately (Day 0) and 24h (Day 1), 48h (Day 2), and 72h (Day 3) after the return of spontaneous circulation (ROSC). The primary outcome was Cerebral Performance Category 3-5 six months after cardiac arrest.

Results:
Of 67 (males, 49; 73.1%) enrolled patients, thirty-nine(58.2%) had a poor neurologic outcome. The poor neurologic outcome group had significantly lower CSF PCO
2
each time after ROSC (Figure 1). The area under the curve of the CSF PCO
2
on Day 1 was 0.823 (95% confidence interval [CI], 0.692-0.915), with a cutoff value of 30 mmHg.

Conclusion:
The CSF PCO
2
was lower at each time point after the ROSC for the patients with poor neurologic outcomes, and it maybe a useful predictor of neurologic outcomes of OHCA survivors treated with TTM.
Abstract 176: Development Of A Novel Score To Predict Brain Death After Out Of Hospital Cardiac Arrest
Authors: Kitlen Eva , Kim Noah , Rubenstein Alexandra , Keenan Caitlyn , Greer David M , gilmore emily j , Beekman Rachel
Published: June 2023

Introduction:
Brain death occurs in 10-15% of successfully resuscitated out-of-hospital cardiac arrest (OHCA) patients. Early identification of potential organ donors is critical to prevent withdrawal of life sustaining therapy (WLST) and ensure adequate organ perfusion. To predict brain death after OHCA, we developed a novel brain death risk (BDR) score.

Methods:
The BDR score was developed from a retrospective, single center cohort of OHCA patients admitted from 2011-2020. After excluding patients with early WLST (defined as < 72 hours from OHCA), univariate regression models identified independent predictors of brain death, which were used to build the BDR score. We included the following variables: non-shockable rhythm (1 point), drug overdose as etiology of arrest (1 point), evidence of grey-white differentiation loss or sulcal effacement on head computed tomography (CT) within 24 hours of arrest (2 points), Full-Outline-Of-UnResponsiveness (FOUR) score of 0 (2 points), FOUR score 1-5 (1 point), and age < 45 years (1 point). Head CT findings were based on neuroradiology reports. We validated the BDR score in an independent single center OHCA cohort. The primary outcome was occurrence of brain death. Using the area under the receiving operator characteristic curve (AUC), we assessed the score’s prediction of brain death.

Results:
The development cohort included 256 OHCA patients; 15.6% (40/256) experienced brain death. The AUC (95% CI) of the BDR score was 0.921 (0.870-0.971). In the validation cohort, 24.4% (21/86) experienced brain death. The AUC (95% CI) of the BDR score was 0.830 (0.7266-0.9335). Table 1 shows the rate of brain death at each BDR score. In both cohorts, a BDR score ≥ 5 was the optimal cut off (sensitivity 0.9 and 0.714, specificity 0.843 and 0.831, respectively).

Conclusion:
Early scoring systems may be able to identify those at highest risk for brain death after OHCA. Our data suggest that a BDR score ≥ 5 could help predict progression to brain death.
Abstract 185: Dual Processing In Surrogate Decision Makers Of Out Of Hospital Cardiac Arrest Patients: A Secondary Qualitative Analysis
Authors: Presciutti Alex , Siry-Bove Bonnie , Scherer Laura D , Kwan Bethany , Matlock Dan D , Daugherty Stacie , Havranek Edward P , Perman Sarah M
Published: June 2023

Introduction:
Out-of-hospital cardiac arrest (OHCA) is an unexpected event that frequently renders patients incapacitated therefore requiring a surrogate decision maker (SDM) to act as a proxy. When exercising judgement under uncertainty, people engage in one of two cognitive processing styles (i.e., dual processing): “fast” processing - automatic and intuitive or “slow” processing - deliberative and rational. Understanding which style(s) SDMs use in making decisions for post-arrest patients is critical to ensuring that (1) patients’ wishes are respected and (2) evidence-based neuro-prognostication is supported.

Methods:
We conducted a secondary analysis of semi-structured interviews with SDMs for OHCA patients. Potential subjects were contacted 30 days after discharge/death. The interviews were recorded and transcribed verbatim. Two investigators thematically coded the transcripts. We conducted secondary coding to specifically explore cognitive processing styles used by SDMs.

Results:
Over 5-months, 34 SDMS were approached and 12 SDMs agreed to be interviewed. SDMs were spouses/partners (5), adult children (3), parent (1) and siblings (3). Within this sample, 66.7% (8/12) of SDMs decided to withdraw life sustaining therapy or discontinue resuscitative efforts for the patient. Our secondary coding yielded variation in cognitive processing styles, with SDMs describing both fast and slow styles. SDMs who employed “fast” cognitive processing described (1) making their decision based on group consensus, (2) employing an affect heuristic (deciding based on “gut feeling” or temporary emotional state), (3) employing an availability heuristic (deciding based on examples of other patients or scenarios that immediately come to mind), and (4) deciding based on providers’ opinions without consulting other sources. SDMs who utilized “slow” cognitive processing described (1) focusing on the patient’s wishes when deciding and (2) gathering information to make an informed decision.

Conclusions:
SDMs utilized “fast” and “slow” cognitive processing approaches to decision making for OHCA patients. Future study should explore the relationship between SDMs’ cognitive processing styles and their decisions for post-arrest care.
Abstract 189: Resuscitative Endovascular Balloon Occlusion Of The Aorta In The Obese Patient
Authors: Broome Jacob , Loe Mallory , Mueller Lauren , Simpson John , Tatum Danielle , Taghavi Sharven , MCGREW PATRICK , Jackson-Weaver Olan , DuBose Joseph , duchesne juan
Published: June 2023

Objectives:
Perceptions of difficulty in obtaining arterial access in obese patients may impact the rate of resuscitative endovascular balloon occlusion of the aorta (REBOA) use in clinical practice. Excess adipose tissue can obstruct palpation of anatomic landmarks, limit sonographic visualization, and potentially increase difficulty of REBOA placement. We aimed to examine the association between obesity and REBOA placement, hypothesizing that increased body habitus would decrease success and increase time to successful aortic occlusion (AO).

Methods:
A retrospective analysis of the Aortic Occlusion for Resuscitation in Trauma and Acute Care Surgery (AORTA) registry was performed on REBOA patients (2013-2022). Patients with systolic blood pressure > 0mmHg admission were included. Patients requiring CPR on arrival to the ED were excluded. Body mass index (BMI) categorized obesity subgroups as follows: non-obese (<30), mildly obese (30-34.9), moderately obese (35-39.9), and severely obese (40+).

Results:
Inclusion criteria was met by 410 patients. There was no statistical difference in injury severity or admission systolic blood pressure (SBP) among the subgroups. At initiation of AO, moderately and severely obese patients had higher median SBP compared to non- and mildly obese patients (p=0.03). On multivariate analysis, BMI did not significantly impact the success of REBOA placement or time to successful AO. When stratified by arterial access technique, there was no difference in success rates, time to successful AO, or mortality between groups. Overall time to successful AO, response SBP, and mortality did not differ across subgroups.

Conclusion:
Following traumatic injury in obese patients, REBOA placement is a feasible intervention. Despite differences in patient body habitus, ultrasound guidance was not superior to landmark palpation for acquiring arterial access. Placement of REBOA is equally effective in obese patients and severe obesity should not impede REBOA use.
Abstract 198: Finding The Sweet Spot Of Chest Compression Rate And Fraction For Improved OHCA 72-hour Survival
Authors: Powell Jonathan R , Nassal Michelle , Aramendi Elisabete , Jaureguibeitia Xabier , Alonso Erik , Idris Ahamed H , Panchal Ashish R , Wang Henry
Published: June 2023

Introduction:
Cardiac arrest resuscitation guidelines recommend optimization of both chest compression rate (CCR) and fraction (CCF). Simultaneous management of CCR and CCF is challenging. The interaction between CCR and CCF is unknown. Our objective was to evaluate the influence of CCR, CCF and their interactions upon OHCA 72-hour survival.

Methods:
Retrospective analysis of adult OHCA in the Pragmatic Airway Resuscitation Trial (PART). We determined CCF and CCR from automated signal analysis of available CPR process files. CCF categories were <80%, 80-89.99%, and ≥90%. CCR categories were <100, 100-129.99, and ≥130 per minute. The primary outcome was 72-hour survival. We evaluated the multiplicative interaction between CCR and CCF using a) heat maps, and b) linear mixed modeling with EMS agency as a random effect, adjusted for Utstein variables.

Results:
Of 3,004 enrolled patients, we included 1,606 with available CPR process data. Mean CCR and CCF were 114 compressions/min (SD 9.96) and 88% (SD 0.08). On linear mixed modeling, CCR of <100 (OR 1.55, 95% CI 0.98, 2.44) and ≥130 (OR 1.29, 95% CI 0.86-1.95), referent 100-129.99, was not associated with improved 72-hour survival. A CCF of <80% (OR 1.55, 95% CI 0.98, 2.44) and ≥90% (OR 1.29, 95% CI 0.86-1.95), referent 120-129.99, was also not associated with improved 72-hour survival. Further, the interaction of CCR and CCF was not associated with improved 72-hour survival (p=0.22). Heat map analysis indicated 72-hour survival was lowest when both CCF <80% and CCR <100 per minute, and highest when CCF >90% and CCR <130 per minute (Figure).

Conclusion:
The interaction between CCR and CCF may influence 72-hour survival. Rescuers must seek to optimize both CCR and CCF during resuscitation attempts. Research in cardiac arrest outcomes should consider this relationship and plan to have sufficient power to explore varying CCR and CCF values when examining OHCA survival.
Abstract 203: Exploratory Study Of The Time Course Of Post-arrest Neurologic Injury In A Porcine Model Of Pediatric Cardiac Arrest
Authors: Senthil Kumaran , Ranganathan Abhay , Piel Sarah , Hefti Marco M , Slovis Julia C , Berg Robert A , Kilbaugh Todd J , Morgan Ryan W
Published: June 2023

Introduction:
In preclinical models, hemodynamic-directed CPR (HD-CPR) mitigates post-arrest neurofunctional impairment and cerebral mitochondrial dysfunction. We aimed to explore the temporal evolution of markers of neurologic injury over five days following cardiac arrest treated with HD-CPR.

Methods:
Pigs (1-month-old) underwent 7min asphyxia, induction of ventricular fibrillation, 10-20min of HD-CPR (goal SBP 90 mmHg, coronary perfusion pressure 20mmHg), randomization to post-ROSC survival duration (24, 48, 72, 96, 120h; n=3 per group) with standardized post-resuscitation care. Plasma neurofilament light (NFL) and glial fibrillary acidic protein (GFAP) were collected at 0, 6, 24, 48, 72, 96, 120h and compared by mixed effects analysis. At terminal endpoints, cerebral cortical tissue was assessed for: mitochondrial electron transport system function; citrate synthase quantification (mitochondrial mass); immunoblot quantification of mitochondrial dynamic proteins (Opa-1, MFN-2, DRP-1, FIS-1); ELISA for 4-HNE and protein carbonyls (oxidative injury); and neuropathologic examination for IBA-1 (microglial activation) and GFAP (reactive astrocytes), all compared via ANOVA.

Results:
All animals had swine cerebral performance category score of 1 (grossly normal) by 24h after injury. Plasma NFL was significantly elevated at 24, 48, 72, 96 (p<0.001) and 120h (p=0.009) compared to baseline. No significant differences were identified between time points for GFAP, mitochondrial measures, or neuropathological outcomes.

Discussion:
Despite grossly normal neurofunctional status, plasma NFL was elevated from baseline at multiple timepoints. No significant temporal differences were identified in other markers of neurologic injury. NFL may be a sensitive marker of mild neurologic injury post-arrest.
Abstract 208: Patient And Event Characteristics Associated With Duration Of Resuscitation In Children Undergoing In-hospital Cpr
Authors: O'Halloran Amanda , Morgan Ryan W , Kennedy Kevin , Berg Robert A , Gathers Cody-Aaron , Naim Maryam , Nadkarni Vinay M , Reeder Ron , Topjian Alexis A , Kleinman Monica E , Wolfe Heather A , Chan Paul S , Sutton Robert M
Published: June 2023

Introduction:
Duration of cardiopulmonary resuscitation (CPR) in patients without return of spontaneous circulation (ROSC) is a proxy measure for the persistence of intense resuscitation efforts. We evaluated the association between patient and event characteristics and resuscitation duration among children who did not survive a CPR event.

Methods:
Retrospective cohort study using the American Heart Association’s Get With The Guidelines
®
-Resuscitation registry. Pediatric CPR events without ROSC (non-survivors) from 2000-2021 were included. Multivariable hierarchical logistic regression evaluated which patient and event characteristics with a bivariate association (p<0.05) were associated with CPR duration among non-survivors.

Results:
Of 13,899 eligible pediatric CPR events, 3850 did not have ROSC and comprised the primary cohort. Median CPR duration was 28 min (IQR: 16-46 min). After multivariable adjustment, several patient and event characteristics were associated with CPR duration. CPR duration was briefer by: age group (neonates compared to older children [-4.9 min, 95% CI: -8.9 to -0.9 min, p=0.02]); need for mechanical ventilation (-7.6 min [95% CI: -10.3 to -4.9 min, p<0.001); and event location: ED vs. PICU (-4.0 min [95% CI: -7.5 to -0.6 min], p=0.02). CPR duration was longer by initial event rhythm as compared with asystole: bradycardia (8.4 min [95% CI: 5.7 to 11.0 min], p<0.001); PEA (8.2 min [95% CI: 5.7 to 11.0 min), p<0.001), and pulseless VT (6.2 min [95% CI: 0.1 to 12.3 min], p=0.047). CPR duration was similar by sex and race.

Conclusions:
Several factors including age, rhythm, and event location are associated with resuscitation duration in pediatric patients requiring CPR but there were no sex or racial differences. Further investigation is needed to determine current practices regarding termination of resuscitation and to generate guidelines for this complex decision-making.
Abstract 210: Norepinephrine Versus Epinephrine For Post-Cardiac Arrest Shock In The Prehospital Setting: A Retrospective Analysis
Authors: Wender Emma R , Cocca Ryan A , Counts Catherine , Sayre Michael R , Maynard Charles , Johnson Nicholas J
Published: June 2023

Introduction:
Shock after out-of-hospital cardiac arrest (OHCA) is common and often treated with vasopressors. Compared with norepinephrine (NOR), infusion of epinephrine (EPI) is associated with higher mortality and morbidity among hospitalized patients; but the optimal prehospital approach is unknown. We sought to examine whether infusion of EPI versus NOR is associated with neurologically-intact survival among OHCA patients.

Methods:
This retrospective cohort study included transported OHCA cases in Seattle, WA from 2014-2021 who received advanced life support. Our primary exposure was infusion of EPI or NOR. Our primary outcome was neurologically-favorable survival (Cerebral Performance Category score of 1 or 2) to hospital discharge. Key secondary outcomes were prehospital rearrest, survival to hospital admission, and hospital mortality. We conducted multivariable logistic regression adjusting for baseline patient and OHCA characteristics.

Results:
Of 1784 OHCA patients, 263 (15%) received NOR and 201 (11%) received EPI infusions, 18 received both, and 1298 received neither. Those who received EPI were older (median 65 [IQR 52-78] vs 62 [IQR 47-75] years), but otherwise had similar baseline characteristics, including initial arrest rhythm (Table 1). Patients who received EPI were over twice as likely to have rearrested in the prehospital setting (53% vs 24%). After adjustment, there was no difference in neurologically-favorable survival (OR 0.91, 95% CI 0.47-1.78). We found no difference in survival to hospital admission or discharge.

Conclusion:
Neurologically-favorable survival was similar among patients who received NOR or EPI infusions for post-OHCA shock, though patients who received EPI had prehospital rearrests more often. Future trials should examine the optimal approach to hemodynamic management for post-OHCA shock.
Abstract 211: Epinephrine Does Not Correct Post-ROSC Hypoperfusion Despite Normalizing Blood Pressure A Rat Model Of Severe Pediatric Asphyxial Cardiac Arrest
Authors: Ton Hoai , Velado Victor , Shoykhet Michael
Published: June 2023

In children resuscitated from cardiac arrest, systemic hypotension occurs frequently and is associated with worse outcome. The first-line vasoactive treatment for post-arrest hypotension is continuous infusion of epinephrine. Epinephrine dose is titrated to maintain normal blood pressure for age. Epinephrine, however, also leads to vasoconstriction which may impair organ perfusion after resuscitation.We hypothesized that epinephrine infusion during the post-resuscitation period restores systemic blood pressure but not flow to vital organs. Using a model of severe pediatric asphyxial cardiac arrest in developing rats, we simultaneously measured blood pressure (ABP) and flow in carotid (Fc) and femoral (Ff) arteries after resuscitation. We then compared the effects of epinephrine or saline infusions on blood pressure vs flow. One hour after resuscitation from 11.5 minutes of asphyxial arrest, ABP, Fc and Ff were 61.73 ± 2.68; 42.58 ± 3.84; and 19.53 ± 7.00 % of baseline. Epinephrine infusion increased ABP in a dose-dependent manner, reaching 95.13 ± 7.93 % of baseline at 0.5 μg/kg/min. Saline infusion at equivalent volumes increased ABP only marginally to 69.88 ± 2.60 % of baseline. In contrast to its effect on ABP, epinephrine infusion increased Fc only to 49.55 ± 6.49 and Ff to 53.28 ± 7.13 % of baseline. Saline infusion at equivalent volumes, on the other hand, had a more salutary effect than epinephrine on improving blood flow (Fc 64.62 ± 6.64 and Ff 60.25 ± 7.60 % of baseline). Notably, a single 10 cc/kg saline bolus, administered when ABP decreased to ~80% of baseline post-ROSC, increased blood flow and ABP to 100% and 90% of baseline, respectively. These data indicate that epinephrine infusion in the post-arrest period adversely affects arterial blood flow despite normalizing arterial blood pressure. Continued fluid resuscitation with crystalloids potentially has beneficial effect on correcting post-ROSC hypoperfusion. Future studies need to explore the impact of targeting flow rather than blood pressure in the post-arrest period and its association to post-arrest end-organ function in children.
Abstract 214: A Counterfactual Machine Learning Model Study To Estimate The Impact Of Coronary Angiography For Out Of Hospital Cardiac Arrest
Authors: Kawagoe Yasuhito , Nishimori Makoto , Ogata Soshiro , Shinohara Masakazu , Akashi Yoshihiro J , Tahara Yoshio
Published: June 2023

Background:
The American Heart Association guidelines for resuscitation 2020 recommends emergency coronary angiography (CAG) in cases of out-of-hospital cardiac arrest (OHCA) after return of spontaneous circulation (ROSC) with ST-segment elevation(STE) and, it is unclear how much CAG actually contributes to improved outcomes in various OHCA patient populations. The aim of this study is to estimate the impact of CAG on OHCA using a counterfactual machine learning model.

Methods:
We analyzed adult non-traumatic OHCA patients (43,977 cases) from June 2014 to December 2019 from the JAAM (Japan Association for Acute Medicine)-OHCA registry, which includes post-hospitalization data from 140 Japanese hospitals. We defined outcomes as favorable neurological outcomes (Cerebral Performance Categories (CPC) 1-2) and survival at 30 and 90 days. We estimated the outcome assuming that all patients had received CAG using a machine learning and counterfactual hypothetical model, and also estimated the outcome assuming that all patients had not received CAG. An average of each individual difference between the two estimations was calculated as average treatment effect (ATE) (%), which represents the effect of CAG on improving outcomes for the population. In addition, subgroup analysis was performed based on ROSC, STE and initial documented rhythm.

Results:
The ATE(%, 95% confidence interval) of CAG in all OHCA patients for CPC 1-2 at 30 and 90 days was 3.11% (2.92-3.30) and 1.85% (1.74-1.95), and survival at 30 and 90 days was 6.25%(5.93-6.57) and 2.20%(1.88-2.52), respectively. The subgroup analysis of ATE for CPC 1-2 at 90 days was particularly lower in the no STE group, initial pulseless electrical activity (PEA) group and initial asystole group than in the STE group and initial ventricular fibrillation(VF) group (Figure).

Conclusions:
In the JAAM-OHCA registry, we used a counterfactual machine learning model to estimate the effect of CAG on OHCA.
Abstract 217: Association Of Ventricular Fibrillation Instantaneous Amplitude At Time Of Defibrillation With Resuscitation Outcome
Authors: Jaureguibeitia Xabier , Kwok Heemun , Coult Jason , Blackwood Jennifer E , Kudenchuk Peter J , Rea Thomas
Published: June 2023

Introduction:
Quantitative measures of the ventricular fibrillation (VF) ECG waveform predict defibrillation outcomes. A prior study observed that greater Instantaneous Amplitude (IA) of the VF ECG, measured at the instant of defibrillation (Figure), predicted better outcome independent of other VF measures. If true, resuscitation might be improved by synchronizing shock to ECG amplitude. We sought to determine whether IA was an independent predictor of shock-specific outcome using a larger independent dataset.

Methods:
We investigated adult out-of-hospital VF cardiac arrest cases in a metropolitan EMS system treated with a Philips MRx defibrillator. For each shock, we computed the IA as the absolute value of the ECG at the time of shock delivery. We also computed the amplitude spectrum area (AMSA), a well-characterized waveform measure, from the 3-second CPR-free period preceding the shock. Study outcome was return of spontaneous circulation (ROSC) after each shock. We used Wilcoxon test to evaluate the unadjusted relationship between IA and shock-specific ROSC, and a generalized linear mixed-effect (GLME) model to assess whether IA was associated with shock-specific ROSC independent of AMSA.

Results:
We included 1516 shocks from 567 patients, with a median (IQR) of 2 (1-3) shocks per patient and shock-specific ROSC rate of 22% (337/1516). IA was correlated with AMSA; Pearson’s R = 0.43. Median (IQR) IA was greater for shocks that resulted in ROSC, with IA of 0.14 (0.05-0.25) mV vs 0.09 (0.04-0.18) mV, (p<0.001). However, when both IA and AMSA were included in a GLME model, AMSA was significantly associated with ROSC (OR 2.09, 95% CI 1.74-2.50 for an IQR change in AMSA) but IA was not (OR 1.04, 95% CI 0.92-1.18 for an IQR change in IA).

Conclusions:
IA did not independently predict ROSC after controlling for AMSA. Thus, IA is likely a surrogate for other waveform measures, limiting its usefulness to guide instantaneous defibrillation timing as a means to improve outcome.
Abstract 224: Rate Of Rehabilitation Referral After Cardiac Arrest Based On Socioeconomic Status
Authors: Prescott Peter , Khan Ramsha , Ledyard Jonathan D , Doshi Ankur A , Callaway Clifton W , Elmer Jonathan , Flickinger Kate
Published: June 2023

Cardiac arrest (CA) survivors often suffer physical and cognitive deficits. Unlike survivors of myocardial infarction or stroke, CA survivors are inconsistently referred to rehabilitation services. Social and structural determinants of health affects access to care. We investigated if rehabilitation referral rates for CA survivors differed across race, ethnicity, sex and socioeconomic status (SES) based on median income of patient’s zip code of residence. We included consecutive CA survivors discharged from a single academic medical center 2014-2019. We performed a structured chart review to identify referrals to inpatient or outpatient rehabilitation. Outpatient services included cardiac rehabilitation, PT/OT, and speech therapy. We used Census data to determine median household income for each patient’s zip code of residence. We used Fisher’s Exact test and Kruskal Wallis tests to investigate the difference in referral rates based on income brackets identified from Census data, age, sex, race, and ethnicity. We included 674 CA patients, of whom 367 (54%) arrested out of hospital, 418 (62%) were male, median age was 60 (IQR 49-69) years, 526 (78%) were white, 553 (82%) were non-Hispanic or Latin-x. Overall 387 (57%) were referred to rehabilitation ( n=316 (47%) inpatient-only, n=42 (6%) outpatient-only, n=29 (4%) both). Rehabilitation referral differed across categories of income (p=0.023) (Figure) but showed no consistent trend across consecutive categories. Age was positively associated with referral (odds ratio per decade 1.33; 95% CI 1.21-1.47, p=0.015). There was no association of race, ethnicity or sex with rehabilitation referral. In our single center data, referral to rehabilitation increased with age and was less frequent for patients from neighborhoods with the lowest median income. It did not differ based on sex, race or ethnicity. Future studies should investigate rehabilitation attendance rates in comparison to SES.
Abstract 226: Long-term Trajectory Of Neurologic Outcome After Severe Traumatic Brain Injury
Authors: Wang Henry , Hu Chengcheng , Barnhart Bruce J , Jansen Jan , Spaite Daniel W
Published: June 2023

Objective
: Little is known about the time-based trajectories of neurologic recovery after traumatic brain injury (TBI). We sought to determine long-term changes in neurologic status after TBI.

Methods:
Data source: Resuscitation Outcomes Consortium Hypertonic Saline TBI Trial. Included: adult TBI, GCS≤8; Excluded: shock (SBP≤70, or SBP 71-90 with HR≥108). Primary outcome: Glasgow Outcome Scale-Extended (GOS-E; 1=dead, 8=no disability) determined at: a) hospital discharge and b) 6-months. We analyzed changes in GOS-E between hospital discharge and 6-months using Sankey graphs and the Wilcoxon signed-rank test. We repeated the analysis for the high acuity subset of patients undergoing EMS advanced airway insertion.

Results:
Among 1,282 TBI, GOS-E at discharge was: dead (GOS-E 1) n=321 (25.0%), unfavorable (2-4) n=664 (51.8%), favorable (5-8) n=220 (17.2%), missing n=77 (6.0%; Figure). GOS-E at 6-months was: dead n=346 (27.0%), unfavorable n=282 (22.0%), favorable n=459 (35.8%), missing n=195 (15.2%). While 7 of 220 (3.2%) with favorable GOS-E at discharge worsened at 6 months (unfavorable or died), 300 of 664 (45.2%) with unfavorable GOS-E improved to favorable at 6 months (Wilcoxon signed-rank for GOS-E change p<0.0001). In the EMS advanced airway subset (n=774), 2 of 96 (7.1%) with favorable GOS-E at discharge worsened to unfavorable (or were dead) at 6 months, while 208 of 433 (48.0%) with unfavorable GOS-E improved to favorable at 6 months (Wilcoxon signed-rank for GOS-E change p<0.0001).

Conclusion:
Among patients with TBI and unfavorable neurologic status at hospital discharge, almost half will progress to favorable neurologic status at 6 months. Very few TBI victims die or worsen to unfavorable neurologic status by the time of 6-month follow-up. Thus, assessment of long-term neurologic outcome should be considered for studies of TBI.
Abstract 230: Spinal Cord Injury In A 14 Days Survival Rat Model Of 6 And 8 Min Of Ventricular Fibrillation Cardiac Arrest, Resuscitated With Conventional Chest Compression
Authors: Weihs Wolfgang , Warenits Alexandra M , Magnet Ingrid A , Müller Matthias , Koch Moritz , Alexander Szinovatz , Holzer Michael , Högler Sandra
Published: June 2023

Introduction:
Impact of global ischemia and reperfusion on brain in resuscitation animal models is well investigated. Investigations on vulnerability of spinal cord in such models are rarely reported. We investigated the spinal cord in a cardiopulmonary resuscitation ventricular fibrillation cardiac arrest (VFCA) rat model and hypothesized that an untreated CA of 6 and 8 min will lead to histological damage and dysfunction in the resuscitated animal′s spinal cord, depending on CA duration.

Methods:
Adult male Sprague-Dawley rats (350-450 g) were subjected to 6 (n=8) or 8 min (n=14) of VFCA and resuscitated with conventional chest compressions with a thumper device, mechanical ventilation and drugs (epinephrine, bicarbonate, heparin). After defibrillation and ROSC, rats survived for 14 days. The spinal cord was removed from the spine after fixation in formalin and embedded in paraffin. Transverse sections of cervical, thoracic and lumbar spinal cord were stained with hematoxylin and eosin (HE). Immunohistochemistry was performed with antibodies against GFAP for astrocytes and Iba1 for microglia. Sections were evaluated by a pathologist blinded to treatment regimens, and compared to sham animals (n=5).

Results:
Resuscitated animals showed high mortality; after 6 min CA four animals and after 8 min CA eleven animals died before endpoint. Surviving animals showed focal bilateral symmetrical loss of neurons and distinct gliosis in the gray matter of the thoracic spinal cord level with the central canal. Similar lesions were detected in other segments of the spinal cord, but were located predominantly in the ventral horn of the spinal cord. These lesions were accompanied by dilated myelin sheaths in the white matter. Immunohistochemistry showed activation of astrocytes and microglia in the damaged regions. There were no differences detectable between animals subjected to 6 or 8 min VFCA. Sham animals showed no lesions in the spinal cord.

Conclusions:
We found consistent histological damage in the spinal cords of rats resuscitated after 6 and 8 min untreated VFCA with CPR after 14 days survival but without clinical symptoms in these animals. However, similar lesions might be cause of paralysis and urinary retention found in animals that died before endpoint.
Abstract 238: A Machine Learning Algorithm To Predict Refractory Ventricular Fibrillation
Authors: Coult Jason , Yang Betty Y , Kwok Heemun , Blackwood Jennifer E , Rajah Anjali , Sotoodehnia Nona , Kutz J. Nathan , Kudenchuk Peter , Rea Thomas
Published: June 2023

Introduction:
Guidelines for resuscitation of ventricular fibrillation (VF) out-of-hospital cardiac arrest (OHCA) advise drug therapy (epinephrine and antiarrhythmics) if a patient requires ≥3 shocks. Given that a higher number of shocks is associated with lower survival, the ability to predict which patients will require ≥3 shocks could enable preemptive, targeted intervention (antiarrhythmics or early hospital transport for invasive interventions) aimed at improving outcome.

Aim:
We sought to design an ECG-based algorithm to predict whether VF OHCA patients will require ≥3 shocks.

Methods:
We evaluated a cohort of adult VF OHCA from a metropolitan EMS system between 2008-2020. Patients were randomized 80%-20% for training-test. We trained an algorithm to predict whether a patient will require ≥3 shocks using 3-s ECG segments collected immediately before and within a minute after initial shock. The method uses a random forest classifier to predict shock count based on singular value decompositions of ECG wavelet transforms. Test performance was quantified by area under the receiver operating characteristic curve (AUC). Association between functional survival and shock count was evaluated with logistic regression. A sensitivity analysis assessed prediction of patients requiring ≥4 shocks.

Results:
Of 1376 VF OHCA patients, 311 (23%) were female; the median (IQR) shock count was 3 (1-6) and 591 (43%) achieved functional survival. Shock count was associated with lower functional survival with an odds ratio (95% CI) of 0.92 (0.89-0.95) for each additional shock. In 275 test patients, AUC (95% CI) was 0.80 (0.74-0.85) for predicting ≥3 shocks and 0.81 (0.75-0.85) for predicting ≥4 (Figure).

Conclusions:
A machine learning algorithm based on ECGs proximal to the initial shock predicts patients likely to experience refractory VF and high shock count, and could enable rescuers to preemptively administer interventions targeted to improve resuscitation outcome.
Abstract 239: Evaluation Of A Shock Advisory Algorithm In An Automated External Defibrillator Using Real-world Data
Authors: Gao Mengqi , Liu Chenguang , Gehman Stacy , Jorgenson Dawn
Published: June 2023

Objective:
Studies have shown that survival rate can be increased with AED deployment, but delivering a shock to patients who may not need one can be harmful. Thus, it is important to evaluate AED shock advisory algorithms in real-world use. This study reports the retrospective performance from out-of-hospital uses of the Philips SMART Analysis algorithm in the FR3 AED.

Methods:
A representative sample of 1,619 de-identified patient uses from four emergency medical services agencies in the United States, between 2015 and 2017, were included in this study. In each case, the first analysis by the SMART Analysis algorithm was always extracted, and a second analysis was randomly selected among the subsequent analyses (if any), resulting in a total of 2,739 analyses. All analyses were independently annotated by three clinical experts who were blinded to AED advisories (shock advised/no-shock advised). Based on the annotations, analyses with undeterminable rhythms or without an AED advisory were excluded. The recorded AED advisories were compared against the rhythm annotations.

Results:
Among the 2,739 analyses, a total of 2,616 (95.5%) were included in this study. Based on the consensus among the experts, there were 12.4% (324/2,616) annotated as shockable rhythms, 84.3% (2,205/2,616) non-shockable and the remaining were intermediate rhythms (benefits of shock are uncertain). The overall sensitivity and specificity (n/N, 90% one-sided LCL) were 96.3% (312/324, 95.0%) and 99.9% (2,202/2,205, 99.8%), respectively. The algorithm performance in each rhythm category is shown in Table 1.

Conclusions:
This study demonstrates that the Philips SMART Analysis algorithm in FR3 AEDs has a high sensitivity to detect shockable rhythms while maintaining a near 100% specificity for non-shockable rhythms. The algorithm’s real-world performance exceeds the requirements in the American Heart Association (AHA) guidelines and shows the safety and effectiveness of the algorithm.
Abstract 243: Drone-delivery Of Automated External Defibrillators Before Ambulance Arrival In Suspected Out-of-hospital Cardiac Arrest
Authors: Schierbeck Sofia , Nord Anette , Svensson Leif , Claesson Andreas
Published: June 2023

Introduction:
Early defibrillation is essential for increasing survival in out-of-hospital-cardiac-arrest (OHCA). Previous studies on AED-delivery using drones have shown that the method is feasible and has potential to shorten time to defibrillation. However, it is still unclear if drones can deliver AEDs before ambulance arrival with clinically relevant time benefits in real-life suspected OHCA. Our aim was to investigate if drones, used as a complement to standard care, can deliver AEDs before ambulance arrival in real-life suspected OHCA in Sweden.

Method:
Five AED-equipped drones were placed in separate sectors within two controlled airspaces around Gothenburg, Sweden. In cases of suspected OHCA during a study period of 11 months, a drone was dispatched by the dispatch center. A drone operator deployed and remotely surveilled the autonomously responding drone (beyond visual line of sight), which on arrival winched down an AED. The dispatchers then instructed the callers to retrieve the AED. The drone range one-way was 6 kilometers and the drone had a velocity of approximately 60 km/h. Alerts to no-fly zones and alerts in rain and wind > 8 m/s were excluded. Time to AED delivery was compared to standard of care ambulance delay in each case.

Results:
A total of 223 suspected OHCA were observed in the study areas. In 72 (32%) cases a drone took off, out of these an AED was delivered in 58 (81%) cases. In 56 cases, arrival times for both drone and ambulance were available. The AED-delivery occurred prior to ambulance arrival in 36 of these cases (64%) with a median time benefit of 3 min and 14 sec. Totally 6 patients (11%) had an AED attached, amongst them two were defibrillated and one patient survived 30 days. The main reasons for non-flights were weather conditions (16%), cancelled by dispatch center (17%) and service offline (13%).

Conclusion:
The use of AED-equipped drones has potential to enable AED delivery prior to ambulance arrival in many cases of suspected OHCA and the time benefit seen in this study indicates potential to facilitate defibrillation before ambulance arrival. However, more improvements and studies are needed to further increase time benefits and the proportion of cases where an AED is attached and used before ambulance arrival.
Abstract 249: Impact Of Partial Pressure Of Carbon Dioxide On Survival And Neurologic Outcomes In In-hospital Cardiac Arrest Patients
Authors: Patel Jignesh K , Millet Natalie , Genchanok Yevgeniy
Published: June 2023

Background:
As cardiac arrest remains an event associated with high morbidity and mortality, interventions to mitigate neurologic injury and improve survival in these patients is an area of ongoing research. As carbon dioxide levels play an important role in cerebral vascular regulation, targeting a specific partial pressure of carbon dioxide (PaCo2) is a potential therapeutic intervention in cardiac arrest care. Our study aims to determine the impact of PaCo2 on survival and neurologic outcomes in in-hospital cardiac arrest (IHCA) patients.

Methods:
This study is a single center prospective observational study. The population included IHCA patients from August 2011 to July 2021. Arterial blood gas data (ABG) was available for 154 patients intra cardiac arrest and 336 patients in the post ROSC period. PaCo2 levels from the ABG data where subdivided into different ranges including hypocapnia (PaCo2 <35mm Hg), normocapnia (35-45 mm Hg) and hypercapnia (>45mmHg). The primary outcomes of interest were survival to hospital discharge and neurologic outcome.

Results:
Analysis of the PaCo2 data demonstrated that intra arrest PaCo2 was not associated with survival to discharge (p value 0.129). Mild hypercapnia (PaCO2 46-54 mmHg) and moderate hypercapnia (55-79mmHg) intra arrest were associated with favorable neurologic outcomes (p value 0.039). A univariate analysis of post ROSC ABG data demonstrated that normocapnia was associated with survival to discharge (p value <0.001) and favorable neurologic outcomes (p value 0.05). Similar findings were seen in two multivariate analyses examining the association of PaCo2 with survival and neurologic outcome. The multivariate analysis examining survival showed that hypocapnia and hypercapnia were associated with a higher mortality compared to normocapnia (p values 0.016 and <0.001). In the multivariate analysis examining neurologic outcomes, hypercapnia was associated with worse neurologic outcome when compared to normocapnia (p value 0.004).

Conclusions:
Post ROSC, normocapnia was associated with favorable neurologic outcomes and survival to discharge. Our study supports targeting normocapnia in the post cardiac arrest period.