Refractory Out-of-hospital Cardiac Arrest Research Articles

Abstract 274: Identifying Target Populations For Extracorporeal Cardiopulmonary Resuscitation Among Patients With Refractory Out-of-hospital Cardiac Arrest Using Machine Learning

Introduction: Extracorporeal cardiopulmonary resuscitation (ECPR) can be used on patients with out-of-hospital cardiac arrest (OHCA) when the cause is potentially reversible. However, little is known about the optimal target populations for ECPR among those with refractory OHCA. Methods: We retrospectively analyzed nationwide OHCA registry data on 57,754 patients from 93 hospitals in Japan, 2014-2019. We identified 1,273 patients having a witness or initially shockable rhythms with refractory OHCA of presumed cardiac origin without return of spontaneous circulation after >3 doses of adrenaline administration and defibrillations when necessary at the emergency department (ED). We used the causal forest—a machine learning method to estimate heterogeneous treatment effects—to determine individual treatment effects of ECPR on a favorable 30-day neurologic outcome defined as the Cerebral Performance Category scale of 1 or 2, adjusting for confounders (e.g., age, sex, initial cardiac rhythms, and laboratory data). We compared patient characteristics in each quintile of individual ECPR effects to identify potential determinants of ECPR effects in patients with refractory OHCA. Finally, to determine optimal targets of ECPR, we evaluated how ECPR effects could vary depending on patient characteristics. Results: We found that the treatment effects of ECPR on a favorable neurologic outcome were heterogeneous (top 20% vs. others, 0.15 vs. 0.00; p<0.001) ( Figure 1 ). The key determinants of ECPR effects were initial cardiac rhythms on the emergency medical service (EMS) and at ED arrival, regardless of EMS transport time or laboratory data. In addition, ECPR effects varied depending on the information on ED arrival (i.e., witness, bystander CPR, and initial cardiac rhythms) ( Figure 2 ). Conclusion: Among patients with refractory OHCA, information available on arrival at the ED could effectively identify patients who may particularly benefit from ECPR.

Abstract 275: The First Series Of Hypothermic Out-of-hospital Cardiac Arrests In A Temperate Urban Area Resuscitated With Prehospital Or Inhospital Extracorporeal Cardiopulmonary Resuscitation: A Fifteen-year Observationnal Study

Introduction: Accidental hypothermia designates an unpredicted drop in body temperature below 35°C. The risk of ventricular fibrillation is major below 28°C and cardiac arrest is almost certain below 24°C. In such cases, conventional cardiopulmonary resuscitation is often inefficient. Hypothesis: Hypothermic out-of-hospital cardiac arrest (OHCA) occurs even in temperate urban areas and extracorporeal cardiopulmonary resuscitation (ECPR) has shown good outcomes with this indication. Methods: We conducted a retrospective observational study of patients admitted to a university hospital in Paris, France. We reviewed patients consecutively admitted between January 1, 2008 and April 31, 2022 and treated with prehospital or inhospital ECPR following refractory hypothermic OHCA. The primary outcome was survival at 28 days with good neurological outcomes, defined as Cerebral Performance Category (CPC) 1 or 2. We compared patients according to their cold air or cold water exposure. Results: A total of 38 patients were analysed. Patient characteristics and outcomes are detailed in Table 1. A total of 15 patients (40%) survived at 28 days, 13 (34%) of whom with good neurological outcomes despite a median low-flow of 85 min. No patient survived with good neurological outcomes in the cold-water group. Conclusion: Survival rates with favourable neurological outcomes at 28 days stood at 34% of all patients with hypothermic OHCA who were resuscitated with ECPR. Prehospital ECPR tended to show better survival results (39% vs 30%) but further data are needed to confirm this as the difference was not statistically significant. We found no survivors in the cold-water group raising the question of ECPR indication for these patients in temperate urban areas. In any case, temperature measurement should be systematic in OHCA and there should be predefined care pathways including ECPR for hypothermic OHCA patients even in urban settings with a temperate climate.

Abstract 283: Cardiac Functional Recovery At One Year In Refractory Out-of-hospital Cardiac Arrest Survivors

Introduction: The survival to discharge of patients presenting with refractory out-of-hospital cardiac arrest (OHCA) in centers with a well-established extracorporeal cardiopulmonary resuscitation (ECPR) program has improved over the last decade. While quality of life is an important consideration for all survivors, long-term cardiac functional recovery as defined by the New York Heart Association (NYHA) of this population remains unknown. Methods: We performed a single center, retrospective analysis to evaluate the functional cardiac recovery of refractory OHCA survivors receiving ECPR with VA-ECMO between 2016 and 2020. Relevant demographic information as well as data on admission characteristics and index hospitalization were collected (Table). NYHA functional class was assessed at one month and at one year after hospital discharge. All patients had a transthoracic echocardiogram before discharge. Results: We identified 54 patients that were discharged following ECPR for OHCA during the study period. Forty-six (85%) were alive at one year. Complete functional outcome data were available for 37 survivors. Compared to the first assessment at 1 month, 15 patients (41%) had symptomatic improvement of at least one NYHA class at 1 year ( Figure ). No patients experienced clinical deterioration. Left ventricular ejection fraction assessed pre-discharge was the only significantly different parameter between those with improved and unchanged NYHA class at one year ( Table ). Conclusions: A large proportion of refractory OHCA survivors treated with ECPR have substantial improvement in their NYHA functional status at 1 year.

Extracorporeal versus conventional cardiopulmonary resuscitation for refractory out-of-hospital cardiac arrest: a secondary analysis of the Prague OHCA trial

BackgroundSurvival rates in refractory out-of-hospital cardiac arrest (OHCA) remain low with conventional advanced cardiac life support (ACLS). Extracorporeal life support (ECLS) implantation during ongoing resuscitation, a method called extracorporeal cardiopulmonary resuscitation (ECPR), may increase survival. This study examined whether ECPR is associated with improved outcomes.MethodsPrague OHCA trial enrolled adults with a witnessed refractory OHCA of presumed cardiac origin. In this secondary analysis, the effect of ECPR on 180-day survival using Kaplan–Meier estimates and Cox proportional hazard model was examined.ResultsAmong 256 patients (median age 58 years, 83% male) with median duration of resuscitation 52.5 min (36.5–68), 83 (32%) patients achieved prehospital ROSC during ongoing conventional ACLS prehospitally, 81 (32%) patients did not achieve prehospital ROSC with prolonged conventional ACLS, and 92 (36%) patients did not achieve prehospital ROSC and received ECPR. The overall 180-day survival was 51/83 (61.5%) in patients with prehospital ROSC, 1/81 (1.2%) in patients without prehospital ROSC treated with conventional ACLS and 22/92 (23.9%) in patients without prehospital ROSC treated with ECPR (log-rank p < 0.001). After adjustment for covariates (age, sex, initial rhythm, prehospital ROSC status, time of emergency medical service arrival, resuscitation time, place of cardiac arrest, percutaneous coronary intervention status), ECPR was associated with a lower risk of 180-day death (HR 0.21, 95% CI 0.14–0.31; P < 0.001).ConclusionsIn this secondary analysis of the randomized refractory OHCA trial, ECPR was associated with improved 180-day survival in patients without prehospital ROSC.Trial registration: ClinicalTrials.gov Identifier: NCT01511666, Registered 19 January 2012.

Extracorporeal cardiopulmonary resuscitation: a national study on the association between favourable neurological status and biomarkers of hypoperfusion, inflammation, and organ injury.

In refractory out-of-hospital cardiac arrest (OHCA) with prolonged whole-body ischaemia, global tissue injury proceeds even after establishment of circulation with extracorporeal cardiopulmonary resuscitation (ECPR). We aimed to investigate the role of biomarkers reflecting hypoperfusion, inflammation, and organ injury in prognostication of patients with refractory OHCA managed with ECPR. This nationwide retrospective study included 226 adults with refractory OHCA managed with ECPR in Denmark (2011-2020). Biomarkers the first days after ECPR-initiation were assessed. Odds ratio of favourable neurological status (Cerebral Performance Category 1-2) at hospital discharge was estimated by logistic regression analyses. Cut-off values were calculated using the Youden's index. Fifty-six patients (25%) survived to hospital discharge, 51 (91%) with a favourable neurological status. Factors independently associated with favourable neurological status were low flow time <81 min, admission leukocytes ≥12.8 × 109/L, admission lactate <13.2 mmol/L, alkaline phosphatase (ALP) < 56 (day1) or <55 U/L (day2), and day 1 creatine kinase MB (CK-MB) < 500 ng/mL. Selected biomarkers (leukocytes, C-reactive protein, and lactate) were significantly better predictors of favourable neurological status than classic OHCA-variables (sex, age, low-flow time, witnessed arrest, shockable rhythm) alone (P = 0.001) after hospital admission. Biomarkers of hypoperfusion (lactate), inflammation (leucocytes), and organ injury (ALP and CK-MB) were independently associated with neurological status at hospital discharge. Biomarkers of hypoperfusion and inflammation (at hospital admission) and organ injury (days 1 and 2 after ECPR) may aid in the clinical decision of when to prolong or terminate ECPR in cases of refractory OHCA.

Initial rhythm and survival in refractory out-of-hospital cardiac arrest. Post-hoc analysis of the Prague OHCA randomized trial

BackgroundThe prognosis of refractory out-of-hospital cardiac arrest (OHCA) is generally poor. A recent Prague OHCA study has demonstrated that an invasive approach (including extracorporeal cardiopulmonary resuscitation, ECPR) is a feasible and effective treatment strategy in refractory OHCA. Here we present a post-hoc analysis of the role of initial rhythm on patient outcomes. MethodsThe study enrolled patients who had a witnessed OHCA of presumed cardiac cause without early recovery of spontaneous circulation. The initial rhythm was classified as either a shockable or a non-shockable rhythm. The primary outcome was a composite of 180 day-survival with Cerebral Performance in Category 1 or 2. Results256 (median age 58y, 17% females) patients were enrolled. The median (IQR) duration of resuscitation was 52 (33–68) minutes. 156 (61%) and 100 (39%) of patients manifested a shockable and non-shockable rhythm, respectively. The primary outcome was achieved in 63 (40%) patients with a shockable rhythm and in 5 (5%) patients with a non-shockable rhythm (p < 0.001). When patients were analyzed separately based on whether the treatment was invasive (n = 124) or standard (n = 132), the difference in the primary endpoint between shockable and non-shockable initial rhythms remained significant (35/72 (49%) vs 4/52 (8%) in the invasive arm and 28/84 (33%) vs 1/48 (2%) in the standard arm; p < 0.001). ConclusionAn initial shockable rhythm and treatment with an invasive approach is associated with a reasonable neurologically favorable survival for 180 days despite refractory OHCA. Non-shockable initial rhythms bear a poor prognosis in refractory OHCA even when ECPR is readily available.

Long-term neurological intact survival and quality of life after refractory out-of-hospital cardiac arrest treated with rescue mechanical circulatory support

Abstract Background Mechanical circulatory support (MCS) with either veno-arterial extracorporeal membrane oxygenation (V-A ECMO) or Impella has emerged as a rescue therapy for refractory out-of-hospital cardiac arrest (OHCA). However, only short-term outcome is specified and most studies do not report follow-up beyond six months. Long-term survival and quality of life in this high-risk population remains unknown. Purpose To determine long-term neurological intact survival and quality of life in patients with refractory OHCA treated with MCS. Methods This was an observational, single-centre study of OHCA-patients from January 2015 to December 2019. Patients treated with MCS for OHCA were compared with patients receiving conventional cardiopulmonary resuscitation (CPR). A follow-up of long-term survivors in the MCS group was conducted (&amp;gt;1 year after arrest). This included health related quality of life questionaries (Short Form-36 [SF-36]) and assessment of neurological function with Cerebral Performance Category (CPC). Good neurological outcome was defined as CPC 1 and CPC 2. Results A total of 1015 with OHCA were included; 101 received MCS for refractory cardiac arrest. Among these V-A ECMO was deployed in 97 patients and Impella in 4 patients. The MCS group had significantly longer low-flow times compared to the conventional group (105 [IQR, 94–123] minutes versus 18 [IQR 10–39] minutes) and were more metabolically deranged upon arrival at hospital (Table 1). In patients receiving MCS, the hospital discharge rate was 27% and good neurological outcome was seen in 93% among patients discharged. At follow-up, 15 out of 21 long-term survivors participated. Median follow-up time was 4.8±1.6 (range 2.8–6.1 years). Mean age at follow-up was 61±7.3 years, 11 (73%) were men. Neurological outcome with CPC 1 was found in 12 patients (80%), with CPC 2 in 2 patients (13%), and with CPC 3 in 1 patient (7%). Two had improved neurological status from CPC 2 to CPC 1 since discharge. Mean scores of the SF-36 revealed an overall high level of psychical and mental health in long-term survivors (Figure 1). Conclusion Long-term survival with good neurological outcome was high in patients with refractory OHCA treated with MCS despite prolonged resuscitation and severe metabolic derangement. These patients may expect a reasonable quality of life after discharge. Funding Acknowledgement Type of funding sources: Public hospital(s). Main funding source(s): Department of Cardiology, Aarhus University HospitalSnedkermester Sophus Jacobsen og hustru Astrid Jacobsens Fond

Extracorporeal cardiopulmonary resuscitation: a national study on the association between survival and biomarkers of hypoperfusion, inflammation, and organ failure

Abstract Background In refractory out-of-hospital cardiac arrest (OHCA) with prolonged whole-body ischemia, global tissue injury proceeds even after establishment of circulation with extracorporeal cardiopulmonary resuscitation (ECPR). Purpose We aimed to investigate the role of biomarkers reflecting hypoperfusion, inflammation, and organ injury in prognostication of patients with refractory OHCA managed with ECPR. Methods This nationwide retrospective study included 226 adults with refractory OHCA managed with ECPR in Denmark (2011–2020). Biomarkers at admission and consecutively two days after ECPR initiation were retrieved. Odds ratio (OR) of 90-day survival were assessed by logistic regression analyses. Cut-off values were calculated from area under the curve (AUC) via the Youden index. Results Fifty-six patients (25%) survived to hospital discharge, all were still alive after 90-days and 91% had a favorable neurological status at discharge. Factors independently associated with 90-day survival were: male sex, shockable presenting rhythm, low flow time, platelets, pH, lactate, C-reactive protein, lactate dehydrogenase (LDH), alkaline phosphatase (ALP), and creatine kinase MB (CK-MB) level. Comparing the ability of standard predictive variables (age, sex, shockable presenting rhythm, witnessed arrest, and low flow time) and selected biomarkers (from multivariate analyses) in predicting 90-day survival, biomarkers day 2 after OHCA were significantly better than standard variables (AUC 0.79 vs. 0.56, p=0.01). Conclusion Biomarkers of hypoperfusion (low lactate and high pH), inflammation (high platelets and CRP), and organ failure (low LDH, ALP, and CK-MB) were independently associated with 90-day survival. Biomarkers on day 2 after OHCA (d-dimer, ALP, and CK-MB) were more predictive of 90-day survival than standard predictive variables. Funding Acknowledgement Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Odense University Hospital's and Rigshospitalet's Common Research Foundation

Selection of patients for mechanical circulatory support for refractory out-of-hospital cardiac arrest: a Danish nationwide multicenter study

Abstract Background Extracorporeal cardiopulmonary resuscitation (ECPR) is a potential salvage therapy for selected patients with refractory out-of-hospital cardiac arrest (OHCA). Purpose The objective of this study was to describe the characteristics of potential ECPR patients. Methods This retrospective, observational cohort study included 579 patients admitted with refractory OHCA for possible ECPR at all tertiary cardiac arrest centers in Denmark between 2015 and 2020. Presenting characteristics, reasons for refraining from ECPR, and survival to hospital discharge were recorded. Results After initial evaluation, 221 patients (38%) proceeded to ECPR, and 358 (62%) were considered futile. Median prehospital low-flow time was 70 minutes [interquartile range 56–85] in ECPR patients and 62 minutes [48–81] in no-ECPR patients, p&amp;lt;0.001. Intra arrest transport was more than 50 km in 92 (42%) ECPR patients and 135 in no-ECPR patients (38%), p=0.25. Treatment decision was taken by a team of three specialists in 513 cases (97%). The leading cause for not initiating ECPR was duration of low flow time (39%). Severe metabolic derangement and low end-tidal CO2 (ETCO2) were contributing factors in 35% and 31%, respectively, Figure 1. 83% of the patients had two or more contributing factors recorded as reasons for not initiating ECPR, Figure 2. The most prevailing combination of contributing factors were non-shockable rhythm, low ETCO2, and metabolic derangement or duration of prehospital low flow time combined with low ETCO2. Survival to discharge was achieved in six patients (1.7%) in the no-ECPR group and 50 (23%) in the ECPR group. Conclusions In this large nationwide study of patients admitted for possible ECPR, 62% were not treated with ECPR. The most frequent reasons to abstain from ECPR were duration of prehospital low flow time, metabolic derangement, and low ETCO2. Funding Acknowledgement Type of funding sources: Foundation. Main funding source(s): The Danish Heart Foundation

Latest in Resuscitation Research: Highlights From the 2021 American Heart Association's Resuscitation Science Symposium.

Latest in Resuscitation Research: Highlights From the 2021 American Heart Association's Resuscitation Science Symposium.

Extracorporeal cardiopulmonary resuscitation in out-of-hospital cardiac arrest (OHCA): a four years experience

Abstract Funding Acknowledgements Type of funding sources: None. Introduction Refractory cardiac arrest, defined as the absence of sustained return of spontaneous circulation (ROSC) despite advanced life support (ALS), remains common and is burden by poor outcome. The Extracorporeal Cardiopulmonary Resuscitation (E-CPR) may benefit organ perfusion, potentially improving OHCA outcomes. Purpose The aim of this study was to evaluate outcome of patients with refractory OHCA managed with E-CPR. Methods Single centre prospective observational registry of all patients with OHCA treated with E-CPR from 1 September 2017 to 28 February 2021. The enrolment to E-CPR was defined according to hospital protocol. Results We enrolled 166 patients with OHCA. Out of 59, 39 cases (66,1%) were included in E-CPR program. Prevalence of shockable rhythms was 59%. Survival at discharge from ICU was 10,2% (4 patients; 3 of them discharged with CPC 1-2 and all with ventricular fibrillation at presentation). E-CPR versus patients without refractory arrest have been compared: patients in the E-CPR group were younger (p=0,0002), had lower mean arterial pressure at ROSC and higher SOFA score (p&amp;lt;0,0001). NSE values between survivor (53,8 ± 17,9 mcg/L) and non-survivor (104,8 ± 44,2 mcg/L) at 24 hours were statistically significant (p=0,0669) as well as lactate clearance in the first 48 hours (p=0,001). In the univariate regression model serum lactate at admission (p&amp;lt;0,001; 95% CI 0,87 to 6,83), longer low flow time (p&amp;lt;0,002; 95% CI 0,99 to 1,29) and lower mean arterial pressure (p&amp;lt;0,01; 95% CI 0,99 to 1,29) were associated to mortality. Whereas only lactates (p&amp;lt;0,001; 95% CI 0,092 to 4,56) and low flow time (p&amp;lt;0,001; 95% CI 0,092 to 0,17) retained the association in the multivariate model (figure 1 for ROC curves). Conclusion Mortality rate in OHCA remains unacceptably high. Patients undertaking E-CPR have worsen hemodynamic and clinical parameters at admission, likely to consequence of refractory cardiac arrest. Low-flow time and lactates level are related to higher mortality as expression of worsen metabolic condition related to hypoperfusion state in patients with delayed ROSC.

Neurological intact survival with rescue mechanical circulatory support for refractory out-of-hospital cardiac arrest despite long low-flow times

Abstract Funding Acknowledgements Type of funding sources: None. Background The potential window for using mechanical circulatory support (MCS) for refractory out-of-hospital cardiac arrest (OHCA) remain unsettled. It has been proposed that a cut-off limit defined as the golden hour may produce higher survival with good neurological outcome. Purpose The present study analyzed the association of low-flow time and neurological intact survival (Cerebral Performance Categories 1-2) at discharge between patients receiving conventional cardiopulmonary resuscitation (CCPR) and MCS. Methods The present retrospective, observational, single centre study from 2015-2019 included all consecutive OHCA patients, who were treated with MCS for refractory OHCA or received CCPR. Low-flow time was defined as the time from CPR to deployment of either veno-arterial extracorporeal membrane oxygenation or Impella support for the MCS group. Time from CPR to return of spontaneous circulation or termination of treatment was recorded for the CCPR group. Rate of neurological intact survival at discharge were analyzed for both groups. Results A total of 101 patients were treated with MCS and 914 patients received CCPR. The MCS group was significantly younger with a median age of 56 (IQR, 46-62) years compared to 67 (IQR, 57-74) years, p &amp;lt; 0.001. In the CCPR group, short low-flow times (0-20 minutes) were associated with high survival with good neurological outcome at discharge. There were no survivors with low-flow times exceeding 70 minutes. All patients receiving MCS survived at low-flow times 31-60 minutes, however neurological intact survival dropped to 21% at low-flow times &amp;gt; 80 minutes. Conclusion Patients treated with MCS with low-flow time 70-80 minutes did show similar favorable neurological outcome at discharge as patients receiving CCPR with low-flow &amp;lt; 10 minutes. Despite, low-flow times exceeding 80 minutes, patients treated with MCS still presented high survival rate of 21%. Hence, the data in this study does not support a golden hour for MCS.

Long-term survival in patients treated with mechanical circulatory support for refractory out-of-hospital cardiac arrest

Abstract Funding Acknowledgements Type of funding sources: None. Background Mechanical circulatory support (MCS) is used increasingly in the setting of refractory out-of-hospital cardiac arrest (OHCA). However, limited data exist on long-term survival. Purpose To investigate the long-term outcome in patients receiving MCS compared to patients with return of spontaneous circulation (ROSC) at hospital admission. Methods Retrospective, observational single centre study from 2015-2019. The study included all patients who achieved ROSC on admission and patients receiving MCS for refractory OHCA defined as either veno-arterial extracorporeal membrane oxygenation or Impella support. Kaplan-Meier survival analysis were performed to evaluate long-term survival in both groups and compared with the log-rank test. Results A total of 698 patients with ROSC on admission and 101 patients receiving MCS were included. Acute myocardial infarction was the most common aetiology of arrest in both groups. There were no differences in witnessed arrest, bystander cardiopulmonary resuscitation or initial presenting rhythm. Low-flow time was substantially longer in the MCS group compared to the ROSC group (median 105 (IQR, 94-123) minutes versus median 15 (IQR, 8-22) minutes, p &amp;lt; 0.001). The 5-day mortality rate was 63% in the MCS group versus 24% in the ROSC group. Long-term survival from day 6 to day 90 was 71% in the MCS group and 83% in the ROSC group, p = 0.072. Conclusions In conclusion, the risk of death within the first 5 days was higher for OHCA patients treated with MCS than in patients with ROSC on admission. Among patients surviving the first 5 days, 90-day mortality was low in both groups.

PO-685-01 INITIAL RHYTHM DETERMINATES CLINICAL OUTCOME IN PROLONGED AND REFRACTORY OUT-OF-HOSPITAL CARDIAC ARREST

Survival to hospital discharge with neurological and functional recovery after refractory and prolonged out-of-hospital cardiac arrest (OHCA) is low. The Prague OHCA study has demonstrated that a hyperinvasive approach (early transport to hospital under mechanical cardiopulmonary resuscitation (CPR), extracorporeal cardiopulmonary resuscitation (ECPR) and immediate invasive assessment and therapy) is a feasible and effective treatment strategy in refractory OHCA.

Beneficial Effects of Adjusted Perfusion and Defibrillation Strategies on Rhythm Control within Controlled Automated Reperfusion of the Whole Body (CARL) for Refractory Out-of-Hospital Cardiac Arrest.

Survival and neurological outcomes after out-of-hospital cardiac arrest (OHCA) remain low. The further development of prehospital extracorporeal resuscitation (ECPR) towards Controlled Automated Reperfusion of the Whole Body (CARL) has the potential to improve survival and outcome in these patients. In CARL therapy, pulsatile, high blood-flow reperfusion is performed combined with several modified reperfusion parameters and adjusted defibrillation strategies. We aimed to investigate whether pulsatile, high-flow reperfusion is feasible in refractory OHCA and whether the CARL approach improves heart-rhythm control during ECPR. In a reality-based porcine model of refractory OHCA, 20 pigs underwent prehospital CARL or conventional ECPR. Significantly higher pulsatile blood-flow proved to be feasible, and critical hypotension was consistently prevented via CARL. In the CARL group, spontaneous rhythm conversions were observed using a modified priming solution. Applying potassium-induced secondary cardioplegia proved to be a safe and effective method for sustained rhythm conversion. Moreover, significantly fewer defibrillation attempts were needed, and cardiac arrhythmias were reduced during reperfusion via CARL. Prehospital CARL therapy thus not only proved to be feasible after prolonged OHCA, but it turned out to be superior to conventional ECPR regarding rhythm control.

Outcomes of patients with refractory out-of-hospital cardiac arrest transported to an ECMO centre compared with transport to non-ECMO centres

Objective: To compare the outcomes of patients with refractory out-of-hospital cardiac arrest (OHCA) transported to a hospital that provides extracorporeal membrane oxygenation (ECMO) during cardiopulmonary resuscitation (ECPR) with patients transported to hospitals without ECPR capability. Design, setting: Retrospective review of patient care records in a pre-hospital and hospital setting. Participants: Adult patients with OHCA who left the scene and arrived with cardiopulmonary resuscitation in progress at 16 hospitals in Melbourne, Australia, between January 2016 and December 2019. Intervention: For selected patients transported to the ECPR centre, initiation of ECMO. Main outcome measures: Survival to hospital discharge and 12-month quality of life. Results: There were 223 eligible patients during the study period. Of 49 patients transported to the ECPR centre, 23 were commenced on ECMO. Of these, survival to hospital with good neurological recovery (Cerebral Performance Category [CPC] score 1/2) occurred in 4/23 patients. Four other patients developed return of spontaneous circulation in the ECPR centre before cannulation of whom one survived, giving overall good functional outcome at 12 months survival of 5/49 (10.2%). There were 174 patients transported to the 15 non-ECPR centres and 3/174 (2%) had good functional outcome at 12 months. After adjustment for baseline differences, the odds ratio for good neurological outcome after transport to an ECPR centre compared with a non-ECPR centre was 4.63 (95% CI, 0.97-22.11; P = 0.055). Conclusion: The survival rate of patients with refractory OHCA transported to an ECPR centre remains low. Outcomes in larger cities might be improved with shorter scene times and additional ECPR centres that would provide for earlier initiation of ECMO.

Effect of Intra-arrest Transport, Extracorporeal Cardiopulmonary Resuscitation, and Immediate Invasive Assessment and Treatment on Functional Neurologic Outcome in Refractory Out-of-Hospital Cardiac Arrest

<h3>Importance</h3> Out-of-hospital cardiac arrest (OHCA) has poor outcome. Whether intra-arrest transport, extracorporeal cardiopulmonary resuscitation (ECPR), and immediate invasive assessment and treatment (invasive strategy) is beneficial in this setting remains uncertain. <h3>Objective</h3> To determine whether an early invasive approach in adults with refractory OHCA improves neurologically favorable survival. <h3>Design, Setting, and Participants</h3> Single-center, randomized clinical trial in Prague, Czech Republic, of adults with a witnessed OHCA of presumed cardiac origin without return of spontaneous circulation. A total of 256 participants, of a planned sample size of 285, were enrolled between March 2013 and October 2020. Patients were observed until death or day 180 (last patient follow-up ended on March 30, 2021). <h3>Interventions</h3> In the invasive strategy group (n = 124), mechanical compression was initiated, followed by intra-arrest transport to a cardiac center for ECPR and immediate invasive assessment and treatment. Regular advanced cardiac life support was continued on-site in the standard strategy group (n = 132). <h3>Main Outcomes and Measures</h3> The primary outcome was survival with a good neurologic outcome (defined as Cerebral Performance Category [CPC] 1-2) at 180 days after randomization. Secondary outcomes included neurologic recovery at 30 days (defined as CPC 1-2 at any time within the first 30 days) and cardiac recovery at 30 days (defined as no need for pharmacological or mechanical cardiac support for at least 24 hours). <h3>Results</h3> The trial was stopped at the recommendation of the data and safety monitoring board when prespecified criteria for futility were met. Among 256 patients (median age, 58 years; 44 [17%] women), 256 (100%) completed the trial. In the main analysis, 39 patients (31.5%) in the invasive strategy group and 29 (22.0%) in the standard strategy group survived to 180 days with good neurologic outcome (odds ratio [OR], 1.63 [95% CI, 0.93 to 2.85]; difference, 9.5% [95% CI, −1.3% to 20.1%];<i>P</i> = .09). At 30 days, neurologic recovery had occurred in 38 patients (30.6%) in the invasive strategy group and in 24 (18.2%) in the standard strategy group (OR, 1.99 [95% CI, 1.11 to 3.57]; difference, 12.4% [95% CI, 1.9% to 22.7%];<i>P</i> = .02), and cardiac recovery had occurred in 54 (43.5%) and 45 (34.1%) patients, respectively (OR, 1.49 [95% CI, 0.91 to 2.47]; difference, 9.4% [95% CI, −2.5% to 21%];<i>P</i> = .12). Bleeding occurred more frequently in the invasive strategy vs standard strategy group (31% vs 15%, respectively). <h3>Conclusions and Relevance</h3> Among patients with refractory out-of-hospital cardiac arrest, the bundle of early intra-arrest transport, ECPR, and invasive assessment and treatment did not significantly improve survival with neurologically favorable outcome at 180 days compared with standard resuscitation. However, the trial was possibly underpowered to detect a clinically relevant difference. <h3>Trial Registration</h3> ClinicalTrials.gov Identifier:NCT01511666

Abstract 12069: Long-Term Trends in the Incidence and Outcome of Refractory and Non-Refractory Ventricular Fibrillation Cardiac Arrest

Introduction: Although many developed countries are reporting temporal improvements in out-of-hospital cardiac arrest (OHCA) outcomes from initial shockable rhythms, trends in the incidence and outcome of refractory ventricular fibrillation are not well understood. Methods: Between 2010 and 2019, we performed a retrospective observational study of OHCA from a population-based registry in Victoria, Australia. We included all adult, non-traumatic OHCA with an initial shockable rhythm. Temporal trends in incidence and survival to hospital discharge were compared across non-refractory and refractory OHCA, defined as cases receiving 3 or more consecutive shocks for a persistent shockable rhythm. Risk-adjusted logistic regression models were used to describe the year-on-year change in the likelihood of refractory OHCA and survival to hospital discharge. Results: Of the 7,267 initial shockable OHCA with an attempted resuscitation, 4168 (57.4%) and 3,099 (42.6%) were non-refractory and refractory OHCA, respectively. The proportion of cases with refractory OHCA declined over the study period from 48.4% in 2010 to 40.2% in 2019 (p trend &lt;0.001). Unadjusted survival to hospital discharge was higher in non-refractory OHCA (46.3% vs. 25.8%, p&lt;0.001), although both populations experienced increases in survival over time (p trend &lt;0.05 for both). After adjustment for arrest confounders, the likelihood of refractory VF decreased by 4.4% every year (adjusted odds ratio [AOR]: 0.96, 95% CI: 0.94, 0.97; p&lt;0.001). Factors reducing the likelihood of refractory OHCA were female sex, bystander CPR, arrest witnessed by emergency medical services, and public location. In the survival model, refractory OHCA was independently associated with a reduction in survival to hospital discharge (AOR 0.50, 95% CI: 0.45, 0.56; p&lt;0.001). Temporal improvements in survival were observed year-on-year (AOR 1.03, 95% CI: 1.02, 1.05; p&lt;0.001) and this did not differ between non-refractory and refractory OHCA (group interaction, p = 0.51). Conclusions: The incidence of refractory OHCA is declining in our region and survival outcomes are improving. Further research identifying factors contributing to the decline in refractory OHCA may help to improve outcomes further.

Abstract 10522: Early Lactate Clearance is Associated With Survival in a National Cohort of Refractory Out-of-Hospital Cardiac Arrest Patients Managed With Extracorporeal Cardiopulmonary Resuscitation

Introduction: In refractory out-of-hospital cardiac arrest (OHCA), prolonged whole-body ischemia with global tissue injury proceeds even after achievement of reperfusion with extracorporeal cardiopulmonary resuscitation (eCPR). Hypothesis: Biomarkers reflecting ischemia and inflammation may be used for prognostication of refractory OHCA managed with eCPR. Methods: This nationwide retrospective study included patients (≥18 years) with refractory OHCA managed with eCPR in Denmark (2011 to 2020). Biomarker levels at admission, at 24 hours (lactate, leukocytes, and platelets), and repeated measures of lactate after eCPR initiation were analyzed. Lactate clearance was calculated as (admission lactate - post eCPR lactate) / admission lactate x100%. Results: Two hundred eighteen patients (80% male; age 52±12yrs) were included. Primary cause of OHCA was acute myocardial infarction (63%), 69% had shockable primary rhythm and 86% witnessed OHCA with a median low-flow time of 105 minutes (Q1-Q3: 86-124 min.). Fifty-three (24%) survived to hospital discharge. Survivors had a significantly lower lactate level at admission (13.1 vs. 15.4 mmol/l, p=0.004) and after 24 hours (2.8 vs. 5.0, p=0.001), and a significantly higher admission platelet level (181 vs. 153 x10 9 /l, p=0.03). No difference in admission levels of leukocytes nor leukocytes and platelets after 24 hours were found between survivors and non-survivors. Lactate clearance was available for 68% and 79% of patients alive after 8 and 24 hours, respectively. All survivors had a lactate level less than admission lactate at 8 hours (lactate clearance &gt;0%) and had cleared &gt;25% of admission lactate at 24 hours after eCPR initiation. There was a significant difference in survival between quartiles of lactate clearance at 8 hours after eCPR initiation (Figure 1). Conclusion: In conclusion, early lactate clearance after eCPR initiation was associated with survival to discharge in refractory OHCA-patients.

Abstract 13071: Supraglottic Airway Devices Are Associated With Asphyxial Physiology Upon Arrival for ECPR in Patients With Refractory OHCA Treated With Prolonged CPR

Introduction: Multiple clinical trials have failed to show significant differences in survival between use of endotracheal intubation (ETI) and supraglottic airway devices (SGA) in patients with out-of-hospital cardiac arrest (OHCA). However, treatment in these trials was limited to standard ACLS, which favors short duration of CPR. We sought to compare the physiological effect of ETI versus SGA use in patients treated with prolonged CPR and extracorporeal pulmonary resuscitation (ECPR) for refractory ventricular fibrillation/ventricular tachycardia (VT/VF) by the Minnesota Mobile Resuscitation Consortium (MMRC). Methods: Consecutive refractory VT/VF OHCA patients transported by the MMRC to the University of Minnesota for ECPR between 2015 and 2021 were included in this retrospective analysis. Patients were considered ineligible for ECPR if they failed specific arterial blood gas metabolic criteria (lactic acid &gt;18 mmol/L, PaO2 &lt;50 mmHg, and ETCO2 &lt;10 mmHg). Metabolic parameters at presentation and survival were compared between patients receiving ETI and SGA. Results: Among 260 patients (58.0±11.8 years), 46.5% received ETI and 53.5% received SGA. During the index hospitalization, 78/260 (30%) achieved neurologically favorable survival. Compared to those receiving ETI, patients receiving SGA had lower PaO2 (116.8±118.7 versus 135.8±128.3 mmHg, p=0.03), higher PaCO2 (69.7±28.9 versus 60.7±25.6 mmHg, p=0.01), and lower pH (7.00±0.19 versus 7.06±0.21, p=0.008). Significantly more patients who received SGA had PaO2 &lt;50mmHg (29.1% versus 16.9%, respectively; p=0.02) and ≥1 ECPR exclusion criteria (33.1% versus 20.7%, respectively; p=0.03). Among patients excluded for PaO2 &lt;50 mmHg, the presenting PaO2 was 35.5±11.0 mmHg and the presenting PaCO2 was 94.5±26.2 mmHg, suggestive of absence of effective ventilation (asphyxia) at presentation. Survival with CPC 1-2 was 34.7% versus 25.9% for ETI versus SGA, respectively (p=0.12). Conclusion: Use of SGA, during prolonged CPR in refractory VT/VF OHCA, was associated with a significant increase in the proportion of patients presenting with significant hypoxemia and asphyxial physiology, thus increasing ineligibility for ECPR.