The effects of prehospital TXA on mortality and neurologic outcomes in patients with traumatic intracranial hemorrhage: A subgroup analysis from the prehospital TXA for TBI trial.

BACKGROUND: In the prehospital tranexamic acid (TXA) for traumatic brain injury (TBI) trial, TXA administered within 2 hours of injury in the out-of-hospital setting did not reduce mortality in all patients with moderate/severe traumatic brain injury (TBI). We examined the association between TXA dosing arms, neurologic outcome, and mortality in patients with intracranial hemorrhage (ICH) on computed tomography (CT). METHODS: This was a secondary analysis of the Prehospital Tranexamic Acid for TBI Trial ( ClinicalTrials.gov [NCT01990768]) that randomized adults with moderate/severe TBI (Glasgow Coma Scale score < 13) and systolic blood pressure ≥ 90 mm Hg within 2 hours of injury to a 2-g out-of-hospital TXA bolus followed by an in-hospital saline infusion, a 1-g out-of-hospital TXA bolus/1-g in-hospital TXA infusion, or an out-of-hospital saline bolus/in-hospital saline infusion (placebo). This analysis included the subgroup with ICH on initial CT. Primary outcomes included 28-day mortality, 6-month Glasgow Outcome Scale-Extended (GOSE) ≤ 4, and 6-month Disability Rating Scale (DRS). Outcomes were modeled using linear regression with robust standard errors. RESULTS: The primary trial included 966 patients. Among 541 participants with ICH, 28-day mortality was lower in the 2-g TXA bolus group (17%) compared with the other two groups (1-g bolus/1-g infusion 26%, placebo 27%). The estimated adjusted difference between the 2-g bolus and placebo groups was -8·5 percentage points (95% confidence interval [CI], -15.9 to -1.0) and between the 2-g bolus and 1-g bolus/1-g infusion groups was -10.2 percentage points (95% CI, -17.6 to -2.9). Disability Rating Scale at 6 months was lower in the 2-g TXA bolus group than the 1-g bolus/1-g infusion (estimated difference - 2.1 [95% CI, -4.2 to -0.02]) and placebo groups (-2.2 [95% CI, -4.3, -0.2]). Six-month GOSE did not differ among groups. CONCLUSION: A 2-g out-of-hospital TXA bolus in patients with moderate/severe TBI and ICH resulted in lower 28-day mortality and lower 6-month DRS than placebo and standard TXA dosing. LEVEL OF EVIDENCE: Therapeutic/Care Management; Level II.

The American Heart Association at 100: A Century of Scientific Progress and the Future of Cardiovascular Science: A Presidential Advisory From the American Heart Association.

In 1924, the founders of the American Heart Association (AHA) envisioned an international society focused on the heart and aimed at facilitating research, disseminating information, increasing public awareness, and developing public health policy related to heart disease. This presidential advisory provides a comprehensive review of the past century of cardiovascular and stroke science, with a focus on the AHA's contributions, as well as informed speculation about the future of cardiovascular science into the next century of the organization's history. The AHA is a leader in fundamental, translational, clinical, and population science, and it promotes the concept of the "learning health system," in which a continuous cycle of evidence-based practice leads to practice-based evidence, permitting an iterative refinement in clinical evidence and care. This advisory presents the AHA's journey over the past century from instituting professional membership to establishing extraordinary research funding programs; translating evidence to practice through clinical practice guidelines; affecting systems of care through quality programs, certification, and implementation; leading important advocacy efforts at the federal, state and local levels; and building global coalitions around cardiovascular and stroke science and public health. Recognizing an exciting potential future for science and medicine, the advisory offers a vision for even greater impact for the AHA's second century in its continued mission to be a relentless force for longer, healthier lives.

Standardized Definitions for Cardiogenic Shock Research and Mechanical Circulatory Support Devices: Scientific Expert Panel From the Shock Academic Research Consortium (SHARC).

The Shock Academic Research Consortium is a multi-stakeholder group, including representatives from the US Food and Drug Administration and other government agencies, industry, and payers, convened to develop pragmatic consensus definitions useful for the evaluation of clinical trials enrolling patients with cardiogenic shock, including trials evaluating mechanical circulatory support devices. Several in-person and virtual meetings were convened between 2020 and 2022 to discuss the need for developing the standardized definitions required for evaluation of mechanical circulatory support devices in clinical trials for cardiogenic shock patients. The expert panel identified key concepts and topics by performing literature reviews, including previous clinical trials, while recognizing current challenges and the need to advance evidence-based practice and statistical analysis to support future clinical trials. For each category, a lead (primary) author was assigned to perform a literature search and draft a proposed definition, which was presented to the subgroup. These definitions were further modified after feedback from the expert panel meetings until a consensus was reached. This manuscript summarizes the expert panel recommendations focused on outcome definitions, including efficacy and safety.

Variation in time to notification of enrollment and rates of withdrawal in resuscitation trials conducted under exception from informed consent.

IMPORTANCE: Emergency research is challenging to do well as it involves time sensitive interventions in unstable patients. There is limited time to obtain informed consent from the patient or their legally authorized representative (LAR). Such research is permitted under exception from informed consent (EFIC) if specific criteria are met, including notification after enrollment. Some question whether the risks of EFIC outweighs its benefits. To date, there is limited empiric information about time to notification (TTN) and rates of withdrawal in such trials. OBJECTIVE: To describe variation in TTN and rates of withdrawal among that patients enrolled in EFIC trials over a twelve-year period. DESIGN: We performed post hoc descriptive analyses of data from five trials conducted under EFIC. SETTING: Emergency medical services and receiving hospitals participating in the Resuscitation Outcomes Consortium in the United States and Canada. PARTICIPANTS: Patients with out-of-hospital cardiac arrest or life-threatening traumatic injury. EXPOSURES: Notification strategies were specified at each site before initiation of enrollment by a local institutional review board. We monitored TTN within each site centrally throughout each study's enrollment period. OUTCOMES: TTN was defined as time from randomization to first-reported notification of patient or LAR of enrollment. Withdrawal was defined as patient or LAR opt out of ongoing participation at the time of notification. RESULTS: Of 35,442 patients enrolled in five trials, 33,805 had cardiac arrest; and 1636 had traumatic injury. TTN varied overall and by patient outcome. Among those with cardiac arrest, TTN ranged from median (5%ile, 95%ile) of 6 (1,27) days to 28 (2, 53) days across sites. 0.3% of notified patients with cardiac arrest withdrew. Among those with traumatic injury, TTN ranged from 0 (0, 5) days to 36 (5, 68) days across sites. 7.7% of notified patients with traumatic injury withdrew. CONCLUSIONS AND RELEVANCE: There is large variation in TTN in trials conducted under EFIC for emergency research. This may be due to several factors. It may or may not be modifiable. Overall rates of withdrawal are low, which suggests current practices related to EFIC are acceptable to those who have participated in emergency research.

Tranexamic acid administration in the field does not affect admission thromboelastography after traumatic brain injury.

BACKGROUND: No Food and Drug Administration-approved medication improves outcomes following traumatic brain injury (TBI). A forthcoming clinical trial that evaluated the effects of two prehospital tranexamic acid (TXA) dosing strategies compared with placebo demonstrated no differences in thromboelastography (TEG) values. We proposed to explore the impact of TXA on markers of coagulation and fibrinolysis in patients with moderate to severe TBI. METHODS: Data were extracted from a placebo-controlled clinical trial in which patients 15 years or older with TBI (Glasgow Coma Scale, 3-12) and systolic blood pressure of ≥90 mm Hg were randomized prehospital to receive placebo bolus/placebo infusion (placebo), 1 g of TXA bolus/1 g of TXA infusion (bolus maintenance), or 2 g of TXA bolus/placebo infusion (bolus only). Thromboelastography was performed, and coagulation measures including prothrombin time, activated partial thromboplastin time, international ratio, fibrinogen, D-dimer, plasmin-antiplasmin (PAP), thrombin antithrombin, tissue plasminogen activator, and plasminogen activator inhibitor 1 were quantified at admission and 6 hours later. RESULTS: Of 966 patients receiving study drug, 700 had laboratory tests drawn at admission and 6 hours later. There were no statistically significant differences in TEG values, including LY30, between groups (p > 0.05). No differences between prothrombin time, activated partial thromboplastin time, international ratio, fibrinogen, thrombin antithrombin, tissue plasminogen activator, and plasminogen activator inhibitor 1 were demonstrated across treatment groups. Concentrations of D-dimer in TXA treatment groups were less than placebo at 6 hours (p < 0.001). Concentrations of PAP in TXA treatment groups were less than placebo on admission (p < 0.001) and 6 hours (p = 0.02). No differences in D-dimer and PAP were observed between bolus maintenance and bolus only. CONCLUSION: While D-dimer and PAP levels reflect a lower degree of fibrinolysis following prehospital administration of TXA when compared with placebo in a large prehospital trial of patients with TBI, TEG obtained on admission and 6 hours later did not demonstrate any differences in fibrinolysis between the two TXA dosing regimens and placebo. LEVEL OF EVIDENCE: Diagnostic test, level III.

Effect of Out-of-Hospital Tranexamic Acid vs Placebo on 6-Month Functional Neurologic Outcomes in Patients With Moderate or Severe Traumatic Brain Injury.

Importance: Traumatic brain injury (TBI) is the leading cause of death and disability due to trauma. Early administration of tranexamic acid may benefit patients with TBI. Objective: To determine whether tranexamic acid treatment initiated in the out-of-hospital setting within 2 hours of injury improves neurologic outcome in patients with moderate or severe TBI. Design, Setting, and Participants: Multicenter, double-blinded, randomized clinical trial at 20 trauma centers and 39 emergency medical services agencies in the US and Canada from May 2015 to November 2017. Eligible participants (N = 1280) included out-of-hospital patients with TBI aged 15 years or older with Glasgow Coma Scale score of 12 or less and systolic blood pressure of 90 mm Hg or higher. Interventions: Three interventions were evaluated, with treatment initiated within 2 hours of TBI: out-of-hospital tranexamic acid (1 g) bolus and in-hospital tranexamic acid (1 g) 8-hour infusion (bolus maintenance group; n = 312), out-of-hospital tranexamic acid (2 g) bolus and in-hospital placebo 8-hour infusion (bolus only group; n = 345), and out-of-hospital placebo bolus and in-hospital placebo 8-hour infusion (placebo group; n = 309). Main Outcomes and Measures: The primary outcome was favorable neurologic function at 6 months (Glasgow Outcome Scale-Extended score >4 [moderate disability or good recovery]) in the combined tranexamic acid group vs the placebo group. Asymmetric significance thresholds were set at 0.1 for benefit and 0.025 for harm. There were 18 secondary end points, of which 5 are reported in this article: 28-day mortality, 6-month Disability Rating Scale score (range, 0 [no disability] to 30 [death]), progression of intracranial hemorrhage, incidence of seizures, and incidence of thromboembolic events. Results: Among 1063 participants, a study drug was not administered to 96 randomized participants and 1 participant was excluded, resulting in 966 participants in the analysis population (mean age, 42 years; 255 [74%] male participants; mean Glasgow Coma Scale score, 8). Of these participants, 819 (84.8%) were available for primary outcome analysis at 6-month follow-up. The primary outcome occurred in 65% of patients in the tranexamic acid groups vs 62% in the placebo group (difference, 3.5%; [90% 1-sided confidence limit for benefit, -0.9%]; P = .16; [97.5% 1-sided confidence limit for harm, 10.2%]; P = .84). There was no statistically significant difference in 28-day mortality between the tranexamic acid groups vs the placebo group (14% vs 17%; difference, -2.9% [95% CI, -7.9% to 2.1%]; P = .26), 6-month Disability Rating Scale score (6.8 vs 7.6; difference, -0.9 [95% CI, -2.5 to 0.7]; P = .29), or progression of intracranial hemorrhage (16% vs 20%; difference, -5.4% [95% CI, -12.8% to 2.1%]; P = .16). Conclusions and Relevance: Among patients with moderate to severe TBI, out-of-hospital tranexamic acid administration within 2 hours of injury compared with placebo did not significantly improve 6-month neurologic outcome as measured by the Glasgow Outcome Scale-Extended. Trial Registration: ClinicalTrials.gov Identifier: NCT01990768.

Bystander automated external defibrillator application in non-shockable out-of-hospital cardiac arrest.

BACKGROUND: An increasing proportion of patients with OHCA present with non-shockable rhythms, among whom the benefit from AED application is not known. METHODS: We performed a retrospective analysis of adults with non-traumatic, public, bystander-witnessed, non-shockable OHCA occurring between 2005-2015 at 9 locations participating in the Resuscitation Outcomes Consortium. Non-shockable arrest was defined as when no shock was administered by a bystander applied AED and confirmed by the initial rhythm on EMS arrival. Outcomes were compared between patients with non-shockable OHCA in whom a bystander AED was or was not applied. RESULTS: Among 2809 patients with non-shockable public, witnessed OHCA, 8.4% had an AED applied. CPR was more often performed in the AED-applied group (99% vs. 51% of patients, p < 0.001). Among patients in whom an AED was not applied, 39.8% had any pre-hospital ROSC, 29.6% had a pulse at ED arrival and 11.1% survived to hospital discharge compared to 44.1%, 29.6% and 9.7%, respectively with AED application. After adjustment for the Utstein variables excluding bystander CPR, the OR for survival to hospital discharge for AED application was 0.90 (95% CI:0.57-1.42); when adjusted for the higher frequency of CPR in the AED group the OR was 0.92 (95% CI:0.57-1.47). CONCLUSIONS: The application of an AED in non-shockable public witnessed OHCA was associated with a higher frequency of bystander CPR. The probabilities of pre-hospital ROSC, pulse at ED arrival, and survival to hospital discharge were not altered by the application of an AED.

Effect of a Strategy of Initial Laryngeal Tube Insertion vs Endotracheal Intubation on 72-Hour Survival in Adults With Out-of-Hospital Cardiac Arrest: A Randomized Clinical Trial.

Importance: Emergency medical services (EMS) commonly perform endotracheal intubation (ETI) or insertion of supraglottic airways, such as the laryngeal tube (LT), on patients with out-of-hospital cardiac arrest (OHCA). The optimal method for OHCA advanced airway management is unknown. Objective: To compare the effectiveness of a strategy of initial LT insertion vs initial ETI in adults with OHCA. Design, Setting, and Participants: Multicenter pragmatic cluster-crossover clinical trial involving EMS agencies from the Resuscitation Outcomes Consortium. The trial included 3004 adults with OHCA and anticipated need for advanced airway management who were enrolled from December 1, 2015, to November 4, 2017. The final date of follow-up was November 10, 2017. Interventions: Twenty-seven EMS agencies were randomized in 13 clusters to initial airway management strategy with LT (n = 1505 patients) or ETI (n = 1499 patients), with crossover to the alternate strategy at 3- to 5-month intervals. Main Outcomes and Measures: The primary outcome was 72-hour survival. Secondary outcomes included return of spontaneous circulation, survival to hospital discharge, favorable neurological status at hospital discharge (Modified Rankin Scale score ≤3), and key adverse events. Results: Among 3004 enrolled patients (median [interquartile range] age, 64 [53-76] years, 1829 [60.9%] men), 3000 were included in the primary analysis. Rates of initial airway success were 90.3% with LT and 51.6% with ETI. Seventy-two hour survival was 18.3% in the LT group vs 15.4% in the ETI group (adjusted difference, 2.9% [95% CI, 0.2%-5.6%]; P = .04). Secondary outcomes in the LT group vs ETI group were return of spontaneous circulation (27.9% vs 24.3%; adjusted difference, 3.6% [95% CI, 0.3%-6.8%]; P = .03); hospital survival (10.8% vs 8.1%; adjusted difference, 2.7% [95% CI, 0.6%-4.8%]; P = .01); and favorable neurological status at discharge (7.1% vs 5.0%; adjusted difference, 2.1% [95% CI, 0.3%-3.8%]; P = .02). There were no significant differences in oropharyngeal or hypopharyngeal injury (0.2% vs 0.3%), airway swelling (1.1% vs 1.0%), or pneumonia or pneumonitis (26.1% vs 22.3%). Conclusions and Relevance: Among adults with OHCA, a strategy of initial LT insertion was associated with significantly greater 72-hour survival compared with a strategy of initial ETI. These findings suggest that LT insertion may be considered as an initial airway management strategy in patients with OHCA, but limitations of the pragmatic design, practice setting, and ETI performance characteristics suggest that further research is warranted. Trial Registration: ClinicalTrials.gov Identifier: NCT02419573.

Variation in Survival After Out-of-Hospital Cardiac Arrest Between Emergency Medical Services Agencies.

Importance: Emergency medical services (EMS) deliver essential initial care for patients with out-of-hospital cardiac arrest (OHCA), but the extent to which patient outcomes vary between different EMS agencies is not fully understood. Objective: To quantify variation in patient outcomes after OHCA across EMS agencies. Design, Setting, and Participants: This observational cohort study was conducted in the Resuscitation Outcomes Consortium (ROC) Epistry, a prospective multicenter OHCA registry at 10 sites in North America. Any adult with OHCA treated by an EMS from April 2011 through June 2015 was included. Data analysis occurred from May 2017 to March 2018. Exposure: Treating EMS agency. Main Outcomes and Measures: The primary outcome was survival to hospital discharge. Secondary outcomes were return of spontaneous circulation at emergency department arrival and favorable functional outcome at hospital discharge (defined as a modified Rankin scale score ≤3). Multivariable hierarchical logistic regression models were used to adjust confounders and clustering of patients within EMS agencies, and calculated median odds ratios (MORs) were used to quantify the extent of residual variation in outcomes between EMS agencies. Results: We identified 43 656 patients with OHCA treated by 112 EMS agencies. At EMS agency level, we observed large variations in survival to hospital discharge (range, 0%-28.9%; unadjusted MOR, 1.43 [95% CI, 1.34-1.54]), return of spontaneous circulation on emergency department arrival (range, 9.0%-57.1%; unadjusted MOR, 1.53 [95% CI, 1.43-1.65]), and favorable functional outcome (range, 0%-20.4%; unadjusted MOR, 1.54 [95% CI, 1.40-1.73]). This variation persisted despite adjustment for patient-level and EMS agency-level factors known to be associated with outcomes (adjusted MOR for survival 1.56 [95% CI 1.44-1.73]; adjusted MOR for return of spontaneous circulation at emergency department arrival, 1.50 [95% CI, 1.41-1.62]; adjusted MOR for functionally favorable survival, 1.53 [95% CI, 1.37-1.78]). After restricting analysis to those who survived more than 60 minutes after hospital arrival and including hospital treatment characteristics, the variation persisted (adjusted MOR for survival, 1.49 [95% CI, 1.36-1.69]; adjusted MOR for functionally favorable survival, 1.34 [95% CI, 1.20-1.59]). Conclusions and Relevance: We found substantial variations in patient outcomes after OHCA between a large group of EMS agencies in North America that were not explained by documented patient-level and EMS agency-level variables.

Impact of Bystander Automated External Defibrillator Use on Survival and Functional Outcomes in Shockable Observed Public Cardiac Arrests.

BACKGROUND: Survival following out-of-hospital cardiac arrest (OHCA) with shockable rhythms can be improved with early defibrillation. Although shockable OHCA accounts for only ≈25% of overall arrests, ≈60% of public OHCAs are shockable, offering the possibility of restoring thousands of individuals to full recovery with early defibrillation by bystanders. We sought to determine the association of bystander automated external defibrillator use with survival and functional outcomes in shockable observed public OHCA. METHODS: From 2011 to 2015, the Resuscitation Outcomes Consortium prospectively collected detailed information on all cardiac arrests at 9 regional centers. The exposures were shock administration by a bystander-applied automated external defibrillator in comparison with initial defibrillation by emergency medical services. The primary outcome measure was discharge with normal or near-normal (favorable) functional status defined as a modified Rankin Score ≤2. Survival to hospital discharge was the secondary outcome measure. RESULTS: Among 49 555 OHCAs, 4115 (8.3%) observed public OHCAs were analyzed, of which 2500 (60.8%) were shockable. A bystander shock was applied in 18.8% of the shockable arrests. Patients shocked by a bystander were significantly more likely to survive to discharge (66.5% versus 43.0%) and be discharged with favorable functional outcome (57.1% versus 32.7%) than patients initially shocked by emergency medical services. After adjusting for known predictors of outcome, the odds ratio associated with a bystander shock was 2.62 (95% confidence interval, 2.07-3.31) for survival to hospital discharge and 2.73 (95% confidence interval, 2.17-3.44) for discharge with favorable functional outcome. The benefit of bystander shock increased progressively as emergency medical services response time became longer. CONCLUSIONS: Bystander automated external defibrillator use before emergency medical services arrival in shockable observed public OHCA was associated with better survival and functional outcomes. Continued emphasis on public automated external defibrillator utilization programs may further improve outcomes of OHCA.

Public Access Defibrillation: Is This Making Any Difference? Controversial Issues in Resuscitation from Cardiac Arrest.

Public access defibrillation is particularly valuable in witnessed cardiac arrests that occur in public places. Bystander and police use of automated external defibrillators (AEDs) has increased over the past 15 years, resulting in improved survival with normal or near-normal neurologic function. There is great promise for increasing bystander use of defibrillators as the technology is applied to linking patients with shockable arrests to volunteers committed to bringing AEDs to the patients. There continues to be controversy as to the value of epinephrine, antiarrhythmic drugs, hypothermia, and mechanical chest compression in resuscitative efforts.

Antiarrhythmic Drugs for Nonshockable-Turned-Shockable Out-of-Hospital Cardiac Arrest: The ALPS Study (Amiodarone, Lidocaine, or Placebo).

BACKGROUND: Out-of-hospital cardiac arrest (OHCA) commonly presents with nonshockable rhythms (asystole and pulseless electric activity). It is unknown whether antiarrhythmic drugs are safe and effective when nonshockable rhythms evolve to shockable rhythms (ventricular fibrillation/pulseless ventricular tachycardia [VF/VT]) during resuscitation. METHODS: Adults with nontraumatic OHCA, vascular access, and VF/VT anytime after ≥1 shock(s) were prospectively randomized, double-blind, to receive amiodarone, lidocaine, or placebo by paramedics. Patients presenting with initial shock-refractory VF/VT were previously reported. The current study was a prespecified analysis in a separate cohort that initially presented with nonshockable OHCA and was randomized on subsequently developing shock-refractory VF/VT. The primary outcome was survival to hospital discharge. Secondary outcomes included discharge functional status and adverse drug-related effects. RESULTS: Of 37 889 patients with OHCA, 3026 with initial VF/VT and 1063 with initial nonshockable-turned-shockable rhythms were treatment-eligible, were randomized, and received their assigned drug. Baseline characteristics among patients with nonshockable-turned-shockable rhythms were balanced across treatment arms, except that recipients of a placebo included fewer men and were less likely to receive bystander cardiopulmonary resuscitation. Active-drug recipients in this cohort required fewer shocks, supplemental doses of their assigned drug, and ancillary antiarrhythmic drugs than recipients of a placebo (P<0.05). In all, 16 (4.1%) amiodarone, 11 (3.1%) lidocaine, and 6 (1.9%) placebo-treated patients survived to hospital discharge (P=0.24). No significant interaction between treatment assignment and discharge survival occurred with the initiating OHCA rhythm (asystole, pulseless electric activity, or VF/VT). Survival in each of these categories was consistently higher with active drugs, although the trends were not statistically significant. Adjusted absolute differences (95% confidence interval) in survival from nonshockable-turned-shockable arrhythmias with amiodarone versus placebo were 2.3% (-0.3, 4.8), P=0.08, and for lidocaine versus placebo 1.2% (-1.1, 3.6), P=0.30. More than 50% of these survivors were functionally independent or required minimal assistance. Drug-related adverse effects were infrequent. CONCLUSIONS: Outcome from nonshockable-turned-shockable OHCA is poor but not invariably fatal. Although not statistically significant, point estimates for survival were greater after amiodarone or lidocaine than placebo, without increased risk of adverse effects or disability and consistent with previously observed favorable trends from treatment of initial shock-refractory VF/VT with these drugs. Together the findings may signal a clinical benefit that invites further investigation. CLINICAL TRIAL REGISTRATION: URL: https://www.clinicaltrials.gov. Unique identifier: NCT01401647.

Post-resuscitation arterial oxygen and carbon dioxide and outcomes after out-of-hospital cardiac arrest.

OBJECTIVE: To determine if arterial oxygen and carbon dioxide abnormalities in the first 24h after return of spontaneous circulation (ROSC) are associated with increased mortality in adult out-of-hospital cardiac arrest (OHCA). METHODS: We used data from the Resuscitation Outcomes Consortium (ROC), including adult OHCA with sustained ROSC ≥1h after Emergency Department arrival and at least one arterial blood gas (ABG) measurement. Among ABGs measured during the first 24h of hospitalization, we identified the presence of hyperoxemia (PaO2≥300mmHg), hypoxemia (PaO2<60mmHg), hypercarbia (PaCO2>50mmHg) and hypocarbia (PaCO2<30mmHg). We evaluated the associations between oxygen and carbon dioxide abnormalities and hospital mortality, adjusting for confounders. RESULTS: Among 9186 OHCA included in the analysis, hospital mortality was 67.3%. Hyperoxemia, hypoxemia, hypercarbia, and hypocarbia occurred in 26.5%, 19.0%, 51.0% and 30.6%, respectively. Initial hyperoxemia only was not associated with hospital mortality (adjusted OR 1.10; 95% CI: 0.97-1.26). However, final and any hyperoxemia (1.25; 1.11-1.41) were associated with increased hospital mortality. Initial (1.58; 1.30-1.92), final (3.06; 2.42-3.86) and any (1.76; 1.54-2.02) hypoxemia (PaO2<60mmHg) were associated with increased hospital mortality. Initial (1.89; 1.70-2.10); final (2.57; 2.18-3.04) and any (1.85; 1.67-2.05) hypercarbia (PaCO2>50mmHg) were associated with increased hospital mortality. Initial (1.13; 0.90-1.41), final (1.19; 1.04-1.37) and any (1.01; 0.91-1.12) hypocarbia (PaCO2<30mmHg) were not associated with hospital mortality. CONCLUSIONS: In the first 24h after ROSC, abnormal post-arrest oxygen and carbon dioxide tensions are associated with increased out of-hospital cardiac arrest mortality.