Hemodynamic Effect of Repeated Epinephrine Doses Decreases With Cardiopulmonary Resuscitation Cycle Progression.

BACKGROUND: Epinephrine is administered to increase coronary perfusion pressure during advanced life support and promote short-term survival. Recent cardiopulmonary resuscitation (CPR) guidelines recommend an epinephrine dosing interval of 3 to 5 minutes during resuscitation; however, scientific evidence supporting this recommendation is lacking. Therefore, we aimed to investigate the hemodynamic effects of repeated epinephrine doses during CPR by monitoring augmented blood pressure after its administration in a swine model of cardiac arrest. METHODS AND RESULTS: A secondary analysis of data from a published study was performed using a swine cardiac arrest model. The epinephrine dose was fixed at 1 mg, and the first dose of epinephrine was administered after no-flow and low-flow times of 2 minutes and 8 minutes, respectively, and subsequently administered every 4 minutes. Four cycles of dosing intervals were defined because a previous study was terminated 26 minutes after the induction of ventricular fibrillation. Augmented blood pressures and corresponding timelines were determined. Augmented blood pressure trends following cycles and the epinephrine effect duration were also monitored. Among the 140 CPR cycles, the augmented blood pressure after epinephrine administration was the highest during the first cycle of CPR and decreased gradually with further cycle repetitions. The epinephrine effect duration did not differ between repeated cycles. The maximum blood pressure was achieved 78 to 97 seconds after epinephrine administration. CONCLUSIONS: Hemodynamic augmentation with repeated epinephrine administration during CPR decreased with cycle progression. Further studies are required to develop an epinephrine administration strategy to maintain its hemodynamic effects during prolonged resuscitation.

End-tidal carbon dioxide after sodium bicarbonate infusion during mechanical ventilation or ongoing cardiopulmonary resuscitation.

PURPOSE: End-tidal CO2 is used to monitor the ventilation status or hemodynamic efficacy during mechanical ventilation or cardiopulmonary resuscitation (CPR), and it may be affected by various factors including sodium bicarbonate administration. This study investigated changes in end-tidal CO2 after sodium bicarbonate administration. MATERIALS AND METHODS: This single-center, prospective observational study included adult patients who received sodium bicarbonate during mechanical ventilation or CPR. End-tidal CO2 elevation was defined as an increase of ≥20% from the baseline end-tidal CO2 value. The time to initial increase (lag time, Tlag), time to peak (Tpeak), and duration of the end-tidal CO2 rise (Tduration) were compared between the patients with spontaneous circulation (SC group) and those with ongoing resuscitation (CPR group). RESULTS: Thirty-three patients, (SC group, n = 25; CPR group, n = 8), were included. Compared with the baseline value, the median values of peak end-tidal CO2 after sodium bicarbonate injection increased by 100% (from 21 to 41 mmHg) in all patients, 89.5% (from 21 to 39 mmHg) in the SC group, and 160.2% (from 15 to 41 mmHg) in the CPR group. The median Tlag was 17 s (IQR: 12-21) and the median Tpeak was 35 s (IQR: 27-52). The median Tduration was 420 s (IQR: 90-639). The median Tlag, Tpeak, and Tduration were not significantly different between the groups. Tduration was associated with the amount of sodium bicarbonate for SC group (correlation coefficient: 0.531, p = 0.006). CONCLUSION: The administration of sodium bicarbonate may lead to a substantial increase in end-tidal CO2 for several minutes in patients with spontaneous circulation and in patients with ongoing CPR. After intravenous administration of sodium bicarbonate, the use of end-tidal CO2 pressure as a physiological indicator may be limited.

Family history, socioeconomic factors, comorbidities, health behaviors, and the risk of sudden cardiac arrest.

Genetic, environment, and behaviour factors have a role in causing sudden cardiac arrest (SCA). We aimed to determine the strength of the association between various risk factors and SCA incidence. We conducted a multicentre case-control study at 17 hospitals in Korea from September 2017 to December 2020. The cases included out-of-hospital cardiac arrest aged 19-79 years with presumed cardiac aetiology. Community-based controls were recruited at a 1:1 ratio after matching for age, sex, and urban residence level. Multivariable conditional logistic regression analysis was conducted. Among the 1016 cases and 1731 controls, 948 cases and 948 controls were analysed. A parental history of SCA, low educational level, own heart disease, current smoking, and non-regular exercise were associated with SCA incidence (Adjusted odds ratio [95% confidence interval]: 2.51 [1.48-4.28] for parental history of SCA, 1.37 [1.38-2.25] for low edication level, 3.77 [2.38-5.90] for non-coronary artery heart disease, 4.47 [2.84-7.03] for coronary artery disease, 1.39 [1.08-1.79] for current smoking, and 4.06 [3.29-5.02] for non-regular exercise). Various risk factors related to genetics, environment, and behaviour were independently associated with the incidence of SCA. Establishing individualised SCA prevention strategies in addition to general prevention strategies is warranted.

Ventricle tracking in transesophageal echocardiography (TEE) images during cardiopulmonary resuscitation (CPR) using deep learning and monogenic filtering.

High-quality cardiopulmonary resuscitation (CPR) is the most important factor in promoting resuscitation outcomes; therefore, monitoring the quality of CPR is strongly recommended in current CPR guidelines. Recently, transesophageal echocardiography (TEE) has been proposed as a potential real-time feedback modality because physicians can obtain clear echocardiographic images without interfering with CPR. The quality of CPR would be optimized if the myocardial ejection fraction (EF) could be calculated in real-time during CPR. We conducted a study to derive a protocol to detect systole and diastole automatically and calculate EF using TEE images acquired from patients with cardiac arrest. The data were supplemented using thin-plate spline transformation to solve the problem of insufficient data. The deep learning model was constructed based on ResUNet + + , and a monogenic filtering method was applied to clarify the ventricular boundary. The performance of the model to which the monogenic filter was added and the existing model was compared. The left ventricle was segmented in the ME LAX view, and the left and right ventricles were segmented in the ME four-chamber view. In most of the results, the performance of the model to which the monogenic filter was added was high, and the difference was very small in some cases; but the performance of the existing model was high. Through this learned model, the effect of CPR can be quantitatively analyzed by segmenting the ventricle and quantitatively analyzing the degree of contraction of the ventricle during systole and diastole. Supplementary Information: The online version contains supplementary material available at 10.1007/s13534-023-00293-9.

Expert opinion on evidence after the 2020 Korean Cardiopulmonary Resuscitation Guidelines: a secondary publication.

Considerable evidence has been published since the 2020 Korean Cardiopulmonary Resuscitation Guidelines were reported. The International Liaison Committee on Resuscitation (ILCOR) also publishes the Consensus on CPR and Emergency Cardiovascular Care Science with Treatment Recommendations (CoSTR) summary annually. This review provides expert opinions by reviewing the recent evidence on CPR and ILCOR treatment recommendations. The authors reviewed the CoSTR summary published by ILCOR in 2021 and 2022. PICO (patient, intervention, comparison, outcome) questions for each topic were reviewed using a systemic or scoping review methodology. Two experts were appointed for each question and reviewed the topic independently. Topics suggested by the reviewers for revision or additional description of the guidelines were discussed at a consensus conference. Forty-three questions were reviewed, including 15 on basic life support, seven on advanced life support, two on pediatric life support, 11 on neonatal life support, six on education and teams, one on first aid, and one related to COVID-19. Finally, the current Korean CPR Guideline was maintained for 28 questions, and expert opinions were suggested for 15 questions.

Circulating Vitamin D Level and Risk of Sudden Cardiac Death and Cardiovascular Mortality: A Dose-Response Meta-Analysis of Prospective Studies.

BACKGROUND: We conducted a comprehensive meta-analysis of prospective cohort studies to analyze the effect of circulating vitamin D level on the risk of sudden cardiac death (SCD) and cardiovascular disease (CVD) mortality. METHODS: Prospective cohort studies evaluating the association between circulating vitamin D and risk of SCD and CVD mortality were systematically searched in the PubMed and Embase. Extracted data were analyzed using a random effects model and results were expressed in terms of hazard ratio (HR) and 95% confidence interval (CI). Restricted cubic spline analysis was used to estimate the dose-response relationships. RESULTS: Of the 1,321 records identified using the search strategy, a total of 19 cohort studies were included in the final meta-analysis. The pooled estimate of HR (95% CI) for low vs. high circulating vitamin D level was 1.75 (1.49-2.06) with I² value of 30.4%. In subgroup analysis, strong effects of circulating vitamin D were observed in healthy general population (pooled HR, 1.84; 95% CI, 1.43-2.38) and the clinical endpoint of SCD (pooled HRs, 2.68; 95% CI, 1.48-4.83). The dose-response analysis at the reference level of < 50 nmol/L showed a significant negative association between circulating vitamin D and risk of SCD and CVD mortality. CONCLUSION: Our meta-analysis of prospective cohort studies showed that lower circulating vitamin D level significantly increased the risk of SCD and CVD mortality.

Interaction effects between insomnia and depression on risk of out-of-hospital cardiac arrest: Multi-center study.

BACKGROUND: Insomnia and depression have been known to be risk factors of several diseases, including coronary heart disease. We hypothesized that insomnia affects the out-of-hospital cardiac arrest (OHCA) incidence, and these effects may vary depending on whether it is accompanied by depression. This study aimed to determine the association between insomnia and OHCA incidence and whether the effect of insomnia is influenced by depression. METHODS: This prospective multicenter case-control study was performed using Phase II Cardiac Arrest Pursuit Trial with Unique Registration and Epidemiology Surveillance (CAPTURES-II) project database for OHCA cases and community-based controls in Korea. The main exposure was history of insomnia. We conducted conditional logistic regression analysis to estimate the effect of insomnia on the risk of OHCA incidence and performed interaction analysis between insomnia and depression. Finally, subgroup analysis was conducted in the patients with insomnia. RESULTS: Insomnia was not associated with increased OHCA risk (0.95 [0.64-1.40]). In the interaction analysis, insomnia interacted with depression on OHCA incidence in the young population. Insomnia was associated with significantly higher odds of OHCA incidence (3.65 [1.29-10.33]) in patients with depression than in those without depression (0.84 [0.59-1.17]). In the subgroup analysis, depression increased OHCA incidence only in patients who were not taking insomnia medication (3.66 [1.15-11.66]). CONCLUSION: Insomnia with depression is a risk factor for OHCA in the young population. This trend was maintained only in the population not consuming insomnia medication. Early and active medical intervention for patients with insomnia may contribute to lowering the risk of OHCA.

Efficacy of Cardiopulmonary Resuscitation Using Automatic Compression-Defibrillation Apparatus: An Animal Study and A Manikin-Based Simulation Study.

BACKGROUND: Chest compression and defibrillation are essential components of cardiac arrest treatment. Mechanical chest compression devices (MCCD) and automated external defibrillators (AED) are used separately in clinical practice. We developed an automated compression-defibrillation apparatus (ACDA) that performs mechanical chest compression and automated defibrillation. We investigated the performance of cardiopulmonary resuscitation (CPR) with automatic CPR (A-CPR) compared to that with MCCD and AED (conventional CPR: C-CPR). METHODS: Pigs were randomized into A-CPR or C-CPR groups: The A-CPR group received CPR+ACDA, and the C-CPR group received CPR+MCCD+AED. Hemodynamic parameters, outcomes, and time variables were measured. During a simulation study, healthcare providers performed a basic life support scenario for manikins with an ACDA, MCCD, and AED, and time variables and chest compression parameters were measured. RESULTS: The animals showed no significant in hemodynamic effects, including aortic pressures, coronary perfusion pressure, carotid blood flow, and end-tidal CO2, and resuscitation outcomes between the two groups. In both animal and simulation studies, the time to defibrillation, time to chest compression, and hands-off time were significantly shorter in the A-CPR group than those in the C-CPR group. CONCLUSIONS: CPR using ACDA showed similar hemodynamic effects and resuscitation outcomes as CPR using AED and MCCD separately, with the advantages of a reduction in the time to compression, time to defibrillation, and hands-off time.

Development of an automatic device performing chest compression and external defibrillation: An animal-based pilot study.

BACKGROUND: Automatic chest compression devices (ACCDs) can promote high-quality cardiopulmonary resuscitation (CPR) and are widely used worldwide. Early application of automated external defibrillators (AEDs) along with high-quality CPR is crucial for favorable outcomes in patients with cardiac arrest. Here, we developed an automated CPR (A-CPR) apparatus that combines ACCD and AED and evaluated its performance in a pilot animal-based study. METHODS: Eleven pigs (n = 5, A-CPR group; n = 6, ACCD CPR and AED [conventional CPR (C-CPR)] group) were enrolled in this study. After 2 min observation without any treatment following ventricular fibrillation induction, CPR with a 30:2 compression/ventilation ratio was performed for 6 min, mimicking basic life support (BLS). A-CPR or C-CPR was applied immediately after BLS, and resuscitation including chest compression and defibrillation, was performed following a voice prompt from the A-CPR device or AED. Hemodynamic parameters, including aortic pressure, right atrial pressure, coronary perfusion pressure, carotid blood flow, and end-tidal carbon dioxide, were monitored during resuscitation. Time variables, including time to start rhythm analysis, time to charge, time to defibrillate, and time to subsequent chest compression, were also measured. RESULTS: There were no differences in baseline characteristics, except for arterial carbon dioxide pressure (39 in A-CPR vs. 33 in C-CPR, p = 0.034), between the two groups. There were no differences in hemodynamic parameters between the groups. However, time to charge (28.9 ± 5.6 s, A-CPR group; 47.2 ± 12.4 s, C-CPR group), time to defibrillate (29.1 ± 7.2 s, A-CPR group; 50.5 ± 12.3 s, C-CPR group), and time to subsequent chest compression (32.4 ± 6.3 s, A-CPR group; 56.3 ± 10.7 s, C-CPR group) were shorter in the A-CPR group than in the C-CPR group (p = 0.015, 0.034 and 0.02 respectively). CONCLUSIONS: A-CPR can provide effective chest compressions and defibrillation, thereby shortening the time required for defibrillation.

Left ventricle segmentation in transesophageal echocardiography images using a deep neural network.

PURPOSE: There has been little progress in research on the best anatomical position for effective chest compressions and cardiac function during cardiopulmonary resuscitation (CPR). This study aimed to divide the left ventricle (LV) into segments to determine the best position for effective chest compressions using the LV systolic function seen during CPR. METHODS: We used transesophageal echocardiography images acquired during CPR. A deep neural network with an attention mechanism and a residual feature aggregation module were applied to the images to segment the LV. The results were compared between the proposed model and U-Net. RESULTS: The results of the proposed model showed higher performance in most metrics when compared to U-Net: dice coefficient (0.899±0.017 vs. 0.792±0.027, p<0.05); intersection of union (0.822±0.026 vs. 0.668±0.034, p<0.05); recall (0.904±0.023 vs. 0.757±0.037, p<0.05); precision (0.901±0.021 vs. 0.859±0.034, p>0.05). There was a significant difference between the proposed model and U-Net. CONCLUSION: Compared to U-Net, the proposed model showed better performance for all metrics. This model would allow us to evaluate the systolic function of the heart during CPR in greater detail by segmenting the LV more accurately.

Interactions between Sleep Apnea and Coronary Artery Disease on the Incidence of Sudden Cardiac Arrest: A Multi-Center Case-Control Study.

PURPOSE: Sleep apnea (SA) is a risk factor for coronary artery disease (CAD), and SA and CAD increase the incidence of sudden cardiac arrest (SCA). This study aimed to investigate the effect of SA on the incidence of SCA and explore the effect of varying degrees of SA with or without CAD on the incidence of SCA. MATERIALS AND METHODS: This prospective multi-center, case-control study was performed using the phase II Cardiac Arrest Pursuit Trial with Unique Registry and Epidemiologic Surveillance (CAPTURES-II) database for SCA cases and community-based controls in Korea. The matching ratio of cases to controls was 1:1, and they were randomly matched within demographics, including age, sex, and residence. The primary variable was a history of SA, and the second variable was a history of CAD. We conducted a conditional logistic regression analysis to estimate the effect of SA and CAD on the SCA risk, and an interaction analysis between SA and CAD. RESULTS: SA was associated with an increased risk of SCA [adjusted odds ratio (AOR) (95% confidence interval, CI): 1.54 (1.16-2.03)], and CAD was associated with an increased risk of SCA [AOR (95% CI): 3.94 (2.50-6.18)]. SA was a risk factor for SCA in patients without CAD [AOR (95% CI): 1.62 (1.21-2.17)], but not in patients with CAD [AOR (95% CI): 0.56 (0.20-1.53)]. CONCLUSION: In the general population, SA is risk factor for SCA only in patients without CAD. Early medical intervention for SA, especially in populations without pre-existing CAD, may reduce the SCA risk. ClinicalTrials.gov (NCT03700203).

Intra-arrest transesophageal echocardiography during cardiopulmonary resuscitation.

Determining the cause of cardiac arrest (CA) and the heart status during CA is crucial for its treatment. Transesophageal echocardiography (TEE) is an imaging method that facilitates close observation of the heart without interfering with cardiopulmonary resuscitation (CPR). Intra-arrest TEE is a point-of-care ultrasound technique that is used during CPR. Intra-arrest TEE is performed to diagnose the cause of CA, determine the presence of cardiac contraction, evaluate the quality of CPR, assist with catheter insertion, and explore the mechanism of blood flow during CPR. The common causes of CA diagnosed using intra-arrest TEE include cardiac tamponade, aortic dissection, pulmonary embolism, and intracardiac thrombus, which can be observed on a few simple image planes at the mid-esophageal and upper esophageal positions. To operate an intra-arrest TEE program, it is necessary to secure a physician who is capable of performing TEE, provide appropriate training, establish implementation protocols, and prepare a plan in collaboration with the CPR team.

Diet-related complications according to the timing of enteral nutrition support in patients who recovered from out-of-hospital cardiac arrest: a propensity score matched analysis.

BACKGROUND: A proper nutritional plan for resuscitated patients is important in intensive care; however, specific nutritional guidelines have not yet been established. This study aimed to determine the incidence of diet-related complications that were affected by the timing of enteral nutrition in resuscitated patients after cardiac arrest. METHODS: This retrospective and 1:1 propensity score matching study involved patients who recovered after nontraumatic, out-of-hospital cardiac arrest at a tertiary hospital. Patients were divided into an early nutrition support (ENS) group and a delayed nutrition support (DNS) group according to the nutritional support time within 48 hours after admission. The incidence of major clinical complications was compared between the groups. RESULTS: A total of 46 patients (ENS: 23, DNS: 23) were enrolled in the study. There were no differences in body mass index, comorbidity, and time of cardiopulmonary resuscitation between the two groups. There were 9 patients (ENS: 4, DNS: 5) with aspiration pneumonia; 4 patients (ENS: 2, DNS: 2) with regurgitation; 1 patient (ENS: 0, DNS: 1) with ileus; 21 patients (ENS: 10, DNS: 11) with fever; 13 patients (ENS: 8, DNS: 5) with hypoglycemia; and 20 patients (ENS: 11, DNS: 9) with hyperglycemia. The relative risk of each complication during post-resuscitation care was no different between groups. CONCLUSIONS: There was a similar incidence of diet-related complications during post cardiac arrest care according to the timing of enteral nutrition.

Right-to-Left Shunts Occur During Cardiopulmonary Resuscitation: Echocardiographic Observations.

OBJECTIVES: A significant proportion of the population has a patent foramen ovale (PFO). The intracardiac pressure during cardiopulmonary resuscitation (CPR) may differ from that of normal circulation, which may result in a right-to-left shunt in the presence of a PFO. In this study, transesophageal echocardiography (TEE) was conducted to evaluate whether CPR carried out in patients after cardiac arrest causes right-to-left shunt. DESIGN: A retrospective observational study. SETTING: One academic medical center from January 2017 to April 2020. PATIENTS: Patients older than 20 years who suffered from nontraumatic out-of-hospital cardiac arrest (OHCA) and underwent intra-arrest TEE. MEASUREMENT AND MAIN RESULTS: Patients who had microbubbles resulting from fluid injection in the right atrium, as indicated on TEE imaging, were included in the analysis. The presence of right-to-left shunt was defined as the appearance of microbubbles in the systemic circulation, including the left atrium, left ventricle, or aorta. A total of 97 patients were included in the final analysis. A right-to-left shunt was observed in 21 patients (21.6%), and no shunt was found in 76 patients (78.4%). The degree of the right-to-left shunt, determined by the number of microbubbles, was mild in 11 patients (52.4%), moderate in eight (38.0%), and severe in two (9.6%). Multivariate analysis showed that no factors were associated with the presence of right-to-left shunt during CPR. CONCLUSIONS: Right-to-left shunts can be appreciated during CPR in patients who experience OHCA. Further studies are needed to verify its clinical significance.

Trends in maintenance status and usability of public automated external defibrillators during a 5-year on-site inspection.

This study aimed to assess the trend of the maintenance status and usability of public automated external defibrillators (AEDs). Public AEDs installed in Seoul from 2013 to 2017 were included. An inspector checked the maintenance status and usability of the AEDs annually using a checklist. During the study period, 23,619 AEDs were inspected. Access to the AEDs was improved, including the absence of obstacles near the AEDs (from 90.2% in 2013 to 99.1% in 2017, p < 0.0001) and increased AED signs (from 34.3% in 2013 to 91.3% in 2017, p < 0.0001). The rate of AEDs in normal operation (from 94.0% in 2013 to 97.6% in 2017, p < 0.0001), good battery status (from 95.6% in 2013 to 96.8% in 2017, p = 0.0016), and electrode availability increased (from 97.1% in 2013 to 99.0% in 2017, p < 0.0001); the rate of electrode validity decreased (from 90.0% in 2013 to 87.2% in 2017, p < 0.0001). The overall rate of the non-ready-to-use AEDs and AEDs with less than 24-h usability accounted for 15.4% and 44.1% of the total number of AEDs, respectively. Although most AEDs had a relatively good maintenance status, a significant proportion of public AEDs were not available for 24-h use. Invalid electrodes and less than 24-h accessibility were the main reasons that limited the 24-h usability of public AEDs.

Healthy lifestyle factors, cardiovascular comorbidities, and the risk of sudden cardiac arrest: A case-control study in Korea.

AIMS: We investigated the impact of healthy lifestyle factors and cardiovascular comorbidities for sudden cardiac arrest. METHODS: A case-control study, including patients with sudden cardiac arrest aged 20-79 years and community-based 1:2 matched controls, was conducted from September 2017 to December 2020. All participants completed a structured questionnaire. Using multivariable logistic regression, we assessed cardiovascular comorbidities (diabetes, hypertension, dyslipidaemia, myocardial infarction, congestive heart failure, arrhythmia, and stroke) and healthy lifestyle factors (low red meat consumption, low fish consumption, high fruit consumption, high vegetable consumption, current non-smoking, regular exercise, and adequate sleep duration) as sudden cardiac arrest risk factors. RESULTS: Among 3027 eligible cases, informed consent was obtained from 949 (31.3%) cases. A total of 1731 controls were enrolled. Cardiovascular comorbidities, except dyslipidaemia, were associated with an increased risk of sudden cardiac arrest, whereas all healthy lifestyle factors were associated with a decreased risk. Relative to patients in the 0-2 healthy lifestyle factors group, the adjusted odds ratio (95% confidence interval) for sudden cardiac arrest was 0.25 (0.16-0.40) in patients with 3 healthy lifestyle factors, 0.08 (0.05-0.13) in patients with 4 healthy lifestyle factors, and 0.04 (0.03-0.06) in patients with over 5 healthy lifestyle factors. When the number of healthy lifestyle factors was analysed as a continuous variable, each additional factor was associated with a significant decrease in the likelihood of sudden cardiac arrest (adjusted odds ratio [95% confidence interval]: 0.41 [0.36-0.46]). CONCLUSION: The increased risk of sudden cardiac arrest by cardiovascular comorbidities could be significantly reduced with healthy lifestyle factors.

Relationship between cooling time and neurological outcomes in targeted temperature management.

OBJECTIVES: The relationship between cooling time (CT) variables and neurological outcomes is controversial. We evaluated the relationship between CT and neurological outcomes in out-of-hospital cardiac arrest (OHCA) patients treated with targeted temperature management (TTM). METHODS: We conducted a multicenter, prospective, and registry-based study of OHCA survivors treated with TTM. CT was defined as the time from restoration of spontaneous circulation to achievement of the target temperature. The primary outcome was a favorable neurological outcome at 6 months. Multilevel logistic regression analysis was performed to test the relationship between CT and the primary outcome. RESULTS: Overall, the favorable neurological outcome rates at 6 months were 29.8% in 937 patients. When CT was stratified into categories of 0-3, 3.1-6, 6.1-9, 9.1-12, and >12 h, according to 3-h intervals, the primary outcome rates were 8.2%, 22.7%, 35.5%, 44.7%, and 44.5%, respectively (p < 0.001). Significant differences were not found in multilevel logistic regression analysis; the adjusted odds ratios (95% confidence interval) of each category for the primary outcome compared to the 0-3-h group were 0.81 (0.32 to 2.04), 0.77 (0.30 to 2.01), 1.26 (0.43 to 3.68), and 1.06 (0.37 to 3.06). CONCLUSIONS: We did not find a relationship between CT and neurological outcomes at 6 months.