Association Between EEG Patterns and Serum Neurofilament Light After Cardiac Arrest: A Post Hoc Analysis of the TTM Trial.

BACKGROUND AND OBJECTIVES: EEG is widely used for prediction of neurologic outcome after cardiac arrest. To better understand the relationship between EEG and neuronal injury, we explored the association between EEG and neurofilament light (NfL) as a marker of neuroaxonal injury, evaluated whether highly malignant EEG patterns are reflected by high NfL levels, and explored the association of EEG backgrounds and EEG discharges with NfL. METHODS: We performed a post hoc analysis of the Target Temperature Management After Out-of-Hospital Cardiac Arrest trial. Routine EEGs were prospectively performed after the temperature intervention ≥36 hours postarrest. Patients who awoke or died prior to 36 hours postarrest were excluded. EEG experts blinded to clinical information classified EEG background, amount of discharges, and highly malignant EEG patterns according to the standardized American Clinical Neurophysiology Society terminology. Prospectively collected serum samples were analyzed for NfL after trial completion. The highest available concentration at 48 or 72 hours postarrest was used. RESULTS: A total of 262/939 patients with EEG and NfL data were included. Patients with highly malignant EEG patterns had 2.9 times higher NfL levels than patients with malignant patterns and NfL levels were 13 times higher in patients with malignant patterns than those with benign patterns (95% CI 1.4-6.1 and 6.5-26.2, respectively; effect size 0.47; p < 0.001). Both background and the amount of discharges were independently strongly associated with NfL levels (p < 0.001). The EEG background had a stronger association with NfL levels than EEG discharges (R2 = 0.30 and R2 = 0.10, respectively). NfL levels in patients with a continuous background were lower than for any other background (95% CI for discontinuous, burst-suppression, and suppression, respectively: 2.26-18.06, 3.91-41.71, and 5.74-41.74; effect size 0.30; p < 0.001 for all). NfL levels did not differ between suppression and burst suppression. Superimposed discharges were only associated with higher NfL levels if the EEG background was continuous. DISCUSSION: Benign, malignant, and highly malignant EEG patterns reflect the extent of brain injury as measured by NfL in serum. The extent of brain injury is more strongly related to the EEG background than superimposed discharges. Combining EEG and NfL may be useful to better identify patients misclassified by single methods. TRIAL REGISTRATION INFORMATION: ClinicalTrials.gov NCT01020916.

Factors associated with physician decision making on withholding cardiopulmonary resuscitation in prehospital medicine.

This study seeks to identify factors that are associated with decisions of prehospital physicians to start (continue, if ongoing) or withhold (terminate, if ongoing) CPR in patients with OHCA. We conducted a retrospective study using anonymised data from a prehospital physician response system. Data on patients attended for cardiac arrest between January 1st, 2010 and December 31st, 2018 except babies at birth were included. Logistic regression analysis with start of CPR by physicians as the dependent variable and possible associated factors as independent variables adjusted for anonymised physician identifiers was conducted. 1525 patient data sets were analysed. Obvious signs of death were present in 278 cases; in the remaining 1247, resuscitation was attempted in 920 (74%) and were withheld in 327 (26%). Factors significantly associated with higher likelihood of CPR by physicians (OR 95% CI) were resuscitation efforts by EMS before physician arrival (60.45, 19.89-184.29), first monitored heart rhythm (3.07, 1.21-7.79 for PEA; 29.25, 1.93-442. 51 for VF / pVT compared to asystole); advanced patient age (modelled using cubic splines), physician response time (0.92, 0.87-0.97 per minute) and malignancy (0.22, 0.05-0.92) were significantly associated with lower odds of CPR. We thus conclude that prehospital physicians make decisions to start or withhold resuscitation routinely and base those mostly on situational information and immediately available patient information known to impact outcomes.

Do manual chest compressions provide substantial ventilation during prehospital cardiopulmonary resuscitation?

INTRODUCTION: Chest compressions have been suggested to provide passive ventilation during cardiopulmonary resuscitation. Measurements of this passive ventilatory mechanism have only been performed upon arrival of out-of-hospital cardiac arrest patients in the emergency department. Lung and thoracic characteristics rapidly change following cardiac arrest, possibly limiting the effectiveness of this mechanism after prolonged resuscitation efforts. Goal of this study was to quantify passive inspiratory tidal volumes generated by manual chest compression during prehospital cardiopulmonary resuscitation. MATERIALS AND METHODS: A flowsensor was used during adult out-of-hospital cardiac arrest cases attended by a prehospital medical team. Adult, endotracheally intubated, non-traumatic cardiac arrest patients were eligible for inclusion. Immediately following intubation, the sensor was connected to the endotracheal tube. The passive inspiratory tidal volumes generated by the first thirty manual chest compressions performed following intubation (without simultaneous manual ventilation) were calculated. RESULTS: 10 patients (5 female) were included, median age was 64 years (IQR 56, 77 years). The median compression frequency was 111 compression per minute (IQR 107, 116 compressions per minute). The median compression depth was 5.6 cm (IQR 5.4 cm, 6.1 cm). The median inspiratory tidal volume generated by manual chest compressions was 20 mL (IQR 13, 28 mL). CONCLUSION: Using a flowsensor, passive inspiratory tidal volumes generated by manual chest compressions during prehospital cardiopulmonary resuscitation, were quantified. Chest compressions alone appear unable to provide adequate alveolar ventilation during prehospital treatment of cardiac arrest.

Predicting factors for long-term survival in patients with out-of-hospital cardiac arrest - A propensity score-matched analysis.

BACKGROUND: Out-of-hospital cardiac arrest (OHCA) is one of the leading causes of death worldwide, with acute coronary syndromes accounting for most of the cases. While the benefit of early revascularization has been clearly demonstrated in patients with ST-segment-elevation myocardial infarction (STEMI), diagnostic pathways remain unclear in the absence of STEMI. We aimed to characterize OHCA patients presenting to 2 tertiary cardiology centers and identify predicting factors associated with survival. METHODS: We retrospectively analyzed 519 patients after OHCA from February 2003 to December 2017 at 2 centers in Munich, Germany. Patients undergoing immediate coronary angiography (CAG) were compared to those without. Multivariate regression analysis and inverse probability treatment weighting (IPTW) were performed to identify predictors for improved outcome in a matched population. RESULTS: Immediate CAG was performed in 385 (74.1%) patients after OHCA with presumed cardiac cause of arrest. As a result of multivariate analysis after propensity score matching, we found that immediate CAG, return of spontaneous circulation (ROSC) at admission, witnessed arrest and former smoking were associated with improved 30-days-survival [(OR, 0.46; 95% CI, 0.26-0.84), (OR, 0.21; 95% CI, 0.10-0.45), (OR, 0.50; 95% CI, 0.26-0.97), (OR, 0.43; 95% CI, 0.23-0.81)], and 1-year-survival [(OR, 0.39; 95% CI, 0.19-0.82), (OR, 0.29; 95% CI, 0.12-0.7), (OR, 0.43; 95% CI, 0.2-1.00), (OR, 0.3; 95% CI, 0.14-0.63)]. CONCLUSIONS: In our study, immediate CAG, ROSC at admission, witnessed arrest and former smoking were independent predictors of survival in cardiac arrest survivors. Improvement in prehospital management including bystander CPR and best practice post-resuscitation care with optimized triage of patients to an early invasive strategy may help ameliorate overall outcome of this critically-ill patient population.

Prognostic value of blood gas parameters and end-tidal carbon dioxide values in out-of-hospital cardiopulmonary arrest patients

Background/aim: This study aimed to evaluate the usefulness of blood gas and end-tidal carbon dioxide (EtCO2) measurements for predicting return of spontaneous circulation (ROSC) and for evaluating post-ROSC neurological survival. Materials and methods: This was a prospective case control study utilizing Atatürk University's database of adult nontraumatic patients (over 18 years old) with out-of-hospital cardiac arrest (OHCA) over the course of a year. The neurological status of the patients was evaluated after 1 h at ROSC and at hospital discharge, as defined by the cerebral performance category score. The blood gas parameters pH, PO2, PCO2, lactate, and BE were compared with EtCO2 from capnography and arteriol/alveolar carbon dioxide difference (AaDCO2) by using both blood gas and capnography upon admission to the emergency department and at ROSC. Results: A total of 155 patients were included in the study to form the control group with ROSC. The PO2, PCO2, and AaDCO2 values showed a prognostic marker for the supply of ROSC (P < 0.05). The EtCO2,lactate, and BE values measured by the blood gas were found to be insignificant in the prediction of ROSC (P > 0.05). Conversely, AaDCO2 was found to be significant in ROSC estimation (P < 0.05), but not in neurological evaluation (P > 0.05). Conclusion: Blood gas parameters and EtCO2 are sufficient in predicting ROSC. The value of AaDCO2 calculated using EtCO2 and PO2may be used in predicting the prognosis of OHCA patients, but this value does not provide any conclusions concerning neurological survival.

Systematic review to assess the possibility of return of cerebral and cardiac activity after normothermic regional perfusion for donors after circulatory death.

BACKGROUND: Normothermic regional perfusion (NRP) is a novel technique that aids organ recovery from donors after circulatory death (DCDs). However, ethical concerns exist regarding the potential return of spontaneous cerebral and cardiac activity (ROSCCA). This study aimed to determine the likelihood of ROSCCA in NRP-DCDs of abdominal organs. METHODS: Extracorporeal cardiopulmonary resuscitation (ECPR) for refractory out-of-hospital cardiac arrest (OOHCA) was identified as a comparator for NRP-DCDs and as a validation cohort. A systematic search identified all articles relating to NRP-DCDs and ECPR-OOHCA. Rates of ROSCCA and survival outcomes (ECPR-OOHCA only) were recorded and analysed according to the duration of no perfusion. RESULTS: In NRP-DCDs, 12 of 410 articles identified by database searching were eligible for inclusion. There were no instances of ROSCCA recorded among 493 donors. In ECPR-OOHCA, eight of 947 screened articles were eligible for inclusion (254 patients). Where the absence of perfusion exceeded 5 min in ECPR-OOHCA, there were no survivors with a favourable neurological outcome. CONCLUSION: ROSCCA is unlikely following commencement of NRP and has not occurred to date. Strict observance of the 5-min interval following asystole provides satisfactory assurance that ROSCCA will not occur following NRP.

Traumatic cardiac arrest and resuscitative endovascular balloon occlusion of the aorta (REBOA): a preliminary analysis utilizing high fidelity invasive blood pressure recording and videography.

PURPOSE: Aortic occlusion (AO) increases proximal perfusion and may improve rates of return of spontaneous circulation (ROSC). The objective of this study was to investigate the hemodynamic effects of cardiopulmonary resuscitation (CPR) and AO by REBOA on patients in traumatic cardiac arrest. METHODS: Patients admitted between February 2013 and May 2017 at a tertiary center who suffered traumatic arrest, had an arterial line placed during resuscitation, and received CPR and REBOA which were included. In-hospital CPR data were obtained from videography. Arterial waveforms were recorded at 240 Hz. RESULTS: 11 consecutive patients were included, 82% male; mean (± SD) age 37 ± 19 years. 55% suffered blunt trauma and the remaining penetrating injuries. 64% arrested out of hospital. During compressions with AO, the mean systolic blood pressure (SBP) was 70 ± 22 mmHg, mean arterial pressure (MAP) 43 ± 19 mmHg, and diastolic blood pressure (DBP) 26 ± 17 mmHg. Nine (82%) had ROSC, with eight having multiple periods of ROSC and arrest in the initial period. In-hospital mortality was 82%. Cardiac ultrasonography was used during arrest in 73%. In two patients with arterial line data before and after AO, SBP (mmHg) improved from 51 to 73 and 55 to 96 during arrest after AO. CONCLUSIONS: High-quality chest compressions coupled with aortic occlusion may generate adequate perfusion pressures to increase the rate of ROSC. New technology capable of transducing central arterial pressure may help us to understand the effectiveness of CPR with and without aortic occlusion. REBOA may be a useful adjunct to high-quality chest compressions during arrest.

Differential association of subtypes of epileptiform activity with outcome after cardiac arrest.

BACKGROUND: Epileptiform activity is common after cardiac arrest, although intensity of electroencephalographic (EEG) monitoring may affect detection rates. Prior work has grouped these patterns together as "malignant," without considering discrete subtypes. We describe the incidence of distinct patterns in the ictal-interictal spectrum at two centers and their association with outcomes. METHODS: We analyzed a retrospective cohort of comatose post-arrest patients admitted at two academic centers from January 2011 to October 2014. One center uses routine continuous EEG, the other acquires "spot" EEG at the treating physicians' discretion. We reviewed all available EEG data and classified epileptiform patterns. We abstracted antiepileptic drugs (AEDs) administrations from the electronic medical record. We compared apparent incidence of each pattern between centers, and compared outcomes (awakening from coma, survival to discharge, discharge modified Rankin Scale (mRS) 0-2) across EEG patterns and number of AEDs administered. RESULTS: We included 818 patients. Routine continuous EEG was associated with a higher apparent incidence of polyspike burst-suppression (25% vs 13% P < 0.001). Frequency of other epileptiform findings did not differ. Among patients with any epileptiform pattern, only 2/258 (1%, 95%CI 0-3%) were discharged with mRS 0-2, although 24/258 (9%, 95%CI 6-14%) awakened and 36/258 (14%, 95%CI 10-19%) survived. The proportions that awakened and survived decreased in a stepwise manner with progressively worse EEG patterns (range 38% to 2% and 32% to 7%, respectively). Among patients receiving ≥3 AEDs, only 5/80 (6%, 95%CI 2-14%) awakened and 1/80 (1%, 95%CI 0-7%) had a mRS 0-2. CONCLUSION: We found high rates of epileptiform EEG findings, regardless of intensity of EEG monitoring. The association of distinct ictal-interictal EEG findings with outcome was variable.

The presence of gasping predicts long-term survival in out-of-hospital cardiac arrest patients.

BACKGROUND: The presence of gasping in out-of-hospital cardiac arrest (OHCA) patients predicts short-term prognosis. We performed a retrospective study to evaluate whether the presence of gasping at the time of Emergency Medical Service (EMS) arrival in the case OHCA patients of presumed cardian origin has any impact on six-month survival and/or sustained return of spontaneous circulation (ROSC). METHODS: We collected and analyzed Utstein Style data for all patients resuscitated for OHCA of presumed cardiac origin by the EMS of the Central Bohemian Region from July 1st, 2013 to June 30th, 2014. RESULTS: During the data collection period, 565 cases of OHCA of presumed cardiac origin were reported. Gasping at the time of EMS arrival was identified in 23.9%. The presence of gasping was associated with a significantly increased frequency of sustained ROSC (48.1 versus 20.7%, P<0.001) and six-month survival (40.7 versus 16.7%, P<0.001) than in non-breathing patients. Presence of gasping upon EMS arrival has been found to be an independent positive predictor of sustained ROSC (OR 2.51, CI 95% 1.59-3.98, P<0.001). The occurrence of gasping at the time of EMS arrival at the scene was significantly related to response time from EMS activation to arrival. CONCLUSION: The presence of gasping upon arrival of the EMS for the patient with OHCA of presumed cardiac origin predicts both improves short-term and long-term prognoses.

Masked inherited primary arrhythmia syndromes in sudden cardiac death patients accompanied by coronary vasospasm.

BACKGROUND/AIMS: Coronary vasospasms are one of the important causes of sudden cardiac death (SCD). Provocation of coronary vasospasms can be useful, though some results may lead to false positives, with patients potentially experiencing recurrent SCD despite appropriate medical treatments. We hypothesized that it is not coronary vasospasms but inherited primary arrhythmia syndromes (IPAS) that underlie the development of SCD. METHODS: We analyzed 74 consecutive patients (3.8%) who survived out-of-hospital cardiac arrest among 1,986 patients who had angiographically proven coronary vasospasms. Electrical abnormalities were evaluated in serial follow-up electrocardiograms (ECGs) during and after the index event for a 3.9 years median follow-up. Major clinical events were defined as the composite of death and recurrent SCD events. RESULTS: Forty five patients (60.8%) displayed electrocardiographic abnormalities suggesting IPAS: Brugada type patterns in six (8.2%), arrhythmogenic right ventricular dysplasia patterns in three (4.1%), long QT syndrome pattern in one (2.2%), and early repolarization in 38 (51.4%). Patients having major clinical events showed more frequent Brugada type patterns, early repolarization, and more diffuse multivessel coronary vasospasms. Brugada type pattern ECGs (adjusted hazard ratio [HR], 4.22; 95% confidence interval [CI], 1.16 to 15.99; p = 0.034), and early repolarization (HR, 2.97; 95% CI, 1.09 to 8.10; p = 0.034) were ultimately associated with an increased risk of mortality. CONCLUSIONS: Even though a number of aborted SCD survivors have coronary vasospasms, some also have IPAS, which has the potential to cause SCD. Therefore, meticulous evaluations and follow-ups for IPAS are required in those patients.

Serum neutrophil gelatinase-associated lipocalin levels predict the neurological outcomes of out-of-hospital cardiac arrest victims.

BACKGROUND: Serum neutrophil gelatinase-associated lipocalin (NGAL) is a well-known biomarker of acute kidney injury. Serum NGAL was recently proposed as a potential predictor of mortality in post cardiac arrest syndrome (PCAS) patients following out-of-hospital cardiac arrest (OHCA). However, the potential predictive value of NGAL for neurological outcomes is unknown. Therefore, we assessed the potential predictive value of NGAL for neurological outcomes after OHCA. We also compared its predictive value with that of neuron-specific enolase (NSE) as an established biomarker. METHODS: Blood samples were prospectively collected from 43 PCAS patients following OHCA. Serum NGAL was measured on days 1 and 2, and NSE was measured on day 2. These biomarkers were compared between patients with favourable (cerebral performance category [CPC] 1-2) and unfavourable (CPC 3-5) outcomes. Receiver operating characteristic (ROC) curve analysis was performed. RESULTS: Serum NGAL and NSE on day 2 (both P < 0.001), but not NGAL on day 1 (P = 0.609), were significantly different between the favourable and unfavourable groups. In ROC curve analysis, the sensitivity and specificity were 83% and 85%, respectively, for NGAL (day 2) at a cutoff value of 204 ng/mL and were 84% and 100% for NSE (day 2) at a cutoff value of 28.8 ng/mL. The area under the ROC curve of NGAL (day 2) was equivalent to that of NSE (day 2) (0.830 vs. 0.918). Additionally, the area under the ROC curve in subgroup of estimated glomerular filtration rate (eGFR) > 20 mL/min/1.73 m2 (n = 38, 0.978 vs. 0.923) showed the potential of NGAL predictability. CONCLUSIONS: Serum NGAL might predict the neurological outcomes of PCAS patients, and its predictive value was equivalent to that of NSE.

Plasma neutrophil gelatinase-associated lipocalin as an early predicting biomarker of acute kidney injury and clinical outcomes after recovery of spontaneous circulation in out-of-hospital cardiac arrest patients.

AIMS: To determine whether the level of plasma neutrophil gelatinase-associated lipocalin (NGAL) can predict acute kidney injury (AKI) and clinical outcomes after recovery of spontaneous circulation (ROSC) in patients with out-of-hospital cardiac arrest (OHCA). METHODS: We conducted a prospective observational study of consecutive admitted patients with ROSC after OHCA between January 2013 and March 2015. Plasma was collected within 4h of ROSC to determine the level of NGAL. Outcome variables were AKI, 30-day survival, and good neurological outcome (GNO). We evaluated the association between NGAL and outcomes. RESULTS: Fifty-four patients were included. AKI occurred in 26 (48.0%); 15 (27.7%) survived over 30 days and 8 had GNO (14.8%). NGAL was significantly lower in the group with non-AKI, 30-day survival, and GNO. To predict AKI, 30-day survival, and GNO, the area under the receiver operating characteristic curve for NGAL was 0.810, 0.728, and 0.875, respectively. In a logistic regression model, NGAL >189 ngml(-1) was strongly associated with AKI (odds ratio [OR] 7.01, 95% confidence interval [CI]: 1.89-26.01) in a multivariate model. A lower level of NGAL was strongly associated with 30-day survival (OR 6.12, 95% CI: 1.64-23.42 at NGAL <153.5 ngml(-1)) and GNO (OR 19.83, 95% CI: 2.21-178.32 at NGAL <129.5 ngml(-1)) in a univariate model, but was not significantly associated with outcomes in a multivariate model. CONCLUSIONS: Plasma NGAL is a strong predictor of AKI in patients exhibiting OHCA at ICU admission. Lower levels of NGAL are associated with greater chance of 30-day survival and GNO.

Extracorporeal life support for cardiac arrest in a 13-year-old girl caused by Wolff-Parkinson-White syndrome.

Generally, Wolff-Parkinson-White (WPW) syndrome presents good prognosis. However, several case reports demonstrated malignant arrhythmia or sudden cardiac death as WPW syndrome's first presentation. Cardiopulmonary resuscitation using extracorporeal life support is a therapeutic option in refractory cardiac arrest. We present a WPW syndrome patient who had sudden cardiac arrest as the first presentation of the disease and treated it using extracorporeal life support with good neurologic outcome.

Effect of therapeutic hypothermia on gas exchange and respiratory mechanics: a retrospective cohort study.

Targeted temperature management (TTM) may improve respiratory mechanics and lung inflammation in acute respiratory distress syndrome (ARDS) based on animal and limited human studies. We aimed to assess the pulmonary effects of TTM in patients with respiratory failure following cardiac arrest. Retrospective review of consecutive cardiac arrest cases occurring out of hospital or within 24 hours of hospital admission (2002-2012). Those receiving TTM (n=44) were compared with those who did not (n=42), but required mechanical ventilation (MV) for at least 4 days following the arrest. There were no between-group differences in age, gender, body mass index, APACHE II, or fluid balance during the study period. The TTM group had lower ejection fraction, Glasgow Coma Score, and more frequent use of paralytics. Matched data analyses (change at day 4 compared with baseline of the individual subject) showed favorable, but not statistically significant trends in respiratory mechanics endpoints (airway pressure, compliance, tidal volume, and PaO2/FiO2) in the TTM group. The PaCO2 decreased significantly more in the TTM group, as compared with controls (-12 vs. -5 mmHg, p=0.02). For clinical outcomes, the TTM group consistently, although not significantly, did better in survival (59% vs. 43%) and hospital length of stay (12 vs. 15 days). The MV duration and Cerebral Performance Category score on discharge were significantly lower in the TTM group (7.3 vs. 10.7 days, p=0.04 and 3.2 vs. 4, p=0.01). This small retrospective cohort suggests that the effect of TTM ranges from equivalent to favorable, compared with controls, for the specific respiratory and clinical outcomes in patients with respiratory failure following cardiac arrest.

Post-conditioning to improve cardiopulmonary resuscitation.

PURPOSE OF REVIEW: Despite decades of advances in prehospital and in-hospital medical care, patients with out-of-hospital cardiac arrest continue to have poor neurologic and cardiac function following otherwise successful resuscitation. This review examines the mechanisms and therapeutic strategies currently under development to activate the post-conditioning pathways and thereby improve survival and function. RECENT FINDINGS: Post-conditioning utilizes the reperfusion injury salvage kinase (RISK) and survivor activating factor enhancement (SAFE) pathways as common avenues to promote cell survival and function. Ischemic post-conditioning and multiple medications activate these pathways resulting in improved cardiac and neurological function in animal models of cardiac arrest. SUMMARY: Detailed knowledge of the RISK and SAFE pathways can be used for further drug development. Human studies are now underway to test some of these strategies, but further clinical trials are necessary to translate these therapies to clinical practice.

Influence of α-stat and pH-stat blood gas management strategies on cerebral blood flow and oxygenation in patients treated with therapeutic hypothermia after out-of-hospital cardiac arrest: a crossover study.

OBJECTIVES: In patients treated with therapeutic hypothermia after out-of-hospital cardiac arrest, two blood gas management strategies are used regarding the PaCO2 target: α-stat or pH-stat. We aimed to compare the effects of these strategies on cerebral blood flow and oxygenation. DESIGN: Prospective observational single-center crossover study. SETTING: ICU of University hospital. PATIENTS: Twenty-one therapeutic hypothermia-treated patients after out-of-hospital cardiac arrest more than 18 years old without history of cerebrovascular disease were included. INTERVENTIONS: Cerebral perfusion and oxygenation variables were compared in α-stat (PaCO2 measured at 37 °C) versus pH-stat (PaCO2 measured at 32-34 °C), both strategies maintaining physiological PaCO2 values: 4.8-5.6 kPa (36-42 torr). MEASUREMENTS AND MAIN RESULTS: Bilateral transcranial middle cerebral artery flow velocities using Doppler and jugular vein oxygen saturation were measured in both strategies 18 hours (14-23 hr) after the return of spontaneous circulation. Pulsatility and resistance indexes and cerebral oxygen extraction were calculated. Data are expressed as median (interquartile range 25-75) in α-stat versus pH-stat. No differences were found in temperature, arterial blood pressure, and oxygenation between α-stat and pH-stat. Significant differences were found in minute ventilation (p = 0.006), temperature-corrected PaCO2 (4.4 kPa [4.1-4.6 kPa] vs. 5.1 kPa [5.0-5.3 kPa], p = 0.0001), and temperature-uncorrected PaCO2 (p = 0.0001). No differences were found in cerebral blood velocities and pulsatility and resistance indexes in the overall population. Significant differences were found in jugular vein oxygen saturation (83.2% [79.2-87.6%] vs. 86.7% [83.2-88.2%], p = 0.009) and cerebral oxygen extraction (15% [11-20%] vs. 12% [10-16%], p = 0.01), respectively. In survivors, diastolic blood velocities were 25 cm/s (19-30 cm/s) versus 29 cm/s (23-35 cm/s) (p = 0.004), pulsatility index was 1.10 (0.97-1.18) versus 0.94 (0.89-1.05) (p = 0.027), jugular vein oxygen saturation was 79.2 (71.1-81.8) versus 83.3% (76.6-87.8) (p = 0.033), respectively. However, similar results were not found in nonsurvivors. CONCLUSIONS: In therapeutic hypothermia-treated patients after out-of-hospital cardiac arrest at physiological PaCO2, α-stat strategy increases jugular vein blood desaturation and cerebral oxygen extraction compared with pH-stat strategy and decreases cerebral blood flow velocities in survivors.