Prognostic performance of diffusion-weighted MRI combined with NSE in comatose cardiac arrest survivors treated with mild hypothermia

Recovery and Survival of Patients After Out-of-Hospital Cardiac Arrest: A Literature Review Showcasing the Big Picture of Intensive Care Unit-Related Factors

As an important public health issue, out-of-hospital cardiac arrest (OHCA) requires several stages of high quality medical care, both on-field and after hospital admission. Post-cardiac arrest shock can lead to severe neurological injury, resulting in poor recovery outcome and increased risk of death. These characteristics make this condition one of the most important issues to deal with in post-OHCA patients hospitalized in intensive care units (ICUs). Also, the majority of initial post-resuscitation survivors have underlying coronary diseases making revascularization procedure another crucial step in early management of these patients. Besides keeping myocardial blood flow at a satisfactory level, other tissues must not be neglected as well, and maintaining mean arterial pressure within optimal range is also preferable. All these procedures can be simplified to a certain level along with using targeted temperature management methods in order to decrease metabolic demands in ICU-hospitalized post-OHCA patients. Additionally, withdrawal of life-sustaining therapy as a controversial ethical topic is under constant re-evaluation due to its possible influence on overall mortality rates in patients initially surviving OHCA. Focusing on all of these important points in process of managing ICU patients is an imperative towards better survival and complete recovery rates.

Predictive Performance of Neuron-Specific Enolase (NSE) for Survival after Resuscitation from Cardiac Arrest: A Systematic Review and Meta-Analysis

The prediction of outcomes following cardiac arrest continues to provide significant difficulties. A preferred strategy involves adopting a multimodal approach, which encompasses the careful evaluation of the biomarker neuron-specific enolase (NSE). This systematic review and meta-analysis aimed to gather and summarize new and existing evidence on the prediction effect of neuron-specific enolase for survival to hospital discharge among adult patients with cardiac arrest. We searched PubMed Central, Scopus, EMBASE databases, and the Cochrane Library without language restrictions from their inceptions until 30 October 2023 and checked the reference lists of the included studies. Pooled results were reported as standardized mean differences (SMDs) and were presented with corresponding 95% confidence intervals (CIs). The primary outcome was survival to hospital discharge (SHD). Eighty-six articles with 10,845 participants were included. NSE showed a notable degree of specificity in its ability to predict mortality as well as neurological status among individuals who experienced cardiac arrest (p < 0.05). This study demonstrates the ability to predict fatality rates and neurological outcomes, both during the time of admission and at various time intervals after cardiac arrest. The use of NSE in a multimodal neuroprognostication algorithm has promise in improving the accuracy of prognoses for persons who have undergone cardiac arrest.

Parieto-Occipital Injury on Diffusion MRI Correlates with Poor Neurologic Outcome following Cardiac Arrest

BACKGROUND AND PURPOSE

MR imaging of the brain provides unbiased neuroanatomic evaluation of brain injury and is useful for neurologic prognostication following cardiac arrest. Regional analysis of diffusion imaging may provide additional prognostic value and help reveal the neuroanatomic underpinnings of coma recovery. The purpose of this study was to evaluate global, regional, and voxelwise differences in diffusion-weighted MR imaging signal in patients in a coma after cardiac arrest.

MATERIALS AND METHODS

We retrospectively analyzed diffusion MR imaging data from 81 subjects who were comatose for >48 hours following cardiac arrest. Poor outcome was defined as the inability to follow simple commands at any point during hospitalization. ADC differences between groups were evaluated across the whole brain, locally by using voxelwise analysis and regionally by using ROI-based principal component analysis.

RESULTS

Subjects with poor outcome had more severe brain injury as measured by lower average whole-brain ADC (740 [SD, 102] × 10-6 mm2/s versus 833 [SD, 23] × 10-6 mm2/s, P < .001) and larger average volumes of tissue with ADC below 650 × 10-6 mms/s (464 [SD, 469] mL versus 62 [SD, 51] mL, P < .001). Voxelwise analysis showed lower ADC in the bilateral parieto-occipital areas and perirolandic cortices for the poor outcome group. ROI-based principal component analysis showed an association between lower ADC in parieto-occipital regions and poor outcome.

CONCLUSIONS

Brain injury affecting the parieto-occipital region measured with quantitative ADC analysis was associated with poor outcomes after cardiac arrest. These results suggest that injury to specific brain regions may influence coma recovery.

Predicting neurological outcome after cardiac arrest by combining computational parameters extracted from standard and deviant responses from auditory evoked potentials

Background

Despite multimodal assessment (clinical examination, biology, brain MRI, electroencephalography, somatosensory evoked potentials, mismatch negativity at auditory evoked potentials), coma prognostic evaluation remains challenging.

Methods

We present here a method to predict the return to consciousness and good neurological outcome based on classification of auditory evoked potentials obtained during an oddball paradigm. Data from event-related potentials (ERPs) were recorded noninvasively using four surface electroencephalography (EEG) electrodes in a cohort of 29 post-cardiac arrest comatose patients (between day 3 and day 6 following admission). We extracted retrospectively several EEG features (standard deviation and similarity for standard auditory stimulations and number of extrema and oscillations for deviant auditory stimulations) from the time responses in a window of few hundreds of milliseconds. The responses to the standard and the deviant auditory stimulations were thus considered independently. By combining these features, based on machine learning, we built a two-dimensional map to evaluate possible group clustering.

Results

Analysis in two-dimensions of the present data revealed two separated clusters of patients with good versus bad neurological outcome. When favoring the highest specificity of our mathematical algorithms (0.91), we found a sensitivity of 0.83 and an accuracy of 0.90, maintained when calculation was performed using data from only one central electrode. Using Gaussian, K-neighborhood and SVM classifiers, we could predict the neurological outcome of post-anoxic comatose patients, the validity of the method being tested by a cross-validation procedure. Moreover, the same results were obtained with one single electrode (Cz).

Conclusion

statistics of standard and deviant responses considered separately provide complementary and confirmatory predictions of the outcome of anoxic comatose patients, better assessed when combining these features on a two-dimensional statistical map. The benefit of this method compared to classical EEG and ERP predictors should be tested in a large prospective cohort. If validated, this method could provide an alternative tool to intensivists, to better evaluate neurological outcome and improve patient management, without neurophysiologist assistance.

Serum Neuron-Specific Enolase Thresholds for Predicting Postcardiac Arrest Outcome: A Systematic Review and Meta-analysis

BACKGROUND AND OBJECTIVES

To determine thresholds of serum neuron-specific enolase (NSE) for prediction of poor outcome after cardiac arrest with >95% specificity using a unique method of multiple thresholds meta-analysis.

METHODS

Data from a systematic review by the European Resuscitation Council (ERC 2014) were updated with literature searches from PubMed, Cochrane, and Scopus until August 2020. Search terms included the MeSH terms "heart arrest" and "biomarkers" and the text words "cardiac arrest," "neuron specific enolase," "coma" and "prognosis." Cohort studies with comatose cardiac arrest survivors aged >16 years undergoing targeted temperature management (TTM) and NSE levels within 96 hours of resuscitation were included. Poor outcome was defined as cerebral performance category 3-5 at hospital discharge or later. Studies without extractable contingency tables were excluded. A multiple thresholds meta-analysis model was used to generate summary receiver operating characteristic curves for various time points. NSE thresholds (and 95% prediction intervals) for >95% specificity were calculated. Evidence appraisal was performed using a method adapted from the American Academy of Neurology grading criteria.

RESULTS

Data from 11 studies (n = 1,982) at 0-24 hours, 21 studies (n = 2,815) at 24-48 hours, and 13 studies (n = 2,557) at 48-72 hours was analyzed. Areas under the curve for prediction of poor outcomes were significantly larger at 24-48 hours and 48-72 hours compared to 0-24 hours (0.82 and 0.83 vs 0.64). Quality of evidence was very low for most studies because of the risk of incorporation bias-knowledge of NSE levels potentially influenced life support withdrawal decisions. To minimize falsely pessimistic predictions, NSE thresholds at the upper 95% limit of prediction intervals are reported. For prediction of poor outcome with specificity >95%, upper limits of the prediction interval for NSE were 70.4 ng/mL at 24-48 hours and 58.6 ng/mL at 48-72 hours. Sensitivity analyses excluding studies with inconsistent TTM use or different outcome criteria did not substantially alter the results.

CONCLUSIONS

NSE thresholds for highly specific prediction of poor outcome are much higher than generally used. Future studies must minimize bias by masking treatment teams to the results of potential predictors and by prespecifying criteria for withdrawal of life support.

Imaging for Neuroprognostication After Cardiac Arrest: Systematic Review and Meta-analysis

BACKGROUND

Predicting neurological outcome in comatose survivors of cardiac arrest relies on clinical findings, radiological and neurophysiological test results. To evaluate the predictive accuracy of brain computed tomography (CT) and magnetic resonance imaging (MRI) for prognostication of neurological outcomes after cardiac arrest.

METHODS

We searched MEDLINE (database inception to August 2018) and included all observational cohort studies or randomized controlled trials including adult (16 years or older) survivors of cardiac arrest which evaluated the diagnostic accuracy of CT or MRI for predicting neurologic outcome or mortality. Study quality was assessed using the Quality Assessment of Diagnostic Accuracy Studies 2 tool. All review stages were conducted independently by 2 reviewers, and where possible data were pooled using bivariate meta-analysis. The main outcome was to evaluate the of accuracy of CT and MRI in neuroprognostication of patients after cardiac arrest.

RESULTS

We included 44 studies that examined brain CT (n = 24) or MRI (n = 21) in 4008 (n per study, 9-398) patients. Decreased grey to white matter ratio on CT (20 studies) was useful for predicting poor neurological outcome (sensitivity 0.44, 95% CI 0.29-0.60; specificity 0.97, 95% CI 0.93-0.99; positive likelihood ratio [LR+] 13.8, 95% CI 6.9-27.7). Similarly, diffusion-weighted imaging (DWI) on MRI (16 studies; sensitivity 0.77, 95% CI 0.65-0.85; specificity 0.92, 95% CI 0.85-0.96; LR+ 9.2, 95% CI 5.2-16.4) and DWI and fluid-attenuated inversion recovery (FLAIR) MRI (4 studies, sensitivity 0.70, 95% CI 0.43-0.88; specificity 0.95, 95% CI 0.79-0.99; LR+ 13.4, 95% CI 3.5-51.2) were useful for predicting poor neurological outcomes. We found marked heterogeneity in timing of radiological examinations and neurological assessments relative to the cardiac arrest.

CONCLUSION

Decreased grey to white matter ratio on CT and DWI or DWI and FLAIR on MRI are useful adjuncts for predicting poor early neurological outcome after cardiac arrest.

Prediction of poor outcome after hypoxic-ischemic brain injury by diffusion-weighted imaging: A systematic review and meta-analysis

Accurate prediction of the neurological outcome following hypoxic-ischemic brain injury (HIBI) remains difficult. Diffusion-weighted imaging (DWI) can detect acute and subacute brain abnormalities following global cerebral hypoxia. Therefore, DWI can be used to predict the outcomes of HIBI. To this end, we searched the PubMed, EMBASE, and Cochrane Library databases for studies that examine the diagnostic accuracy of DWI in predicting HIBI outcomes in adult patients between January1995 and September 2019. Next, we conducted a comprehensive meta-analysis using the Meta-DiSc and several complementary techniques. Following the application of inclusion and exclusion criteria, a total of 28 studies were included with 98 data subsets. The overall sensitivity and specificity, with 95% confidence interval, were 0.613(0.599-0.628) and 0.958(0.947-0.967), respectively, and the area under the curve was 0.9090. Significant heterogeneity among the included studies and a threshold effect were observed (p<0.001). Different positive indices were the major sources for the heterogeneity, followed by the anatomical region examined, both of which significantly affected the prognostic accuracy. In conclusion, we demonstrated that DWI can be an instrumental modality in predicting the outcome of HIBI with good prognostic accuracy. However, the lack of clear and generally accepted positive indices limits its clinical application. Therefore, using more reliable positive indices and combining DWI with other clinical predictors may improve the diagnostic accuracy of HIBI.

Standards for Studies of Neurological Prognostication in Comatose Survivors of Cardiac Arrest: A Scientific Statement From the American Heart Association

Significant improvements have been achieved in cardiac arrest resuscitation and postarrest resuscitation care, but mortality remains high. Most of the poor outcomes and deaths of cardiac arrest survivors have been attributed to widespread brain injury. This brain injury, commonly manifested as a comatose state, is a marker of poor outcome and a major basis for unfavorable neurological prognostication. Accurate prognostication is important to avoid pursuing futile treatments when poor outcome is inevitable but also to avoid an inappropriate withdrawal of life-sustaining treatment in patients who may otherwise have a chance of achieving meaningful neurological recovery. Inaccurate neurological prognostication leading to withdrawal of life-sustaining treatment and deaths may significantly bias clinical studies, leading to failure in detecting the true study outcomes. The American Heart Association Emergency Cardiovascular Care Science Subcommittee organized a writing group composed of adult and pediatric experts from neurology, cardiology, emergency medicine, intensive care medicine, and nursing to review existing neurological prognostication studies, the practice of neurological prognostication, and withdrawal of life-sustaining treatment. The writing group determined that the overall quality of existing neurological prognostication studies is low. As a consequence, the degree of confidence in the predictors and the subsequent outcomes is also low. Therefore, the writing group suggests that neurological prognostication parameters need to be approached as index tests based on relevant neurological functions that are directly related to the functional outcome and contribute to the quality of life of cardiac arrest survivors. Suggestions to improve the quality of adult and pediatric neurological prognostication studies are provided.

Neuron-specific enolase kinetics: an additional tool for neurological prognostication after cardiac arrest

INTRODUCTION AND OBJECTIVES

To analyze neuron-specific enolase (NSE) kinetics as a prognostic biomarker of neurological outcome in cardiac arrest survivors treated with targeted temperature management.

METHODS

We performed a retrospective analysis of patients resuscitated from in- or out-of-hospital cardiac arrest admitted from September 2006 to May 2018 in a single tertiary care center and cooled to 32°C to 34°C for 24 hours. Blood samples for measurement of NSE values were drawn at hospital admission and at 24, 48, and 72hours after return of spontaneous circulation (ROSC). Neurological outcome was evaluated by means of the Cerebral Performance Category (CPC) score at 3 months and was characterized as good (CPC 1-2) or poor (CPC 3-5).

RESULTS

Of 451 patients, 320 fulfilled the inclusion criteria and were analyzed (80.3% male, mean age 61±14.1 years). Among these, 174 patients (54.4%) survived with good neurological status. Poor outcome patients had higher median NSE values at hospital admission and at 24, 48 and 72 hours after ROSC. At 48 and 72 hours after ROSC, NSE predicted poor neurological outcome with areas under the receiver-operating characteristic curves of 0.85 (95%CI, 0.81-0.90) and 0.88 (95%CI, 0.83-0.93), respectively. In addition, delta NSE values between 72hours after ROSC and hospital admission predicted poor neurological outcome with an area under the receiver-operating characteristic curve of 0.90 (95%CI, 0.85-0.95) and was an independent predictor of unfavorable outcome on multivariate analysis (P <.001).

CONCLUSIONS

In cardiac arrest survivors treated with targeted temperature management, delta NSE values between 72 hours after ROSC and hospital admission strongly predicted poor neurological outcome.

Brain imaging in comatose survivors of cardiac arrest: Pathophysiological correlates and prognostic properties

INTRODUCTION

Hypoxic-ischemic brain injury is the main cause of death and disability of comatose patients after cardiac arrest. Early and reliable prognostication is challenging. Common prognostic tools include clinical neurological examination and electrophysiological measures. Brain imaging is well established for diagnosis of focal cerebral ischemia but has so far not found worldwide application in this patient group.

OBJECTIVE

To review the value of Computed Tomography (CT), Magnetic Resonance Imaging (MRI), and Positron Emission Tomography (PET) for early prediction of neurological outcome of comatose survivors of cardiac arrest.

METHODS

A literature search was performed to identify publications on CT, MRI or PET in comatose patients after cardiac arrest.

RESULTS

We included evidence from 51 articles, 21 on CT, 27 on MRI, 1 on CT and MRI, and 2 on PET imaging. Studies varied regarding timing of measurements, choice of determinants, and cut-off values predicting poor outcome. Most studies were small (n = 6-398) and retrospective (60%). In general, cytotoxic oedema, defined by a grey-white matter ratio <1.10, derived from CT, or MRI-diffusion weighted imaging <650 × 10^-6 mm²/s in >10% of the brain could differentiate between patients with favourable and unfavourable outcomes on a group level within 1-3 days after cardiac arrest. Advanced imaging techniques such as functional MRI or diffusion tensor imaging show promising results, but need further evaluation.

CONCLUSION

CT derived grey-white matter ratio and MRI based measures of diffusivity and connectivity hold promise to improve outcome prediction after cardiac arrest. Prospective validation studies in a multivariable approach are needed to determine the additional value for the individual patient.

Serial NSE measurement identifies non-survivors following out of hospital cardiac arrest

AIMS

Prognostication following out-of-hospital cardiac arrest (OHCA) remains challenging. A multimodal approach is favoured, including consideration of the biomarker neuron-specific enolase (NSE) (Sandroni et al., 2014). Our objective was to investigate the utility of serial NSE measurements and to determine an appropriate cut-off value for prediction of death before hospital discharge using data from our tertiary care center.

METHODS

Retrospective analysis of patients admitted to the critical care unit of a tertiary center critical care unit in the UK following an out-of-hospital cardiac arrest.

MEASUREMENTS AND MAIN RESULTS

We analysed data from 72 patients admitted to our unit over 8 months following out-of-hospital cardiac arrest. Initial NSE level (NSE₀) was a poor predictor of outcome. Both NSE level at 48 h post-admission (NSE₄₈) and change in NSE from baseline to 48 h post-admission (Δ_NSE) were good predictors of outcome. A cut-off of NSE₄₈ > 69.8 ng/ml gave a specificity of 1.00 and sensitivity of 0.62 for prediction of death before hospital discharge in our patient group, whilst a cut-off of Δ_NSE > 31.3 ng/ml gave a specificity of 1.00 and sensitivity of 0.54. In patients who did not survive to hospital discharge, Δ_NSE > 9.4 ng/ml was associated with other poor prognostic factors (asytolic/PEA arrest, long downtime before ROSC) and with more rapid deterioration before death.

CONCLUSION

Serial measurement of NSE levels (at 0 and 48 h after admission) provides a useful tool to aid prognostication following out-of-hospital cardiac arrest.

Therapeutic hypothermia after cardiac arrest: outcome predictors

OBJECTIVE

The determination of coma patient prognosis after cardiac arrest has clinical, ethical and social implications. Neurological examination, imaging and biochemical markers are helpful tools accepted as reliable in predicting recovery. With the advent of therapeutic hypothermia, these data need to be reconfirmed. In this study, we attempted to determine the validity of different markers, which can be used in the detection of patients with poor prognosis under hypothermia.

METHODS

Data from adult patients admitted to our intensive care unit for a hypothermia protocol after cardiac arrest were recorded prospectively to generate a descriptive and analytical study analyzing the relationship between clinical, neurophysiological, imaging and biochemical parameters with 6-month outcomes defined according to the Cerebral Performance Categories scale (good 1-2, poor 3-5). Neuron-specific enolase was collected at 72 hours. Imaging and neurophysiologic exams were carried out in the 24 hours after the rewarming period.

RESULTS

Sixty-seven patients were included in the study, of which 12 had good neurological outcomes. Ventricular fibrillation and electroencephalographic theta activity were associated with increased likelihood of survival and improved neurological outcomes. Patients who had more rapid cooling (mean time of 163 versus 312 minutes), hypoxic-ischemic brain injury on magnetic resonance imaging or neuron-specific enolase > 58ng/mL had poor neurological outcomes (p < 0.05).

CONCLUSION

Hypoxic-ischemic brain injury on magnetic resonance imaging and neuron-specific enolase were strong predictors of poor neurological outcomes. Although there is the belief that early achievement of target temperature improves neurological prognoses, in our study, there were increased mortality and worse neurological outcomes with earlier target-temperature achievement.

Cerebral Effects of Targeted Temperature Management Methods Assessed by Diffusion-Weighted Magnetic Resonance Imaging

The aim of this randomized porcine study was to compare surface targeted temperature management (TTM) to endovascular TTM evaluated by cerebral diffusion-weighted magnetic resonance imaging (MRI): apparent diffusion coefficient (ADC), and by intracerebral/intramuscular microdialysis. It is well known that alteration in the temperature affects ADC, but the relationship between cerebral ADC values and the cooling method per se has not been established. Eighteen anesthetized 60-kg female swine were hemodynamically and intracerebrally monitored and subsequently subjected to a baseline MRI. The animals were then randomized into three groups: (1) surface cooling (n = 6) at 33.5°C using EMCOOLSpad^®, (2) endovascular cooling (n = 6) at 33.5°C using an Icy^® cooling catheter with the CoolGard 3000^®, or (3) control (n = 6) at 38.5°C using a Bair Hugger™. The swine were treated with TTM for 6 hours followed by a second MRI examination, including ADC. Blood and microdialysate were sampled regularly throughout the experiment, and glucose, lactate, pyruvate, glycerol, and the lactate/pyruvate ratio did not differ among groups, neither intracerebrally nor intramuscularly. Surface cooling yielded a significantly lower median ADC than endovascular cooling: 714 (634; 804) × 10^-6 mm²/s versus 866 (828; 927) × 10^-6 mm²/s, (p < 0.05). The surface cooling ADC was lowered to a range usually attributed to cytotoxic edema and these low values could not be explained solely by the temperature effect per se. To what extent the ADC is fully reversible at rewarming is unknown and the clinical implications should be further investigated in clinical studies.

Neuroprotective strategies and neuroprognostication after cardiac arrest

Neurocognitive disturbances are common among survivors of cardiac arrest (CA). Although initial management of CA, including bystander cardiopulmonary resuscitation, optimal chest compression, and early defibrillation, has been implemented continuously over the last years, few therapeutic interventions are available to minimize or attenuate the extent of brain injury occurring after the return of spontaneous circulation. In this review, we discuss several promising drugs that could provide some potential benefits for neurological recovery after CA. Most of these drugs have been investigated exclusively in experimental CA models and only limited clinical data are available. Further research, which also considers combined neuroprotective strategies that target multiple pathways involved in the pathophysiology of postanoxic brain injury, is certainly needed to demonstrate the effectiveness of these interventions in this setting. Moreover, the evaluation of neurological prognosis of comatose patients after CA remains an important challenge that requires the accurate use of several tools. As most patients with CA are currently treated with targeted temperature management (TTM), combined with sedative drug therapy, especially during the hypothermic phase, the reliability of neurological examination in evaluating these patients is delayed to 72-96 h after admission. Thus, additional tests, including electrophysiological examinations, brain imaging and biomarkers, have been largely implemented to evaluate earlier the extent of brain damage in these patients.

The risk factors and prognostic implication of acute pulmonary edema in resuscitated cardiac arrest patients

Objective

Pulmonary edema is frequently observed after a successful resuscitation in out-of-hospital cardiac arrest (OHCA) patients. Currently, its risk factors and prognostic implications are mostly unknown.

Methods

Adult OHCA patients with a presumed cardiac etiology who achieved sustained return of spontaneous circulation (ROSC) in emergency department were retrospectively analyzed. The patients were grouped according to the severity of consolidation on their initial chest X-ray (group I, no consolidation; group II, patchy consolidations; group III, consolidation involving an entire lobe; group IV, total white-out of any lung). The primary objective was to identify the risk factors of developing severe pulmonary edema (group III or IV). The secondary objective was to evaluate the association between long-term prognosis and the severity of pulmonary edema.

Results

One hundred and seven patients were included. Total duration of cardiopulmonary resuscitation (CPR) and initial pCO₂ level were both independent predictors of developing severe pulmonary edema with their odds ratio (OR) being 1.02 (95% confidence interval [CI], 1.00 to 1.04; per 1 minute) and 1.04 (95% CI, 1.01 to 1.07; per 1 mmHg), respectively. The long term prognosis was significantly poor in patients with severe pulmonary edema with a OR for good outcome (6-month cerebral performance category 1 or 2) being 0.22 (95% CI, 0.06 to 0.79) in group III and 0.16 (95% CI, 0.04 to 0.63) in group IV compared to group I.

Conclusion

The duration of CPR and initial pCO₂ level were both independent predictors for the development of severe pulmonary edema after resuscitation in emergency department. The severity of the pulmonary edema was significantly associated with long-term outcome.

Neurological prognostication after cardiac arrest

PURPOSE OF REVIEW

Prediction of neurological prognosis in patients who are comatose after successful resuscitation from cardiac arrest remains difficult. Previous guidelines recommended ocular reflexes, somatosensory evoked potentials and serum biomarkers for predicting poor outcome within 72  h from cardiac arrest. However, these guidelines were based on patients not treated with targeted temperature management and did not appropriately address important biases in literature.

RECENT FINDINGS

Recent evidence reviews detected important limitations in prognostication studies, such as low precision and, most importantly, lack of blinding, which may have caused a self-fulfilling prophecy and overestimated the specificity of index tests. Maintenance of targeted temperature using sedatives and muscle relaxants may interfere with clinical examination, making assessment of neurological status before 72  h or more after cardiac arrest unreliable.

SUMMARY

No index predicts poor neurological outcome after cardiac arrest with absolute certainty. Prognostic evaluation should start not earlier than 72  h after ROSC and only after major confounders have been excluded so that reliable clinical examination can be made. Multimodality appears to be the most reasonable approach for prognostication after cardiac arrest.

Resuscitation duration inequality by patient characteristics in emergency department out-of-hospital cardiac arrest: an observational study

Objective

Out-of-hospital cardiac arrest (OHCA) patients unresponsive to basic life support are frequently transferred to emergency departments (EDs) for further resuscitation. Although some survive with good neurologic outcomes, additional resuscitation in EDs is often futile. Without a dedicated termination of resuscitation (TOR) rule for ED resuscitation, the decision when to stop the resuscitation is up to emergency physicians. In this study, we assessed the association between patient characteristics and duration of resuscitation in EDs to understand how emergency physicians decide when to terminate cardiopulmonary resuscitation.

Methods

A retrospective analysis of the OHCA registry of a single ED was conducted. Adult (18 years or older) patients without any return of spontaneous circulation (ROSC) after unsuccessful ED advanced cardiac life support were included. The primary endpoint was duration of resuscitation attempts. Prehospital and demographic factors were assessed as independent variables. The relationship between these factors and duration of resuscitative attempts was analyzed with multivariable quantile regression.

Results

From January 2008 to August 2012, ED resuscitation was terminated without ROSC in 266 patients (53.5%). The duration of resuscitative attempts was significantly shorter if any of the currently recognized poor prognostic factors was present. Interestingly, controversial factors such as female sex and older age were significantly associated with shorter resuscitation duration, while factors definitively indicating poor prognosis, such as severe trauma and poor baseline neurological status, showed no significant association.

Conclusion

The results of this study suggest that physicians adjust the resuscitation duration according to their subjective prediction of futility despite the absence of evidence-based TOR guidelines.

Prognostication in comatose survivors of cardiac arrest: an advisory statement from the European Resuscitation Council and the European Society of Intensive Care Medicine

Objectives

To review and update the evidence on predictors of poor outcome (death, persistent vegetative state or severe neurological disability) in adult comatose survivors of cardiac arrest, either treated or not treated with controlled temperature, to identify knowledge gaps and to suggest a reliable prognostication strategy.

Methods

GRADE-based systematic review followed by expert consensus achieved using Web-based Delphi methodology, conference calls and face-to-face meetings. Predictors based on clinical examination, electrophysiology, biomarkers and imaging were included.

Results and conclusions

Evidence from a total of 73 studies was reviewed. The quality of evidence was low or very low for almost all studies. In patients who are comatose with absent or extensor motor response at ≥72 h from arrest, either treated or not treated with controlled temperature, bilateral absence of either pupillary and corneal reflexes or N20 wave of short-latency somatosensory evoked potentials were identified as the most robust predictors. Early status myoclonus, elevated values of neuron-specific enolase at 48–72 h from arrest, unreactive malignant EEG patterns after rewarming, and presence of diffuse signs of postanoxic injury on either computed tomography or magnetic resonance imaging were identified as useful but less robust predictors. Prolonged observation and repeated assessments should be considered when results of initial assessment are inconclusive. Although no specific combination of predictors is sufficiently supported by available evidence, a multimodal prognostication approach is recommended in all patients.

Electronic supplementary material

The online version of this article (doi:10.1007/s00134-014-3470-x) contains supplementary material, which is available to authorized users.

Feasibility of optic nerve sheath diameter measured on initial brain computed tomography as an early neurologic outcome predictor after cardiac arrest

OBJECTIVES

Few parameters are available to predict neurologic outcome of post-cardiac arrest patients in the early stage of treatment. Optic nerve sheath diameter (ONSD) has been used to indirectly assess intracranial pressure. This study evaluated whether ONSD, an additional parameter in initial brain computed tomography (CT) scans, can be an early predictor of neurologic outcome in post-cardiac arrest patients.

METHODS

A total of 112 cardiac arrest patients between November 2012 and October 2013 were identified. Ninety-eight comatose cardiac arrest patients were evaluated with brain CT. Of these patients, after exclusion of patients whose brain CT scans were done too late or with poor baseline neurology (Cerebral Performance Category [CPC] ≥ 3), 91 patients were included for this study. The parameters of initial brain CT, i.e., gray matter-to-white matter ratio (GWR) and ONSD, were measured after clinical care as part of a retrospective reanalysis of images. ONSD on brain CT was bilaterally measured 3 mm behind the eyeball at fixed window width and level and averaged to yield the mean value. The performance of ONSD to predict poor neurologic outcome (CPC = 3 to 5) was analyzed using multiple logistic regression analysis, receiver operating characteristic (ROC) curve analysis, and cross-tabulations.

RESULTS

Twenty-three patients showed good neurologic outcomes at hospital discharge. Mean (±SD) ONSD was 5.6 (±0.3) mm in the good outcome group versus 6.3 (±0.5) mm in the poor outcome group (p < 0.001). After basic clinical covariates were controlled for, i.e., age, Glasgow Coma Scale (GCS) score (3 vs. 4-15), and time from collapse to return of spontaneous circulation (ROSC), ONSD (odds ratio [OR] = 2.1; 95% confidence interval [CI] = 1.1 to 3.9) and GWR (OR = 0.6; 95% CI = 0.4 to 0.9) were found to be significant factors for predicting poor neurologic outcome. ROC curve analysis showed that ONSD and GWR had areas under the ROC curve of 0.931 (95% CI = 0.87 to 0.98) and 0.922 (95% CI = 0.86 to 0.97), respectively. Combining the cutoff values of ONSD (6.21 mm, sensitivity = 56%; 95% CI = 43% to 68%) and GWR (1.23, sensitivity = 84%; 95% CI = 73% to 92%) to have 100% specificities, the sensitivity was improved to 92% (95% CI = 84% to 98%). Intrarater and interrater intraclass correlation coefficients between the investigators measuring ONSD were 0.888 and 0.833, respectively.

CONCLUSIONS

Optic nerve sheath diameter on initial brain CT correlated closely with the neurologic outcome of hypoxic ischemic encephalopathy and had good reliability. Additional prospective work may be justified evaluating the standardization and diagnostic performance in real time use as a predictive tool for neurologic outcome following cardiac arrest.

Neuroprognostication of hypoxic-ischaemic coma in the therapeutic hypothermia era

Neurological prognostication after cardiac arrest has always been challenging, and has become even more so since the advent of therapeutic hypothermia (TH) in the early 2000s. Studies in this field are prone to substantial biases--most importantly, the self-fulfilling prophecy of early withdrawal of life-sustaining therapies--and physicians must be aware of these limitations when evaluating individual patients. TH mandates sedation and prolongs drug metabolism, and delayed neuronal recovery is possible after cardiac arrest with or without hypothermia treatment; thus, the clinician must allow an adequate observation period to assess for delayed recovery. Exciting advances have been made in clinical evaluation, electrophysiology, chemical biomarkers and neuroimaging, providing insights into the underlying pathophysiological mechanisms of injury, as well as prognosis. Some clinical features, such as pupillary reactivity, continue to provide robust information about prognosis, and EEG patterns, such as reactivity and continuity, seem promising as prognostic indicators. Evoked potential information is likely to remain a reliable prognostic tool in TH-treated patients, whereas traditional serum biomarkers, such as neuron-specific enolase, may be less reliable. Advanced neuroimaging techniques, particularly those utilizing MRI, hold great promise for the future. Clinicians should continue to use all the available tools to provide accurate prognostic advice to patients after cardiac arrest.

How to assess prognosis after cardiac arrest and therapeutic hypothermia

The prognosis of patients who are admitted in a comatose state following successful resuscitation after cardiac arrest remains uncertain. Although the introduction of therapeutic hypothermia (TH) and improvements in post-resuscitation care have significantly increased the number of patients who are discharged home with minimal brain damage, short-term assessment of neurological outcome remains a challenge. The need for early and accurate prognostic predictors is crucial, especially since sedation and TH may alter the neurological examination and delay the recovery of motor response for several days. The development of additional tools, including electrophysiological examinations (electroencephalography and somatosensory evoked potentials), neuroimaging and chemical biomarkers, may help to evaluate the extent of brain injury in these patients. Given the extensive literature existing on this topic and the confounding effects of TH on the strength of these tools in outcome prognostication after cardiac arrest, the aim of this narrative review is to provide a practical approach to post-anoxic brain injury when TH is used. We also discuss when and how these tools could be combined with the neurological examination in a multimodal approach to improve outcome prediction in this population.

Good functional outcome after prolonged postanoxic comatose myoclonic status epilepticus in a patient who had undergone bone marrow transplantation

In anoxic coma, myoclonic status epilepticus and other nonreactive epileptiform patterns are considered as signs of poor prognosis. We report the case of a good recovery in a prolonged comatose myoclonic status epilepticus (MSE) after a cardiac arrest (CA) treated with mild therapeutic hypothermia (TH) in a patient who had undergone a bone marrow transplantation for Hodgkin's lymphoma. This case emphasizes the opportunity of performing an electroencephalogram (EEG) in the acute period after an hypoxic-ischemic insult and underlines the diagnostic difficulties between MSE and Lance-Adams syndrome, which classically occurs after the patient has regained consciousness, but can also begin while the patient is still comatose or sedated. Major problems in prognostication for postarrest comatose patients will also be pointed out.

Combining brain computed tomography and serum neuron specific enolase improves the prognostic performance compared to either alone in comatose cardiac arrest survivors treated with therapeutic hypothermia

AIM OF THE STUDY

We determined whether combining the grey-to-white matter ratio (GWR) on brain computed tomography (CT) and serum neuron specific enolase (NSE) improves the prognostic performance when compared to either alone in cardiac arrest patients treated with therapeutic hypothermia (TH).

METHODS

We performed a retrospective study of a cohort of cardiac arrest patients treated with TH. The Hounsfield unit was measured in the caudate nucleus (CN), putamen (P), posterior limb of internal capsule (PIC) and corpus callosum (CC); GWR was calculated as CN/PIC and P/CC. The NSE value was obtained at 0, 24, and 48h after restoration of spontaneous circulation (ROSC). We analysed the prognostic performance of GWR and NSE, singly and in combination, in predicting poor neurologic outcome (cerebral performance category 3-5).

RESULTS

Of the 224 included patients, 82 showed good neurologic outcome at hospital discharge, while 142 showed poor neurologic outcome. The P/CC (area under receiver operating characteristics (AUROC) 0.864, sensitivity/specificity 52.9%/100%) showed better prognostic performance than did the CN/PIC (AUROC 0.721, sensitivity/specificity 19.8%/100%). The NSE value at 48h after ROSC (AUROC 0.895, sensitivity/specificity 60.2%/100%) showed the highest prognostic value among the three NSE time points. Analysis of 119 patients undergoing both brain CT and NSE at 48h indicated that combining P/CC and NSE improved the sensitivity (78.6%) compared to either alone (48.6%, 62.9%).

CONCLUSION

Combining brain CT and serum NSE improves the prognostic performance when compared to either alone in predicting poor neurologic outcome in cardiac arrest patients treated with TH.