Predicting neurological outcome following cardiac arrest

Temperature Variability Does Not Attenuate the Beneficial Effects of Therapeutic Hypothermia on Cellular Apoptosis and Endoplasmic Reticulum Stress in the Cerebral Cortex of a Swine Cardiac Arrest Model

BACKGROUND

Endoplasmic reticulum stress (ERS) plays a vital role in mediating apoptosis in the brain following cardiac arrest (CA). Studies have shown that therapeutic hypothermia (TH) provides neuroprotection through anti-apoptosis; however, the effects of temperature variability in TH on the brain remain unclear. In this study, we investigated the different effects of temperature variability through extracorporeal membrane oxygenation on apoptosis and ERS in the brain following CA.

METHODS

Eighteen male domestic pigs underwent 6-min duration of no-flow induced by ventricular fibrillation. Extracorporeal cardiopulmonary resuscitation was then performed, and the return of spontaneous circulation (ROSC) was achieved. The animals were randomly assigned to the following groups: normothermia, non-temperature variability, and temperature variability. TH (core temperature, 33-35 °C) was maintained for 24 h post-ROSC, and the animals were rewarmed for 8 h. Quantitative real-time polymerase chain reaction (qRT-PCR) and immunohistochemistry for Bax and Bcl-2 transcripts and proteins, respectively, were used to investigate apoptosis in the cerebral cortex. Expression levels of the ERS molecules, GRP78 and CHOP, were also detected by qRT-PCR, and cellular morphology was evaluated using transmission electron microscopy.

RESULTS

qRT-PCR and immunohistochemistry results revealed that TH significantly increased the expression levels of Bcl-2 and GRP78 and decreased that of Bax and CHOP than under normothermia conditions. Compared to the non-temperature variability group, temperature variability did not decrease the expression levels of Bcl-2 and GRP78 and not increase the levels of Bax and CHOP. Endoplasmic reticulum ultrastructural changes were significantly improved under TH. No statistical difference was observed between the temperature variability and non-temperature variability groups.

CONCLUSION

TH can reduce neuronal apoptosis by ERS, while temperature variability does not attenuate this beneficial effect.

Predictors and their prognostic value for no ROSC and mortality after a non-cardiac surgery intraoperative cardiac arrest: a retrospective cohort study

Data on predictors of intraoperative cardiac arrest (ICA) outcomes are scarce in the literature. This study analysed predictors of poor outcome and their prognostic value after an ICA. Clinical and laboratory data before and 24 hours (h) after ICA were analysed as predictors for no return of spontaneous circulation (ROSC) and 24 h and 1-year mortality. Receiver operating characteristic curves for each predictor and sensitivity, specificity, positive and negative likelihood ratios, and post-test probability were calculated. A total of 167,574 anaesthetic procedures were performed, including 158 cases of ICAs. Based on the predictors for no ROSC, a threshold of 13 minutes of ICA yielded the highest area under curve (AUC) (0.867[0.80–0.93]), with a sensitivity and specificity of 78.4% [69.6–86.3%] and 89.3% [80.4–96.4%], respectively. For the 1-year mortality, the GCS without the verbal component 24 h after an ICA had the highest AUC (0.616 [0.792–0.956]), with a sensitivity of 79.3% [65.5–93.1%] and specificity of 86.1 [74.4–95.4]. ICA duration and GCS 24 h after the event had the best prognostic value for no ROSC and 1-year mortality. For 24 h mortality, no predictors had prognostic value.

Nursing knowledge of and attitude in cardiopulmonary arrest: cross-sectional survey analysis

BACKGROUND

Nurses are often the first to activate the chain of survival when a cardiorespiratory arrest happens. That is why it is crucial that they keep their knowledge and skills up-to-date and their attitudes to resuscitation are very important. The main aim of this study was to analyse whether the level of theoretical and practical understanding affected the attitudes of nursing staff.

METHODS

A questionnaire was designed using the Delphi technique (three rounds). The questionnaire was adjusted and it was piloted on a test-retest basis with a convenience sample of 30 registered nurses. The psychometric characteristics were evaluated using a sample of 347 nurses using Cronbach's alpha. Descriptive analysis was performed to describe the sociodemographic variables and Spearman's correlation coefficient to assess the relationship between two scale variables. Pearson's chi-squared test has been used to study the relationship between two categorical variables. Wilcoxon Mann Whitney test and the Kruskal-Wallis test were performed to establish relationships between the demographic/work related characteristics and the level of understanding.

RESULTS

The Knowledge and Attitude of Nurses in the Event of a Cardiorespiratory Arrest (CAEPCR) questionnaire comprised three sections: sociodemographic information, theoretical and practical understanding, and attitudes of ethical issues. Cronbach's alpha for the internal consistency of the attitudes questionnaire was 0.621. The knowledge that nurses self-reported with regard to cardiopulmonary arrest directly affected their attitudes. Their responses raised a number of bioethical issues.

CONCLUSIONS

CAEPCR questionnaire is the first one which successfully linked knowledge of cardiopulmonary resuscitation to the attitudes towards ethical issues Health policies should ensure that CPR training is mandatory for nurses and all healthcare workers, and this training should include the ethical aspects.

Predictive value of EEG-awakening for behavioral awakening from coma

BACKGROUND

A reliable predictor for early recovery of consciousness in comatose patients is of great clinical significance. Here we aimed to investigate the potentially prognostic value of electroencephalogram-reactivity (EEG-R) in combination with sleep spindles, termed EEG-awakening, for behavioral awakening in etiologically diverse comatose patients.

METHODS

We performed a prospectively observational study on a sample of patients, all of whom were in coma lasting longer than 3 days. Continuous EEG monitoring was performed for at least 24 h to detect the presence of EEG-R and sleep spindles. We then followed patients for 1 month to determine their subsequent level of consciousness, classifying them as either awakened or non-awakened. Finally, Univariate and multivariate analyses were employed to assess the association of predictors with consciousness recovery.

RESULTS

One hundred and six patients with different etiologies leading to coma were included in the study. Of these, 48 patients (45.3 %) awoke and 58 patients (54.7 %) did not awake in the month after the onset of the study. Of note, 26 patients (24.5 %) had a good neurological outcome, and 31 patients (29.3 %) died. Univariate analysis revealed that the Glasgow Coma Scale (GCS) score, EEG-R, sleep spindles, and EEG-awakening were all associated with one-month awakening. Comparisons of the area under the receiving operator characteristic curve (AUC) showed that EEG-awakening (0.839; 0.757-0.921) was superior to all of the following: EEG-R (0.798; 0.710-0.886), sleep spindles (0.772; 0.680-0.864), and GCS scores (0.720; 0.623-0.818). However, age, gender, etiology, and pupillary light reflex did not correlate significantly with one-month awakening. Further logistic regression analysis showed that only EEG-awakening and GCS scores at study entry were significant independent predictors of awakening and that the prognostic model containing these two variables yielded an outstanding predictive performance with an AUC of 0.903.

CONCLUSIONS

EEG-awakening incorporates both EEG-R and sleep spindles and is an excellent predictor for early behavioral awakening in comatose patients. The prognostic model combining EEG-awakening and GCS scores shows an outstanding discriminative power for awakening.

Cardiopulmonary Resuscitation in Children With In-Hospital and Out-of-Hospital Cardiopulmonary Arrest: Multicenter Study From Turkey

OBJECTIVES

The objectives of this study were to determine the causes, location of cardiopulmonary arrest (CPA) in children, and demographics of cardiopulmonary resuscitation (CPR) in Turkish pediatric emergency departments and pediatric intensive care units (PICUs) and to determine survival rates and morbidities for both in-hospital and out-of-hospital CPA.

METHODS

This multicenter descriptive study was conducted prospectively between January 15 and July 15, 2011, at 18 centers (15 PICUs, 3 pediatric emergency departments) in Turkey.

RESULTS

During the study period, 239 children had received CPR. Patients' average age was 42.4 (SD, 58.1) months. The most common cause of CPA was respiratory failure (119 patients [49.8%]). The location of CPA was the PICU in 168 (68.6%), hospital wards in 43 (18%), out-of-hospital in 24 (10%), and pediatric emergency department in 8 patients (3.3%). The CPR duration was 30.7 (SD, 23.6) minutes (range, 1-175 minutes) and return of spontaneous circulation was achieved in 107 patients (44.8%) after the first CPR. Finally, 58 patients (24.2%) were discharged from hospital; survival rates were 26% and 8% for in-hospital and out-of-hospital CPA, respectively (P = 0.001). Surviving patients' average length of hospital stay was 27.4 (SD, 39.2) days. In surviving patients, 19 (32.1%) had neurologic disability.

CONCLUSION

Pediatric CPA in both the in-hospital and out-of-hospital setting has a poor outcome.

Early prognostication in acute brain damage: where is the evidence?

PURPOSE OF REVIEW

Early prognostication in acute brain damage remains a challenge in the realm of critical care. There remains controversy over the most optimal methods that can be utilized to predict outcome. The utility of recently reported prognostic biomarkers and clinical methods will be reviewed.

RECENT FINDINGS

Recent guidelines touch upon prognostication techniques as part of management recommendations. In addition to novel laboratory values, there have been few reports on the use of clinical parameters, diagnostic imaging techniques, and electrophysiological techniques to assist in prognostication.

SUMMARY

Although encouraging, newer markers are not capable of providing accurate estimates on outcomes in acute injuries of the central nervous system. Traditional markers of prognostication may not be applicable in the light of newer and effective therapies (i.e. hypothermia). Substantial research in the field of outcome determination is in progress, but these studies need to be interpreted with caution.

Hypothermia-induced neuroprotection is associated with reduced mitochondrial membrane permeability in a swine model of cardiac arrest

Increasing evidence has shown that mild hypothermia is neuroprotective for comatose patients resuscitated from cardiac arrest, but the mechanism of this protection is not fully understood. The aim of this study was to determine whether prolonged whole-body mild hypothermia inhibits mitochondrial membrane permeability (MMP) in the cerebral cortex after return of spontaneous circulation (ROSC). Thirty-seven inbred Chinese Wuzhishan minipigs were successfully resuscitated after 8 minutes of untreated ventricular fibrillation (VF) and underwent recovery under normothermic (NT) or prolonged whole-body mild hypothermic (HT; 33°C) conditions for 24 or 72 hours. Cerebral samples from the frontal cortex were collected at 24 and 72 hours after ROSC. Mitochondria were isolated by differential centrifugation. At 24 hours, relative to NT, HT was associated with reductions in opening of the mitochondrial permeability transition pore, release of pro-apoptotic substances from mitochondria, caspase 3 cleavage, apoptosis, and neurologic deficit scores, as well as increases in mitochondrial membrane potential and mitochondrial respiration. Together, these findings suggest that mild hypothermia inhibits ischemia-induced increases in MMP, which may provide neuroprotection against cerebral injury after cardiac arrest.

Blood pH is a useful indicator for initiation of therapeutic hypothermia in the early phase of resuscitation after comatose cardiac arrest: a retrospective study

BACKGROUND

Therapeutic hypothermia (TH) is one of the key treatments after cardiac arrest (CA). Selection of post-CA patients for TH remains problematic, as there are no clinically validated tools to determine who might benefit from the therapy.

OBJECTIVE

The aim of this study was to investigate retrospectively whether laboratory findings or other patient data obtained during the early phase of hospital admission could be correlated with neurological outcome after TH in comatose survivors of CA.

METHODS

Medical charts of witnessed CA patients admitted between June 2003 and July 2009 who were treated with TH were reviewed retrospectively. The subjects were grouped based on their cerebral performance category (CPC) 6 months after CA, as either good recovery (GR) for CPC 1-2 or non-good recovery (non-GR) for CPC 3-5. The following well-known determinants of outcome obtained during the early phase of hospital admission were evaluated: age, gender, body mass index, cardiac origin, presence of ventricular fibrillation (VF), time from collapse to cardiopulmonary resuscitation, time from collapse to return of spontaneous circulation, body temperature, arterial blood gases, and blood test results.

RESULTS

We analyzed a total of 50 (25 GR and 25 non-GR) patients. Multivariate logistic analysis showed that initial heart rhythm and pH levels were significantly higher in the GR group than in the non-GR group (ventricular tachycardia/VF rate: p = 0.055, 95% confidence interval [CI] 0.768-84.272, odds ratio [OR] 8.047; pH: 7.155 ± 0.139 vs. 6.895 ± 0.100, respectively, p < 0.001, 95% CI 1.838-25.827; OR 6.89).

CONCLUSION

These results imply that in addition to initial heart rhythm, pH level may be a good candidate for neurological outcome predictor even though previous research has found no correlation between initial pH value and neurological outcome.

The changes of brain water diffusion and blood flow on diffusion-weighted and perfusion-weighted imaging in a canine model of cardiac arrest

OBJECTIVE

To study the changes of brain water diffusion and cerebral haemodynamics of cortical areas using magnetic resonance imaging (MRI) in canine models of cardiac arrest (CA) and restoration of spontaneous circulation (ROSC). The secondary study objective was to evaluate whether MRI can be used to observe haemodynamic disorders in brain microcirculation.

METHODS

CA was induced in six beagle dogs using electrical stimulation followed by resuscitation to spontaneous circulation 3 min later. The dogs were scanned using MRI for echo planar, diffusion-weighted imaging (DWI) and perfusion-weighted imaging (PWI) with injection of Gd-diethylene triamine pentaacetic acid (DTPA) prior to induction of CA and 3 days after ROSC. The arterial blood pressure, unilateral common carotid artery flow and intracranial microcirculation were recorded.

RESULTS

All dogs successfully underwent electric-induced ventricular fibrillation which lasted 3 min and were resuscitated to maintain blood pressure stability. Serial MRI scans found that cerebral blood flow (RCBF) decreased in day 1 after ROSC and returned to baseline on day 3. Apparent diffusion coefficient (ADC), however, decreased on day 1 and remained lower than baseline on day 3, with 765.8±82.5×10(-6) mm(2) s(-1) on day 1 and 770.4±59.4×10(-6) mm(2) s(-1) on day 3 comparing to 855.8±43.4×10(-6) mm(2) s(-1) on baseline.

CONCLUSIONS

These data provide the evidence that early MRI can be used to observe acute haemodynamic disorders in brain microcirculation in a canine model of cardiac arrest.

The role of cranial computed tomography in the immediate post-cardiac arrest period

Patients who initially survive cardiac arrest are often admitted to an intensive care unit comatose and on mechanical ventilation. It is not clear whether or not a screening cranial computed tomography (CT scan) is necessary in the immediate post-arrest period. We hypothesized that there may be clinically relevant information gleaned from head CT scans obtained early in the post-arrest period that could affect immediate management of these patients, even when non-neurologic causes of cardiac arrest are suspected. A retrospective data analysis was conducted of all survivors (age >18 years) of non-traumatic out-of-hospital cardiac arrest (OHCA) who underwent non-contrast head CT (NCHCT) within the first 24 h of admission. A total of 84 patients were identified and 51 (60.7%) met the inclusion criteria. As much as 45 (88.2%) patients in the total cohort had an NCHCT negative for ICH or herniation; of this group, 39 (76.5%) had a normal NCHCT, while six (11.8%, 95% CI: 5.1-23.8%) demonstrated varying degrees of cerebral edema or loss of gray-white matter distinction consistent with anoxic brain injury, but without herniation. Six patients (11.8%, 95% CI: 5.1-23.8%) exhibited findings consistent with either an ICH (with or without herniation) or herniation without an ICH. Four (7.8%) of these patients had an ICH without herniation, one had an acute SAH with edema and herniation, and one had frank herniation due to massive cerebral edema. The overall incidence of any kind of intracranial hemorrhage in our cohort was 9.8% (95% CI: 3.8-21.4%). In this cohort of post-cardiac arrest patients who underwent cranial computed tomography, 11.8% of patients had clinically significant abnormalities identified. The exact role of neuroimaging in this population is still in evolution, and further prospective evaluation is warranted.

Complement inhibition as a proposed neuroprotective strategy following cardiac arrest

Out-of-hospital cardiac arrest (OHCA) is a devastating disease process with neurological injury accounting for a disproportionate amount of the morbidity and mortality following return of spontaneous circulation. A dearth of effective treatment strategies exists for global cerebral ischemia-reperfusion (GCI/R) injury following successful resuscitation from OHCA. Emerging preclinical as well as recent human clinical evidence suggests that activation of the complement cascade plays a critical role in the pathogenesis of GCI/R injury following OHCA. In addition, it is well established that complement inhibition improves outcome in both global and focal models of brain ischemia. Due to the profound impact of GCI/R injury following OHCA, and the relative lack of effective neuroprotective strategies for this pathologic process, complement inhibition provides an exciting opportunity to augment existing treatments to improve patient outcomes. To this end, this paper will explore the pathophysiology of complement-mediated GCI/R injury following OHCA.

Management of cardiac arrest patients to maximize neurologic outcome

PURPOSE OF REVIEW

Each year, hundreds of thousands of people will be resuscitated after a cardiac arrest. A significant portion of these patients will lapse into a disease state which is the product of modern emergency and critical care medicine: the postcardiac arrest syndrome. The ability to return a patient to his or her prior state of health after cardiac arrest, once completely beyond the capacities of clinicians, is now one of the most important areas of medical science. Much of this ability depends on preserving the nervous system from a complicated sequence of secondary injuries, which ensue from global ischemia.

RECENT FINDINGS

The International Liaison Committee On Resuscitation has recently given new direction to the care of patients after cardiac arrest by addressing the variety of medical problems encountered after resuscitation as a single postcardiac arrest syndrome. This paradigm centers on supportive care to optimize neurological outcomes and especially focuses on therapeutic hypothermia.

SUMMARY

This study reviews the latest advances in treating patients after cardiac arrest in the emergency department and critical care unit environments.

S-100B and neuron-specific enolase as predictors of neurological outcome in patients after cardiac arrest and return of spontaneous circulation: a systematic review

INTRODUCTION

Neurological prognostic factors after cardiopulmonary resuscitation (CPR) in patients with cardiac arrest (CA) as early and accurately as possible are urgently needed to determine therapeutic strategies after successful CPR. In particular, serum levels of protein neuron-specific enolase (NSE) and S-100B are considered promising candidates for neurological predictors, and many investigations on the clinical usefulness of these markers have been published. However, the design adopted varied from study to study, making a systematic literature review extremely difficult. The present review focuses on the following three respects for the study design: definitions of outcome, value of specificity and time points of blood sampling.

METHODS

A Medline search of literature published before August 2008 was performed using the following search terms: "NSE vs CA or CPR", "S100 vs CA or CPR". Publications examining the clinical usefulness of NSE or S-100B as a prognostic predictor in two outcome groups were reviewed. All publications met with inclusion criteria were classified into three groups with respect to the definitions of outcome; "dead or alive", "regained consciousness or remained comatose", and "return to independent daily life or not". The significance of differences between two outcome groups, cutoff values and predictive accuracy on each time points of blood sampling were investigated.

RESULTS

A total of 54 papers were retrieved by the initial text search, and 24 were finally selected. In the three classified groups, most of the studies showed the significance of differences and concluded these biomarkers were useful for neurological predictor. However, in view of blood sampling points, the significance was not always detected. Nevertheless, only five studies involved uniform application of a blood sampling schedule with sampling intervals specified based on a set starting point. Specificity was not always set to 100%, therefore it is difficult to indiscriminately assess the cut-off values and its predictive accuracy of these biomarkers in this meta analysis.

CONCLUSIONS

In such circumstances, the findings of the present study should aid future investigators in examining the clinical usefulness of these markers and determination of cut-off values.

Types of brain dysfunction in critical illness

Cerebral dysfunction and injury in the ICU presents as focal neurologic deficits, seizures, coma, and delirium. These syndromes may result from a primary brain insult, such as stroke or trauma, but commonly are a complication of a systemic insult, such as cardiac arrest, hypoxemia, sepsis, metabolic derangements, and pharmacologic exposures. Many survivors of critical illness have cognitive impairment, which is believed to underlie the poor long-term functional status and quality of life observed in many critical illness survivors. Although progress has been made in characterizing the epidemiology of cerebral dysfunction in the ICU, more research is needed to elucidate underlying mechanisms that might represent targets for therapeutic intervention.

Mismatch of neurophysiological findings in partial recovery of consciousness: a case report

AIM

Electroencephalography (EEG) and somatosensory potentials (SEP) are regarded as useful tools for exploring residual brain activity and providing information for recovery in patients with anoxic encephalopaty. However, the diagnoses of vegetative and minimally conscious states can only be made by means of repeated specific neurological examinations. In this respect, this study describes the case of a patient with mismatch of neurophysiological findings despite partial recovery to a minimally conscious state.

CASE REPORT

A 52-year-old man was admitted to the Post-Coma Intensive and Rehabilitation Care Unit with a diagnosis of anoxic encephalopathy. EEG, according to Hockaday, was severely abnormal (Grade IVa). SEP showed bilateral loss of all cortical components. Four weeks after admission the Coma Recovery Scale Revised (CRS-R) score moved from 7/23 to 13/23.

CONCLUSIONS

This patient persistently showed a mismatch of neurophysiological findings which did not anticipate the slight but discriminating improvement ascertained through the neurological examination. This observation confirms that electrophysiological evaluations can only be regarded as ancillary tools since level of consciousness may be reliably evaluated only by means of repeated specific neurological assessments. As this case-report suggests, neurophysiological findings may turn out to be inconclusive and misleading in relation to the assessment of consciousness and may lead to an underestimate of minimal signs of recovery across the grey-zone from the vegetative to the minimally conscious state.