Evaluation of hypoxic brain injury with spinal fluid enzymes, lactate, and pyruvate

Differences in Cerebral Metabolism between Moderate- and High-Severity Groups of Patients with Out-of-Hospital Cardiac Arrest Undergoing Target Temperature Management

The aim of this study was to investigate the differences in cerebral metabolism and the prognostic value of cerebrospinal fluid (CSF) lactate 24 h after the return of spontaneous circulation (ROSC) in patients with out-of-hospital cardiac arrest (OHCA). CSF lactate and pyruvate levels were measured immediately and every 2 h for 24 h after the ROSC. The distribution of cerebral mitochondrial dysfunction (MD) and cerebral ischemia was also evaluated. In the moderate-severity group, the absence of cerebral MD or ischemia was observed in six patients (40.0%) immediately after ROSC and in nine patients (60.0%) 24 h after the ROSC. In the high-severity group, the absence of cerebral MD or ischemia was observed in four patients (30.8%) immediately after ROSC and in three patients (23.1%) 24 h after the ROSC. The distribution of cerebral metabolism over time varied depending on the severity of the OHCA. The predictive value of CSF lactate levels for a poor neurological prognosis was better for patients in the moderate-severity group than for the overall patient cohort. Therefore, the severity in the patients with OHCA should be considered when studying cerebral metabolism or using CSF lactate as a prognostic tool.

Maternal microvascular dysfunction during preeclamptic pregnancy

Preeclampsia is a hypertensive disorder of pregnancy effecting ∼5-8% of pregnancies in the United States, and ∼8 million pregnancies worldwide. Preeclampsia is clinically diagnosed after the 20th week of gestation and is characterized by new onset hypertension accompanied by proteinuria and/or thrombocytopenia, renal insufficiency, impaired liver function, pulmonary edema, or cerebral or visual symptoms. This broad definition emphasizes the heterogeneity of the clinical presentation of preeclampsia, but also underscores the role of the microvascular beds, specifically the renal, cerebral, and hepatic circulations, in the pathophysiology of the disease. While the diagnostic criteria for preeclampsia relies on the development of de novo hypertension and accompanying clinical symptoms after 20-week gestation, it is likely that subclinical dysfunction of the maternal microvascular beds occurs in parallel and may even precede the development of overt cardiovascular symptoms in these women. However, little is known about the physiology of the non-reproductive maternal microvascular beds during preeclampsia, and the mechanism(s) mediating microvascular dysfunction during preeclamptic pregnancy are largely unexplored in humans despite their integral role in the pathophysiology of the disease. Therefore, the purpose of this review is to provide a summary of the existing literature on maternal microvascular dysfunction during preeclamptic pregnancy by reviewing the functional evidence in humans, highlighting potential mechanisms, and providing recommendations for future work in this area.

Cerebrospinal Fluid Lactate Levels, Brain Lactate Metabolism and Neurologic Outcome in Patients with Out-of-Hospital Cardiac Arrest

BACKGROUND/OBJECTIVE

Cerebrospinal fluid (CSF) and serum lactate levels were assessed to predict poor neurologic outcome 3 months after return of spontaneous circulation (ROSC). We compared arterio-CSF differences in the lactate (ACDL) levels between two neurologic outcome groups.

METHODS

This retrospective observational study involved out-of-hospital cardiac arrest (OHCA) survivors who had undergone target temperature management. CSF and serum samples were obtained immediately (lactate₀), and at 24 (lactate₂₄), 48 (lactate₄₈), and 72 (lactate₇₂) h after ROSC, and ACDL was calculated at each time point. The primary outcome was poor 3-month neurologic outcome (cerebral performance categories 3-5).

RESULTS

Of 45 patients, 27 (60.0%) showed poor neurologic outcome. At each time point, CSF lactate levels were significantly higher in the poor neurologic outcome group than in the good neurologic outcome group (6.97 vs. 3.37, 4.20 vs. 2.10, 3.50 vs. 2.00, and 2.79 vs. 2.06, respectively; all P < 0.05). CSF lactate's prognostic performance was higher than serum lactate at each time point, and lactate₂₄ showed the highest AUC values (0.89, 95% confidence interval, 0.75-0.97). Over time, ACDL decreased from - 1.30 (- 2.70-0.77) to - 1.70 (- 3.2 to - 0.57) in the poor neurologic outcome group and increased from - 1.22 (- 2.42-0.32) to - 0.64 (- 2.31-0.15) in the good neurologic outcome group.

CONCLUSIONS

At each time point, CSF lactate showed better prognostic performance than serum lactate. CSF lactate₂₄ showed the highest prognostic performance for 3-month poor neurologic outcome. Over time, ACDL decreased in the poor neurologic outcome group and increased in the good neurologic outcome group.

Cerebrospinal fluid lactate dehydrogenase as a potential predictor of neurologic outcomes in cardiac arrest survivors who underwent target temperature management

PURPOSE

Cerebrospinal fluid (CSF) lactate dehydrogenase (LDH) levels increase in patients with brain injury. We investigated neurologic outcomes associated with CSF LDH levels in out-of-hospital cardiac arrest (OHCA) survivors who underwent target temperature management (TTM).

MATERIALS AND METHODS

This was a prospective single-centre observational study from April 2018 to May 2019 on a cohort of 41 patients. CSF and serum LDH samples were obtained immediately (LDH₀) and at 24 (LDH₂₄), 48 (LDH₄₈), and 72 h (LDH₇₂) after return of spontaneous circulation (ROSC). Neurologic outcomes were assessed at 3 months after ROSC using the Cerebral Performance Category scale.

RESULTS

Twenty-one patients had a poor neurologic outcome. CSF LDH levels were significantly higher in the poor neurologic outcome group at each time point. The area under the curve (AUC) of CSF LDH₄₈ was 0.941 (95% confidence interval [CI], 0.806-0.992). With a cut off value of 250 U/L, CSF LDH₄₈ had a high sensitivity (94.1%; 95% CI, 71.3-99.9) at 100% specificity.

CONCLUSIONS

CSF LDH level at 48 h was a highly specific and sensitive marker for 3-month poor neurologic outcome. This may constitute a useful predictive marker for neurologic outcome in OHCA survivors treated with TTM.

Ability of neuron-specific enolase to predict survival to hospital discharge after successful cardiopulmonary resuscitation

Background:

Accurate prediction of survival to hospital discharge in patients who achieve return of spontaneous circulation after cardiopulmonary resuscitation (CPR) has significant ethical and socioeconomic implications. We investigated the prognostic performance of serum neuron-specific enolase (NSE), a biochemical marker of ischemic brain injury, after successful CPR.

Methods:

In-hospital or out-of-hospital patients with nontraumatic normothermic cardiac arrest who achieved return of spontaneous circulation (ROSC) following at least 5 minutes of CPR were eligible. Neuron-specific enolase levels were assessed immediately, 6 hours, 12 hours and 2 days after ROSC. Subjects were followed to death or hospital discharge.

Results:

Seventeen patients (7 men, 10 women) were enrolled during a 1-year period. Median (range) NSE levels in survivors and non-survivors respectively were as follows: immediately after ROSC: 14.0 μg/L (9.1–51.4 μg/L) versus 25.9 μg/L (10.2–57.5 μg/L); 6 hours after ROSC: 15.2 μg/L (9.7–30.8 μg/L) versus 25.6 μg/L (12.7–38.2 μg/L); 12 hours after ROSC: 14.0 μg/L (8.6–32.4 μg/L) versus 28.5 μg/L (11.0–50.7 μg/L); and 48 hours after ROSC: 13.1 μg/L (7.8–29.5 μg/L) versus 52.0 μg/L (29.1–254.0 μg/L). Non-survivors had significantly higher NSE levels 48 hours after ROSC than surivors (p = 0.04) and showed a trend toward higher values during the entire time course following ROSC. An NSE concentration of &gt;30 μg/L 48 hours after ROSC predicted death with a high specificity (100%: 95% confidence interval [CI] 85%–100%), and a level of 29 μg/L or less at 48 hours predicted survival with a high specificity (100%: 95% CI 83%–100%).

Conclusions:

Serum NSE levels may have clinical utility for the prediction of survival to hospital discharge in patients after ROSC following CPR over 5 minutes in duration. This study is small, and our results are limited by wide confidence intervals. Further research on ability of NSE to facilitate prediction and clinical decision-making after cardiac arrest is warranted.

Hypoxic-state estimation of brain cells by using wireless near-infrared spectroscopy

Near-infrared spectroscopy (NIRS) is a modern measuring technology in neuroscience. It can be used to noninvasively measure the relative concentrations of oxyhemoglobin (OxyHb) and deoxyhemoglobin (DeoHb), which can reflect information related to cerebral blood volume and cerebral oxygen saturation. Therefore, it has the potential for noninvasive monitoring of cerebral ischemia. However, there is still a lack of reliable physiological information on the relationship between the concentrations of OxyHb and DeoHb in cerebral blood and the exact hypoxic state of brain cells under cerebral ischemia. In this study, we describe a wireless multichannel NIRS system, which we designed to noninvasively monitor the relative concentrations of OxyHb and DeoHb in bilateral cerebral blood before, during, and after middle cerebral artery occlusion. By comparing the results with the lactate/pyruvate ratio measured by microdialysis, we investigated the correlation between the relative concentrations of OxyHb and DeoHb in cerebral blood and the hypoxic state of brain cells. The results showed that the relationship between the concentration changes of DeoHb in cerebral blood and the hypoxic state of brain cells was significant. Therefore, by monitoring the changes in concentrations of DeoHb, the wireless NIRS can be used to estimate the hypoxic state of brain cells indirectly.

Single-center experience with extracorporeal life support in 103 nonpostcardiotomy patients

Extracorporeal membrane oxygenation (ECMO) has been successfully used to support patients with cardiac arrest failing to respond to conventional cardiopulmonary resuscitation (CPR). Preimplant factors being indicative for success are unknown up to now. The study describes single center experience with special focus on differences between survivors and nonsurvivors. Between 2002 and 2009, 103 patients were supported within the scope of CPR by means of ECMO. Besides primary diagnosis, duration, and outcome, pH, lactate, mean arterial pressure, aspartate aminotransferase, bilirubin, catecholamine dosage, and oxygenation ratio before ECMO, after 2 h, 1 day, and at explantation were analyzed. One hundred three patients (51.2 ± 16 years, 35 women, 68 men) were analyzed. Primary cardiac failure led to CPR in 54%. Duration of support was 4.8 ± 0.6 days. Twenty-nine (28.1%) patients survived to hospital discharge. On ECMO support, pH, lactate, and mean arterial pressure improved significantly. Catecholamine dosage was significantly reduced after ECMO implantation. Demographic data and primary diagnosis revealed no significant influence on outcome. pH, lactate, creatinine, and bilirubin differed significantly between survivors and nonsurvivors in the course of ECMO support. ECMO support during CPR reliably improves the circulatory and respiratory situation. Considering observed survival critical patient selection is mandatory. Although there are several significant differences between surviving patients and patients with fatal outcome, patient selection turns out to be difficult as clinically relevant factors show only limited predictive value. Future research should focus on better defining a population that may be best of all suited for the use of ECMO support in CPR.

Prognosis in severe brain injury

BACKGROUND

The prediction of neurologic outcome is a fundamental concern in the resuscitation of patients with severe brain injury.

OBJECTIVE

To provide an evidence-based update on neurologic prognosis following traumatic brain injury and hypoxic-ischemic encephalopathy after cardiac arrest.

DATA SOURCE

Search of the PubMed database and manual review of bibliographies from selected articles to identify original data relating to prognostic methods and outcome prediction models in patients with neurologic trauma or hypoxic-ischemic encephalopathy.

DATA SYNTHESIS AND CONCLUSION

Articles were scrutinized regarding study design, population evaluated, interventions, outcomes, and limitations. Outcome prediction in severe brain injury is reliant on features of the neurologic examination, anatomical and physiological changes identified with CT and MRI, abnormalities detected with electroencephalography and evoked potentials, and physiological and biochemical derangements at both the brain and systemic levels. Use of such information in univariable association studies generally lacks specificity in classifying neurologic outcome. Furthermore, the accuracy of established prognostic classifiers may be affected by the introduction of outcome-modifying interventions, such as therapeutic hypothermia following cardiac arrest. Although greater specificity may be achieved with scoring systems derived from multivariable models, they generally fail to predict outcome with sufficient accuracy to be meaningful at the single patient level. Discriminative models which integrate knowledge of genetic determinants and biologic processes governing both injury and repair and account for the effects of resuscitative and rehabilitative care are needed.

A systematic literature review of cerebrospinal fluid biomarkers in delirium

BACKGROUND

Cerebrospinal fluid (CSF) analysis has great potential to advance understanding of delirium pathophysiology.

METHODS

A systematic literature review of CSF studies of DSM or ICD delirium was performed.

RESULTS

In 8 studies of 235 patients, delirium was associated with: elevated serotonin metabolites, interleukin-8, cortisol, lactate and protein, and reduced somatostatin, β-endorphin and neuron-specific enolase. Elevated acetylcholinesterase predicted poor outcome after delirium and higher dopamine metabolites were associated with psychotic features.

CONCLUSIONS

No clear conclusions emerged, but the current literature suggests multiple areas for further investigation with more detailed studies.

Lactic dehydrogenase in cerebrospinal fluid may differentiate between structural and non-structural central nervous system lesions in patients with diminished levels of consciousness

BACKGROUND

Impaired consciousness without a history of trauma is a common reason for emergency department (ED) visits. Among critically ill patients with a history and physical findings suggestive of a cerebrovascular accident (CVA), it may be difficult to differentiate between a structural and a non-structural cause for their condition.

OBJECTIVES

This study was conducted to determine if lactic dehydrogenase (LDH) levels in the cerebrospinal fluid (CSF) of patients with acute non-traumatic neurological disorders could distinguish between structural and non-structural etiologies.

MATERIAL AND METHODS

Over a 6-month period, CSF specimens were collected from 54 critically ill patients admitted to the ED with impaired consciousness and findings consistent with a CVA. The patients had moderate to severe impairment of consciousness, had a new motor or sensory deficit, or had meningeal signs of recent onset. CSF-LDH levels were analyzed because CSF levels of the enzyme are typically elevated in meningitis, metastatic cancer, and disorders resulting in ischemic necroses. Patients were excluded if a computed tomography scan showed contraindications to performing a lumbar puncture, if they had a coagulopathy, or if the CSF was xanthochromic or produced visible blood sediment after centrifuging. The data were analyzed according to the patients' admission diagnoses-structural vs. non-structural lesion.

RESULTS

Of the samples collected from 54 patients, eight were excluded. Among the 46 patients included in the study, the mean age was 56.1 +/- 2.75 years, mean APACHE II score was 20.93 +/- 0.98, Glasgow Coma Scale (GCS) score was 7.15 +/- 0.49, and mortality was 55% (22 patients). The 30 patients with a structural abnormality had a mean age of 56.7 +/- 3.55 years, GCS score of 7.3 +/- 0.61, APACHE II score of 20.2 +/- 1.1, mortality of 43% (13 patients), and CSF-LDH level of 128.8 +/- 24.8 IU/L (95% confidence interval [CI] 78.1-179.6). The 16 patients with a non-structural (metabolic) disturbance had: a mean age of 55.0 +/- 4.42 years, GCS score of 6.87 +/- 0.86, APACHE II score of 22.2 +/- 1.94, mortality of 56% (9 patients), and CSF-LDH level of 29.8 +/- 2.9 IU/L (95% CI 23.6-36.1). Analysis by Student's t-test was p < 0.05. When the diagnostic value of CSF-LDH level was evaluated using a cutoff point of 40 IU/L, the following results were obtained: sensitivity: 86.7%, specificity: 81.3%, pretest likelihood: 65%, positive predictive value: 90%, negative predictive value: 76%, Likelihood Ratio (LR)+: 4.62, LR-: 0.16 (6.25-fold increase).

CONCLUSIONS

In critically ill patients with acutely altered levels of consciousness but without a history of trauma, a CSF-LDH value < or = 40 IU/L is associated with non-structural pathology.

Biochemical markers (NSE, S-100, IL-8) as predictors of neurological outcome in patients after cardiac arrest and return of spontaneous circulation

Predicting the neurological outcome after resuscitation and a return of spontaneous circulation of resuscitated patients still remains a difficult issue. Over the past decade numerous studies have been elaborated to provide the physician with tools to assess as early as possible the neurological outcome of patients with cardiac arrest and return of spontaneous circulation and to decide about further therapeutic management. We summarise the most important ones, giving special focus to three biochemical markers (neuron specific enolase, a protein soluble in 100% ammonium sulfate and interleukin-8), which, when combined with standard neuro-functional and imaging techniques, can serve as potent predictors of neurological outcome in these patients. Despite current limitations about the prognostic significance of these markers - their inferior sensitivity, the different cut-off levels used by several investigators and their variable unequal rise over time - they can give useful information about short and long-term neurological outcome. A comprehensive set of clinical, electrophysiological, biochemical and imaging measures, obtained in a uniform manner in a cohort of patients without limitations in care, could provide a more objective set of comprehensive prognostic indicators.

Neuroimaging and Serologic Markers of Neurologic Injury after Cardiac Arrest

Determining prognosis in the setting of hypoxic-ischemic injury following cardiac arrest is difficult based solely on clinical parameters in the patient who is critically ill. The article discusses bio- chemical markers in the blood and in the cerebrospinal fluid that are evaluated for prognostic information, along with radiologic indicators of anoxic cerebral damage. It includes a recommended algorithm using a combination of serologic and radiologic markers of cerebral injury for assessing prognosis in the patient who is comatose following cardiac arrest.

Approach to the comatose patient

BACKGROUND

Coma is a medical emergency and may constitute a diagnostic and therapeutic challenge for the intensivist.

OBJECTIVE

To review currently available data on the etiology, diagnosis, and outcome of coma. To propose an evidence-based approach for the clinical management of the comatose patient.

DATA SOURCE

Search of Medline and Cochrane databases; manual review of bibliographies from selected articles and monographs.

DATA SYNTHESIS AND CONCLUSIONS

Coma and other states of impaired consciousness are signs of extensive dysfunction or injury involving the brainstem, diencephalon, or cerebral cortex and are associated with a substantial risk of death and disability. Management of impaired consciousness includes prompt stabilization of vital physiologic functions to prevent secondary neurologic injury, etiological diagnosis, and the institution of brain-directed therapeutic or preventive measures. Neurologic prognosis is determined by the underlying etiology and may be predicted by the combination of clinical signs and electrophysiological tests.

Late Auditory and Event-Related Potentials Can Be Useful to Predict Good Functional Outcome After Coma

OBJECTIVE

To investigate whether late auditory and event-related potentials, and in particular N100 and mismatch negativity, together with clinical parameters, can help to predict good functional outcome in comatose patients.

DESIGN

Prospective cohort study.

SETTING

Hospital.

PARTICIPANTS

Consecutively sampled comatose patients (N=346) whose etiologies of coma were stroke (125 patients), brain injury (96 patients), anoxia (64 patients), complication of neurosurgery (54 patients), and encephalitis (7 patients).

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Glasgow Outcome Scale score at 1 year postonset. Patients in a minimally conscious state and those who awoke and died during the follow-up period were classified separately.

RESULTS

Univariate analysis showed that all variables studied, except brainstem auditory evoked potentials, correlated significantly with functional outcome. Mismatch negativity showed the highest positive predictive value for good outcome. A validated model was obtained with multivariate logistic analysis, including pupillary light reflex, N100, mismatch negativity, etiology, and age.

CONCLUSIONS

Late auditory and event-related potentials, and particularly N100 and mismatch negativity, provide strong prognostic factors for good functional outcome. Furthermore, these components may enhance the accuracy of prognosis when associated with other clinical parameters available at the early stage of coma.

Brain arrest neurological outcome scale (BrANOS): predicting mortality and severe disability following cardiac arrest

BACKGROUND

To create a predictive scale of neurological outcome following cardiac arrest (CA) that incorporates radiological and clinical markers of brain injury.

METHODS AND RESULTS

Brain arrest neurologic outcome scale (BrANOS) is a prospective 16-point scale. It consisted of three variables: (1) duration of arrest (DAR), (2) reversed Glasgow coma scale (GCS), and (3) Hounsfield unit (HU) ratio on non-contrast CT scan of the head. Reversed GCS score was defined as 15-GCS (best GCS in the first 24 h). HU ratio was defined as the density ratio of the caudate nucleus over the posterior limb of the internal capsule measured on unenhanced CT scan of the brain. We identified 32 comatose patients who had: (1) CT scan performed within 48 h of event; (2) no previous history of either coma, severe head trauma, cardiac arrest or stroke. Primary outcome was defined as alive or dead. Secondary outcome was the Glasgow outcome score recorded on discharge. Patient demographics were collated from retrospective chart review. Patients' mean age was 63 +/- 3 years (mean +/- S.E.M.); 44% were females. Mortality rate was 81%. Mean DAR was 21 +/- 2 min. Survivors had a significantly lower BrANOS score (8 +/- 2 points) compared to non-survivors (13 +/- 1) (P = 0.006). BrANOS was a strong predictor of mortality alone (ROC = 0.86) and mortality with severe disability combined (ROC = 0.9). The scale had a 100% specificity and positive predictive value.

CONCLUSIONS

BrANOS is a reliable predictor of neurological outcome following CA. It is the first scale to incorporate clinical and radiological markers of brain injury.

S-100 protein as early predictor of regaining consciousness after out of hospital cardiac arrest

BACKGROUND AND PURPOSE

Patients resuscitated from cardiac arrest (CA) have a high mortality rate. Prognostic evaluation based on clinical observations is uncertain and would benefit from the use of biochemical markers of hypoxic brain damage. The purpose of the study was to validate the use of the serum astroglial protein S-100 levels at admission with regard to regaining consciousness after out of hospital CA.

METHODS

Fifty-eight patients resuscitated from out-of-hospital CA were followed up until they regained consciousness or until their death or permanent vegetative state occurred. Serum samples for measurement of S-100, using an immunoradiometric assay, were obtained at admission.

RESULTS

At admission, the mean value+/-standard error of the mean of serum S-100 protein was significantly higher in patients who did not regain consciousness compared with patients who regained consciousness, respectively 4.66+/-0.61 microg/l and 0.84+/-0.21 microg/l. A serum S-100 value of >0.7 microg/l at admission was found to be a predictor that consciousness would not be regained, with a specificity of 85%, a sensitivity of 66.6%, a positive predictive value of 84%, a negative predictive value of 78% and an accuracy of 77.6%.

CONCLUSIONS

Serum S-100 protein at admission gives reliable and independent information concerning the short term neurological outcome after resuscitation; and could be a good marker of brain cell damage.

Neurological outcome prediction in a cardiorespiratory arrest survivor

Outcome prediction of neurological recovery in an unconscious survivor of cardiorespiratory arrest is difficult and uncertain. We describe the case of a 25-yr-old post-arrest survivor who made a remarkable neurological improvement despite a seemingly hopeless prognosis. Conventional clinical and neurophysiological assessments need to be interpreted with care in the presence of uncontrolled seizure activity and sedative medications. The measurement of biochemical markers in the serum and cerebrospinal fluid may be useful in helping the clinician to arrive at a more accurate neurological outcome prediction.

Successful out-of-hospital cardiopulmonary resuscitation: what is the optimal in-hospital treatment strategy?

The aim of the study was to evaluate prognostic factors in patients after successful out-of-hospital resuscitation (sOHR) within 30 min after admission. A prognostic scoring scale in patients surviving OHR was analysed. We also studied the effect of these predictive factors and the in-hospital treatment (percutaneous transluminal coronary angioplasty (PTCA) vs. thrombolysis) on mortality. We performed a retrospective analysis of the emergency medical system forms and medical files of 72 consecutive patients aged > or =18 years with sOHR. Of these 72 patients 37 (51%) met the electrocardiographic and enzymatic criteria for acute myocardial infarction (AMI). Ten of the 37 AMI patients (27%) underwent acute PTCA as primary treatment and seven patients (19%) received thrombolytic therapy for AMI despite prolonged (mean 24+/-13 min) cardiopulmonary resuscitation (CPR). The remaining 20 patients had no specific infarct treatment. Despite successful PTCA, in eight out of ten patients, their mortality in hospital was 60% (6/10). Mortality in the thrombolysis group was 57% (4/7). For the remaining 20 MI-patients the mortality was 65% (13/20). Univariate and multivariate analyses were performed to design a weighted prognostic scoring system. The Glasgow coma scale (GCS) was the strongest independent predictor (r=0.76, P< or =0.001) for in-hospital death.

CONCLUSIONS

in-hospital mortality after successful OHR seems to largely depend on neurological status at admission and much less on the specific treatment of myocardial infarction. The prognostic scoring system accurately predicted the in-hospital mortality and can be used for early treatment stratification; however, it should be proven in a prospective study.

Effects of naloxone on lactate, pyruvate metabolism and antioxidant enzyme activity in rat cerebral ischemia/reperfusion

Whether naloxone may modulate energy metabolism and endogenous antioxidant enzyme activities in ischemic cortex was studied. Cerebral ischemia/reperfusion (I/R) was produced by occluding two common carotid arteries and the right middle cerebral artery for 90 min followed by reperfusion in anesthetized Sprague-Dawley rats. Both pre-treatment (0.03 or 0.3 mg) and post-treatment (0.3 mg) of naloxone by intracerebroventricular infusion significantly reduced cortical infarct volumes. Pre-treatment with 0.03 mg reduced ischemia-induced suppression of extracellular pyruvate level and enhancement of lactate/pyruvate ratio as well as cerebral I/R-induced increases of endogenous catalase, glutathione peroxidase, and manganese superoxide dismutase activities. In conclusion, neuroprotective effects of naloxone in terms of reducing brain infarction involve attenuation of the disturbance of cellular functions following cerebral I/R via restoration of mitochondrial activities or energy metabolism.

Time course of serum neuron-specific enolase. A predictor of neurological outcome in patients resuscitated from cardiac arrest

BACKGROUND AND PURPOSE

The prediction of neurological outcome in comatose cardiac arrest survivors has enormous ethical and socioeconomic implications. The purpose of the present study was to investigate the prognostic relevance of the time course of serum neuron-specific enolase (NSE) as a biochemical marker of hypoxic brain damage.

METHODS

Serial analysis of serum NSE levels was performed in 56 patients resuscitated from witnessed, nontraumatic, normothermic, in- or out-of-hospital cardiac arrest. The neurological outcome was evaluated with the use of the cerebral performance category (CPC) within 6 months after restoration of spontaneous circulation (ROSC). The Mann-Whitney U test was used to compare patients with good (CPC 1 to 2) and bad (CPC 3 to 4) neurological outcome. The diagnostic performance at different time points after ROSC was described in terms of areas under receiver operating characteristic curves according to standard methods.

RESULTS

Patients with a bad neurological outcome (CPC 3 to 4) had significantly higher NSE levels than those with a good neurological outcome at 12 (P=0.004), 24 (P=0.04), 48 (P<0.001), and 72 hours (P<0.001) after ROSC. The maximum NSE level measured within 72 hours after ROSC was also significantly higher in patients with a bad neurological outcome (P<0.001). The NSE value at 72 hours after ROSC was the best predictor of neurological outcome (area under the curve=0.92+/-0.04). In addition, we also found a significant difference in the time course of NSE concentrations during the first 3 days after ROSC.

CONCLUSIONS

Serum NSE levels are valuable adjunctive parameters for assessing neurological outcome after cardiac arrest.

Affected enzyme activities in Alzheimer's disease are sensitive to antemortem hypoxia

Many enzyme activities in Alzheimer's disease (AD) are changed. Some of these enzyme activities are related to certain neurotransmitter systems. Enzymes in the brain can also be sensitive to antemortem hypoxia. In the present study it was determined if enzyme activities that are altered in AD are also subject to alteration by antemortem hypoxia. As an indicator of antemortem hypoxia brain lactate concentration was used. Enzyme activities measured were those of prolyl endopeptidase (PE), aminopeptidase (AP), phosphatidylinositol (PI) kinase, phosphatidylinositol phosphate kinase, alpha-ketoglutarate dehydrogenase (alpha-KGDH), choline acetyltransferase and beta-glucuronidase. All of these enzyme activities have been measured in AD patients before and several of them have been found to be decreased. In accordance with previous findings, PE, alpha-KGDH and ChAT activities were reduced in AD patients. PI kinase and beta-glucuronidase activities, however, were not reduced, contrary to previous findings. All enzyme activities, except that of beta-glucuronidase, correlated with brain lactate concentration, suggesting that antemortem hypoxia has a major influence on the activity of enzymes in the brain. PE, AP, alpha-KGDH and ChAT activities were still different between AD and control samples when these were matched for lactate concentration. The enzyme activities that were changed in AD were also significantly correlated with lactate concentration, an indicator of antemortem hypoxia, in brain specimens. This suggests that antemortem hypoxia and AD have some factor in common that may be responsible for changes in enzyme activities. Since both PE and alpha-KGDH are known to be sensitive to oxidative stress this factor could be oxidative stress.

The conundrum of the Glasgow Coma Scale in intubated patients: a linear regression prediction of the Glasgow verbal score from the Glasgow eye and motor scores

BACKGROUND

The Glasgow Coma Scale (GCS), which is the foundation of the Trauma Score, Trauma and Injury Severity Score, and the Acute Physiology and Chronic Health Evaluation scoring systems, requires a verbal response. In some series, up to 50% of injured patients must be excluded from analysis because of lack of a verbal component for the GCS. The present study extends previous work evaluating derivation of the verbal score from the eye and motor components of the GCS.

METHODS

Data were obtained from a state trauma registry for 24,565 unintubated patients. The eye and motor scores were used in a previously published regression model to predict the verbal score: Derived Verbal Score = -0.3756 + Motor Score * (0.5713) + Eye Score * (0.4233). The correlation of the actual and derived verbal and GCS scales were assessed. In addition the ability of the actual and derived GCS to predict patient survival in a logistic regression model were analyzed using the PC SAS system for statistical analysis. The predictive power of the actual and the predicted GCS were compared using the area under the receiver operator characteristic curve and Hosmer-Lemeshow goodness-of-fit testing.

RESULTS

A total of 24,085 patients were available for analysis. The mean actual verbal score was 4.4 +/- 1.3 versus a predicted verbal score of 4.3 +/- 1.2 (r = 0.90, p = 0.0001). The actual GCS was 13.6 + 3.5 versus a predicted GCS of 13.7 +/- 3.4 (r = 0.97, p = 0.0001). The results of the comparison of the prediction of survival in patients based on the actual GCS and the derived GCS show that the mean actual GCS was 13.5 + 3.5 versus 13.7 + 3.4 in the regression predicted model. The area under the receiver operator characteristic curve for predicting survival of the two values was similar at 0.868 for the actual GCS compared with 0.850 for the predicted GCS.

CONCLUSIONS

The previously derived method of calculating the verbal score from the eye and motor scores is an excellent predictor of the actual verbal score. Furthermore, the derived GCS performed better than the actual GCS by several measures. The present study confirms previous work that a very accurate GCS can be derived in the absence of the verbal component.

High-dose phenobarbital therapy in term newborn infants with severe perinatal asphyxia: a randomized, prospective study with three-year follow-up

OBJECTIVE

To determine whether 40 mg/kg phenobarbital given to term infants with severe asphyxia would result in a lower incidence of seizures in the newborn period and an improved neurologic outcome.

METHODS

We conducted a randomized, controlled, prospective study. Entry criteria included (1) an initial arterial pH less than or equal to 7.0 with a base deficit 15 mEq/L or more, (2) Apgar score less than or equal to 3 at 5 minutes of age, or (3) failure to initiate spontaneous respiration by 10 minutes of age. Sample size was calculated to detect a 50% reduction in the incidence of neonatal seizures.

RESULTS

No differences were present between treatment and control groups with respect to severity of asphyxia assessed by initial arterial pH, base excess, cerebrospinal fluid lactate dehydrogenase concentration or detection of CSF creatine kinase of its BB isoenzyme. Seizures occurred in 9 of 15 infants in the treatment group and 14 of 16 infants in the control group (p = 0.11). No adverse effects were observed from phenobarbital on heart rate, respiratory rate, blood pressure, or arterial blood gas values. Three-year follow-up revealed normal outcome in 11 of 15 infants in the treatment group and 3 of 16 in the control group (p = 0.003).

CONCLUSION

Phenobarbital, when administered in a dose of 40 mg/kg intravenously over 1 hour in term, severely asphyxiated newborn infants appeared to be safe and was associated with a 27% reduction in the incidence of seizures and a significant improvement in neurologic outcome at 3 years of age.

Serum neuron-specific enolase as early predictor of outcome after cardiac arrest

OBJECTIVE

To examine the prognostic value of serum neuron-specific enolase for early prediction of outcome in patients at risk for anoxic encephalopathy after cardiac arrest.

DESIGN

Prospective study.

SETTING

Coronary intensive care unit of the University of Heidelberg.

PATIENTS

Forty-three patients (66.8 +/- 12.7 [SD] yrs, range 33 to 85) who had had either primary or secondary cardiac arrest, followed by cardiopulmonary resuscitation (CPR).

INTERVENTIONS

Serial blood samples and clinical examinations.

MEASUREMENTS AND MAIN RESULTS

Serum neuron-specific enolase concentrations were determined after CPR on 7 consecutive days. Twenty-five patients remained comatose and subsequently died; 18 patients survived the first 3 months and had no relevant functional deficit at 3-month follow-up. Neuron-specific enolase concentrations were correlated with neurologic outcome. Concentrations of >33 ng/mL predicted persistent coma with a high specificity (100%) and a positive predictive value of 100%. Overall sensitivity was 80%, with a negative predictive value of 78%. Serum concentrations of neuron-specific enolase exceeded this cutoff value no more than 3 days after cardiac arrest in 95% of patients in whom these concentrations had exceeded 33 ng/mL.

CONCLUSIONS

In patients who have been resuscitated after cardiac arrest, serum neuron-specific enolase concentrations of >33 ng/mL predict persistent coma with a high specificity. Values below this cutoff level do not necessarily indicate complete recovery, because this method has a sensitivity of 80%.

Cardiopulmonary resuscitation: what cost to cheat death?

OBJECTIVES

To review the various outcomes from cardiopulmonary resuscitation (CPR), the factors that influence these outcomes, the costs associated with CPR, and the application of cost-analyses to CPR.

DATA SOURCES

Data used to prepare this article were drawn from published articles and work in progress.

STUDY SELECTION

Articles were selected for their relevance to the subjects of CPR and cost-analysis by MEDLINE keyword search.

DATA EXTRACTION

The authors extracted all applicable data from the English literature.

DATA SYNTHESIS

Cost-analysis studies of CPR programs are limited by the high variation in resources consumed and attribution of cost to these resources. Furthermore, cost projections have not been adjusted to reflect patient-dependent variation in outcome. Variation in the patient's underlying condition, presenting cardiac rhythm, time to provision of definitive CPR, and effective perfusion all influence final outcome and, consequently, influence the cost-effectiveness of CPR programs. Based on cost data from previous studies, preliminary estimates of the cost-effectiveness of CPR programs for all 6-month survivors of a large international multicenter collaborative trial are $406,605.00 per life saved (range $344,314.00 to $966,759.00), and $225,892.00 per quality-adjusted-life-year (range $191,286.00 to $537,088.00).

CONCLUSIONS

Reported outcome from CPR has varied from reasonable rates of good recovery, including return to full employment to 100% mortality. Appropriate CPR is encouraged, but continued widespread application appears extremely expensive.

Appropriate use of the Glasgow Coma Scale in intubated patients: a linear regression prediction of the Glasgow verbal score from the Glasgow eye and motor scores

The Glasgow Coma Scale (GCS) has been shown to be a valuable tool in assessing the neurologic and physiologic status of critically ill patients. Unfortunately, the GCS requires assessment of the verbal response of the patient and this can be blocked by intubation. The purpose of this study was to assess the ability of a regression model based upon the eye and motor components of the GCS to accurately predict the verbal response of the GCS. The primary hypothesis was that the verbal response could be derived from the motor and eye responses of the GCS.

METHODS

Data were collected prospectively in an intensive care unit computer data base. Patients were divided into training and test data sets. Linear regression was used to derive a model of verbal score from the motor and eye scores of the GCS in the training data set. Correlation between the actual and the predicted verbal scores was calculated.

RESULTS

A total of 2,521 GCS assessments were available for analysis. The second order multiple regression model was an accurate predictor of the verbal score (Pearson's Correlation r = 0.9, R2 = 0.8, p = 0.0001) in 1,463 observations in the training data set. Second Order Multiple Regression Model: Estimated GCS Verbal = (2.3976) + [GCS Motor x (-0.9253)] + [GCS Eye x (-0.9214)] + [(GCS Motor)2 x (0.2208)] + [(GCS Eye)2 x (0.2318)] where r = 0.91, R2 = 0.83, and p = 0.0001. The accuracy of this model was confirmed by comparing the predicted verbal score to the actual verbal score in the test data set (n = 736, r = 0.92, R2 = 0.85, p = 0.0001)

CONCLUSIONS

The GCS is a useful tool in the intensive care unit and a critical part of the APACHE II assessment of patient acuity. GCS has been shown to be a useful tool in its own right as a predictor of outcome in the critically ill. Its use is limited with intubation. (See Segatore M, Way C: Heart Lung 21:548, 1992; and Lieh-Lai MW, Theodorou AA, Sarnaik AP, et al: J Pediatr 120:195, 1992.) The present study demonstrates that a relatively simple regression model can use the eye and motor components of the GCS to predict the expected verbal component of the GCS, thus allowing the calculation of the GCS sum score in intubated patients.

Autonomic control of heart rate after brain injury in children

OBJECTIVES

To study sequential changes in heart rate, respiratory rate, blood pressure, heart rate power spectra, and plasma catecholamine concentrations in patients with acute brain injury and correlate these variables with the severity of neurologic dysfunction and patient outcome.

DESIGN

Prospective, clinical study.

SETTING

Pediatric intensive care unit.

PATIENTS

Thirty-seven pediatric patients with acute brain injury caused by trauma, anoxia/ischemia, hemorrhage, or infection.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

We found significant associations between low-frequency (0.01 to 0.15 Hz) heart rate power and severity of neurologic dysfunction (as assessed by the admission Glasgow Coma Scale) (p < .001) and patient outcome (as assessed by the Glasgow Outcome Scale) (p = .05). The admission (p = .05) and maximum (p < .001) values for low-frequency heart rate power and the minimum value for high-frequency (0.15 to 0.50 Hz) heart rate power obtained during hospitalization (p = .001) predicted an increased likelihood of survival. Ten brain-dead patients had significantly decreased low-frequency heart rate power (p = .008) and plasma norepinephrine (p = .015), epinephrine (p = .03), and dopamine (p = .04) concentrations when compared with six non-brain-dead patients with a Glasgow Coma Scale score of 3.

CONCLUSIONS

Our results imply that autonomic nervous system control of heart rate is disrupted in proportion to the degree of neurologic insult in children after acute brain injury. Thus, heart rate power spectral analysis and plasma catecholamine concentrations may prove to be useful adjuncts in determining severity of neurologic injury and prognosis for recovery in children suffering from brain injury. In addition, these techniques may aid in the determination of brain death.

Markers of cerebral ischemia after cardiac surgery

The objective of this review is to provide an overview of the use of biochemical markers for the detection of Central Nervous System (CNS) complications after cardiac surgery and extracorporeal circulation (ECC). A computerized literature search in MEDLINE from 1966 onward was the basis for the references. The literature covering the following biochemical markers is reviewed: adenylkinase, creatine phosphokinase isoenzyme BB (CK-BB), lactate, neuron-specific enolase (NSE), S-100 protein, myelin basic protein, lactate dehydrogenase, aspartate aminotransferase, glutathione, vasointestinal neuropeptide, and 7B2-specific neuropeptide. For clinical purposes, it is necessary to have a biochemical marker that can be measured in blood. Lactate, although a primary marker of anaerobic metabolism, and CK-BB values, calculated from the arterio-internal jugular venous difference, appear to correlate with periods of ischemia during ECC. S-100 protein levels have been shown to correlate with duration of ECC, and when combined with NSE values, could be used to identify patients with CNS dysfunction after cardiac surgery. The use of NSE may be limited by its presence in erythrocytes and platelets because the high levels that can result from hemolysis can render it less specific. Although recently introduced, S-100 protein may have the potential to be a valuable marker for CNS dysfunction after ECC.

Early determination of neurological outcome after prehospital cardiopulmonary resuscitation

BACKGROUND AND PURPOSE

Although there are various methods of determining neurological prognosis after cardiopulmonary resuscitation, the final outcome of patients often remains unclear for quite a long time.

METHODS

We investigated 30 consecutively admitted patients who had been successfully resuscitated by the team of the local mobile intensive care unit after cardiac arrest. Determinations of the period of anoxia and of the cardiopulmonary resuscitation time, clinical investigation, echocardiography, electroencephalography, evoked potentials, magnetic resonance imaging, and magnetic resonance spectroscopy were performed.

RESULTS

Demonstration of brain lactate in proton magnetic resonance spectroscopy (P < .01) and absent N20 waves in short-latency somatosensory evoked potentials (P < .01) proved to be significant in terms of a poor prognosis. Correlations between both duration of anoxia and cardiopulmonary resuscitation time and neurological outcome could be shown as well (both P < .05).

CONCLUSIONS

Proton magnetic resonance spectroscopy and short-latency evoked potentials are of great benefit in the prognostic evaluation after cardiopulmonary resuscitation.

Differences in oxygen content between mixed venous blood and cerebral venous blood for outcome prediction after cardiac arrest

OBJECTIVE

To assess the usefulness of differences in oxygen content between mixed venous blood and cerebral venous blood for predicting neurological outcome after cardiac arrest.

DESIGN

Observational study.

SETTING

Medical-surgical intensive care unit (IUC) in a university hospital.

PATIENTS AND PARTICIPANTS

34 acutely comatose patients who had been admitted to the ICU after cardiac arrest and successful cardiopulmonary resuscitation, classified according to outcome (group A, brain death; group B, vegetative state; group C, neurological recovery).

MEASUREMENTS AND RESULTS

Between 6 and 18 h (mean 12 +/- 16.3 h) after hemodynamic stability and 24 h later, the patient's neurological status was assessed by means of the Glasgow Coma Scale and blood gas analysis, partial pressure of O2, oxygen content in venous blood from the jugular bulb and mixed venous blood, O2 saturation, and lactate and creatine kinase activity (CK) in CSF were determined. Group C patients had significantly lower lactate and CK levels in CSF as compared with patients in groups A and B. Mean oxygen content in mixed venous blood was higher than that in cerebral venous blood in group C patients, whereas the opposite was found in patients with unfavourable outcome. A positive difference in oxygen content between mixed venous blood and cerebral venous blood showed a sensitivity of 95%, specificity of 100%, positive predictive value of 100%, and negative predictive value of 92% for predicting recovery of consciousness.

CONCLUSIONS

Differences between oxygen content of blood samples from the pulmonary artery and the jugular bulb is a simple measurement that has provided good accuracy in the outcome prediction of brain damage after cardiac arrest treated by resuscitation.

Factors affecting outcome following cardiopulmonary resuscitation

Many patients who receive cardiopulmonary resuscitation (CPR) for cardiac arrest do not survive to leave hospital. Factors associated with adverse outcomes include unwitnessed cardiac arrest in general wards, particularly at night, prolonged resuscitation, asystole, associated disorders (e.g. sepsis, malignancy, renal failure, and left ventricular dysfunction), absent pupillary responses, hypoxaemia, low PetCO2 during resuscitation, and severe acid base imbalance. Outside hospitals, cardiac arrests result in more favourable outcomes if they occur at work, and bystander CPR and early defibrillation are initiated. On admission to ICU, likely predictors of death or severe neurological disability include prolonged coma, impaired brainstem reflexes, and persistent convulsions. Experience with cerebrospinal fluid enzymes and electrophysiological measurements is limited. Multivariate scoring systems are not sufficiently reliable. The importance of hyperglycaemia, the required level of CPR training, and the appropriateness of responding to some cases, remain debatable.

CSF and serum brain-specific creatine kinase isoenzyme (CK-BB), neuron-specific enolase (NSE) and neural cell adhesion molecule (NCAM) as prognostic markers for hypoxic brain injury after cardiac arrest in man

Creatine kinase (CK) and its brain-specific isoenzyme (CK-BB), neuron-specific enolase (NSE), neural cell adhesion molecule (NCAM) and the ions sodium, potassium, chloride and calcium were measured both in CSF and serum and inorganic phosphate in CSF in order to assess their prognostic value in total brain ischemia due to cardiac arrest. The samples were collected at 4, 28 and 76 h after resuscitation. Twenty consecutive patients resuscitated from ventricular fibrillation or asystole were included in the study. Nine of the patients recovered consciousness (recovered) but eleven remained comatose (disabled). The follow-up period was 2 years after which only one patient was still alive. The earliest statistically significant differences between neurologically recovered and disabled patient groups were seen in CSF inorganic phosphate (P = 0.030) already at 4 h and CK-BB (P = 0.046) and NSE (P = 0.020) activity at 28 h. Later, at 76 h after the resuscitation CSF NSE differentiated the groups most clearly (P = 0.014). The values were higher in the disabled patients. A negative correlation between CSF parameters and Glasgow Coma scores was also seen at these timepoints. Statistically significant differences between the groups were seen in both CSF and blood pCO2, pO2, base excess (BE) and actual bicarbonate (HCO3-). CSF or serum NCAM has no prognostic value in anoxic-ischemic coma. The results suggest that in CSF CK-BB and NSE are useful prognostic indicators of hypoxic brain injury when measured 28-76 h after cardiac arrest whereas blood samples have no prognostic value.