Jaume Revuelto-Rey

Role of early cell-free DNA levels decrease as a predictive marker of fatal outcome after severe traumatic brain injury.

INTRODUCTION Circulating cell-free DNA levels are increased after trauma injury. This increase is higher since the first hours after trauma and may be related with primary outcome. A sensitive and reliable biomarker for patients at higher risk is needed to identify these patients to initiate early intervention. In this way, circulating DNA may be a possible biological marker after severe TBI. MATERIALS AND METHODS We investigated DNA plasma concentrations after severe traumatic brain injury and during the next 96 h in the Intensive Care Unit (ICU) by real time PCR. 65 patients suffering severe TBI were included in the study. RESULTS Cell-free DNA levels were considerably higher in patients samples compared with voluntary control ones. After the following four days we observed a 51% decrease during the first 24h and a 71% fall from 48 h. TBI population was stratified for the primary outcome (survivors/non-survivor) and DNA levels decrease ratio was calculated for the first 48 h. A higher decrease in the survivors from 0 h to 24h compared with the non-survivors was found. A cut-off point of 1.95 ratio was established for the detection of the highest proportions of patients after the TBI that will not survive after the injury with a sensitivity of 70% and specificity of 66%. CONCLUSIONS In summary we showed that severe TBI is associated with elevated cf-DNA levels and we propose that cf-DNA decrease during the first 24h may predict patient outcome.

Role of S100B protein in urine and serum as an early predictor of mortality after severe traumatic brain injury in adults

S100B is a calcium-binding protein released into the blood from astroglial cells due to brain injury. Some authors have described a correlation between S100B serum concentration and severity of brain damage. There is not much information about the accuracy of urinary S100B for predicting outcome after severe traumatic brain injury (TBI). 55 patients with severe TBI were included in the study. Blood and urine samples were drawn to determine S100B levels on admission and on the subsequent 24, 48, 72 and 96 h. S100B concentrations (serum and urine) were significantly higher in patients who were dead a month after the accident compared to survivors. ROC-analysis showed that S100B at 24h post-severe TBI is a useful tool for predicting mortality (serum: AUC 0.958, urine: AUC 0.778). The best cut-offs for S100B were 0.461 μg/L and 0.025 μg/L (serum and urine respectively), with a sensitivity of 90% for both measurements and a specificity of 88.4% (serum) and 62.8% (urine). We can state that the determination of S100B levels both in urine and serum acts as a sensitive and an effective biomarker for the early prediction of mortality after severe TBI.

S100B Protein May Detect Brain Death Development after Severe Traumatic Brain Injury

Despite improvements in the process of organ donation and transplants, the number of organ donors is progressively declining in developed countries. Therefore, the early detection of patients at risk for brain death (BD) is a priority for transplant teams seeking more efficient identification of potential donors. In the extensive literature on S100B as a biomarker for traumatic brain injury (TBI), no evidence appears to exist on its prognostic capacity as a predictor of BD after severe TBI. The objective of this study is to assess the value of including acute S100B levels in standard clinical data as an early screening tool for BD after severe TBI. This prospective study included patients with severe TBI (Glasgow Coma Scale score [GCS] ≤ 8) admitted to our Neurocritical Care Unit over a 30 month period. We collected the following clinical variables: age, gender, GCS score, pupillary alterations at admission, hypotension and pre-hospital desaturation, CT scan results, isolated TBI or other related injuries, Injury Severity Score (ISS), serum S100B levels at admission and 24 h post-admission, and a final diagnosis regarding BD. Of the 140 patients studied, 11.4% developed BD and showed significantly higher S100B concentrations (p<0.001). Multivariate analysis showed that bilateral unresponsive mydriasis at admission and serum S100B at 24 h post-admission had odds ratios (ORs) of 21.35 (p=0.005) and 4.9 (p=0.010), respectively. The same analysis on patients with photomotor reflex in one pupil at admission left only the 24 h S100B sample in the model (OR=15.5; p=0.009). Receiver operating characteristics (ROC) curve analysis on this group showed the highest area under the curve (AUC) (0.86; p=0.001) for 24 h S100B determinations. The cut off was set at 0.372 μg/L (85.7% sensitivity, 79.3% specificity, positive predictive value [PPV]=18.7% and negative predictive value [NPV]=98.9%). This study shows that pupillary responsiveness at admission, as well as 24 h serum S100B levels, could serve as screening tools for the early detection of patients at risk for BD after severe TBI.

Clinical Variables and Neuromonitoring Information (Intracranial Pressure and Brain Tissue Oxygenation) as Predictors of Brain-Death Development After Severe Traumatic Brain Injury

BACKGROUND AND PURPOSE The aim of this study was to ascertain the role of clinical variables and neuromonitoring data as predictors of brain death (BD) after severe traumatic brain injury (TBI). PATIENTS AND METHODS This prospective observational study involved severe TBI patients admitted to the intensive care unit between October 2009 and May 2011. The following variables were recorded: gender, age, reference Glasgow Coma Scale after resuscitation, pupillary reactivity, prehospital hypotension and desaturation, injury severity score, computed tomography (CT) findings, intracranial hypertension, and low brain tissue oxygenation (Pti02) levels (<16 mm Hg), as well as the final result of BD. RESULTS Among 61 patients (86.9% males) who met the inclusion criteria, the average age was 37.69 ± 16.44 years. Traffic accidents were the main cause of TBI (62.3%). The patients at risk of progressing to BD (14.8% of the entire cohort) were those with a mass lesion on CT (odds ratio [OR] 33.6; 95% confidence interval [CI]: 3.75-300.30; P = .002), altered pupillary reaction at admission (OR 25.5; 95% CI: 2.27-285.65; P = .009), as well low Pti02 levels on admission (OR 20.41; 95% CI: 3.52-118.33; P < .001) and during the first 24 hours of neuromonitoring (OR 20; 95% CI: 2.90-137.83; P < .001). Multivariate logistic regression showed that a low Pti02 level on admission was the best independent predictor for BD (OR 20.41; 95% CI: 3.53-118.33; P = .001). CONCLUSIONS Clinical variables and neuromonitoring information may identify TBI patients at risk of deterioration to BD.

Modelo experimental de lesión cerebral tipo masa en rata: expresión del daño cerebral mediante enolasa neuroespecífica y proteína S100B

OBJECTIVE To determine whether a model of transient mass-type brain damage (MTBD) in the rat produces early release of neurospecific enolase (NSE) and protein S100B in peripheral blood, as an expression of the induced brain injury. DESIGN An experimental study with a control group. SETTING Experimental operating room of the Institute of Biomedicine (IBiS) of Virgen del Rocío University Hospital (Seville, Spain). PARTICIPANTS Fourteen adult Wistar rats. INTERVENTIONS Blood was sampled at baseline, followed by: MTBD group, a trephine perforation was used to insert and inflate the balloon of a catheter at a rate of 500 μl/20 sec, followed by 4 blood extractions every 20 min. Control group, the same procedure as before was carried out, though without trephine perforation. PRIMARY STUDY VARIABLES Weight, early mortality, serum NSE and S100B concentration. RESULTS Differences in NSE and S100B concentration were observed over time within the MTBD group (P<.001), though not so in the control group. With the exception of the baseline determination, differences were observed between the two groups in terms of the mean NSE and S100B values. Following MTBD, NSE and S100B progressively increased at all measurement timepoints, with r=0.765; P=.001 and r=0.628; P=.001, respectively. In contrast, the control group showed no such correlation for either biomarker. CONCLUSIONS Serum NSE and S100B concentrations offer an early indication of brain injury affecting the gray and white matter in an experimental model of mass-type MTBD in the rat.

La microdiálisis cerebral en el ámbito clínico actual

Cerebral microdialysis, introduced in experimental studies 40 years ago, has been used clinically since 1992 for the neurochemical monitoring of patients in intensive care. The principles underlying this technique are closely related to brain metabolism. The study of the metabolites detected at brain interstitial tissue level, through the semipermeable membrane of the device, allows us to assess different physiological pathways in the brain, analyzing the changes that occur when they become less efficient in terms of energy, and also detecting waste products secondary to tissue damage. Despite its current limitations, this technique provides relevant information for research and the clinical management of critical neurological patients.

A new percutaneous model of Subarachnoid Haemorrhage in rats

OBJECTIVE Describe the results obtained with a new percutaneous, intracisternal model of Subarachnoid Haemorrhage (SAH) in Wistar rats by a single injection of non-heparinised, autologous blood. METHODS Once anaesthetized the rat was fixed prone in a stereotaxic frame. After identifying the projection of the occipital bone, the needle of the stereotaxic frame aspirated towards the foramen magnum until it punctured through the atlanto-occipital membrane and obtained cerebrospinal fluid. Autologous blood (100 μl) was withdrawn from the tail and injected intracisternally. This procedure was repeated in the sham group, injecting 100 μl of isotonic saline. On the fifth day post-intervention, the rats were anaesthetized and the brain was exposed. After a lethal injection of ketamine the brain was explanted and fixed in paraformaldehyde. Gross and microscopic inspection of the slices revealed the existence or non-existence of pathological findings. RESULTS A total of 26 rats were operated on (13 in the SAH group/13 in the sham group). The average time between obtaining the blood and the start of the intracisternal injection was 10 (±1.2)s. The mortality rate was 16.12%. Intra- and extraparenchymal ischemic-haemorrhagic lesions were found in three animals (23.07%)--all from the SAH group--with ischemic neuronal cell injury detected in two of the three. CONCLUSIONS The new murine model of SAH is easy to perform, with low mortality, minimally invasive, which makes it interesting for future studies on vasospasm-related delayed SAH complications.

Serologic behavior of S100B protein in patients who are brain dead: preliminary results.

OBJECTIVE The objective of this study is to assess the S100B protein serum concentrations from brain dead (BD) donors to understand whether its level could provide clinical information during BD diagnosis as a potential confirmatory test. METHODS During 12 months, 26 patients declared BD were prospectively included in this study. Once the diagnosis of BD was achieved, serum S100B protein levels were measured using an electrochemiluminescence assay. For analytical purposes, we selected the maximum S100B serum value reached during the first 5 days of evolution from a historical cohort of 124 survived patients after a severe brain injury (SBI), as well as from 18 healthy donors (HD) and a subgroup of patients who had severe traumatic brain injuries (TBIs) without extracranial injuries. RESULTS Mean age was 53.48 years (SD, 18.91 years). The BD group had significantly higher S100B serum levels (1.44 μg/L; interquartile ratio [IR], 0.63-3.68) than the SBI (0.34 μg/L; IR, 0.21-0.60) and HD groups (0.06 μg/L; IR, 0.03-0.07; P < .001). Analysis of S100B levels depending on the main cause responsible for BD development showed significant differences between subgroups (P = .012). S100B serum levels were higher in the isolated TBI BD group (P = .004). The S100B value showed an odds ratio for BD diagnosis of 8.38 (95% confidence interval [CI], 1.16-60.45; P = .035). Reciever operating characteristic analysis revealed an area under the curve of 0.92 (95% CI, 0.79-1.00; P = .007). We set a cut-off value of 2 μg/L in S100B serum concentrations. At this level, the diagnostic properties of S100B would reach 100% of specificity and positive predictive value (PPV), and sensitivity and negative predictive value (NPV) of 60% and 86.7%, respectively. CONCLUSION This preliminary analysis shows for the very first time that BD is associated with higher S100B serum levels, compared with other neurocritical care patients. We also found that the cause of BD development must be considered. Specifically, S100B serum levels in severe isolated TBI patients-with clinical exploration compatible with BD-could be used in a future as confirmatory test.