Intrathecal and Systemic Concentration of NT-proBNP in Patients with Severe Traumatic Brain Injury

Pediatric Traumatic Brain Injury: An Update on Preclinical Models, Clinical Biomarkers, and the Implications of Cerebrovascular Dysfunction

Traumatic brain injury (TBI) is a leading cause of pediatric morbidity and mortality. Recent studies suggest that children and adolescents have worse post-TBI outcomes and take longer to recover than adults. However, the pathophysiology and progression of TBI in the pediatric population are studied to a far lesser extent compared to the adult population. Common causes of TBI in children are falls, sports/recreation-related injuries, non-accidental trauma, and motor vehicle-related injuries. A fundamental understanding of TBI pathophysiology is crucial in preventing long-term brain injury sequelae. Animal models of TBI have played an essential role in addressing the knowledge gaps relating to pTBI pathophysiology. Moreover, a better understanding of clinical biomarkers is crucial to diagnose pTBI and accurately predict long-term outcomes. This review examines the current preclinical models of pTBI, the implications of pTBI on the brain’s vasculature, and clinical pTBI biomarkers. Finally, we conclude the review by speculating on the emerging role of the gut-brain axis in pTBI pathophysiology.

Role of Brain Natriuretic Peptide in the Prediction of Early Postoperative Seizures Following Surgery for Traumatic Acute Subdural Hematoma: A Prospective Study

INTRODUCTION

Brain natriuretic peptide (BNP) is a reliable biomarker in the acute phase of traumatic brain injury. However, the relationship between BNP and traumatic acute subdural hematoma (aSDH) has not yet been addressed. This study aimed to analyze BNP levels on admission in surgically treated patients and assess their relationship with early postoperative seizures (EPS) and functional outcomes.

METHODS

Patients with unilateral traumatic aSDH who were surgically treated in our department between July 2017 and May 2020 were included in the study. BNP was preoperatively measured. Patients' neurologic condition, radiographic variables on initial cranial computed tomography, sodium serum levels on admission, and occurrence of EPS were prospectively assessed. Functional outcome was assessed using the modified Rankin Scale (mRS) at discharge and follow-up (at 2-3 months). A poor outcome was defined by a mRS score > 3.

RESULTS

EPS occurred in 20 (19.6%) of 102 surgically treated patients in the final cohort on the median day 3. A significant association between EPS and a poor Glasgow Coma Scale score at the 7th postoperative day was found, which in turn independently predicted a poor functional outcome at discharge and follow-up. Nonetheless, EPS were not associated with poor functional outcomes. The multivariate analysis revealed BNP > 95.4 pg/ml (aOR = 5.7, p = 0.003), sodium < 137.5 mmol/l (aOR = 4.6, p = 0.009), and left-sided aSDH (aOR = 4.4, p = 0.020) as independent predictors of EPS.

CONCLUSION

In the early postoperative phase of traumatic aSDH, EPS were associated with worse neurologic conditions, which in turn independently predicted poor outcomes at discharge and follow-up. Although several EPS risk factors have already been elucidated, this study presents BNP as a novel reliable predictor of EPS. Further larger studies are needed to determine whether a more precise estimate of EPS risk using BNP levels can be reached.

Analysis of Brain Natriuretic Peptide Levels after Traumatic Acute Subdural Hematoma and the Risk of Post-Operative Cerebral Infarction

Traumatic acute subdural hematoma (aSDH) is associated with a high mortality rate caused by post-operative cerebral infarction. Recently, brain natriuretic peptide (BNP) was considered a reliable biomarker in the acute phase of traumatic brain injuries. We therefore aimed in this study to analyze BNP levels on admission, identify the predictors of their elevation, and assess the relationship between BNP and the risk of post-operative cerebral infarction. Patients with isolated, unilateral, traumatic aSDH who were admitted to our department between July 2017 and May 2020 were enrolled in this study. On admission, cranial computer tomography (CCT) and BNP sampling were simultaneously performed. Additionally, the time between head trauma and BNP sampling (TTS) was assessed. Admission radiographic variables included hematoma volumes, midline shift, and degree of brain edema. Cerebral infarction was detected on postoperative CCT. In total, 130 patients were included in this study. Surgical treatment was performed in 82.3% (n = 107) of cases. The multiple regression analysis showed that larger hematoma volumes (p = 0.032) and advanced age (p = 0.005) were independent predictors of elevated BNP when TTS <24 h. The binomial logistical regression analysis identified BNP with a cutoff value of <29.4 pg/mL (TTS = 3-12 h, adjusted odds ratio [aOR] = 16.5, p = 0.023) as an independent predictor of post-operative cerebral infarction. Elevated BNP levels in the first 24 h post-trauma were related to larger hematoma volumes and advanced age. Further, an increased risk of post-operative cerebral infarction was identified in patients with lower BNP levels in the post-traumatic period 3-12 h.

BNP and NT-proBNP Concentrations in Paired cerebrospinal Fluid and Plasma Samples of Patients with Traumatic Brain Injury

BACKGROUND

The aim of this study was to investigate the secretion patterns of brain natriuretic peptide (BNP) and N-terminal-proBNP (NT-proBNP) after traumatic brain injury (TBI) and to analyze the source of them in cerebrospinal fluid (CSF).

MATERIALS AND METHODS

We synchronously measured BNP and NT-proBNP concentrations in paired CSF and plasma samples from 22 moderate to severe TBI patients and 40 healthy control patients. The CSF and/or plasma ratio of albumin (Q_Albumin) was calculated daily. The BNP and NT-proBNP levels of CSF and plasma were compared between TBI patients and control patients.

RESULTS

CSF BNP and NT-proBNP levels peaked on day 3 after injury, as did the plasma BNP and NT-proBNP levels. The CSF BNP and NT-proBNP levels in TBI patients were elevated from day 1, which was significantly higher than control group (P < 0.05 and P < 0.01, respectively). However, in plasma, only NT-proBNP levels were significantly higher than in the control group from day 2 (P < 0.05). In addition, Q_BNP, defined as CSF BNP concentration and/or plasma BNP concentration, was significantly higher in TBI patients than in the control group (P < 0.01). However, Q_Albumin remained within ranges of a mild to moderate dysfunction of blood-brain-barrier in TBI patients.

CONCLUSIONS

CSF BNP concentrations are elevated and peak on day 3 after moderate to severe TBI. CSF BNP may originate from the brain and may be a potential biomarker of TBI.

Predictors of Brain Natriuretic Peptide Serum Level Elevation in Patients with Symptomatic Chronic Subdural Hematoma: A Prospective Study

Background: Brain natriuretic peptide serum levels (BNP) on admission are frequently elevated in patients with symptomatic chronic subdural hematoma (cSDH) and predict unfavorable long-term functional outcomes. However, the reasons for these elevated levels remain unclear. Therefore, we aimed to identify the predictors of BNP elevation. Methods: Patients with unilateral symptomatic cSDH who were surgically treated in our department between November 2016 and May 2020 were enrolled. Patients’ symptoms and neurological deficits were prospectively assessed using a study questionnaire. On initial computer tomography, hematoma volumes and midline shift (MLS) values were measured to analyze the degree of brain compression. Results: In total, 100 patients were analyzed. Linear regression analysis showed that higher BNP levels were significantly associated with smaller hematoma volumes (p = 0.003) and littler MLS values (p = 0.022). Multivariate analysis revealed that presence of a neurological deficit (p = 0.041), a hematoma volume < 140 mL (p = 0.047), advanced age (p = 0.023), and head trauma within 24 h of admission (p = 0.001) were independent predictors of BNP elevation. Conclusion: In symptomatic cSDH, BNP elevation is related, among others, to the presence of neurological deficits and smaller hematoma volumes. Whether BNP elevation may coincide with the early stage of hematoma growth, i.e., immaturity of cSDH neomembrane, requires further investigations.

Biomarkers for traumatic brain injury: a short review

Cellular response to TBI is a mixture of excitotoxicity, neuroinflammation, and cell death. Biomarkers that can track these lesions and inflammatory processes are being explored for their potential to provide objective measures in the evaluation of TBI, from prehospital care to rehabilitation. By understanding the pathways involved, we could be able to improve diagnostic accuracy, guide management, and prevent long-term disability. We listed some of the recent advances in this translational, intriguing, fast-growing field. Although the knowledge gaps are still significant, some markers are showing promising results and could be helping patients in the near future.

Analysis of Brain Natriuretic Peptide Serum Levels in Patients with Symptomatic Chronic Subdural Hematoma: A Potential Reliable Biomarker

The purpose of this study was to analyze brain natriuretic peptide (BNP) serum levels of patients with chronic subdural hematoma (cSDH) and their clinical implication. Patients with cSDH who underwent surgery in our department between November 2016 and October 2019 were eligible for enrollment in the study. Patients with recurrent bleedings, traumatic brain injury, cSDH associated with other intracranial pathologies, and those with a history of congestive heart failure, renal or endocrine disease were excluded. We measured BNP serum levels pre- and post-operatively and at discharge. The BNP values were analyzed with respect to patient medical history and neurological condition. The Glasgow Coma Scale score and the modified Rankin Scale score classified the clinical and neurological condition at the time of admission and discharge, respectively. The data of 100 surgically treated patients with cSDH (mean age 73.2, range 42 − 94 years, male/female 3.5:1) were analyzed. Pre-operative BNP serum levels (BNP-1) were elevated in 67% of the patients (n = 67; median = 101.6 pg/mL; p < 0.001). These serum levels increased after surgery (p < 0.001) and decreased thereafter (p < 0.001), reaching a level at discharge (day 7) that was not statistically different from BNP-1 (p > 0.05). In addition, elevated BNP-1 showed a significant statistical association with the presence of atrial fibrillation (p < 0.01) and antiplatelet and/or anticoagulant therapy (p < 0.01). This study provides new evidence regarding BNP serum levels and their secretion pattern in patients with cSDH. Whether BNP-1 can predict the long-term functional outcome of patients with cSDH is being investigated in this ongoing prospective study.

NT-Pro Brain Natriuretic Peptide: Is it a New Indicator of Brain Oedema?

Objective

To assess the role of the N-terminal prohormone form of brain natriuretic peptide (NT-proBNP) in patients with acute brain oedema.

Methods

This is a case control study. Twenty-two patients with acute brain oedema evidenced by computed tomography (CT) were recruited and compared to a control group of 30 healthy adult volunteers. Levels of NT-proBNP were measured in all patients at hospital admission and on the 12th and 24th hours after admission; as well as in a control group of 30 healthy blood donors.

Results

Twenty-two patients with brain oedema and 30 controls were included. There were significant differences between the brain oedema group and the control group on the NT-proBNP levels at admission time, on 12th or 24th hours after admission. There was no significant difference in NT-proBNP levels at admission time with the severity of brain oedema evidenced by CT. When we considered the relationship between mannitol usage and NT-proBNP levels, we found a significant difference between brain oedema severity and NT-proBNP level according to brain oedema severity after anti-oedema treatment, for 12th and 24th hours NT-proBNP levels.

Conclusions

There is a possible association between brain oedema and elevated serum NT-proBNP levels. (Hong Kong j.emerg.med. 2014;21:167-171)

Preoperative N-terminal pro-B-type natriuretic peptide concertation and prognosis of brain tumor patients: a 5-year follow up study

Increased N-terminal pro-B-type natriuretic peptide (NT-proBNP) concentration predicts poor prognosis of non-CNS cancer patients. We evaluated the association of NT-proBNP concentration with disease severity, discharge outcomes and prognosis of patients undergoing craniotomy for brain tumor. From January, 2010 until September, 2011 two-hundred and forty-five patients (age 55.05 ± 14.62 years) admitted for brain tumor surgery were evaluated for NT-proBNP serum concentration. Outcome at hospital discharge was evaluated with the Glasgow Outcome Scale (GOS). Most common diagnoses were meningioma (37%) and high-grade glioma (20%). Greater NT-proBNP concentration was associated with lower Barthel index (rho = −0.305, p = 0.001) and Mini Mental State Examination scores (rho = −0.314, p = 0.001) and with greater Hospital Anxiety and Depression scale Depression score (rho = 0.240, p = 0.026). Greater admission NT-proBNP concentration was associated with lower discharge GOS score after adjusting for patient age, gender and histological brain tumor diagnosis (β = −0.253, p < 0.001). Greater NT-proBNP concentration was also associated with greater 5-year mortality risk (HR = 1.845; 95%CI [1.166–2.920], p = 0.009) controlling for patient age, gender, history of cardiovascular disease, histological diagnosis and adjuvant therapy. In sum, greater pre-operative NT-proBNP concentration is associated with worse health status, unfavorable discharge outcome and shorter survival of brain tumor patients.

N-Terminal Pro-Brain Natriuretic Peptide Concentrations After Hypertensive Intracerebral Hemorrhage: Relationship With Hematoma Size, Hyponatremia, and Intracranial Pressure

Introduction:

The role of N-terminal pro-brain natriuretic peptide (NT-proBNP) in patients with hypertensive intracerebral hemorrhage (HICH) is poorly understood. This study aimed to investigate the secretion pattern of NT-proBNP in patients with HICH and to assess its relationship with hematoma size, hyponatremia, and intracranial pressure (ICP).

Methods:

This prospective study enrolled 147 isolated patients with HICH. Blood samples were obtained from each patient, and values of serum NT-proBNP, hematoma size, blood sodium, and ICP were collected for each patient.

Results:

The peak-to-mean concentration of NT-proBNP was 666.8 ± 355.1 pg/mL observed on day 4. The NT-proBNP levels in patients with hematoma volume >30 mL were significantly higher than those in patients with hematoma volume <30 mL ( P < .05). In patients with severe HICH, the mean concentration of NT-proBNP was statistically higher than that in patients with mild–moderate HICH ( P < .05), and the mean level of NT-proBNP in hyponatremia group was significantly higher than that in normonatremic group ( P < .05). In addition, the linear regression analysis indicated that serum NT-proBNP concentrations were positively correlated with ICP ( r = .703, P < .05) but negatively with blood sodium levels only in patients with severe HICH ( r = −.704, P < .05). The serum NT-proBNP levels on day 4 after admission were positively correlated with hematoma size ( r = .702, P < .05).

Conclusion:

The NT-proBNP concentrations were elevated progressively and markedly at least in the first 4 days after HICH and reached a peak level on the fourth day. The NT-proBNP levels on day 4 were positively correlated with hematoma size. There was a notable positive correlation between plasma NT-proBNP levels and ICP in patients with severe HICH. Furthermore, only in patients with severe HICH, the plasma NT-proBNP levels presented a significant correlation with hyponatremia, which did not occur in patients with mild–moderate HICH.

Principal components derived from CSF inflammatory profiles predict outcome in survivors after severe traumatic brain injury

Studies have characterized absolute levels of multiple inflammatory markers as significant risk factors for poor outcomes after traumatic brain injury (TBI). However, inflammatory marker concentrations are highly inter-related, and production of one may result in the production or regulation of another. Therefore, a more comprehensive characterization of the inflammatory response post-TBI should consider relative levels of markers in the inflammatory pathway. We used principal component analysis (PCA) as a dimension-reduction technique to characterize the sets of markers that contribute independently to variability in cerebrospinal (CSF) inflammatory profiles after TBI. Using PCA results, we defined groups (or clusters) of individuals (n=111) with similar patterns of acute CSF inflammation that were then evaluated in the context of outcome and other relevant CSF and serum biomarkers collected days 0-3 and 4-5 post-injury. We identified four significant principal components (PC1-PC4) for CSF inflammation from days 0-3, and PC1 accounted for the greatest (31%) percentage of variance. PC1 was characterized by relatively higher CSF sICAM-1, sFAS, IL-10, IL-6, sVCAM-1, IL-5, and IL-8 levels. Cluster analysis then defined two distinct clusters, such that individuals in cluster 1 had highly positive PC1 scores and relatively higher levels of CSF cortisol, progesterone, estradiol, testosterone, brain derived neurotrophic factor (BDNF), and S100b; this group also had higher serum cortisol and lower serum BDNF. Multinomial logistic regression analyses showed that individuals in cluster 1 had a 10.9 times increased likelihood of GOS scores of 2/3 vs. 4/5 at 6 months compared to cluster 2, after controlling for covariates. Cluster group did not discriminate between mortality compared to GOS scores of 4/5 after controlling for age and other covariates. Cluster groupings also did not discriminate mortality or 12 month outcomes in multivariate models. PCA and cluster analysis establish that a subset of CSF inflammatory markers measured in days 0-3 post-TBI may distinguish individuals with poor 6-month outcome, and future studies should prospectively validate these findings. PCA of inflammatory mediators after TBI could aid in prognostication and in identifying patient subgroups for therapeutic interventions.

Cerebral salt-wasting syndrome after hematopoietic stem cell transplantation in adolescents: 3 case reports

Cerebral salt-wasting syndrome (CSWS) is a rare disease characterized by a extracellular volume depletion and hyponatremia induced by marked natriuresis. It is mainly reported in patients who experience a central nervous system insult, such as cerebral hemorrhage or encephalitis. The syndrome of inappropriate antidiuretic hormone secretion is a main cause of severe hyponatremia after hematopoietic stem cell transplantation, whereas CSWS is rarely reported. We report 3 patients with childhood acute leukemia who developed CSWS with central nervous system complication after hematopoietic stem cell transplantation. The diagnosis of CSW was made on the basis of severe hyponatremia accompanied by increased urine output with clinical signs of dehydration. All patients showed elevated natriuretic peptide and normal antidiuretic hormone. Aggressive water and sodium replacement treatment was instituted in all 3 patients and 2 of them were effectively recovered, the other one was required to add fludrocortisone administration.

Serum N-Terminal Pro-B-Type Natriuretic Peptide (NTproBNP) Levels Are Elevated During the Acute Phase of Acute Encephalopathy-Associated Virus Infection

Acute virus-associated encephalopathy induces seizures. Serum N-terminal pro-B-type natriuretic peptide (NTproBNP) levels are elevated following febrile and afebrile seizures. However, the role of NTproBNP in acute virus-associated encephalopathy pathology is unknown. We enrolled 10 patients with acute virus-associated encephalopathy and convulsions (E group: 7 boys, 3 girls; median age, 3.10 ± 1.92 years) and 130 patients with febrile seizure (FS group: 80 boys, 50 girls; median age, 3.23 ± 2.44 years). The E group had significantly higher NTproBNP levels (345 ± 141 pg/mL) compared with the FS group (166 ± 228 pg/mL) (P < .0005). Furthermore, subjects with prolonged seizure within the E group had significantly higher NTproBNP levels (303 ± 107 pg/mL) compared with subjects with prolonged seizure within the FS group (134 ± 100 pg/mL) (P < .005). Our findings suggest that serum NTproBNP levels are increased during the acute phase of acute virus-associated encephalopathy associated with convulsion.

Natriuretic hormones in brain function

Natriuretic hormones (NH) include three groups of compounds: the natriuretic peptides (ANP, BNP and CNP), the gastrointestinal peptides (guanylin and uroguanylin), and endogenous cardiac steroids. These substances induce the kidney to excrete sodium and therefore participate in the regulation of sodium and water homeostasis, blood volume, and blood pressure (BP). In addition to their peripheral functions, these hormones act as neurotransmitters or neuromodulators in the brain. In this review, the established information on the biosynthesis, release and function of NH is discussed, with particular focus on their role in brain function. The available literature on the expression patterns of each of the NH and their receptors in the brain is summarized, followed by the evidence for their roles in modulating brain function. Although numerous open questions exist regarding this issue, the available data support the notion that NH participate in the central regulation of BP, neuroprotection, satiety, and various psychiatric conditions, including anxiety, addiction, and depressive disorders. In addition, the interactions between the different NH in the periphery and the brain are discussed.

B-type (brain) natriuretic peptide and pruritus in hemodialysis patients

Introduction and objective

While pruritus is a common complication in hemodialysis patients, the pathophysiological mechanisms remain obscure. Recently, B-type (brain) natriuretic peptide (BNP) has been defined as an itch-selective neuropeptide in pruriceptive neurons in mice, and higher serum levels of BNP are frequently observed in hemodialysis patients. The objective of the present study was to evaluate the role of serum BNP in pruritus in patients undergoing hemodialysis.

Patients and methods

The current cross-sectional study was performed on 43 patients undergoing maintenance hemodialysis. A visual analog scale (VAS) measuring the general severity of pruritus (values from 0 to 10, with higher values indicating more severe pruritus) in daytime and at night was self-reported by patients. Each patient’s background and laboratory tests, including serum BNP in the post-hemodialysis period, were collected. The correlation between VAS and clinical parameters was evaluated.

Results

Both daytime and nighttime VAS scores in diabetic patients were significantly less than those in nondiabetic patients. Multiple regression analysis revealed that pruritus in daytime was worsened by serum BNP (β=2.0, t=2.4, P=0.03), calcium (β=4.4, t=5.2, P<0.0001), and β₂-microglobulin (β=2.0, t=3.0, P=0.007), while it was eased by age (β=−2.2, t=−3.2, P=0.0004). Nocturnal pruritus was severe in nondiabetic patients (β=1.7, t=3.8, P=0.0005) and weakened by the total iron binding capacity (β=−2.9, t=−3.1, P=0.004).

Conclusion

It is suggested that a higher level of serum BNP increases the pruritus of hemodialysis patients in daytime and that diabetic patients are less sensitive to itch, especially at nighttime.

Fingerprint changes in CSF composition associated with different aetiologies in human neonatal hydrocephalus: inflammatory cytokines

PURPOSE

Hydrocephalus (HC) has a multifactorial and complex picture of pathophysiology due to aetiology, age at and duration since onset. We have previously identified distinctions in markers of cell death associated with different aetiologies. Here, we examined cerebrospinal fluid (CSF) from human HC neonates for cytokines to identify further distinguishing features of different aetiologies.

METHODS

CSF was collected during routine lumbar puncture or ventricular tap from neonates with hydrocephalus, or with no neurological condition (normal controls). Total protein, Fas receptor, Fas ligand, stem cell factor (SCF), hepatocyte growth factor (HGF), vascular endothelial growth factor (VEGF), insulin growth factor-1 (IGF-1), tumour necrosis factor alpha (TNF-α) and interleukin 6 (IL-6) were measured and compared between 8 unaffected and 28 HC neonatal CSF samples.

RESULTS

Total protein was significantly (P < 0.05) raised in late-onset hydrocephalus (LOH). Fas receptor was raised (P < 0.05) in post-haemorrhagic hydrocephalus (PHH) and spina bifida with hydrocephalus (SB/HC), but no difference in Fas ligand was found. SCF was raised (P < 0.05) in SB/HC. HGF was found in all HC and was increased (P < 0.01) in PHH. Increased VEGF was found in PHH (P < 0.01) and SB/HC (P < 0.05). Variable levels of IL-6, TNF-α and IGF-1 were found in all HC groups compared with none in normal.

CONCLUSIONS

LOH was unusual with significantly raised total protein indicating an inflammatory state. Increased Fas receptor, VEGF, IGF-1 and HGF suggest anti-apoptotic and repair mechanism activation. By contrast, elevated TNF-α and IL-6 indicate inflammatory processes in these neonatal brains. Taken with our previous study, these data indicate that different pathophysiology, inflammation and repair are occurring in HC of different aetiologies and that additional treatment strategies may benefit these infants in addition to fluid diversion.

Serum levels of N-terminal proB-type natriuretic peptide in mechanically ventilated critically ill patients--relation to tidal volume size and development of acute respiratory distress syndrome

Background

Serum levels of N–terminal proB–type natriuretic peptide (NT–proBNP) are elevated in patients acute respiratory distress syndrome (ARDS). Recent studies showed a lower incidence of acute cor pulmonale in ARDS patients ventilated with lower tidal volumes. Consequently, serum levels of NT–proBNP may be lower in these patients.

We investigated the relation between serum levels of NT–proBNP and tidal volumes in critically ill patients without ARDS at the onset of mechanical ventilation.

Methods

Secondary analysis of a randomized controlled trial of lower versus conventional tidal volumes in patients without ARDS. NT–pro BNP were measured in stored serum samples. Serial serum levels of NT–pro BNP were analyzed controlling for acute kidney injury, cumulative fluid balance and presence of brain injury. The primary outcome was the effect of tidal volume size on serum levels of NT–proBNP. Secondary outcome was the association with development of ARDS.

Results

Samples from 150 patients were analyzed. No relation was found between serum levels of NT–pro BNP and tidal volume size. However, NT-proBNP levels were increasing in patients who developed ARDS. In addition, higher levels were observed in patients with acute kidney injury, and in patients with a more positive cumulative fluid balance.

Conclusion

Serum levels of NT–proBNP are independent of tidal volume size, but are increasing in patients who develop ARDS.

Clinical and biomarker profile of trauma-induced secondary cardiac injury

BACKGROUND

Secondary cardiac injury has been demonstrated in critical illness and is associated with worse outcomes. The aim of this study was to establish the existence of trauma-induced secondary cardiac injury, and investigate its impact on outcomes in injured patients.

METHODS

Injured adult patients eligible for enrolment in the Activation of Coagulation and Inflammation in Trauma 2 study, and admitted to the intensive care unit between January 2008 and January 2010, were selected retrospectively for the study. Markers of cardiac injury (brain natriuretic peptide (BNP), heart-type fatty acid binding protein (H-FABP) and troponin I) were measured on admission, and after 24 and 72 h in blood samples from injured patients. Individual records were reviewed for adverse cardiac events and death.

RESULTS

During the study period, 135 patients were enrolled (106 male, 78·5 per cent) with a median age of 40 (range 16-89) years. Eighteen patients (13·3 per cent) had an adverse cardiac event during admission and these events were not associated with direct thoracic injury. The in-hospital mortality rate was higher among the adverse cardiac event cohort: 44 per cent (8 of 18) versus 17·1 per cent (20 of 117) (P = 0·008). Raised levels of H-FABP and BNP at 0, 24 and 72 h, and troponin I at 24 and 72 h, were associated with increased adverse cardiac events. BNP levels were higher in non-survivors on admission (median 550 versus 403 fmol/ml; P = 0·022), after 24 h (794 versus 567 fmol/ml; P = 0·033) and after 72 h (1043 versus 753 fmol/ml; P = 0·036), as were admission troponin I levels.

CONCLUSION

Clinical and cardiac biomarker characteristics support the existence of trauma-induced secondary cardiac injury, which is associated with death, and unrelated to direct thoracic injury.

B-type Natriuretic Peptide: Diagnostic and Therapeutic Applications in Infants and Children

The natriuretic peptide system plays an active role in the regulation of fluid balance and systemic vascular resistance. Peptides of the natriuretic system produced through recombinant DNA technology are now available for clinical use including both atrial natriuretic peptide (ANP) and brain-type natriuretic peptide (BNP). Assays of BNP are available and may be used for both diagnostic and prognostic purposes in various clinical scenarios. The basic physiology of the natriuretic peptide system is presented, applications of BNP monitoring as a diagnostic tool are reviewed, and reports regarding the use of recombinant BNP in the pediatric population are discussed.

Hyponatremia and brain injury: absence of alterations of serum brain natriuretic peptide and vasopressin

OBJECTIVE

To study any possible relation between hyponatremia following brain injury and the presence of cerebral salt-wasting syndrome (CSWS) or the syndrome of inappropriate secretion of antidiuretic hormone (SIADH), and if vasopressin, brain natriuretic peptide (BNP) and aldosterone have a role in its mechanism.

METHOD

Patients with brain injury admitted to the intensive care unit were included and had their BNP, aldosterone and vasopressin levels dosed on day 7.

RESULTS

Twenty six adult patients were included in the study. Nine (34.6%) had hyponatremia and presented with a negative water balance and higher values of urinary sodium, serum potassium and diuresis than patients with normonatremia. The serum levels of BNP, aldosterone, and vasopressin were normal and no relation was observed between plasma sodium and BNP, aldosterone or vasopressin.

CONCLUSION

The most likely cause of hyponatremia was CSWS and there was no correlation between BNP, aldosterone and vasopressin with serum sodium level.

Blood-brain barrier breakdown as a therapeutic target in traumatic brain injury

Traumatic brain injury (TBI) is the leading cause of death in young adults and children. The treatment of TBI in the acute phase has improved substantially; however, the prevention and management of long-term complications remain a challenge. Blood-brain barrier (BBB) breakdown has often been documented in patients with TBI, but the role of such vascular pathology in neurological dysfunction has only recently been explored. Animal studies have demonstrated that BBB breakdown is involved in the initiation of transcriptional changes in the neurovascular network that ultimately lead to delayed neuronal dysfunction and degeneration. Brain imaging data have confirmed the high incidence of BBB breakdown in patients with TBI and suggest that such pathology could be used as a biomarker in the clinic and in drug trials. Here, we review the neurological consequences of TBI, focusing on the long-term complications of such injuries. We present the clinical evidence for involvement of BBB breakdown in TBI and examine the primary and secondary mechanisms that underlie such pathology. We go on to consider the consequences of BBB injury, before analyzing potential mechanisms linking vascular pathology to neuronal dysfunction and degeneration, and exploring possible targets for treatment. Finally, we highlight areas for future basic research and clinical studies into TBI.

Brain natriuretic peptide improves long-term functional recovery after acute CNS injury in mice

There is emerging evidence to suggest that brain natriuretic peptide (BNP) is elevated after acute brain injury, and that it may play an adaptive role in recovery through augmentation of cerebral blood flow (CBF). Through a series of experiments, we tested the hypothesis that the administration of BNP after different acute mechanisms of central nervous system (CNS) injury could improve functional recovery by improving CBF. C57 wild-type mice were exposed to either pneumatic-induced closed traumatic brain injury (TBI) or collagenase-induced intracerebral hemorrhage (ICH). After injury, either nesiritide (hBNP) (8 microg/kg) or normal saline were administered via tail vein injection at 30 min and 4 h. The mice then underwent functional neurological testing via rotorod latency over the following 5 days and neurocognitive testing via Morris water maze testing on days 24-28. Cerebral blood flow (CBF) was assessed by laser Doppler from 25 to 90 min after injury. After ICH, mRNA polymerase chain reaction (PCR) and histochemical staining were performed during the acute injury phase (<24 h) to determine the effects on inflammation. Following TBI and ICH, administration of hBNP was associated with improved functional performance as assessed by rotorod and Morris water maze latencies (p < 0.01). CBF was increased (p < 0.05), and inflammatory markers (TNF-alpha and IL-6; p < 0.05), activated microglial (F4/80; p < 0.05), and neuronal degeneration (Fluoro-Jade B; p < 0.05) were reduced in mice receiving hBNP. hBNP improves neurological function in murine models of TBI and ICH, and was associated with enhanced CBF and downregulation of neuroinflammatory responses. hBNP may represent a novel therapeutic strategy after acute CNS injury.

Interpretation and use of natriuretic peptides in non-congestive heart failure settings

Natriuretic peptides (NPs) have been found to be useful markers in differentiating acute dyspneic patients presenting to the emergency department (ED) and emerged as potent prognostic markers for patients with congestive heart failure (CHF). The best-established and widely used clinical application of BNP and NT-proBNP testing is for the emergent diagnosis of CHF in patients presenting with acute dyspnea. Nevertheless, elevated NPs levels can be found in many circumstances involving left ventricular (LV) dysfunction or hypertrophy; right ventricular (RV) dysfunction secondary to pulmonary diseases; cardiac inflammatory or infectious diseases; endocrinology diseases and high output status without decreased LV ejection fraction. Even in the absence of significant clinical evidence of volume overload or LV dysfunction, markedly elevated NP levels can be found in patients with multiple comorbidities with a certain degree of prognostic value. Potential clinical applications of NPs are expanded accompanied by emerging reports regarding screening the presence of secondary cardiac dysfunction; monitoring the therapeutic responses, risk stratifications and providing prognostic values in many settings. Clinicians need to have expanded knowledge regarding the interpretation of elevated NPs levels and potential clinical applications of NPs. Clinicians should recognize that currently the only reasonable application for routine practice is limited to differentiation of acute dyspnea, rule-out-diagnostic-tests, monitoring of therapeutic responses and prognosis of acute or decompensated CHF. The rationales as well the potential applications of NPs in these settings are discussed in this review article.

Intraoperative hyponatremia during craniofacial surgery

BACKGROUND

Hyponatremia is an important cause of morbidity in some groups of hospitalized children. Our aim is to describe the incidence and severity of intraoperative hyponatremia in children undergoing craniofacial surgery, and determine the associated risk factors.

METHODS

A descriptive retrospective study of children who underwent primary craniofacial surgery between March 1994 and February 2008 was performed. All administered fluids contained a minimum sodium concentration of 140 mmol.l(-1). Hyponatremia was classified as follows: severe < or =125 mmol.l(-1); moderate 126-130 mmol.l(-1); and, mild 131-134 mmol.l(-1).

RESULTS

Hundred and seven cases are reported. Severe, moderate and mild intraoperative hyponatremia occurred in 14 (13%), 21 (19%) and 23 (22%) children respectively. Mannitol was given to 31 (29%) children, but was not associated with the development of hyponatremia. Neither the type nor duration of surgery, type of fluid replacement nor hourly urinary output, was associated with development of hyponatremia. Most episodes of significant intraoperative hyponatremia (44%) were detected between the 2nd and the 4th hour of surgery. There were no identified neurological sequelae (e.g. coma, neurological deficit) attributable to the hyponatremia.

CONCLUSION

Despite strict avoidance of low sodium solutions (<140 mmol.l(-1)), hyponatremia occurs frequently in children undergoing craniofacial surgery in our practice; and is unrelated to the administration of mannitol. Although the mechanisms are yet to be determined, anesthesiologists should be aware of this issue and be prepared to monitor and treat this potentially serious complication.

Analysis of N-terminal pro-B-type natriuretic peptide and cardiac index in multiple injured patients: a prospective cohort study

Introduction

Increased serum B-type natriuretic peptide (BNP) has been identified for diagnosis and prognosis of impaired cardiac function in patients suffering from congestive heart failure, ischemic heart disease, and sepsis. However, the prognostic value of BNP in multiple injured patients developing multiple organ dysfunction syndrome (MODS) remains undetermined. Therefore, the aims of this study were to assess N-terminal pro-BNP (NT-proBNP) in multiple injured patients and to correlate the results with invasively assessed cardiac output and clinical signs of MODS.

Methods

Twenty-six multiple injured patients presenting a New Injury Severity Score of greater than 16 points were included. The MODS score was calculated on admission as well as 24, 48, and 72 hours after injury. Patients were subdivided into groups: group A showed minor signs of organ dysfunction (MODS score less than or equal to 4 points) and group B suffered from major organ dysfunction (MODS score of greater than 4 points). Venous blood (5 mL) was collected after admission and 6, 12, 24, 48, and 72 hours after injury. NT-proBNP was determined using the Elecsys proBNP^® assay. The hemodynamic monitoring of cardiac index (CI) was performed using transpulmonary thermodilution.

Results

Serum NT-proBNP levels were elevated in all 26 patients. At admission, the serum NT-proBNP values were 116 ± 21 pg/mL in group A versus 209 ± 93 pg/mL in group B. NT-proBNP was significantly lower at all subsequent time points in group A in comparison with group B (P < 0.001). In contrast, the CI in group A was significantly higher than in group B at all time points (P < 0.001). Concerning MODS score and CI at 24, 48, and 72 hours after injury, an inverse correlation was found (r = -0.664, P < 0.001). Furthermore, a correlation was found comparing MODS score and serum NT-proBNP levels (r = 0.75, P < 0.0001).

Conclusions

Serum NT-proBNP levels significantly correlate with clinical signs of MODS 24 hours after multiple injury. Furthermore, a distinct correlation of serum NT-proBNP and decreased CI was found. The data of this pilot study may indicate a potential value of NT-proBNP in the diagnosis of post-traumatic cardiac impairment. However, further studies are needed to elucidate this issue.

Plasma B-type natriuretic peptide monitoring to evaluate cardiovascular function prior to organ procurement in patients with brain death

BACKGROUND

The natriuretic peptide system plays an active role in the regulation of fluid balance and systemic vascular resistance. Assays of plasma concentrations of B-type natriuretic peptide (BNP) may have a diagnostic role in evaluating myocardial function. We present our experience with BNP monitoring to assess myocardial function after the proclamation of brain death in potential organ donors.

METHODS

After the proclamation of brain death and prior to organ donation, a plasma BNP or aminoterminal pro-BNP level was obtained. Additional information from the donor included shortening fraction (SF) or ejection fraction, central venous pressure (CVP) reading, and renal function including blood urea nitrogen and creatinine. When available, data from the pulmonary artery (PA) catheter including pulmonary capillary wedge pressure (PCWP) and cardiac index were also collected.

RESULTS

The cohort for the study included eight patients (age range: 6 months to 21 years). The diagnosis of brain death by clinical or radiological examination had been completed in all patients and the patients were scheduled for organ procurement. Myocardial contractility as assessed by echocardiogram using SF was within normal limits. The CVP varied from 7 to 12 mmHg (9 +/- 2) and the PCWP was 10-11 mmHg in the two patients who had PA catheters in place. No patient was receiving inotropic medications. In five of the six patients, the BNP value was above the upper limit of normal (100 pg x ml(-1)). In two patients, an NT-pro-BNP value was obtained and found to be higher than the upper limits of normal (450 pg x ml(-1)). All eight patients were acceptable cardiac donors and the transplanted hearts functioned without difficulty in the recipients.

CONCLUSIONS

Assays of plasma BNP concentrations have been shown to be helpful in differentiating myocardial dysfunction from primary lung disease in both the adult and pediatric population. However, our data demonstrate that mechanisms other than myocardial performance may regulate BNP levels in patients with severe central nervous system injury who progress to brain death. Our preliminary data suggest that these assays appear to be of limited value in assessing myocardial performance in this population.

BNP or NTproBNP? A clinician's perspective

Existing literature on two natriuretic peptides--B-type natriuretic peptide (BNP) and amino terminal pro-brain natriuretic peptide (NTproBNP)--is overwhelming. Both peptides are acknowledged markers for cardiac dysfunction. Most of the sources present data on either BNP or NTproBNP making the comparison difficult. This paper focuses on reviewing studies directly comparing two peptides in the setting of chronic and acute heart failure (HF) and coronary artery disease. Many concomitant diseases influence these two peptides to varying extent. These characteristics should be taken into consideration when interpreting results. For most practical purposes, BNP and NTproBNP are interchangeable, and can be used based on local preferences and availability. NTproBNP seems to be more advantageous for diagnosing mild HF or asymptomatic left ventricular dysfunction.

The differential diagnosis of an elevated amino-terminal pro-B-type natriuretic peptide level

Although amino-terminal pro-B-type natriuretic peptides (NT-proBNP) are useful for the diagnosis or exclusion of heart failure (HF), this marker may identify a wide range of disease processes other than HF. Indeed, elevation of NT-proBNP may occur in a number of heart diseases (including heart muscle disease, valve disease, rhythm abnormalities, pulmonary hypertension, and cytotoxic injury to the heart) and in disease processes other than primary cardiac illnesses, including gram-negative sepsis. Importantly, although NT-proBNP may increase in settings other than HF, the presence and severity of such NT-proBNP release is often significantly associated with risk for adverse outcome. Accordingly, elevation of NT-proBNP in the context of non-HF situations should not be regarded as a "false-positive" finding, and elevated NT-proBNP values should not be discarded without consideration of the serious adverse outcomes associated with the elevation. Future studies will be necessary to further understand the utility of NT-proBNP testing in states other than cardiovascular disease.

Hyponatremia and Comparison of NT-pro-BNP Concentrations in Blood Samples from Jugular Bulb and Arterial Sites after Traumatic Brain Injury in Adults: A Pilot Study

BACKGROUND

Hyponatremia after traumatic brain injury (TBI) may influence neurological function and treatment. A causal relationship between elevated serum concentrations of Type B natriuretic peptide (BNP) and hyponatremia has been implied after subarachnoid hemorrhage and other neurosurgical disorders, although the source of BNP has not been identified. We evaluated if hyponatremia and increased BNP occur after TBI and if BNP is produced/released by the brain within 24 h after injury.

RESULTS

NT-proBNP was measured in concomitant jugular venous and arterial blood samples within 24 h after TBI. NT-proBNP was elevated in both samples in six patients (24%). One patient (4%) showed an increased jugular NT-proBNP concentration above a normal arterial concentration, suggesting a brain source. In the other 24 patients the difference between jugular and arterial NT-proBNP was not statistically significant. Hyponatremia (< or =136 mEq/l) also occurred in six patients (24%), but only two (8%) had both increased arterial NT-proBNP and hyponatremia. In both the urine sodium was slightly elevated above normal, but not statistically different from other patients. The difference in serum sodium between hypo- and normo-natremic groups was significant, but mean NT-proBNP and jugular:arterial NT-proBNP differences were not.

CONCLUSIONS

In this pilot study BNP is elevated within 24 h after TBI in some patients. However, it does not originate from the brain and increased NT-proBNP concentrations are not consistently associated with hyponatremia or increased urinary sodium loss.