Plasma concentrations of brain natriuretic peptide in patients with subarachnoid hemorrhage

Prevention and Correction of Dysnatremia After Aneurysmal Subarachnoid Hemorrhage

BACKGROUND

Dysnatremia occurs commonly in patients with aneurysmal subarachnoid hemorrhage (aSAH). The mechanisms for development of sodium dyshomeostasis are complex, including the cerebral salt-wasting syndrome, the syndrome of inappropriate secretion of antidiuretic hormone, diabetes insipidus. Iatrogenic occurrence of altered sodium levels plays a role, as sodium homeostasis is tightly linked to fluid and volume management.

METHODS

Narrative review of the literature.

RESULTS

Many studies have aimed to identify factors predictive of the development of dysnatremia, but data on associations between dysnatremia and demographic and clinical variables are variable. Furthermore, although a clear relationship between serum sodium serum concentrations and outcomes has not been established-poor outcomes have been associated with both hyponatremia and hypernatremia in the immediate period following aSAH and set the basis for seeking interventions to correct dysnatremia. While sodium supplementation and mineralocorticoids are frequently administered to prevent or counter natriuresis and hyponatremia, evidence to date is insufficient to gauge the effect of such treatment on outcomes.

CONCLUSIONS

In this article, we reviewed available data and provide a practical interpretation of these data as a complement to the newly issued guidelines for management of aSAH. Gaps in knowledge and future directions are discussed.

Donor heart selection: Evidence-based guidelines for providers

The proposed donor heart selection guidelines provide evidence-based and expert-consensus recommendations for the selection of donor hearts following brain death. These recommendations were compiled by an international panel of experts based on an extensive literature review.

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.

Hyponatraemia and hypernatraemia: Disorders of Water Balance in Neurosurgery

Disorders of tonicity, hyponatraemia and hypernatraemia, are common in neurosurgical patients. Tonicity is sensed by the circumventricular organs while the volume state is sensed by the kidney and peripheral baroreceptors; these two signals are integrated in the hypothalamus. Volume is maintained through the renin-angiotensin-aldosterone axis, while tonicity is defended by arginine vasopressin (antidiuretic hormone) and the thirst response. Edelman found that plasma sodium is dependent on the exchangeable sodium, potassium and free-water in the body. Thus, changes in tonicity must be due to disproportionate flux of these species in and out of the body. Sodium concentration may be measured by flame photometry and indirect, or direct, ion-sensitive electrodes. Only the latter method is not affected by changes in plasma composition. Classification of hyponatraemia by the volume state is imprecise. We compare the tonicity of the urine, given by the sodium potassium sum, to that of the plasma to determine the renal response to the dysnatraemia. We may then assess the activity of the renin-angiotensin-aldosterone axis using urinary sodium and fractional excretion of sodium, urate or urea. Together, with clinical context, these help us determine the aetiology of the dysnatraemia. Symptomatic individuals and those with intracranial catastrophes require prompt treatment and vigilant monitoring. Otherwise, in the absence of hypovolaemia, free-water restriction and correction of any reversible causes should be the mainstay of treatment for hyponatraemia. Hypernatraemia should be corrected with free-water, and concurrent disorders of volume should be addressed. Monitoring for overcorrection of hyponatraemia is necessary to avoid osmotic demyelination.

Plasma brain natriuretic peptide level on admission predicts long-term outcome in patients with non-traumatic subarachnoid hemorrhage

INTRODUCTION

Non-traumatic subarachnoid hemorrhage (SAH) is a type of stroke that still has a high mortality rate. Some patients with SAH have electrocardiography (ECG) abnormalities or asymptomatic left ventricular apical ballooning, and requires intervention by cardiologists. However, the impact of cardiac abnormalities after SAH onset remains unclear. We investigated whether ECG abnormalities, myocardial damage, sympathetic nervous activity or echocardiographic left ventricular wall motion abnormalities (WMA) could provide additional risk stratification in patients with SAH.

METHODS

We studied 118 SAH patients (78 women, age 63 ± 15) without a history of heart disease. Neurological grade (Hunt and Kosnik Grade) and clinical factors were evaluated. A standard 12-lead ECG, echocardiography and blood samples were obtained within 48 h after SAH onset. ECG abnormalities were defined as abnormal Q wave, ST elevation, giant T-wave inversion or QT prolongation.

RESULTS

Twenty of 118 patients (17%) died during the follow-up (35 ± 31 months). Death was significantly associated with higher age (p < 0.0001), neurological grade (p < 0.0001), elevated BNP level (p < 0.0001), increased plasma norepinephrine levels (p < 0.0001) and WMA (p = 0.0070), while ECG abnormalities were not significantly associated. Neurological grade (p < 0.0001), age (p = 0.0047) and BNP (p = 0.0014, hazard ratio 1.0255 for each 1 pg/mL increase in BNP, 95%CI 1.0088 to 1.0499) were independently associated with death. Patients with BNP ≥ 96.6 had a higher risk of death (log- rank p < 0.0001).

CONCLUSION

Plasma BNP might provide an additional risk stratification in patients with non-traumatic SAH that requires intervention by cardiologists for both its prevention management after onset.

Mechanism of Hyponatremia in Community-Acquired Pneumonia: Does B-type Natriuretic Peptide Play a Causative Role?

OBJECTIVE

Hyponatremia is a well-known sequela of community-acquired pneumonia (CAP). B-type natriuretic peptide (BNP) has a natriuretic effect and was found to be elevated in patients with CAP. We investigated whether BNP has a role in the pathophysiology of hyponatremia in pediatric CAP.

METHODS

Serum and urine electrolytes and osmolality, as well as NT-pro-BNP (N-BNP), were obtained in 49 hospitalized pediatric patients with CAP (29 with hyponatremia, 20 with normal sodium levels.

RESULTS

Urine sodium levels were lower in the hyponatremic group compared with the normonatremic group (24.3 meq/L vs 66.7 meq/L, P = 0.006). No difference in N-BNP levels was found between groups (median, 103.8 vs 100.1; P = 0.06; interquartile range, 63.7-263.3 pg/mL vs 47.4-146.4 pg/mL). N-BNP was not associated with serum or urinary sodium levels.

CONCLUSIONS

These results indicate that BNP is unlikely to play a causative role in the mechanism of hyponatremia in CAP.

Hyponatremia is a potential predictor of progression in radiation-induced brain necrosis: a retrospective study

Background

To investigate the prognostic value of hyponatremia, defined as serum sodium level < 135 mEq/L, in radiation-induced brain necrosis (RN) patients.

Methods

We performed a retrospective analysis of the RN patients (The patients included in our study had a history of primary cancers including nasopharyngeal carcinoma/glioma/oral cancer and received radiotherapy previously and then were diagnosed with RN) treated in Sun yat-sen Memorial Hospital from January 2013 to August 2015. Patients without cranial magnetic resonance imaging (MRI) scan and serum sodium data were excluded. Progression was identified when the increase of edema area ≥ 25% on the MRI taken in six months comparing with those taken at the baseline. Factors that might associate with prognosis of RN were collected. Multivariable logistic regression analyses were used to identify potential predictors.

Results

We total included 135 patients, 32 (23.7%) of them with hyponatremia and 36 (26.7%) with RN progression. Percentage of progression was roughly three fold in hyponatremia patients compared with nonhyponatremia patients (53.1% versus 18.4%), translating into a 5-fold increased odds ratio (P <  0.001). Multivariable analyses identified hyponatremia as a potential predictor of progression (OR, 4.82; 95% CI [1.94–11.94]; P = 0.001).

Conclusions

Hyponatremia was identified as a potential predictor for the progression of patients with RN. Hyponatremia management in patients with RN should be paid much more concern in clinical practice.

Acute Cardiac Complications in Critical Brain Disease

Acute cardiac complications in critical brain disease should be understood as a clinical condition representing an intense brain-heart crosstalk and might mimic ischemic heart disease. Two main entities (neurogenic stunned myocardium [NSM] and stress cardiomyopathy) have been better characterized in the neurocritically ill patients and they portend worse clinical outcomes in these cases. The pathophysiology of NSM remains elusive. However, significant progress has been made on the early identification of neurocardiac compromise following acute critical brain disease. Effective prevention and treatment interventions are yet to be determined.

Acute Cardiac Complications in Critical Brain Disease

Acute cardiac complications in critical brain disease should be understood as a clinical condition representing an intense brain-heart crosstalk and might mimic ischemic heart disease. Two main entities (neurogenic stunned myocardium [NSM] and stress cardiomyopathy) have been better characterized in the neurocritically ill patients and they portend worse clinical outcomes in these cases. The pathophysiology of NSM remains elusive. However, significant progress has been made on the early identification of neurocardiac compromise following acute critical brain disease. Effective prevention and treatment interventions are yet to be determined.

Altered vasopressin and natriuretic peptide levels in a rat model of spinal cord injury: implications for the development of polyuria

Urinary dysfunction is a common complaint following spinal cord injury (SCI) and is a leading issue for individuals with SCI that impacts their quality of life. One urinary complication that has received little attention is SCI-induced polyuria, even though individuals with SCI will significantly restrict their fluid intake to decrease urine production, leading to sequelae of medical complications. Understanding the mechanisms instigating the development of polyuria will allow us to target interventions that may alleviate polyuria symptoms, leading to significant improvements in the quality of life and urinary health of individuals with SCI. In a rat SCI contusion model, an increase in the amount of urine excreted over a 24-h period ( P ≤ 0.001) was found at 2 wk postinjury. The urine excreted was more dilute with decreased urinary creatinine and specific gravity ( P ≤ 0.001). Several factors important in fluid balance regulation, vasopressin (AVP), natriuretic peptides, and corticosterone (CORT), also changed significantly postinjury. AVP levels decreased ( P = 0.042), whereas atrial natriuretic peptide (ANP) and CORT increased ( P = 0.005 and P = 0.031, respectively) at 2 wk postinjury. There was also a positive correlation between the increase in ANP and urine volume postinjury ( P = 0.033). The changes in AVP, ANP, and CORT are conducive to producing polyuria, and the timing of these changes coincides with the development of SCI-induced polyuria. This study identifies several therapeutic targets that could be used to ameliorate polyuria symptoms and improve quality of life in individuals with SCI.

Exophytic bulbar pilocytic astrocytoma and post-operative cerebral salt wasting syndrome

Cerebral salt wasting syndrome (CSWS) is a well-described consequence of several neurological disorders. Although the exact etiology of CSWS is still not completely elucidated, it is believed that the hypothalamus plays a pivotal role in the genesis of this disorder. We report for the first time 3 cases of CSWS occurring during the post-operative course following surgical resection of exophytic bulbar pilocytic astrocytomas in children. Since these 3 cases shared in common a medial implication of the medulla, we suggest that specific interconnectivity between the dorso-medial portion of the medulla oblongata and the hypothalamus might thus represent an anatomical pathway of interest in the pathogenesis of CSWS. Our findings suggest that the resection of medially located exophytic bulbar tumors might constitutes a risk factor in the development of CSWS. Particular care should thus be carried towards the prompt detection and treatment of CSWS in the post-operative courses of exophytic bulbar tumors.

Cerebral salt wasting following traumatic brain injury

Summary

Hyponatraemia is the most commonly encountered electrolyte disturbance in neurological high dependency and intensive care units. Cerebral salt wasting (CSW) is the most elusive and challenging of the causes of hyponatraemia, and it is vital to distinguish it from the more familiar syndrome of inappropriate antidiuretic hormone (SIADH). Managing CSW requires correction of the intravascular volume depletion and hyponatraemia, as well as mitigation of on-going substantial sodium losses. Herein we describe a challenging case of CSW requiring large doses of hypertonic saline and the subsequent substantial benefit with the addition of fludrocortisone.

Learning points:

The Neurocardiogenic Spectrum in Subarachnoid Hemorrhage: A Case Report and Review of the Literature

A 36-year-old man was brought to our emergency department after successful resuscitation of out-of-hospital cardiac arrest with the whole spectrum of neurocardiogenic effects in subarachnoid hemorrhage: electrocardiographic changes, regional wall motion abnormalities, and elevations of cardiac enzymes. Coronary angiography revealed normal coronary arteries but showed the midventricular type of Takotsubo cardiomyopathy in the left ventriculography. Subsequently, cerebral computed tomography revealed diffuse subarachnoid hemorrhage and generalized cerebral edema with brain herniation. Brain death was diagnosed. This case highlights the possibility of an acute cerebral illness (especially subarachnoid hemorrhage) as an underlying cause of cardiac abnormalities mimicking myocardial ischemia.

N-terminal pro-brain natriuretic peptide levels and short term prognosis in acute ischemic stroke

BACKGROUND

Sparse published data are available regarding the prognostic importance of plasma N-terminal pro-brain natriuretic peptide (NT-proBNP) in patients with acute ischemic stroke.

MATERIALS AND METHODS

We prospectively studied 74 consecutive patients presenting with acute ischemic stroke within 24 hours of onset. All of them underwent laboratory and imaging evaluation and were treated as per guidelines. In all subjects, plasma NT-proBNP levels were measured at initial admission and again on day 7.

RESULTS

Their mean age was 54 ± 13.5years; there were 49 males; 18 (24%) patients died during the hospital stay. A statistically significant negative correlation between log NT-proBNP and Glasgow coma scale (GCS) score (P < 0.001); and a significant positive correlation between log NT-proBNP and National Institutes of Health Stroke Scale (NIHSS) score (P < 0.001) were observed. Baseline log NT-proBNP levels were higher among non-survivors compared with survivors (6.7 ± 0.47 vs. 5.37 ± 0.62; P = 0.06); day 7 log NT-proBNP levels were significantly higher in non-survivors compared with survivors (7.3 ± 0.26 vs. 4.5 ± 0.4; P = 0.000). In survivors, there was a statistically significant decline in log NT-proBNP levels from baseline to day 7 (5.3710 ± 0.620 vs. 4.5320 ± 0.451; P < 0.001). In contrast, among non-survivors, log NT-proBNP levels showed a statistically significant increase from baseline to day 7 (4.5322 ± 0.451 vs. 7.2992 ± 0.263; P < 0.001). On receiver operator characteristic curve (ROC) analysis, at a cut-off value of ≥ 6.0661, log NT-proBNP had a sensitivity and specificity of 98.2 and 88.9, respectively, in predicting death.

CONCLUSIONS

Plasma log NT-pro-BNP level appears to be a useful biological marker for predicting in-hospital mortality inpatients presenting with acute ischemic stroke.

Cerebral salt wasting after traumatic brain injury: a review of the literature

Electrolyte imbalances are common among patients with traumatic brain injury (TBI). Cerebral salt wasting (CSW) is an electrolyte imbalance characterized by hyponatremia and hypovolemia. Differentiating the syndrome of inappropriate antidiuretic hormone and CSW remains difficult and the pathophysiological mechanisms underlying CSW are unclear. Our intent was to review the literature on CSW within the TBI population, in order to report the incidence and timing of CSW after TBI, examine outcomes, and summarize the biochemical changes in patients who developed CSW. We searched MEDLINE through 2014, hand-reviewed citations, and searched abstracts from the American Association for the Surgery of Trauma (2003-2014). Publications were included if they were conducted within a TBI population, presented original data, and diagnosed CSW. Publications were excluded if they were review articles, discussed hyponatremia but did not differentiate the etiology causing hyponatremia, or presented cases with chronic disease. Fifteen of the 47 publications reviewed met the selection criteria; nine (60%) were case reports, five (33%) were prospective and 1 (7%) was a retrospective study. Incidence of CSW varied between 0.8 - 34.6%. The populations studied were heterogeneous and the criteria used to define hyponatremia and CSW varied. Though believed to play a role in the development of CSW, increased levels of natriuretic peptides in patients diagnosed with CSW were not consistently reported. These findings reinforce the elusiveness of the CSW diagnosis and the need for strict and consistent diagnostic criteria.

Hyponatremia in the intensive care unit: How to avoid a Zugzwang situation?

Hyponatremia is a common electrolyte derangement in the setting of the intensive care unit. Life-threatening neurological complications may arise not only in case of a severe (<120 mmol/L) and acute fall of plasma sodium levels, but may also stem from overly rapid correction of hyponatremia. Additionally, even mild hyponatremia carries a poor short-term and long-term prognosis across a wide range of conditions. Its multifaceted and intricate physiopathology may seem deterring at first glance, yet a careful multi-step diagnostic approach may easily unravel the underlying mechanisms and enable physicians to adopt the adequate measures at the patient’s bedside. Unless hyponatremia is associated with obvious extracellular fluid volume increase such as in heart failure or cirrhosis, hypertonic saline therapy is the cornerstone of the therapeutic of profound or severely symptomatic hyponatremia. When overcorrection of hyponatremia occurs, recent data indicate that re-lowering of plasma sodium levels through the infusion of hypotonic fluids and the cautious use of desmopressin acetate represent a reasonable strategy. New therapeutic options have recently emerged, foremost among these being vaptans, but their use in the setting of the intensive care unit remains to be clarified.

Admission B-type natriuretic peptide levels are associated with in-hospital cardiac events in patients with intracranial hemorrhage

BACKGROUND

Intracranial hemorrhage (ICH) is often associated with cardiac events. Twelve-lead electrocardiography (ECG) and transthoracic echocardiography are essential diagnostic tools for preoperative risk assessment. B-type natriuretic peptide (BNP) is a well-known predictor of cardiac outcome in various clinical settings. This study examined whether BNP levels on admission are associated with in-hospital cardiac events among ICH patients.

METHOD

This prospective study enrolled 77 ICH patients who were admitted to this hospital for emergency neurosurgery. On admission, BNP levels, 12-lead ECG and transthoracic echocardiography were carried out for all patients. These patients were divided into two groups: Group I included 19 patients (10 men and 9 women) having 24 in-hospital cardiac events (mean age of 57 ± 15 years); Group II included 57 patients (29 men, mean age of 71 ± 11 years) without cardiac events.

RESULTS

Admission BNP levels of Group I patients were significantly higher than those of Group II patients (683.8 ± 1,043.8 pg/ml vs 168.5 ± 173.5 pg/ml, p = 0.001). In multivariate analysis, BNP levels and T-wave inversion are independent predictors of in-hospital cardiac events. A cutoff value of BNP levels (156.6 pg/ml) predicted in-hospital cardiac events in ICH patients with 80 % sensitivity and 66 % specificity.

CONCLUSIONS

Serum BNP levels and electrocardiographic T-wave inversion on admission are independent predictors of in-hospital cardiac events in patients with ICH who undergo emergency neurosurgery.

Incidence, Etiology and Outcomes of Hyponatremia after Transsphenoidal Surgery: Experience with 344 Consecutive Patients at a Single Tertiary Center

Hyponatremia is often seen after transsphenoidal surgery and is a source of considerable economic burden and patient-related morbidity and mortality. We performed a retrospective review of 344 patients who underwent transsphenoidal surgery at our institution between 2006 and 2012. Postoperative hyponatremia was seen in 18.0% of patients at a mean of 3.9 days postoperatively. Hyponatremia was most commonly mild (51.6%) and clinically asymptomatic (93.8%). SIADH was the primary cause of hyponatremia in the majority of cases (n = 44, 71.0%), followed by cerebral salt wasting (n = 15, 24.2%) and desmopressin over-administration (n = 3, 4.8%). The incidence of postoperative hyponatremia was significantly higher in patients with cardiac, renal and/or thyroid disease (p = 0.0034, Objective Risk (OR) = 2.60) and in female patients (p = 0.011, OR = 2.18) or patients undergoing post-operative cerebrospinal fluid drainage (p = 0.0006). Treatment with hypertonic saline (OR = −2.4, p = 0.10) and sodium chloride tablets (OR = −1.57, p = 0.45) was associated with a non-significant trend toward faster resolution of hyponatremia. The use of fluid restriction and diuretics should be de-emphasized in the treatment of post-transsphenoidal hyponatremia, as they have not been shown to significantly alter the time-course to the restoration of sodium balance.

Biomarkers and acute brain injuries: interest and limits

For patients presenting with acute brain injury (such as traumatic brain injury, subarachnoid haemorrhage and stroke), the diagnosis and identification of intracerebral lesions and evaluation of the severity, prognosis and treatment efficacy can be challenging. The complexity and heterogeneity of lesions after brain injury are most probably responsible for this difficulty. Patients with apparently comparable brain lesions on imaging may have different neurological outcomes or responses to therapy. In recent years, plasmatic and cerebrospinal fluid biomarkers have emerged as possible tools to distinguish between the different pathophysiological processes. This review aims to summarise the plasmatic and cerebrospinal fluid biomarkers evaluated in subarachnoid haemorrhage, traumatic brain injury and stroke, and to clarify their related interests and limits for diagnosis and prognosis. For subarachnoid haemorrhage, particular interest has been focused on the biomarkers used to predict vasospasm and cerebral ischaemia. The efficacy of biomarkers in predicting the severity and outcome of traumatic brain injury has been stressed. The very early diagnostic performance of biomarkers and their ability to discriminate ischaemic from haemorrhagic stroke were studied.

Brain-heart crosstalk: the many faces of stress-related cardiomyopathy syndromes in anaesthesia and intensive care

Neurogenic stress cardiomyopathy (NSC) is a well-known syndrome complicating the early phase after an acute brain injury, potentially affecting outcomes. This article is a review of recent data on the putative role of localization and lateralization of brain lesions in NSC, cardiac innervation abnormalities, and new polymorphisms and other genetic causes of the sympathetic nervous system over-activity. Concerns regarding the management of stress-related cardiomyopathy syndromes during the perioperative period are also discussed. Future clinical research should explore whether specific factors explain different patient susceptibilities to the disease and should be directed towards early identification and stratification of patients at risk, so that such patients can be more carefully monitored and appropriately managed in critical care and during the perioperative period.

Predictors of increased cumulative serum levels of the N-terminal prohormone of brain natriuretic peptide 4 days after acute spontaneous subarachnoid hemorrhage

Object

The rupture of an intracranial aneurysm is followed by increased intracranial pressure and decreased cerebral blood flow. A major systemic stress reaction follows, presumably to restore cerebral blood flow. However, this reaction can also cause adverse effects, including myocardial abnormalities, which are common and can be serious, and increased levels of natriuretic peptides, especially brain natriuretic peptide (BNP). The association of BNP with fluid and salt balance, vasospasm, brain ischemia, and cardiac injury has been studied but almost exclusively regarding events after admission. Brain natriuretic peptide has also been measured at various time points and analyzed in different ways statistically. The authors approached BNP measurement in a new way; they used the calculated area under the curve (AUC) for the first 4 days to quantitatively measure the BNP load during the first critical part of the disease state. Their rationale was a suspicion that early BNP load is a marker of the severity of the ictus and will influence the subsequent course of the disease by disturbing the fluid and salt balance.

Methods

The study included 156 patients with acute spontaneous subarachnoid hemorrhage (SAH). Mean patient age was 59.8 ± 11.2 years, and 105 (67%) of the patients were female. An aneurysm was found in 138 patients. A total of 82 aneurysms were treated by endovascular coiling, 50 were treated by surgery, and 6 were untreated. At the time of admission, serum samples were collected for troponin-I analysis and for the N-terminal prohormone of BNP (NT-proBNP); daily thereafter, samples were collected for the NT-proBNP analysis. The cumulative BNP load was calculated as the AUC for NT-proBNP during the first 4 days. The following variables were studied in terms of their influence on the AUC for NT-proBNP: sex, age, World Federation of Neurosurgical Societies grade of SAH, Fisher grade, angiographic result, treatment of aneurysm, clinical neurological deterioration, verified infections, vasospasm treatment, and 6-month outcome.

Results

The AUC for NT-proBNP was larger when variables indicated a more severe SAH. These variables were higher Fisher and World Federation of Neurosurgical Societies grades, high levels of troponin-I at admission, an aneurysm, neurological deficits, and infections. The AUC for NT-proBNP was also larger among women, older patients, and patients with poor outcomes. Linear regression showed that the best predicting model for large AUC for NT-proBNP was the combination of the following: female sex, high levels of troponin-I, an aneurysm, neurological deficits, and advanced age.

Conclusions

The cumulative BNP load during the first days after SAH can be predicted by variables describing the severity of the disease already known at the time of admission. This information can be used to identify patients at risk for an adverse course of the disease.

Treatment of endocrine disorders in the neuroscience intensive care unit

OPINION STATEMENT

This review discusses concepts and treatments associated with the most clinically relevant areas of acute endocrine dysfunction amongst patients with common diseases in neuroscience intensive care units (Neuro ICUs). We highlight the following points:• While a thorough work-up for hyponatremia when it is present is always warranted, subarachnoid hemorrhage (SAH) patients who are in a time window concerning for cerebral vasospasm and who are hyponatremic with high urine output are generally thought to have cerebral salt wasting. These patients are typically treated with a combination of continuous hypertonic saline infusion and fludrocortisone.• Diabetes insipidus (DI) is often seen in patients fulfilling death by neurological criteria, as well as in patients with recent pituitary surgery and less often in SAH and traumatic brain injury patients who are not brain dead. Patients with DI in the Neuro ICU often cannot drink to thirst and may require a combination of desmopression/vasopressin administration, aggressive fluid repletion, and serum sodium monitoring.• Diagnosing adrenal insufficiency immediately following pituitary injury is complicated by the fact that the expected atrophy of the adrenal glands, due to lack of a stimulus from pituitary adrenocorticotropic hormone, may take up to 6 weeks to develop. Cosyntropin testing can be falsely normal during this period.• Both hyperglycemia (glucose >200 mg/dL) and hypoglycemia (glucose <50 mg/dL) are strongly associated with neurological morbidity and mortality in ICUs and should be avoided. Glucose concentrations between 120-160 mg/dL can serve as a reasonable target for insulin infusion protocols.• There is no data to suggest that treatment of abnormal thyroid function tests in nonthyroidal illness syndrome/sick euthyroid leads to benefits in either mortality or morbidity. True myxedema coma is a rare clinical diagnosis that is treated with intravenous levothyroxine accompanied by stress-dose steroids.

Brain natriuretic peptide in acute ischemic stroke

Elevated serum brain natriuretic peptide (BNP) levels are associated with cardioembolic stroke mainly because of atrial fibrillation (AF). However, the mechanisms of increased serum BNP levels are hitherto unclear. We aimed to identify the factors associated with increased BNP levels in patients with acute ischemic stroke. We measured serum BNP levels in consecutive patients aged 18 years or older. Stroke subtypes were classified using the Trial of ORG 10172 in Acute Stroke Treatment criteria. Categorical variables included age, sex, smoking status, alcohol consumption status, hypertension, diabetes mellitus, dyslipidemia, coronary artery disease (CAD), AF, antiplatelet therapy, and anticoagulant therapy. Continuous variables included hemoglobin, creatinine (Cr), β-thromboglobulin, platelet factor 4, thrombin-antithrombin complex, and d-dimer levels. We further determined the relationship between serum BNP and intima-media thickness, left ventricular ejection fraction, size of infarction, National Institutes of Health Stroke Scale score on admission, and modified Rankin Scale (mRS) score at discharge. Of the 231 patients (mean age, 71 ± 12 years) with acute ischemic stroke (AIS), 36% were women. Serum BNP levels significantly correlated with CAD, AF, Cr, mRS, and cardioembolism (CE) (Dunnett method, P = .004). BNP levels were significantly higher in patients with larger infarcts, higher mRS scores, and higher CHADS2 scores. The levels were higher in patients with larger infarcts, higher mRS scores at discharge, and higher CHADS2 scores among AF patients.

Pituitary dysfunction after aneurysmal subarachnoid hemorrhage

Patients recovering from aneurysmal SAH often complain about weakness, fatigue and impaired cognitive skills. Pituitary dysfunction might be one possible reason for these complaints, as in patients with traumatic brain injury, hypopituitarism is known to be a common complication. There are only a few studies dealing with this problem in SAH patients, but these studies suggest that pituitary disturbances are very frequent after aneurysmal SAH. But anterior pituitary lobe disturbances might not be the only one responsible for some complaints or complications in patients suffering from aneurysmal SAH. Hyponatremia in the early state after SAH could be a hint for posterior pituitary lobe dysfunction.

High plasma concentration of brain natriuretic peptide in patients with ruptured anterior communicating artery aneurysm

The purpose of this study is to investigate the mechanism of increased atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) in patients with subarachnoid hemorrhage due to ruptured aneurysms. ANP and BNP plasma concentrations were measured by immunoradiometoric assay in 53 patients at the day of onset of ruptured aneurysm, the correlation between values of increased ANP or BNP, and sex, age, location of ruptured aneurysm, degree of SAH, and severity of WFNS were statistically studied. The concentration of BNP in ruptured anterior communicating artery aneurysm (A-com) shows a significant elevation compared with other site aneurysms (p = 0.0007). The patients classified as WFNS Grade V, show a significantly higher concentration of BNP, compared with the patients classified as Grade I-IV (p =0.01). It is concluded that the hypersecretion of BNP, but not ANP, is caused by direct mechanical damage at the anterior hypothalamus by ruptured A-com aneurysm and a higher increase of BNP is also observed in cases suffering from severe neurological deficit.

Clinical and predictive significance of hyponatremia after aneurysmal subarachnoid hemorrhage

OBJECTIVE

Hyponatremia after SAH was the object of several studies with conflicting results. The aim of this study was to determine a predictive correlation of hyponatremia with delayed cerebral ischemia (DCI) and poor clinical outcome.

MATERIAL AND METHODS

We have used a retrospective hospital chart review of 82 patients with SAH treated from August 2008 to August 2010. Patients were divided into hyponatremia and normonatremia groups. Hyponatremia was defined as serum sodium level <135 mmol/l. Information compared and analyzed included demographics, preoperative neurological status, aneurysm characteristics, postoperative intensive care, duration of stay, DCI and clinical outcome at hospital discharge. P<0.05 was considered significant.

RESULTS

Thirty-two patients with SAH (39%) developed hyponatremia. In that group we had a significantly higher WFNS score at admission (p=0.03) and longer duration of stay in intensive care (p=0.001). DCI with transit or definitive deficit included 20 patients (62%) in the hyponatremia group, and 19 patients (38%) in the normonatremia group (p=0.03). Binary enter logistic regression revealed a significant correlation of hyponatremia with DCI (p=0.03) and poor clinical outcome (p=0.001).

CONCLUSION

This result revealed a possible use of hyponatremia as an additional predictor of developing DCI and poor clinical outcome.

The importance of early brain injury after subarachnoid hemorrhage

Aneurysmal subarachnoid hemorrhage (aSAH) is a medical emergency that accounts for 5% of all stroke cases. Individuals affected are typically in the prime of their lives (mean age 50 years). Approximately 12% of patients die before receiving medical attention, 33% within 48 h and 50% within 30 days of aSAH. Of the survivors 50% suffer from permanent disability with an estimated lifetime cost more than double that of an ischemic stroke. Traditionally, spasm that develops in large cerebral arteries 3-7 days after aneurysm rupture is considered the most important determinant of brain injury and outcome after aSAH. However, recent studies show that prevention of delayed vasospasm does not improve outcome in aSAH patients. This finding has finally brought in focus the influence of early brain injury on outcome of aSAH. A substantial amount of evidence indicates that brain injury begins at the aneurysm rupture, evolves with time and plays an important role in patients' outcome. In this manuscript we review early brain injury after aSAH. Due to the early nature, most of the information on this injury comes from animals and few only from autopsy of patients who died within days after aSAH. Consequently, we began with a review of animal models of early brain injury, next we review the mechanisms of brain injury according to the sequence of their temporal appearance and finally we discuss the failure of clinical translation of therapies successful in animal models of aSAH.

Hyponatremia is predictable in patients with aneurysmal subarachnoid hemorrhage--clinical significance of serum atrial natriuretic peptide

PURPOSE

Serum atrial natriuretic peptide (ANP) that is elevated after aneurysmal subarachnoid hemorrhage (SAH) causes diuresis and natriuresis (cerebral salt wasting) and might exacerbate delayed ischemic neurological deficit (DIND). We investigated relationships among hyponatremia, serum ANP elevation, and the onset of DIND after SAH.

MATERIALS AND METHODS

Thirty-nine consecutive patients (15 women and 24 men) with SAH were assigned to a normonatremia group or a group that developed hyponatremia after SAH. Serum ANP and brain natriuretic peptide were assessed after SAH. All patients remained normovolemic and normotensive. We attributed DIND to vasospasm only in the absence of other causes and when supported by cerebral angiography.

RESULTS

Hyponatremia developed after SAH in 11 patients (28.2%), among whom serum ANP concentrations at 0 and 3 days thereafter were significantly increased. Furthermore, DIND developed in five (45.5%) and two (7.1%) hyponatremic and normonatremic patients, respectively (P < 0.05). The serum ANP levels on day 0 after SAH were higher in Hunt and Kosnik grades 3-4 than in 1-2 and in Fisher groups 3-4 than in 1-2 (P < 0.05).

CONCLUSIONS

Increasing serum ANP concentrations were independently associated with hyponatremia resulting in DIND. Early treatment of hyponatremia might prevent DIND in patients after SAH.

Cerebral salt wasting: pathophysiology, diagnosis, and treatment

Cerebral salt wasting (CSW) is a syndrome of hypovolemic hyponatremia caused by natriuresis and diuresis. The mechanisms underlying CSW have not been precisely delineated, although existing evidence strongly implicates abnormal elevations in circulating natriuretic peptides. The key in diagnosis of CSW lies in distinguishing it from the more common syndrome of inappropriate secretion of antidiuretic hormone. Volume status, but not serum and urine electrolytes and osmolality, is crucial for making this distinction. Volume and sodium repletion are the goals of treatment of patients with CSW, and this can be performed using some combination of isotonic saline, hypertonic saline, and mineralocorticoids.

Hyponatremia in neurosurgical patients: clinical guidelines development

OBJECTIVE

Neurosurgical patients have a high risk of hyponatremia and associated complications. We critically evaluated the existing literature to identify the determinants for the development of hyponatremia and which management strategies provided the best outcomes.

METHODS

A multidisciplinary panel in the areas of neurosurgery, nephrology, critical care medicine, endocrinology, pharmacy, and nursing summarized and classified hyponatremia literature scientific studies published in English from 1950 through 2008. The panel's recommendations were used to create an evaluation and treatment protocol for hyponatremia in neurosurgical patients at the University of Florida.

RESULTS

Hyponatremia should be further investigated and treated when the serum sodium level is less than 131 mmol/L (class II). Evaluation of hyponatremia should include a combination of physical examination findings, basic laboratory studies, and invasive monitoring when available (class III). Obtaining levels of hormones such as antidiuretic hormone and natriuretic peptides is not supported by the literature (class III). Treatment of hyponatremia should be based on severity of symptoms (class III). The serum sodium level should not be corrected by more than 10 mmol/L/d (class III). Cerebral salt wasting should be treated with replacement of serum sodium and intravenous fluids (class III). Fludrocortisone may be considered in the treatment of hyponatremia in subarachnoid hemorrhage patients at risk of vasospasm (class I). Hydrocortisone may be used to prevent natriuresis in subarachnoid hemorrhage patients (class I). Hyponatremia in subarachnoid hemorrhage patients at risk of vasospasm should not be treated with fluid restriction (class II). Syndrome of inappropriate antidiuretic hormone may be treated with urea, diuretics, lithium, demeclocycline, and/or fluid restriction (class III).

CONCLUSION

The summarized literature on the evaluation and treatment of hyponatremia was used to develop practice management recommendations for hyponatremia in the neurosurgical population. However, the practice management recommendations relied heavily on expert opinion because of a paucity of class I evidence literature on hyponatremia.

Clinical significance of elevated natriuretic peptide levels and cardiopulmonary parameters after subarachnoid hemorrhage

Daily changes in serum concentrations of natriuretic peptides and various cardiopulmonary parameters were measured after the onset of subarachnoid hemorrhage (SAH) to investigate the pathogenesis of the cardiac and pulmonary consequences in 15 patients with acute phase SAH, divided into the control group (n = 5) with consciousness continuously preserved from SAH onset to admission, and the consciousness disturbance group (n = 10). Daily changes in serum A-type and B-type natriuretic peptides (ANP and BNP, respectively) were measured for 10 days, and intrathoracic blood volume index and extravascular lung water index (EVLWI) were measured for 5 days by the single transpulmonary thermodilution method. Natriuretic peptides in the consciousness disturbance group showed significantly higher values during the 10-day period, with ANP 119.2 +/- 12.4 pg/ml (mean +/- standard error of the mean, p = 0.005) on day 2 and BNP 354.1 +/- 80.3 pg/ml (p = 0.009) on day 1. EVLWI showed higher values in the consciousness disturbance group compared to the control group throughout the 5-day period. The increases in natriuretic peptide levels and increase in pulmonary extravascular water content found in SAH patients with consciousness disturbance show that load on the left ventricle or atrium as well as pulmonary capillary pressure are increased immediately after onset, supporting the contention that excessive release of catecholamines occurs at this time.

Endocrine response after severe subarachnoid hemorrhage related to sodium and blood volume regulation

BACKGROUND

Hyponatremia is often associated with, and worsens, the prognosis of severe aneurysmal subarachnoid hemorrhage (SAH). Several possible endocrine perturbations of variable severity and variable sodium and water intake have been described in SAH. However, a comprehensive study of the different hormonal systems involved in sodium and water homeostasis and circulating blood volume modifications is still needed. Our aim was to assess water and sodium regulation after severe SAH by investigating blood volume and several hormonal regulatory systems in the context of hyponatremia prevention by controlled sodium intake.

METHODS

Nineteen mechanically ventilated patients with severe SAH, were prospectively studied. Replacement of sodium was at least 4.5 mmol x kg(-1) x d(-1) and adjusted on natriuresis. Hormones involved in electrolyte and water homeostasis: vasopressin, renin, angiotensin, aldosterone, and natriuretic peptides were assessed every 3 days for 12 days. Red blood cell volume was measured by the isotopic method (technetium-labeled red blood cells), in the first 48 h after admission and at day 7. Cardiac function was assessed using electrocardiogram, transthoracic echocardiography, and troponin Ic (cTnI). Outcome was assessed at 3 mo.

RESULTS

After SAH onset, hyponatremia, but not decreased circulating blood volume, was prevented by high sodium and water infusion adapted to renal excretion. The hormonal profiles were characterized by an increase in renin, angiotensin II, natriuretic peptide concentrations associated with increased troponin Ic, stable low levels of vasopressin, and the absence of increased aldosterone concentrations. There were no correlations between hormone concentrations and natriuresis.

CONCLUSION

After severe SAH, in the context of multiple clinical interventions, increased natriuresis and low blood volume are consistent with cerebral salt wasting syndrome, probably related to the sequence of severe SAH, highly increased sympathetic tone, hyperreninemic hypoaldosteronism syndrome, and increased natriuretic peptides release.

B-type natriuretic peptide release and left ventricular filling pressure assessed by echocardiographic study after subarachnoid hemorrhage: a prospective study in non-cardiac patients

INTRODUCTION

Serum B-type natriuretic peptide (BNP) is frequently elevated after subarachnoid hemorrhage (SAH), but whether this high BNP level is related to transient elevation of left ventricular filling pressure (LVFP) is unknown. However, in patients with preexistent cardiac pathologies, it is impossible to differentiate between BNP elevation caused by chronic cardiac abnormalities and BNP related to acute neurocardiac injury.

METHODS

All adult patients with SAH admitted to our intensive care unit were eligible. Patients were excluded for the following reasons: admission >48 hours after aneurysm rupture, pre-existing hypertension, or cardiac disease. Levels of BNP and cardiac troponin Ic were measured daily for 7 days. Echocardiography was performed by a blinded cardiologist on days 1, 2, and 7. Doppler signals from the mitral inflow, tissue Doppler, and the color M-mode-derived flow propagation velocity (FPV) were obtained to assess echo-estimated LVFP.

RESULTS

During a 3-year period, sixty-six consecutive patients with SAH were admitted. Thirty one patients were studied. The BNP level was >100 ng/L in 25 patients (80%) during the first 3 days, with a peak on day 2 (median, 126 ng/L) followed by a gradual decrease (median variation days 1 to 7, 70%). All patients had an ejection fraction >50%. Early transmitral velocity/tissue Doppler mitral annular early diastolic velocity was low: 5.4 (+/- 1.5) on day 1, 5.8 (+/- 1.2) on day 2, and 5.1 (+/- 0.9) on day 7. Early transmitral velocity/FPV was also low: 1.27 (+/- 0.4), 1.25 (+/- 0.3), and 1.1 (+/- 0.2) on days 1, 2, and 7, respectively. Cardiac troponin Ic levels ranged from 0 to 3.67 microg/L and were correlated with BNP (r = 0.63, P < 0.01).

CONCLUSIONS

BNP rises gradually over two days and return to normal within a week after SAH. Its release is associated with myocardial necrosis, but is unrelated to elevated LVFP assessed by echocardiography.

Prevalence and clinical demographics of cerebral salt wasting in patients with aneurysmal subarachnoid hemorrhage

Hyponatremia is a frequent complication following subarachnoid hemorrhage (SAH), and is commonly attributed either to the syndrome of inappropriate antidiuretic hormone secretion (SIADH) or cerebral salt wasting syndrome (CSW). The object of this study is to elucidate the clinical demographics and sequelae of hyponatremia due to CSW in subjects with aneurysmal SAH. Retrospective chart review of patients >18 years with aneurysmal SAH admitted between January 2004 and July 2007 was performed. Subjects with moderate to severe hyponatremia (serum sodium <130 mmol l(-1)) were divided into groups consistent with CSW and SIADH based on urine output, fluid balance, natriuresis, and response to saline infusion. Clinical demographics were compared. Of 316 subjects identified, hyponatremia (serum sodium <135 mmol l(-1)) was detected in 187 (59.2%) subjects and moderate to severe hyponatremia in 48 (15.2%). Of the latter group, 35.4% were categorized with SIADH and 22.9% with CSW. Compared to eunatremic subjects, hyponatremia was associated with significantly longer hospital stay (15.7 +/- 1.9 vs. 9.6 +/- 1.1 days, p < 0.001). Subjects with CSW had similar mortality and duration of hospital stay vs. those with SIADH. Though less common than SIADH, CSW was detected in approximately 23% of patients with history of aneurysmal SAH and was not clearly associated with enhanced morbidity and mortality compared to subjects with SIADH. Further studies regarding the pathogenesis and management, along with the medical consequences, of CSW are important.

Brain natriuretic peptide correlates with the extent of atrial fibrillation-associated silent brain lesions

OBJECTIVE

Identification of plasma markers indicative for atrial fibrillation-associated silent brain lesions.

DESIGN AND METHODS

1. Comparative determination of the plasma concentrations of secretagogin, S100B, neuropeptide Y, brain fatty acid binding protein, matrix metalloprotease 9, brain natriuretic peptide, and of D-Dimer in 222 patients with atrial fibrillation and 28 controls by immunoassays. 2. Correlation of the biochemical marker plasma concentration with the extent of silent white matter brain lesions, as determined by the Fazekas score and N-acetylaspartate-spectroscopy.

RESULTS

1. Plasma concentrations of brain natriuretic peptide, of neuropeptide Y, and of matrix metalloprotease 9 were significantly higher (all with a p<0.05) in patients suffering from atrial fibrillation than in control subjects. 2. Brain natriuretic peptide correlated significantly with the Fazekas score (R=0.41; p<0.005). 3. Brain natriuretic peptide plasma concentrations were significantly higher in patients with a pathological N-acetylaspartate magnetic resonance-spectrometry (p<0.05).

CONCLUSION

Brain natriuretic peptide plasma concentrations correlate with the extent of atrial fibrillation-associated silent brain lesions.

Cerebral salt wasting syndrome: review

Hyponatremia is the most frequent electrolyte disorder in critically neurological patients. Cerebral salt wasting syndrome (CSW) is defined as a renal loss of sodium during intracranial disease leading to hyponatremia and a decrease in extracellular fluid volume. The pathogenesis of this disorder is still not completely understood. Sympathetic responses as well as some natriuretic factors play a role in this syndrome. Distinction between SIADH and CSW might be difficult. The essential point is the volemic state. It is necessary to rule out other intermediate causes. Treatment requires volume replacement and maintenance of a positive salt balance. Mineral corticoids may be useful in complicated cases.

Plasmatic B-type natriuretic peptide and C-reactive protein in hyperacute stroke as markers of CT-evidence of brain edema

OBJECTIVE

Plasmatic B-type-natriuretic peptide (NT-PBNP) and C-reactive protein (CRP) have been reportedly elevated in stroke patients; however their clinical significance remains uncertain. The purpose of this work is to investigate whether elevation of these proteins at baseline predicts CT-evidence of brain edema.

METHODS

We recruited 41 consecutive patients with stroke and determined NT-PBNP and CRP at baseline (within 5 hours after onset), after 48-72 hours, and at discharge. Stroke severity was measured by means of the NIHS scale at baseline and at discharge. We also carried out brain CT at admittance and after 48 hours.

RESULTS

There were 29 ischemic strokes and 12 hemorrhagic strokes. Evidence of brain edema on delayed scan was seen in 14 patients. Baseline levels of NT-PBNP did not predict CT-evidence of edema but CRP levels did so significantly (0.7 mg/dl in patients without edema versus 4.7 mg in patients with edema; p=0.001). Both NT-PBNP and PC levels correlated poorly to NIHSS score and increased markedly from baseline to the second determination in patients with edema. For these patients the NT-PBNP increase was 133.6 pmol/l in comparison to 1.58 pmol/l in patients without edema (p=0.002). Neither CRP nor NT-PBNP baseline levels were predictive of dependency or death.

CONCLUSIONS

We conclude that CRP at baseline but not NT-PBNP predicts CT evidence of brain edema in stroke patients. We hypothesize that NT-PBNP levels elevated in response to edema after 48 hours of admission.