A study of atrial and brain natriuretic peptides in tuberculous meningitis and acute encephalitis

High Urinary Sodium Concentrations in Severe SIADH: Case Reports of 2 Patients and Literature Review

We present two cases of severe hyponatremia secondary to syndrome of inappropriate secretion of antidiuretic hormone (SIADH) with very high urine sodium concentrations (>130 mmol/L). The first patient had hyponatremia from traumatic brain injury (TBI) while the second case had a history of recurrent SIADH triggered by various causes including gastritis. In both cases, fluid administration and/or consumption worsened the hyponatremia. Although a low urine sodium of <30 mmol/L is highly suggestive of hypovolemic hyponatremia and good response to saline infusion, there is lack of clarity of the threshold of which high urine sodium concentration can differentiate various causes of natriuresis such as SIADH, renal or cerebral salt wasting. Apart from high urine osmolality (>500 mOsm/kg), persistence of high urine sodium concentrations may be useful to predict poor response to fluid restriction in SIADH. More studies are needed to delineate treatment pathways of patients with very high urine osmolality and urine sodium concentrations in SIADH.

Cerebral Salt-Wasting Syndrome in a Patient With Active Pulmonary Tuberculosis

A 37-year-old female with a medical history of recently diagnosed active pulmonary tuberculosis and a new intracranial lesion presented with altered mental status, nausea, and vomiting for two days. An initial physical examination revealed that the patient was euvolemic. Laboratory findings revealed a serum sodium concentration of 105 mEq/L. During her admission, she was initially managed with lactated ringer solution in the emergency department, followed by 3% normal saline in the intensive care unit, and, eventually, on oral sodium chloride and fluid restriction on discharge. Once she was stabilized, she had episodes of dizziness, and concerns were raised about the salt-wasting syndrome.

Clinical analysis of 103 cases of tuberculous meningitis complicated with hyponatremia in adults

OBJECTIVE

Tuberculous meningitis (TBM) is a common infection of the central nervous system. TBM with hyponatremia is very common. If hyponatremia is not treated properly, it might affect the outcome of TBM patients.

METHODS

We included 226 patients diagnosed with TBM who were admitted from August 2010 to August 2015 and retrospectively analyzed the clinical data of patients with and without hyponatremia.

RESULTS

In total, 45.6% (103/226) patients had hyponatremia and 54.4% (123/226) patients did not have hyponatremia. Serum sodium and severity of TBM were independent prediction factors of poor outcomes in TBM. The prognosis of patients with hyponatremia was worse than that of patients without hyponatremia. The mortality was 3.9% (4/103) in the hyponatremia group, while 0% (0/123) in the non-hyponatremia group. The degree of hyponatremia was related to imaging, cerebrospinal fluid (CSF) cell count and protein, severity of TBM, time to correct hyponatremia, and prognosis. We analyzed the causes of hyponatremia and found syndrome of inappropriate secretion of antidiuretic hormone (SIADH) was the most common cause (77.7%, 80/103), followed by cerebral salt wasting (CSW) (17.5%, 18/103). Comparing SIADH and CSW, there was a significant difference in mean blood pressure, albumin, and hematocrit, and no significant difference in demographic characteristics, imaging, CSF cell count and protein, severity, occurrence and correction time of hyponatremia, or prognosis.

CONCLUSION

TBM with hyponatremia was dominated by moderate hyponatremia, which often manifested as SIADH. The more severe hyponatremia was, the longer the correction time of hyponatremia, which will affect the prognosis of TBM patients.

Clinical value of NT-proBNP measurements in assessing patients in the pediatric intensive care unit

BACKGROUND

N-terminal brain natriuretic peptide precursor (NT-proBNP) and brain natriuretic peptide (BNP) are mainly produced and secreted in the heart. In 2008, the European Heart Association recommended that serum BNP/NT-proBNP levels should be included in one of the diagnostic criteria of heart failure. Serum NT-proBNP is more stable than BNP, and the detection results are less affected by objective factors, so it is widely used. At present, NT-proBNP has long been beyond the scope of heart failure markers, and has a wide range of clinical value in the evaluation and prediction of some serious diseases. This study prospectively studied the predictive value of serum NT-proBNP in pediatric intensive care unit (PICU).

METHODS

This was a prospective study involving 375 children in the PICU. The patients were divided into three groups: non-risk, low-risk, and high-risk groups. Serum NT-proBNP levels and the 28-day mortality rate were analyzed.

RESULTS

The serum NT-proBNP levels and the mortality of the high-risk group was significantly higher than those of the low- and non-risk groups (P<0.01 in both cases). Receiver operating characteristic curve (ROC curve) analysis showed that the area under the curve was 0.705 (P<0.001, sensitivity =0.643, specificity =0.692). Death multivariate binary logistic regression analysis indicated that NT-proBNP was not an independent factor for 28-day mortality.

CONCLUSIONS

Serum NT-proBNP was significantly correlated with the severity of illness for critically ill patients in PICU. Although high levels of NT-proBNP indicated greater severity, this was not an independent risk factor affecting the prognosis of patients.

Mechanism, spectrum, consequences and management of hyponatremia in tuberculous meningitis

Hyponatremia is the commonest electrolyte abnormality in hospitalized patients and is associated with poor outcome. Hyponatremia is categorized on the basis of serum sodium into severe (< 120 mEq/L), moderate (120-129 mEq/L) and mild (130-134mEq/L) groups. Serum sodium has an important role in maintaining serum osmolality, which is maintained by the action of antidiuretic hormone (ADH) secreted from the posterior pituitary, and natriuretic peptides such as atrial natriuretic peptide and brain natriuretic peptide. These peptides act on kidney tubules via the renin angiotensin aldosterone system. Hyponatremia <120mEq/L or a rapid decline in serum sodium can result in neurological manifestations, ranging from confusion to coma and seizure. Cerebral salt wasting (CSW) and syndrome of inappropriate secretion of ADH (SIADH) are important causes of hyponatremia in tuberculosis meningitis (TBM). CSW is more common than SIADH. The differentiation between CSW and SIADH is important because treatment of one may be detrimental for the other; evidence of hypovolemia in CSW and euvolemia or hypervolemia in SIADH is used for differentiation. In addition, evidence of dehydration, polyuria, negative fluid balance as assessed by intake output chart, weight loss, laboratory evidence and sometimes central venous pressure are helpful in the diagnosis of these disorders. Volume contraction in CSW may be more protracted than hyponatremia and may contribute to border zone infarctions in TBM. Hyponatremia should be promptly and carefully treated by saline and oral salt, while 3% saline should be used in severe hyponatremia with coma and seizure. In refractory patients with hyponatremia, fludrocortisone helps in early normalization of serum sodium without affecting polyuria or functional outcome. In SIADH, V2 receptor antagonist conivaptan or tolvaptan may be used if the patient is not responding to fluid restriction. Fluid restriction in SIADH has not been found to be beneficial in TBM and should be avoided.

An Integrative Review of Cerebral Salt Wasting Syndrome

BACKGROUND

Although cerebral salt wasting syndrome (CSWS) is widely recognized, its clinical characteristics, diagnostic criteria, and management have not been clearly defined. This study was undertaken to comprehensively review current literature and provide a more complete picture of CSWS. This review also aimed to provide information for nurses on how to differentiate cerebral salt wasting syndrome from syndrome of inappropriate antidiuretic hormone secretion.

METHODS

An integrative review was performed. Searches were conducted between May and July 2018. The primary information sources were CINAHL, Google Scholar, MEDLINE, PubMed, Scopus, and Web of Science. Included articles were published from 1954 to July 2018.

RESULTS

The essential features of CSWS are hyponatremia, hypovolemia, and increased urine output. Treatment regimens may be determined based on the acuity and severity of hyponatremia and hypovolemia as well as evident symptoms and signs.

CONCLUSION

This review may help neuroscience nurses become knowledgeable about CSWS for the drafting of appropriate nursing care plans and also be able to differentiate CSWS from syndrome of inappropriate antidiuretic hormone secretion as early as possible for timely and proper management.

International Survey Reveals Opportunities to Improve Tuberculous Meningitis Management and the Need for Standardized Guidelines

BACKGROUND

Tuberculous meningitis (TBM) is a medical emergency, yet there are no standardized treatment guidelines for the medical or neurosurgical management of these patients and little data on neurocritical care. We conducted an international survey to understand current medical and neurosurgical TBM management and resource availability to provide baseline data needed for future multicenter trials addressing unanswered clinical research questions and the establishment of standardized guidelines.

METHODS

An online survey of 77 questions covering medical and neurosurgical TBM management aimed at clinicians/nurses treating TBM was distributed as an anonymous link through email invitation, international organizations' membership distribution, and direct links on organizational webpages or social media. The survey remained open for 5 months. Data were summarized with frequencies and percentages.

RESULTS

The survey had 222 responses from 43 countries representing 6 continents. Most respondents were from tertiary care facilities, with broad access to medical and neurosurgical resources. There was significant heterogeneity in general supportive care, and TBM-specific management demonstrated considerable divergence from current standard-of-care practices. The lack of standardized guidelines was identified as a major challenge in TBM management. General and neurocritical care were largely absent. Resources for bedside supportive care and noninvasive monitoring were broadly accessible.

CONCLUSIONS

These findings suggest that current TBM management could be improved by the establishment of internationally accepted treatment guidelines based on available evidence, and that numerous centers have resources available to participate in future multicenter trials, even for basic interventions, that may further improve patient outcomes globally.

A Diagnostic Formula for Discrimination of Tuberculous and Bacterial Meningitis Using Clinical and Laboratory Features

Background: The discrimination of tuberculous meningitis and bacterial meningitis remains difficult at present, even with the introduction of advanced diagnostic tools. This study aims to differentiate these two kinds of meningitis by using the rule of clinical and laboratory features.

Methods: A prospective observational study was conducted to collect the clinical and laboratory parameters of patients with tuberculous meningitis or bacterial meningitis. Logistic regression was used to define the diagnostic formula for the discrimination of tuberculous meningitis and bacterial meningitis. A receiver operator characteristic curve was established to determine the best cutoff point for the diagnostic formula.

Results: Five parameters (duration of illness, coughing for two or more weeks, meningeal signs, blood sodium, and percentage of neutrophils in cerebrospinal fluid) were predictive of tuberculous meningitis. The diagnostic formula developed from these parameters was 98% sensitive and 82% specific, while these were 95% sensitive and 91% specific when prospectively applied to another 70 patients.

Conclusion: The diagnostic formula developed in the present study can help physicians to differentiate tuberculous meningitis from bacterial meningitis in high-tuberculosis-incidence-areas, particularly in settings with limited microbiological and radiological resources.

Mechanism, spectrum, consequences and management of hyponatremia in tuberculous meningitis

Hyponatremia is the commonest electrolyte abnormality in hospitalized patients and is associated with poor outcome. Hyponatremia is categorized on the basis of serum sodium into severe (< 120 mEq/L), moderate (120-129 mEq/L) and mild (130-134mEq/L) groups. Serum sodium has an important role in maintaining serum osmolality, which is maintained by the action of antidiuretic hormone (ADH) secreted from the posterior pituitary, and natriuretic peptides such as atrial natriuretic peptide and brain natriuretic peptide. These peptides act on kidney tubules via the renin angiotensin aldosterone system. Hyponatremia <120mEq/L or a rapid decline in serum sodium can result in neurological manifestations, ranging from confusion to coma and seizure. Cerebral salt wasting (CSW) and syndrome of inappropriate secretion of ADH (SIADH) are important causes of hyponatremia in tuberculosis meningitis (TBM). CSW is more common than SIADH. The differentiation between CSW and SIADH is important because treatment of one may be detrimental for the other; evidence of hypovolemia in CSW and euvolemia or hypervolemia in SIADH is used for differentiation. In addition, evidence of dehydration, polyuria, negative fluid balance as assessed by intake output chart, weight loss, laboratory evidence and sometimes central venous pressure are helpful in the diagnosis of these disorders. Volume contraction in CSW may be more protracted than hyponatremia and may contribute to border zone infarctions in TBM. Hyponatremia should be promptly and carefully treated by saline and oral salt, while 3% saline should be used in severe hyponatremia with coma and seizure. In refractory patients with hyponatremia, fludrocortisone helps in early normalization of serum sodium without affecting polyuria or functional outcome. In SIADH, V2 receptor antagonist conivaptan or tolvaptan may be used if the patient is not responding to fluid restriction. Fluid restriction in SIADH has not been found to be beneficial in TBM and should be avoided.

Inappropriate Antidiuretic Hormone Secretion and Cerebral Salt-Wasting Syndromes in Neurological Patients

The differential diagnosis of syndrome of inappropriate antidiuretic hormone secretion (SIADH) and cerebral salt-wasting syndrome (CSWS) in patients with neurological disorders has been a perplexing clinical controversy. The purpose of this review is to summarize the characteristics and risk factors of patients with different types of neurological disorders complicated by hyponatremia (HN) and review various methods to distinguish SIADH from CSWS. Common neurological disorders with high rates of HN include subarachnoid hemorrhage (SAH), traumatic brain injuries, stroke, cerebral tumors, central nervous system (CNS) infections, and Guillain-Barré syndrome (GBS), which have their own characteristics. Extracellular volume (ECV) status of patients is a key point to differentiate SIADH and CSWS, and a comprehensive assessment of relevant ECV indicators may be useful in differentiating these two syndromes. Besides, instead of monitoring the urinary sodium excretion, more attention should be paid to the total mass balance, including Na⁺, K⁺, Cl^-, and extracellular fluid. Furthermore, the dynamic detection of fractional excretions (FE) of urate before and after correction of HN and a short-term infusion of isotonic saline solution may be useful in identifying the etiology of HN. As for brain natriuretic peptide (BNP) or N-terminal prohormone of BNP (NT-proBNP), more prospective studies and strong evidence are needed to determine whether there is a pertinent and clear difference between SIADH and CSWS.

A Cross-Sectional Study of Hyponatremia Associated with Acute Central Nervous System Infections

Hyponatremia can occur with central nervous system (CNS) infections, but the frequency and severity may depend on the organism and nature of CNS involvement. In this cross-sectional study at a large Australian hospital network from 2015 to 2018, we aimed to determine the prevalence and severity of hyponatremia associated with CNS infection clinical syndromes, and the association with specific organisms. We examined the results of cerebrospinal fluid analysis from lumbar punctures performed in 184 adult patients with a serum sodium below 135 mmol/L who had abnormal cerebrospinal fluid analysis and a clinical syndrome consistent with an acute CNS infection (meningitis or encephalitis). Hyponatremia affected 39% of patients and was more severe and frequent in patients with encephalitis compared to meningitis (odds ratio = 3.03, 95% CI: 1.43–6.39, after adjusting for age). Hyponatremia was present on admission in 85% of cases. Herpes simplex virus infection was associated with the highest odds of hyponatremia (odds ratio = 3.25, 95% CI: 1.13–7.87) while enterovirus infection was associated with the lowest (odds ratio = 0.36, 95% CI: 0.14–0.92), compared to cases without an isolated organism. We concluded that the risk of hyponatremia may vary by the organism isolated but the clinical syndrome was a useful surrogate for predicting the probability of developing hyponatremia.