Hypertonic saline and desmopressin: a simple strategy for safe correction of severe hyponatremia

Pharmacological management of hyponatremia

INTRODUCTION

Hyponatremia is the most common electrolyte disorder with a prevalence of up to 30% in hospitalized patients. Furthermore, it is associated with increased morbidity and mortality.

AREAS COVERED

This review discusses the efficacy and side effects of the currently available treatment options for hyponatremia and the differences in the pharmacological approach between the European and USA guidelines. Additionally, the authors provide their expert perspectives on current treatment strategies and what they expect from this field in the future.

EXPERT OPINION

Several pharmacological options are available for the treatment of hyponatremia, but data from trials examining and comparing these treatments are missing. Regarding chronic hyponatremia, the role of vaptans should be further analyzed, focusing on comparisons with other active treatments on patient-relevant outcomes and not only on serum sodium concentration. Clinicians should be cautious to an overly rapid increase in serum sodium levels with all available treatment strategies. Finally, it is important to ascertain whether correction of serum sodium levels improves mortality in hyponatremic patients.

Managing hyponatraemia secondary to primary polydipsia: beware too rapid correction of hyponatraemia

We describe three cases of severe hyponatraemia in the setting of primary polydipsia that were managed in our centre in 2016. Despite receiving different solute loads, large volume diuresis and rapid correction of serum sodium occurred in all cases. Given the potentially catastrophic consequence of osmotic demyelination, we highlight the judicious use of desmopressin and hypotonic fluid infusion to mitigate sodium overcorrection in this setting.

Treatment of Severe Hyponatremia

Patients with severe (serum sodium ≤120 mEq/L), symptomatic hyponatremia can develop life-threatening or fatal complications from cerebral edema if treatment is inadequate and permanent neurologic disability from osmotic demyelination if treatment is excessive. Unfortunately, as is true of all electrolyte disturbances, there are no randomized trials to guide the treatment of this challenging disorder. Rather, therapeutic decisions rest on physiologic principles, animal models, observational studies, and single-patient reports. European guidelines and recommendations of an American Expert panel have come to similar conclusions on how much correction of hyponatremia is enough and how much is too much, but there are important differences. We review the evidence supporting these recommendations, identifying areas that rest on relatively solid ground and highlighting areas in greatest need of additional data.

The Role of Desmopressin in the Management of Severe, Hypovolemic Hyponatremia: A Single-Center, Comparative Analysis

Background

The role of desmopressin (DDAVP) to prevent or treat rapid serum sodium concentration ([Na]s) correction during hyponatremia management remains unclear.

Objective

To assess DDAVP use during the first 48 hours of severe, hypovolemic hyponatremia management. The primary study hypothesis was that the use of DDAVP would slow the rate of [Na]s correction compared with those not receiving DDAVP.

Design

A retrospective, observational, comparison study.

Setting

A single, Canadian, tertiary center.

Patients

All admitted patients referred to the nephrology service for severe, hypovolemic hyponatremia ([Na]s < 125 mmol/L) over a 12-month period from November 2015.

Measurements

The primary outcomes measure was the [Na]s after medical management for 48 hours. The length of hospital stay was also measured.

Methods

Patients were grouped based on whether they received DDAVP during the first 48 hours of treatment, and [Na]s correction was compared between groups using linear regression. An exploratory, multivariable, linear regression model was used to adjust for diabetes status, active malignancy, intensive care unit (ICU) admission, and hypertonic saline administration.

Results

Twenty-eight patients were identified, with baseline mean [Na]s of 112.7 ± 6.6 mmol/L versus 117 ± 4.3mmol/L (P = .06) in those receiving (n = 16) and not receiving DDAVP (n = 12), respectively. The DDAVP group had a more rapid [Na]s correction on the first day compared with those not receiving DDAVP, 7.7 ± 3.8 mmol/L/d versus 5.1 ± 2.0 mmol/L/d (P = .04). On the second day, there was a similar rate of [Na]s correction between groups: 1.3 ± 4.3 mmol/L/d versus 2.6 ± 3.2 mmol/L/d (P = .39), respectively. Overall, there was no difference in [Na]s correction after 48 hours between those who received DDAVP and those who did not: 121.7 ± 7.5 mmol/L versus 124.8 ± 5.7 mmol/L (P = .24). Patients who had experienced an overcorrection were successfully treated with DDAVP (n = 5), so that no patient had an ongoing overcorrection by 48 hours.

Limitations

The limited sample size and lack of randomization preclude definitive conclusion on the additional benefit of DDAVP to standard care.

Conclusion

DDAVP appears to be safe and effective in the management of severe, hypovolemic hyponatremia, associated with similar [Na]s correction to those who did not receive DDAVP after 48 hours, despite an initial more rapid correction. A randomized trial should examine what benefit DDAVP confers in addition to standard care in the management of severe, hypovolemic hyponatremia.

Outcomes in Severe Hyponatremia Treated With and Without Desmopressin

BACKGROUND

Overcorrection of plasma sodium in severe hyponatremia is associated with osmotic demyelination syndrome. Desmopressin (DDAVP) can prevent overcorrection of plasma sodium in hyponatremia. The objective of this study was to compare outcomes in hyponatremia according to DDAVP usage.

METHODS

This was a retrospective observational study including all admissions to internal medicine with hyponatremia (plasma sodium concentration <123 mEq/L) from 2004 to 2014 at 2 academic hospitals in Toronto, Canada. The primary outcome was safe sodium correction (≤12 mEq/L in any 24-hour and ≤18 mEq/L in any 48-hour period).

RESULTS

We identified 1450 admissions with severe hyponatremia; DDAVP was administered in 254 (17.5%). Although DDAVP reduced the rate of change of plasma sodium, fewer patients in the DDAVP group achieved safe correction (174 of 251 [69.3%] vs 970 of 1164 [83.3%]); this result was driven largely by overcorrection occurring before DDAVP administration in the rescue group. Among patients receiving DDAVP, most received it according to a reactive strategy, whereby DDAVP was given after a change in plasma sodium within correction limits (174 of 254 [68.5%]). Suspected osmotic demyelination syndrome was identified in 4 of 1450 admissions (0.28%). There was lower mortality in the DDAVP group (3.9% vs 9.4%), although this is likely affected by confounding. Length of stay in hospital was longer in those who received DDAVP according to a proactive strategy.

CONCLUSIONS

Although observational, these data support a reactive strategy for using DDAVP in patients at average risk of osmotic demyelination syndrome, as well as a more stringent plasma sodium correction limit of 8 mEq/L in any 24-hour period for high-risk patients. Further studies are urgently needed on DDAVP use in treating hyponatremia.

Fluid balance concepts in medicine: Principles and practice

The regulation of body fluid balance is a key concern in health and disease and comprises three concepts. The first concept pertains to the relationship between total body water (TBW) and total effective solute and is expressed in terms of the tonicity of the body fluids. Disturbances in tonicity are the main factor responsible for changes in cell volume, which can critically affect brain cell function and survival. Solutes distributed almost exclusively in the extracellular compartment (mainly sodium salts) and in the intracellular compartment (mainly potassium salts) contribute to tonicity, while solutes distributed in TBW have no effect on tonicity. The second body fluid balance concept relates to the regulation and measurement of abnormalities of sodium salt balance and extracellular volume. Estimation of extracellular volume is more complex and error prone than measurement of TBW. A key function of extracellular volume, which is defined as the effective arterial blood volume (EABV), is to ensure adequate perfusion of cells and organs. Other factors, including cardiac output, total and regional capacity of both arteries and veins, Starling forces in the capillaries, and gravity also affect the EABV. Collectively, these factors interact closely with extracellular volume and some of them undergo substantial changes in certain acute and chronic severe illnesses. Their changes result not only in extracellular volume expansion, but in the need for a larger extracellular volume compared with that of healthy individuals. Assessing extracellular volume in severe illness is challenging because the estimates of this volume by commonly used methods are prone to large errors in many illnesses. In addition, the optimal extracellular volume may vary from illness to illness, is only partially based on volume measurements by traditional methods, and has not been determined for each illness. Further research is needed to determine optimal extracellular volume levels in several illnesses. For these reasons, extracellular volume in severe illness merits a separate third concept of body fluid balance.

Central Pontine Myelinolysis After Living-Donor Liver Transplant: A Report of 2 Cases

Here, we present 2 patients who developed central pontine myelinolysis after living-donor liver transplant. Both patients had abnormal sodium level before living-donor liver transplant. Patient 1 presented with severe hyponatremia on admission. After administration of 3% saline, her sodium level during the first 24 hours was kept at 100 mEq/L and then increased to 116 mEq/L during the next 24 hours. The level increased 5.8 mEq/L during the 4- to 5-hour transplant procedure. Patient 2 was admitted to the hospital with an unprovoked seizure. The serum sodium concentration was 111 mEq/L, which was treated with 3% saline infusion. Serum sodium concentration escalated to 118 mEq/L over an 8-hour period. Intraoperatively, both patients received large amounts of replacement fluids (0.9% normal saline and albumin), blood transfusion, and sodium bicarbonate during the anhepatic phase, all of which carry high sodium load. Variations in sodium levels changed rapidly in patient 1 during transplant surgery. After they underwent liver transplant, patient 1 had clear mental status and patient 2 demonstrated worsened mental status. On approximately day 14 and day 4 after liver transplant, magnetic resonance imaging showed diffuse abnormalities of the pons, resulting in diagnosis of central pontine myelinolysis. Although both patients survived, 1 remains in a vegetative state and the other continues to present with mild balance and swallowing abnormalities. To reduce the chance of inadvertent overcorrection in patients with hyponatremia, it is therefore important that sodium concentrations should be monitored frequently and fluids and electrolytes titrated carefully.

A low initial serum sodium level is associated with an increased risk of overcorrection in patients with chronic profound hyponatremia: a retrospective cohort analysis

Background

Even with abundant evidence for osmotic demyelination in patients with hyponatremia, the risk factors for overcorrection have not been fully investigated. Therefore the purpose of this study is to clarify the risks for overcorrection during the treatment of chronic profound hyponatremia.

Methods

This is a single-center retrospective observational study. We enrolled 56 adult patients with a serum sodium (SNa) concentration of ≤125 mEq/L who were treated in an intensive care unit by nephrologists using a locally developed, fixed treatment algorithm between February 2012 and April 2014. The impact of patient parameters on the incidence of overcorrection was estimated using univariable and multivariable logistic regression models. Overcorrection was defined as an increase of SNa by >10 mEq/L and >18 mEq/L during the first 24 and 48 h, respectively.

Results

The median age was 78 years, 48.2% were male, and 94.6% of the patients presented with symptoms associated with hyponatremia. The initial median SNa was 115 mEq/L (quartile, 111–119 mEq/L). A total of 11 (19.6%) patients met the criteria for overcorrection with 9 (16.0%) occurring at 24 h, 6 (10.7%) at 48 h, and 4 (7.1%) at both 24 and 48 h. However, none of these patients developed osmotic demyelination. Primary polydipsia, initial SNa, and early urine output were the significant risk factors for overcorrection on univariable analysis. Multivariable analysis revealed that the initial SNa had a statistically significant impact on the incidence of overcorrection with an adjusted odds ratio of 0.84 (95% confidence interval, 0.70–0.98; p = 0.037) for every 1 mEq/L increase. Additionaly, the increase in SNa during the first 4 h and early urine output were significantly higher in patients with overcorrection than in those without (p = 0.001 and 0.005, respectively).

Conclusions

An initial low level of SNa was associated with an increased risk of overcorrection in patients with profound hyponatremia. In this regard, the rapid increase in SNa during the first 4 h may play an important role.

Hyponatremia and the Brain

Hyponatremia is defined by low serum sodium concentration and is the most common electrolyte disorder encountered in clinical practice. Serum sodium is the main determinant of plasma osmolality, which, in turn, affects cell volume. In the presence of low extracellular osmolality, cells will swell if the adaptation mechanisms involved in the cell volume maintenance are inadequate. The most dramatic effects of hyponatremia on the brain are seen when serum sodium concentration decreases in a short period, allowing little or no adaptation. The brain is constrained inside a nonextensible envelope; thus, brain swelling carries a significant morbidity because of the compression of brain parenchyma over the rigid skull. Serum sodium concentration is an important determinant of several biological pathways in the nervous system, and recent studies have suggested that hyponatremia carries a significant risk of neurological impairment even in the absence of brain edema. The brain can also be affected by the treatment of hyponatremia, which, if not undertaken cautiously, could lead to osmotic demyelination syndrome, a rare demyelinating brain disorder that occurs after rapid correction of severe hyponatremia. This review summarizes the pathophysiology of brain complications of hyponatremia and its treatment.

Electrolyte Disturbances in Critically Ill Cancer Patients: An Endocrine Perspective

Electrolyte disturbances are frequently encountered in critically ill oncology patients. Hyponatremia and hypernatremia as well as hypocalcemia and hypercalcemia are among the most commonly encountered electrolyte abnormalities. In the intensive care unit, management of critical electrolyte disturbances is focused on initial evaluation and immediate treatment plan to prevent severe complications. A PubMed search was performed to identify best available evidence for evaluation and management of dysnatremias, hypocalcemia, and hypercalcemia. Current literature was reviewed regarding the management of electrolyte disturbances. The role of new therapeutic options, for example, vaptans for hyponatremia, teriparatide for hypocalcemia, and denosumab for hypercalcemia, is discussed. Early diagnosis and appropriate management are expected to reduce adverse outcomes.

Clinical aspects of changes in water and sodium homeostasis in the elderly

The population of elderly individuals is increasing worldwide. With aging, various hormonal and kidney changes occur, both affecting water homeostasis. Aging is a risk factor for chronic kidney disease (CKD) and many features of CKD are reproduced in the aging kidney. Dehydration and hyperosmolarity can be triggered by diminished thirst perception in this population. Elderly with dementia are especially susceptible to abnormalities of their electrolyte and body water homeostasis and should be (re-)assessed for polypharmacy. Hypo- and hypernatremia can be life threatening and should be diagnosed and treated promptly, following current practice guidelines. In severe cases of acute symptomatic hyponatremia, a rapid bolus of 100 to 150 ml of intravenous 3% hypertonic saline is appropriate to avert catastrophic outcomes; for asymptomatic hyponatremia, a very gradual correction is preferred. In summary, the body sodium (Na+) balance is regulated by a complex interplay of environmental and individual factors. In this review, we attempt to provide an overview on this topic, including dehydration, hyponatremia, hypernatremia, age-related kidney changes, water and sodium balance, and age-related changes in the vasopressin and renin-angiotensin-aldosterone system.

Diagnosis and Treatment of Hyponatremia: Compilation of the Guidelines

Hyponatremia is a common water balance disorder that often poses a diagnostic or therapeutic challenge. Therefore, guidelines were developed by professional organizations, one from within the United States (2013) and one from within Europe (2014). This review discusses the diagnosis and treatment of hyponatremia, comparing the two guidelines and highlighting recent developments. Diagnostically, the initial step is to differentiate hypotonic from nonhypotonic hyponatremia. Hypotonic hyponatremia is further differentiated on the basis of urine osmolality, urine sodium level, and volume status. Recently identified parameters, including fractional uric acid excretion and plasma copeptin concentration, may further improve the diagnostic approach. The treatment for hyponatremia is chosen on the basis of duration and symptoms. For acute or severely symptomatic hyponatremia, both guidelines adopted the approach of giving a bolus of hypertonic saline. Although fluid restriction remains the first-line treatment for most forms of chronic hyponatremia, therapy to increase renal free water excretion is often necessary. Vasopressin receptor antagonists, urea, and loop diuretics serve this purpose, but received different recommendations in the two guidelines. Such discrepancies may relate to different interpretations of the limited evidence or differences in guideline methodology. Nevertheless, the development of guidelines has been important in advancing this evolving field.

Transurethral Resection of the Prostate, Bladder Explosion and Hyponatremic Encephalopathy: A Rare Case Report of Malpractice

We present an original case report of a bladder explosion during a TURP intervention for benign prostatic hypertrophy, that was brought on by the absorption of about 5 liters of glycine 1.5% and then onset of a severe hyponatremia. The quick and inappropriate correction of this electrolyte imbalance led the onset of encephalopathy and the death of the patient. The authors discuss the pathogenesis of these uncommon diseases and, considering the most recent Italian Legislation, they highlight the importance to respect good clinical practice standards and guidelines to ensure the most appropriate treatments for the patient and remove any assumptions of medical liability.

Physiopathology, clinical diagnosis, and treatment of hyponatremia

Hyponatremia is the commonest electrolyte disorder encountered in clinical practice. It develops when the mechanisms regulating water and electrolyte handling are impaired, which in many instances occur in the setting of concurrent diseases such as heart failure, liver failure, renal failure etc… Hyponatremia as an electrolyte disorder has several specificities: when profound it can be quickly fatal and when moderate it carries a high risk of mortality and morbidity, but at the same time incorrect treatment of profound hyponatremia can lead to debilitating neurological disease and it remains unclear if treatment of moderate hyponatremia is associated with a decrease in mortality and morbidity. A proper diagnosis is the keystone for an adequate treatment for hyponatremia and in the last few years many diagnosis algorithms have been developed to aid in the evaluation of the hyponatremic patient. Also because of the availability of vasopressin receptor antagonists and the advances made in the research regarding complications associated with hyponatremia treatment, new treatment recommendations have been published recently by several panels. This review will discuss the physiopathology, epidemiology, and clinical manifestations of hyponatremia and also the diagnosis and the treatment of this disorder with special emphasis on the complication from overly rapid correction of hyponatremia.

Challenges in the acute management of profound hyponatremia presenting with severe symptoms

Currently available guidelines in the acute management of severely symptomatic hypotonic hyponatremia vary in their approach to the use of hypertonic saline. In the acute setting, deciding on when to implement available treatment algorithm using hypertonic saline may be difficult, given that the duration of hyponatremia and potential alternative diagnoses presenting with similar symptoms may be hard to establish promptly. We present the case of a young female with symptomatic profound hyponatremia who subsequently developed osmotic demyelination syndrome due to rapid overcorrection of serum sodium concentration. We discuss the interplay between the dynamic pathophysiological processes responsible for hypotonic hyponatremia in adrenal insufficiency and conduct a detailed analysis of currently available guidelines to highlight the challenges in acute and reactive treatment in clinical practice.

Clinical aspects of symptomatic hyponatremia

Hyponatremia (HN) is a common condition, with a large number of etiologies and a complicated treatment. Although chronic HN has been shown to be a predictor of poor outcome, sodium-increasing treatments in chronic stable and asymptomatic HN have not proven to increase life expectancy. For symptomatic HN, in contrast, the necessity for urgent treatment has broadly been accepted to avoid the development of fatal cerebral edema. On the other hand, a too rapid increase of serum sodium in chronic HN may result in cerebral damage due to osmotic demyelinisation. Recently, administration of hypertonic saline bolus has been recommended as first-line treatment in patients with moderate-to-severe symptomatic HN. This approach is easy to memorize and holds the potential to greatly facilitate the initial treatment of symptomatic HN. First-line treatment of chronic HN is fluid restriction and if ineffective treatment with tolvaptan or in some patients other agents should be considered. A number of recommendations and guidelines have been published on HN. In the present review, the management of patients with HN in relation to everyday clinical practice is summarized with focus on the acute management.

Role of tolvaptan in the management of hyponatremia in patients with lung and other cancers: current data and future perspectives

Hyponatremia is the most frequently observed electrolyte abnormality in clinical practice, and its frequency is almost double in hospitalized cancer patients. As a subset of cancer, hyponatremia is quite common in lung cancer patients, and it is often coupled with the diagnosis of syndrome of inappropriate antidiuretic hormone secretion. The presence of hyponatremia is consequential in that its presence adversely affects cancer patients’ prognosis and outcomes. Limited data suggest that correcting hyponatremia in lung cancer patients can increase response to anticancer treatment, may help reduce length of hospital stay and cost, and reduce morbidity and mortality. The type of treatment for hyponatremia depends on several factors; the key factors are the duration and severity of neurological symptoms of hyponatremia and the status of extracellular volume. When hyponatremia is caused by syndrome of inappropriate antidiuretic hormone, hypertonic saline is indicated for acute symptomatic cases, whereas fluid restriction is recommended in chronic asymptomatic hyponatremia. The latter allows a slower rate of correction, thus avoiding the dreaded complication of osmotic demyelination syndrome. Fluid restriction is, however, insufficient or impractical, and often the use of pharmacological therapy such as antidiuretic hormone receptor antagonists becomes necessary. Availability of these antagonists as an effective treatment in the management of hyponatremia has been a major breakthrough, and furthermore, its clinical or investigational use in cancer-related hyponatremia may offer a potential opportunity to gain further insights into the prognostic impact of hyponatremia correction on cancer patients’ outcomes. Tolvaptan is a prototype of ADH receptor antagonists that acts at renal tubular levels to increase free water excretion without inducing major systemic electrolyte abnormalities such as hypokalemia or alkalosis. The aim of this paper is to provide a brief review while focusing on cancer hyponatremia; (1) of the epidemiology of hyponatremia and its pathophysiology and diagnostic approaches and (2) of the pharmacokinetics of tolvaptan and its clinical efficacy, safety, and compliance.

The utility and accuracy of four equations in predicting sodium levels in dysnatremic patients

BACKGROUND

Improper correction of hyponatremia can cause severe complications, including osmotic demyelination syndrome (ODS). The Adrogué-Madias equation (AM), the Barsoum-Levine (BL) equation, the Electrolyte Free Water Clearance (EFWC) equation and the Nguyen-Kurtz (NK) equation are four derived equations based on the empirically derived Edelman equation for predicting sodium at a later time (Na2) from a known starting sodium (Na1), fluid/electrolyte composition and input and output volumes.

METHODS

Our retrospective study included 43 data points from 31 mostly hyponatremic patients. We calculated Na2 based on five sets of rules that were progressively more precisely calculated. Sets A-D included all 31 patients and 43 data points and set E was based on 15 patients and 27 data points.

RESULTS

The root mean square error was calculated and found to be between 4.79 and 6.37 mmol/L (mEq/L) for all sets. Bland-Altman analysis showed high variability and discrepancies between the predicted and actual Na2.

CONCLUSIONS

Like similar studies in hypernatremic patients, the data suggest that hyponatremic modeling equations are not reliably accurate in predicting Na2 from Na1 and available clinical data regarding sodium, potassium and fluid balance over longer time frames (12-30 h). Our study was retrospective and was done in an inpatient setting and thus was subject to limitations and laboratory measurement variability, but showed that all four equations are not able to reliably predict Na2 from Na1 and inputs across a 12-30 h period.

Formulas for fixing serum sodium: curb your enthusiasm

A variety of formulas have been proposed to predict changes in serum sodium concentration. All are based on an experiment done over 50 years ago by Edelman, who derived a formula relating the plasma sodium concentration to isotopically measured body sodium, potassium, and water. Some of these formulas fail because they do not include urinary losses of electrolytes and water. Even those that include these essential variables are not accurate enough for clinical use because it is impractical to adjust calculations to rapid changes in urinary composition, and because the formulas do not account for changes in serum sodium caused by internal exchanges between soluble and bound sodium stores or shifts of water into or out of cells resulting from changes in intracellular organic osmolytes. Nephrologists should curb their enthusiasm for predictive formulas and rely instead on frequent measurements of the serum sodium when correcting hyponatremia and hypernatremia.

Diagnosis and treatment of hyponatraemia

Hyponatraemia is the most common electrolyte abnormality encountered by physicians in the hospital setting. It is associated with increased mortality and length of hospital stay. However, the basis of the relationship of hyponatraemia with clinical outcome is not clear. Doubt remains as to whether the relationship is causal. It may reflect the association of two independent variables both of which are linked with disease severity. Serum sodium concentration is regulated through integrated neuro-humeral mechanisms that overlap with those regulating circulating volume. A mechanistic approach to the classification of hyponatraemia can support a framework for investigation and differential diagnosis based on urine osmolality and urine sodium concentration. Such a framework is more reliable than those based on the clinical assessment of volume status. In the emergency setting, the initial management of hyponatraemia is cause-independent. In other clinical contexts, a cause-specific approach is recommended. Over-rapid correction of serum sodium risks precipitating osmotic demyelination syndrome. Avoiding over-rapid correction is critical in any approach to patient care. Sodium is the major circulating cation and thus a key determinant of overall plasma osmolality. Serum sodium concentration is maintained within a tight physiological range over time, despite wide variation in both sodium and water intake. Hyponatraemia (serum sodium concentration <135 mmols/L) is the most common electrolyte disturbance in clinical practice. All clinicians should be aware of the scope and scale of the problem.

Desmopressin to Prevent Rapid Sodium Correction in Severe Hyponatremia: A Systematic Review

BACKGROUND

Hyponatremia is common among inpatients and is associated with severe adverse outcomes such as osmotic demyelination syndrome. Current guidelines recommend serum sodium concentration correction targets of no more than 8 mEq/L per day in patients at high risk of osmotic demyelination syndrome. Desmopressin is recommended to control high rates of serum sodium concentration correction in severe hyponatremia. However, recommendations are based on limited data. The objective of this study is to review current strategies for DDAVP use in severe hyponatremia.

METHODS

Systematic literature search of 4 databases of peer-reviewed studies was performed and study quality was appraised.

RESULTS

The literature search identified 17 observational studies with 80 patients. We found 3 strategies for desmopressin administration in hyponatremia: 1) proactive, where desmopressin is administered early based on initial serum sodium concentration; 2) reactive, where desmopressin is administered based on changes in serum sodium concentration or urine output; 3) rescue, where desmopressin is administered after serum sodium correction targets are exceeded or when osmotic demyelination appears imminent. A proactive strategy of desmopressin administration with hypertonic saline was associated with lower incidence of exceeding serum sodium concentration correction targets, although this evidence is derived from a small case series.

CONCLUSIONS

Three distinct strategies for desmopressin administration are described in the literature. Limitations in study design and sample size prevent definitive conclusions about the optimal strategy for desmopressin administration to correct hyponatremia. There is a pressing need for better quality research to guide clinicians in managing severe hyponatremia.

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.

Sodium Correction Practice and Clinical Outcomes in Profound Hyponatremia

OBJECTIVES

To assess the epidemiology of nonoptimal hyponatremia correction and to identify associated morbidity and in-hospital mortality.

PATIENTS AND METHODS

An electronic medical record search identified all patients admitted with profound hyponatremia (sodium <120 mmol/L) from January 1, 2008, through December 31, 2012. Patients were classified as having optimally or nonoptimally corrected hyponatremia at 24 hours after admission. Optimal correction was defined as sodium correction in 24 hours of 6 through 10 mmol/L. We investigated the association between sodium correction and demographic and outcome variables, including occurrence of osmotic demyelination syndrome (ODS). Baseline characteristics by correction outcome categories were compared using the Kruskal-Wallis test for continuous variables and the χ(2) test for categorical variables. Odds ratios for in-hospital mortality between groups were assessed using logistic regression. Adjusted differences in hospital length of stay (LOS) and intensive care unit (ICU) LOS were assessed using the Dunnett 2-tailed t test.

RESULTS

A total of 412 patients satisfied inclusion criteria of whom 174 (42.2%) were admitted to the ICU. A total of 211 (51.2%) had optimal correction of their hyponatremia at 24 hours, 87 (21.1%) had undercorrected hyponatremia, and 114 (27.9%) had overcorrected hyponatremia. Both patient factors and treatment factors were associated with nonoptimal correction. There was a single case of ODS. Overcorrection was not associated with in-hospital mortality or ICU LOS. When adjusted for patient factors, undercorrection of profound hyponatremia was associated with an increase in hospital LOS (9.3 days; 95% CI, 1.9-16.7 days).

CONCLUSION

Nonoptimal correction of profound hyponatremia is common. Fortunately, nonoptimal correction is associated with serious morbidity only infrequently.

Special medical conditions associated with catatonia in the internal medicine setting: hyponatremia-inducing psychosis and subsequent catatonia

Diagnosis and treatment of catatonia in the psychiatry consultation service is not infrequent. Usually, the patient either presents to the Emergency Department or develops catatonia on the medical floor. This condition manifests with significant behavioral changes (from mildly decreased speech output to complete mutism) that interfere with the ability to communicate. After structural brain disorders are excluded, one of the diagnoses that always should be considered is catatonia. However, the causes of catatonia are numerous, ranging from psychiatric causes to a plethora of medical illnesses. Therefore, it is not surprising that there are many proposed underlying mechanisms of catatonia and that controversy persists about the etiology of specific cases.There are only 6 reports of hyponatremia-induced catatonia and psychosis in the literature. Here, we present the case of a 30-year-old woman with catatonia and psychosis induced by hyponatremia, and we use this report to exemplify the multitude of biologic causes of catatonia and to propose a new way to look at the neuroanatomical basis of processing, particularly the vertical processing systems we believe are involved in catatonia.

Can empirical hypertonic saline or sodium bicarbonate treatment prevent the development of cardiotoxicity during serious amitriptyline poisoning? Experimental research

OBJECTIVE

The aim of this experimental study was to investigate whether hypertonic saline or sodium bicarbonate administration prevented the development of cardiotoxicity in rats that received toxic doses of amitriptyline.

METHOD

Thirty-six Sprague Dawley rats were used in the study. The animals were divided into six groups. Group 1 received toxic doses of i.p. amitriptyline. Groups 2 and 3 toxic doses of i.p. amitriptyline, plus i.v. sodium bicarbonate and i.v. hypertonic saline, respectively. Group 4 received only i.v. sodium bicarbonate, group 5 received only i.v. hypertonic saline, and group 6 was the control. Electrocardiography was recorded in all rats for a maximum of 60 minutes. Blood samples were obtained to measure the serum levels of sodium and ionised calcium.

RESULTS

The survival time was shorter in group 1. In this group, the animals' heart rates also decreased over time, and their QRS and QTc intervals were significantly prolonged. Groups 2 and 3 showed less severe changes in their ECGs and the rats survived for a longer period. The effects of sodium bicarbonate or hypertonic saline treatments on reducing the development of cardiotoxicity were similar. The serum sodium levels decreased in all the amitriptyline-applied groups. Reduction of serum sodium level was most pronounced in group 1.

CONCLUSION

Empirical treatment with sodium bicarbonate or hypertonic saline can reduce the development of cardiotoxicity during amitriptyline intoxication. As hypertonic saline has no adverse effects on drug elimination, it should be considered as an alternative to sodium bicarbonate therapy.

Risk factors, complication and measures to prevent or reverse catastrophic sodium overcorrection in chronic hyponatremia

Hyponatremia is the most common electrolyte disorder encountered in clinical practice. Patients who develop this condition for more than 48 hours are at risk for severe neurological sequelae if correction of the serum sodium occurs too rapidly. Certain medical disorders are known to place patients at an increased risk for rapid correction of serum sodium concentration. Large-volume polyuria in this setting is an ominous sign. For these patients, early identification of risk factors, close monitoring of serum sodium correction and the use of 5% dextrose with or without desmopressin to prevent or reverse overcorrection are important components of treatment.

Hyponatremia: A Review

Hyponatremia is the most frequently occurring electrolyte abnormality and can lead to life-threatening complications. This disorder may be present on admission to the intensive care setting or develop during hospitalization as a result of treatment or multiple comorbidities. Patients with acute hyponatremia or symptomatic chronic hyponatremia will likely require treatment in the intensive care unit (ICU). Immediate treatment with hypertonic saline is needed to reduce the risk of permanent neurologic injury. Chronic hyponatremia should be corrected at a rate sufficient to reduce symptoms but not at an excessive rate that would create a risk of osmotic injury. Determination of the etiology of chronic hyponatremia requires analysis of serum osmolality, volume status, and urine osmolality and sodium level. Correct diagnosis points to the appropriate treatment and helps identify risk factors for accelerated correction of the serum sodium level. Management in the ICU facilitates frequent laboratory draws and allows close monitoring of the patient's mentation as well as quantification of urine output. Overly aggressive correction of serum sodium levels can result in neurological injury caused by osmotic demyelination. Therapeutic measures to lower the serum sodium level should be undertaken if the rate increases too rapidly.

Management of severe hyponatremia: infusion of hypertonic saline and desmopressin or infusion of vasopressin inhibitors?

Rapid correction of severe hyponatremia carries the risk of osmotic demyelination. Two recently introduced methods of correction of hyponatremia have diametrically opposite effects on aquaresis. Inhibitors of vasopressin V2 receptor (vaptans) lead to the production of dilute urine, whereas infusion of desmopressin causes urinary concentration. Identification of the category of hyponatremia that will benefit from one or the other treatment is critical. In general, vaptans are effective in hyponatremias presenting with concentrated urine and, with the exception of hypovolemic hyponatremia, can be used as their primary treatment. Desmopressin is effective in hyponatremias presenting with dilute urine or developing urinary dilution after saline infusion. In this setting, desmopressin infusion helps prevent overcorrection of the hyponatremia. Monitoring of the changes in serum sodium concentration as a guide to treatment changes is imperative regardless of the initial treatment of severe hyponatremia.

Hyponatremia: A practical approach

Hyponatremia is an important and common clinical problem. The etiology is multifactorial. Hyponatremia may be euvolemic, hypovolemic or hypervolemic. Proper interpretation of the various laboratory tests helps to differentiate the various types of hyponatremia. Treatment varies with the nature of onset -acute or chronic, severity and symptoms. Normal saline forms the mainstay of treatment for hypovolemic hyponatremia while 3% NaCl and fluid restriction are important for euvolemic hyponatremia. Hypervolemic hyponatremia responds well to fluid restriction and diuretics. There have been several recent advances in the last year with revision in the guidelines for treatment and availability of vaptans. Judicious use of vaptans may help in treatment of hyponatremia.

Hyponatremia: pathophysiology, classification, manifestations and management

Hyponatremia has complex pathophysiology, is frequent and has potentially severe clinical manifestations, and its treatment is associated with high risks. Hyponatremia can be hypertonic, isotonic or hypotonic. Hypotonic hyponatremia has multiple etiologies, but only two general mechanisms of development, defective water excretion, usually because of elevated serum vasopressin levels, or excessive fluid intake. The acute treatment of symptomatic hypotonic hyponatremia requires understanding of its targets and risks and requires continuous monitoring of the patient's clinical status and relevant serum biochemical values. The principles of fluid restriction, which is the mainstay of management of all types of hypotonic hyponatremia, should be clearly understood and followed. Treatment methods specific to various categories of hyponatremia are available. The indications and risks of these treatments should also be well understood. Rapid correction of chronic hypotonic hyponatremia may lead to osmotic demyelination syndrome, which has severe clinical manifestations, and may lead to permanent neurological disability or death. Prevention of this syndrome should be a prime concern of the treatment of hypotonic hyponatremia.

Clinical practice guideline on diagnosis and treatment of hyponatraemia

Hyponatraemia, defined as a serum sodium concentration <135 mmol/l, is the most common disorder of body fluid and electrolyte balance encountered in clinical practice. It can lead to a wide spectrum of clinical symptoms, from subtle to severe or even life threatening, and is associated with increased mortality, morbidity and length of hospital stay in patients presenting with a range of conditions. Despite this, the management of patients remains problematic. The prevalence of hyponatraemia in widely different conditions and the fact that hyponatraemia is managed by clinicians with a broad variety of backgrounds have fostered diverse institution- and speciality-based approaches to diagnosis and treatment. To obtain a common and holistic view, the European Society of Intensive Care Medicine (ESICM), the European Society of Endocrinology (ESE) and the European Renal Association - European Dialysis and Transplant Association (ERA-EDTA), represented by European Renal Best Practice (ERBP), have developed the Clinical Practice Guideline on the diagnostic approach and treatment of hyponatraemia as a joint venture of three societies representing specialists with a natural interest in hyponatraemia. In addition to a rigorous approach to methodology and evaluation, we were keen to ensure that the document focused on patient-important outcomes and included utility for clinicians involved in everyday practice.

Clinical practice guideline on diagnosis and treatment of hyponatraemia

Hyponatraemia, defined as a serum sodium concentration <135 mmol/l, is the most common disorder of body fluid and electrolyte balance encountered in clinical practice. It can lead to a wide spectrum of clinical symptoms, from subtle to severe or even life threatening, and is associated with increased mortality, morbidity and length of hospital stay in patients presenting with a range of conditions. Despite this, the management of patients remains problematic. The prevalence of hyponatraemia in widely different conditions and the fact that hyponatraemia is managed by clinicians with a broad variety of backgrounds have fostered diverse institution- and speciality-based approaches to diagnosis and treatment. To obtain a common and holistic view, the European Society of Intensive Care Medicine (ESICM), the European Society of Endocrinology (ESE) and the European Renal Association - European Dialysis and Transplant Association (ERA-EDTA), represented by European Renal Best Practice (ERBP), have developed the Clinical Practice Guideline on the diagnostic approach and treatment of hyponatraemia as a joint venture of three societies representing specialists with a natural interest in hyponatraemia. In addition to a rigorous approach to methodology and evaluation, we were keen to ensure that the document focused on patient-important outcomes and included utility for clinicians involved in everyday practice.

Use of desmopressin acetate in severe hyponatremia in the intensive care unit

BACKGROUND AND OBJECTIVES

Excessive correction of chronic and profound hyponatremia may result in central pontine myelinolysis and cause permanent brain damage. In the case of foreseeable or established hyponatremia overcorrection, slowing down the correction rate of sodium plasma levels (PNa) or reinducing mild hyponatremia may prevent this neurologic complication.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

This retrospective and observational study was performed with 20 consecutive patients admitted to two intensive care units for severe hyponatremia, defined by PNa <120 mmol/L and/or neurologic complications ascribable to hyponatremia and subsequently treated by desmopressin acetate (DDAVP) during correction of hyponatremia when the rate of correction was overtly or predictably excessive. The primary endpoint was the effectiveness of DDAVP on PNa control.

RESULTS

DDAVP dramatically decreased the rate of PNa correction (median 0.81 mmol/L per hour [interquartile range, 0.46, 1.48] versus -0.02 mmol/L per hour [-0.16, 0.22] before and after DDAVP, respectively; P<0.001) along with a concurrent decrease in urine output (650 ml/h [214, 1200] versus 93.5 ml/h [43, 143]; P=0.003), and a rise in urine osmolarity (86 mmol/L [66, 180] versus 209 mmol/L [149, 318]; P=0.002). The maximal magnitude of PNa variations was also markedly reduced after DDAVP administration (11.5 mmol/L [8.25, 14.5] versus 5 mmol/L [4, 6.75]; P<0.001). No patient developed seizures after DDAVP or after subsequent relowering of PNa that occurred in 11 patients.

CONCLUSIONS

Desmopressin acetate is effective in curbing the rise of PNa in patients admitted in the intensive care unit for severe hyponatremia, when the initial rate of correction is excessive.

Diagnosis, evaluation, and treatment of hyponatremia: expert panel recommendations

Hyponatremia is a serious, but often overlooked, electrolyte imbalance that has been independently associated with a wide range of deleterious changes involving many different body systems. Untreated acute hyponatremia can cause substantial morbidity and mortality as a result of osmotically induced cerebral edema, and excessively rapid correction of chronic hyponatremia can cause severe neurologic impairment and death as a result of osmotic demyelination. The diverse etiologies and comorbidities associated with hyponatremia pose substantial challenges in managing this disorder. In 2007, a panel of experts in hyponatremia convened to develop the Hyponatremia Treatment Guidelines 2007: Expert Panel Recommendations that defined strategies for clinicians caring for patients with hyponatremia. In the 6 years since the publication of that document, the field has seen several notable developments, including new evidence on morbidities and complications associated with hyponatremia, the importance of treating mild to moderate hyponatremia, and the efficacy and safety of vasopressin receptor antagonist therapy for hyponatremic patients. Therefore, additional guidance was deemed necessary and a panel of hyponatremia experts (which included all of the original panel members) was convened to update the previous recommendations for optimal current management of this disorder. The updated expert panel recommendations in this document represent recommended approaches for multiple etiologies of hyponatremia that are based on both consensus opinions of experts in hyponatremia and the most recent published data in this field.