Severe Hyponatremia Correction, Mortality, and Central Pontine Myelinolysis

Hyponatremia Correction and Osmotic Demyelination Syndrome Risk: A Systematic Review and Meta-Analysis

Rationale & Objective

Osmotic demyelination syndrome (ODS) is a rare but severe condition often attributed to the rate of sodium collection. We evaluated the association between the overly rapid sodium correction in adult hospitalized patients with ODS.

Study Design

Systematic review and meta-analysis.

Setting & Study Populations

Adults hospitalized hyponatremia patients.

Selection Criteria for Studies

The studies comparing the incidence of ODS with and without rapid sodium correction inception to January 2024.

Data Extraction

Two reviewers independently extracted data and assessed the risk of bias and the certainty of evidence.

Analytic Approach

The incidence of ODS following a rapid and nonrapid sodium correction was pooled using the random effects model. Subgroup and meta-regression analyses were performed for the robustness and the source of heterogeneity.

Results

Eleven cohort studies were included with 26,710 hospitalized hyponatremia patients. The definition of hyponatremia varied from <116 to <130 mmol/L, and overly rapid sodium correction was defined as >8 to 12 mmol/L within 24 hours. The overall incidence of ODS was 0.23%. The incidence of ODS in rapid and nonrapid sodium correction was 0.73% and 0.10%, respectively. Meta-analysis demonstrated that a rapid rate of sodium correction was associated with a higher incidence of ODS (odds ratio 3.16, 95% CI, 1.54-6.49, I2 = 27%), whereas some patients with hyponatremia developed ODS without rapid sodium level correction. The sensitivity analysis based on the quality of the studies was consistent with the main result.

Limitation

Various definition criteria for ODS diagnosis across studies, lack of potential electrolyte and treatment data that may affect the incidence of ODS.

Conclusions

The rapid rate of sodium correction had a statistical correlation with a higher incidence of ODS. Among ODS without rapid correction, further studies are recommended to evaluate and comprehend the relationship for better and proper management of hospitalized patients with hyponatremia.

Correcting hyponatraemia is associated with improved survival in hyponatraemic metastatic cancer patients

Background

Hyponatraemia in cancer patients admitted to the hospital is associated with longer stays, higher costs and increased mortality. We examined the impact of hyponatraemia correction on survival in hospitalized patients with advanced cancer.

Methods

We reviewed records of patients with solid tumours who were hospitalized between January 2018 and December 2022 with serum sodium ≤125 mEq/l at admission. Cox regression analysis examined associations of demographic and clinical characteristics, including sodium levels at admission and discharge, with overall survival.

Results

Among 1100 patients, median sodium levels were 122 mEq/l at admission and 132 mEq/l at discharge. A total of 165 patients (15%) died during hospitalization and 414 of 688 discharged home (60.2%) died within 5 years. Multivariable analysis showed that among patients discharged alive, a decrease in sodium from admission to discharge (P = .0081), sodium ≤125 mEq/l at discharge [hazard ratio (HR) 1.42; P = .0382], albumin <3.5 g/dl at admission (HR 1.48; P < .0001), metastatic stage (HR 1.37; P = .0004), emergency admission (HR 1.20; P = .0390), discharge to hospice (HR 2.57; P < .0001), lung cancers (HR 1.51; P = .0044) and metastatic disease (HR 1.37; P = .0004) were associated with poorer overall survival. Sodium level at admission was not a significant predictor of overall survival from hospital admission. In patients with metastatic disease, an increase in sodium from admission to discharge was associated with improved overall survival from hospital discharge.

Conclusions

Correcting hyponatraemia in hospitalized patients with metastatic cancer increases overall survival, but metastatic cancer in itself is also associated with poor survival. This highlights the importance of early palliative care involvement in patients with advanced cancer.

Effectiveness of bundle of care on tolerance of awake-prone positioning in patients with acute respiratory failure. A multicenter observational study

PURPOSE

This study aimed to assess the impact of a bundle of care strategy on the duration of awake prone positioning (AW-PP) and other key clinical outcomes in patients with acute respiratory failure (ARF) who require high-flow nasal oxygen (HFNO).

METHODS

In this secondary analysis of a prospective, multicenter cohort study, we included patients admitted with COVID-19-related ARF who required HFNO. The protocol encouraged AW-PP for as long as possible. The main exposure was a bundle of care including light sedation, monitoring, and information to patients about the strategy (bundle) compared to no bundle (control). The primary outcome was the duration of AW-PP (hours/day), while secondary outcomes included endotracheal intubation and in-hospital mortality. Directed acyclic graphs (DAGs) were employed to identify variables related to both exposure and outcomes. Four models were used to evaluate exposure-outcome associations: inverse probability of treatment weighting (IPTW), "double-robust" approximation (DR), traditional regression (TR), and mixed-effects model (MEM).

RESULTS

Out of 499 patients, 197 were exposed to bundle, and 302 did not. The exposure group had a median (IQR) AW-PP duration of 16 (10-18) hours/day, compared to 10 (7-14) hours/day in the control group. Regression coefficients (95% CI) were 3.39 (1.67-5.11), 3.35 (1.55-5.14), 3.95 (2.63-5.28), and 3.72 (2.5-4.94) for IPTW, DR, TR and MEM, respectively. The odds ratios (95% CI) for intubation were 0.34 (0.15-0.76), 0.23 (0.10-0.50), 0.42 (0.23-0.77), and 0.48 (0.16-0.49), and for in-hospital mortality were 0.38 (0.11-1.27), 0.43 (0.14-1.26), 0.47 (0.22-0.91), and 0.46 (0.12-1.43) in the respective models.

CONCLUSION

In the evaluated population of patients with COVID-19-related ARF, implementing a bundle-of-care strategy was associated with a longer AW-PP exposure and a reduced risk of endotracheal intubation.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov. Identifier NCT05178212. Date of registration: January 5th, 2022.

STUDY TYPE

Observational.

The risk of sodium overcorrections in severe hyponatremia and the utility of desmopressin: a large retrospective study

Background

The suggested narrow rate of serum sodium (sNa) correction in hyponatremia can be difficult to respect, leading to overcorrections. Our ability to anticipate the rapidity of correction according to the mechanism of hyponatremia is uncertain. While desmopressin is often used to pause a rapid rise in sNa, its dose-related effect is also not well described. We studied the rate of hyponatremia overcorrections, its prediction and the utility of desmopressin in its management.

Methods

We retrospectively reviewed all cases of severe hyponatremia (sNa <120 mmol/L) in a large university hospital that occurred over 10 years. We assessed investigations, causes and treatments. We compared all sNa separated by at least 8 h and calculated correction rates. Significant overcorrection rates were defined by any rise of sNa >9 mmol/L per day sustained over at least 24 h.

Results

After exclusions, we found 355 episodes of severe hyponatremia. Low, appropriate and inappropriate antidiuretic hormone (ADH)-defined mechanisms accounted for 17%, 24% and 29% of etiologies, respectively, with the remaining 25% secondary to diuretics and 5% of uncertain causes. First urinary sodium and osmolality were consistent with the final diagnosis in 73%. Significant overcorrections were seen in 45% and were frequent in the setting of low ADH. Desmopressin was given in 82 episodes, more often as a rescue than a preventive measure, with the subsequent sNa dropping by ≥5 mmol/L by 12 h in eight instances. The dose of desmopressin (≥2 µg versus 1 µg) and a higher volume of intravenous free-water coadministration resulted in a clinically meaningful greater reduction in sNa in the following 12 h.

Conclusions

Overcorrections in severe hyponatremia are common, mainly when ADH is low. Initial urinary measurements anticipate this risk. Desmopressin effectively halted the rate of correction in a dose-dependent manner. Caution should be given when coadministrating water, which can significantly lower the sNa.

Correction of profound hyponatraemia following rapid bolus therapy: effectiveness of the Barsoum-Levine formula based on the Edelman equation

Background

The optimal treatment for profound hyponatraemia remains uncertain. Recent clinical studies have demonstrated that a standardized bolus of hypertonic saline is effective, but relying solely on this approach may not fully address the individual variability of hyponatraemia among patients. We evaluated the effectiveness of rapid bolus (RB) administration of hypertonic saline followed by predictive correction (PC) using an infusate and fluid loss formula identical to the Barsoum-Levine formula based on the Edelman equation (RB-PC) for managing profound hyponatraemia.

Methods

In this retrospective observational cohort study, we evaluated 276 patients aged >18 years with s[Na] levels ≤120 mEq/L (January 2014-December 2023). Using propensity score matching (PSM), we assessed s[Na] elevations at 6 h post-treatment initiation and the rate of appropriate hyponatraemia correction between the RB-PC and PC groups. We defined the appropriate correction as a change in s[Na] in the range of 4-10 mEq/L within the first 24 h and ≤18 mEq/L within the first 48 h following corrective treatment initiation.

Results

Among 276 patients with profound hyponatraemia (s[Na] ≤120 mEq/L), 49 and 108 underwent treatment with RB-PC therapy and with PC therapy without RB, respectively. Post-PSM, 84 patients were selected and allocated to the RB-PC (n = 42) or PC group (n = 42). In PSM analysis, patients with RB-PC experienced a higher elevation in s[Na] at 6 h after treatment initiation than PC (4.0 vs 2.4 mEq/L, P < 0.001). The rate of appropriate correction was similar between the RB-PC and PC groups (90.5% vs 90.5%, P = 1).

Conclusions

RB-PC can quickly elevate s[Na] levels and achieve appropriate correction of s[Na] in patients with profound hyponatraemia.

Comparative study of the effectiveness of tolvaptan versus urea in patients with hyponatremia caused by SIADH

BACKGROUND AND OBJECTIVES

Hyponatraemia is common in elderly and hospitalised patients, often caused by the syndrome of inappropriate antidiuretic hormone secretion (SIADH). This study evaluates the efficacy and safety of tolvaptan and urea in patients with hyponatraemia and SIADH.

MATERIALS AND METHODS

An observational cohort study was conducted on 198 patients with SIADH and hyponatraemia (Na+ <135 mmol/L) at the Complejo Hospitalario Universitario de Pontevedra from January 2015 to May 2022. Of these, 86 were treated with tolvaptan (average dose of 7.5 mg) and 112 with urea (average dose of 15 g). The primary outcome was the normalization of sodium levels (Na ≥ 135 mmol/L).

RESULTS

The tolvaptan group showed higher sodium concentrations at the end of therapy compared to the urea group (ME = 136, IQR = 135-137 vs. ME = 134, IQR = 132-137; p < 0.001). The time to normalise sodium was shorter with tolvaptan (4 ± 3.4 days) compared to urea (6 ± 3.6 days; p = 0.03). A higher percentage of patients achieved sodium normalization with tolvaptan (83.72% vs. 59.82%; p = 0.005). Tolvaptan had more adverse effects, such as dry mouth, thirst, and sodium overcorrection, while urea caused dysgeusia, abdominal pain, and diarrhea. There were no significant differences in mortality between the groups.

CONCLUSIONS

Tolvaptan was more effective and quicker than urea in normalising sodium levels, though it showed a higher percentage of adverse effects, which did not require discontinuation of the drug.

Correction Rates and Clinical Outcomes in Hospitalized Adults With Severe Hyponatremia: A Systematic Review and Meta-Analysis

Importance

Hyponatremia treatment guidelines recommend limiting the correction of severe hyponatremia during the first 24 hours to prevent osmotic demyelination syndrome (ODS). Recent evidence suggests that slower rates of correction are associated with increased mortality.

Objective

To evaluate the association of sodium correction rates with mortality among hospitalized adults with severe hyponatremia.

Data Sources

We searched MEDLINE, Embase, the Cochrane Library, LILACS, Web of Science, CINAHL, and international congress proceedings for studies published between January 2013 and October 2023.

Study Selection

Comparative studies assessing rapid (≥8-10 mEq/L per 24 hours) vs slow (<8 or 6-10 mEq/L per 24 hours) and very slow (<4-6 mEq/L per 24 hours) correction of severe hyponatremia (serum sodium <120 mEq/L or <125 mEq/L plus severe symptoms) in hospitalized patients.

Data Extraction and Synthesis

Pairs of reviewers (N.A.F., J.R.M., J.M.A., A.C.) independently reviewed studies, extracted data, and assessed each included study's risk of bias using ROBINS-I. Cochrane methods, PRISMA reporting guidelines, and the GRADE (Grading of Recommendations Assessment, Development and Evaluation) approach to rate the certainty of evidence were followed. Data were pooled using a random-effects model.

Main Outcomes and Measures

Primary outcomes were in-hospital and 30-day mortality, and secondary outcomes were hospital length of stay (LOS) and ODS.

Results

Sixteen cohort studies involving a total of 11 811 patients with severe hyponatremia were included (mean [SD] age, 68.22 [6.88] years; 56.7% female across 15 studies reporting sex). Moderate-certainty evidence showed that rapid correction was associated with 32 (odds ratio, 0.67; 95% CI, 0.55-0.82) and 221 (odds ratio, 0.29; 95% CI, 0.11-0.79) fewer in-hospital deaths per 1000 treated patients compared with slow and very slow correction, respectively. Low-certainty evidence suggested that rapid correction was associated with 61 (risk ratio, 0.55; 95% CI, 0.45-0.67) and 134 (risk ratio, 0.35; 95% CI, 0.28-0.44) fewer deaths per 1000 treated patients at 30 days and with a reduction in LOS of 1.20 (95% CI, 0.51-1.89) and 3.09 (95% CI, 1.21-4.94) days, compared with slow and very slow correction, respectively. Rapid correction was not associated with a statistically significant increased risk of ODS.

Conclusions and Relevance

In this systematic review and meta-analysis, slow correction and very slow correction of severe hyponatremia were associated with an increased risk of mortality and hospital LOS compared to rapid correction.

A Rare Case of Hyponatremia Caused by Urinary Retention

An elderly man was hospitalized after a fall following an episode of dizziness. During the initial examination, he was found to have a distended bladder, caused by urinary retention. Moreover, he was diagnosed with severe hypoosmotic hyponatremia. After the urinary retention was resolved, the patient developed severe diuresis, and the hyponatremia corrected rapidly and spontaneously.

LEARNING POINTS

Hyponatremia is a common affliction in the elderly population, with diverse causes, some of which are still not well understood.In cases of hyponatremia, urinary retention should be considered a possible cause.

Key Considerations for Frail Patients Undergoing Hip Fracture Surgery

Improving preoperative care for elderly patients with hip fractures is crucial for achieving the best outcomes. A multidisciplinary team that can improve overall care quality by addressing patient's medical conditions, analgesia, timely surgery, and early postoperative mobilization is required. This narrative review provides insights regarding the extent of preoperative optimization needed for hip fracture surgery.

Intensive Care Management of Severe Hyponatraemia-An Observational Study

Background and Subject: Hyponatraemia is a common electrolyte disorder. For patients with severe hyponatraemia, intensive care unit (ICU) admission may be required. This will enable close monitoring and allow safe management of sodium levels effectively. While severe hyponatraemia may be associated with significant symptoms, rapid overcorrection of hyponatraemia can lead to complications. We aimed to describe the management and outcomes of severe hyponatraemia in our ICU and identify risk factors for overcorrection. Materials and Methods: This was a retrospective single-centre cohort that included consecutive adults admitted to the ICU with serum sodium < 120 mmol/L between 1 January 2017 and 8 March 2023. Anonymised data were collected from electronic records. We included 181 patients (median age 67 years, 51% male). Results: Median admission serum sodium was 113 mmol/L (IQR: 108-117), with an average rate of improvement over the first 48 h of 10 mmol/L/day (IQR: 5-15 mmol/L). A total of 62 patients (34%) met the criteria for overcorrection at 48 h, and they were younger, presented with severe symptoms (seizures/arrythmias), and had lower admission sodium concentration. They were more likely to be treated with hypertonic saline infusions. Lower admission sodium was an independent risk factor for overcorrection within 48 h, whereas the presence of liver cirrhosis and fluid restriction was associated with normal correction. No difference was identified between the normal and overcorrected cohorts for ICU/hospital length of stay or mortality. Conclusions: In some patients with severe hyponatraemia, overcorrection is inevitable to avoid symptoms such as seizures and arrhythmias, and consequently, we highlight the key factors associated with overcorrection. Overall, we identified that overcorrection was common and concordant with the current literature.

A Reassessment of Sodium Correction Rates and Hospital Length of Stay Accounting for Admission Diagnosis

Background Slow correction of severe hyponatremia has been historically recommended due to the risk of rare but catastrophic neurologic events with rapid correction. A recent study challenging this paradigm reported that rapid correction is associated with shorter hospital length of stay, but that study did not control for admission diagnosis. The objective of this study was to determine whether rapid correction is associated with shorter length of stay when controlling for admission diagnosis. Methods This retrospective cohort study is based on the fourth edition of the Medical Information Mart for Intensive Care, MIMIC-IV, a deidentified, publicly available clinical research database which includes admissions from 2008-2019. Patients were identified who presented to the hospital with initial sodium <120 mEq/L and were categorized according to total sodium correction achieved in the first day (<6 mEq/L; 6-10 mEq/L; >10 mEq/L). Linear regression was used to assess for an association between correction rate and hospital length of stay, and to determine if this association was significant when controlling for admission diagnosis classifications based on diagnosis related groups (DRGs). Results There were 419 patients with severe hyponatremia (<120 mEq/L) included in this study, of whom 374 survived to discharge. Median [IQR] hospital length of stay was 6 [4, 11] days. In a univariable linear regression, there was a trend towards a significant association between the highest rate of correction (>10 mEq/L) and shorter length of stay, as compared with a moderate rate of correction (coef. -2.764, 95% CI [-5.791, 0.263], p=0.073), but the association was not significant when controlling for admission diagnosis group (coef. -1.561, 95% CI [-4.398, 1.276], p=0.280). There was a significant association in the survivor subset (coef. -3.455, 95% CI [-6.668, -0.242], p=0.035), but it was also not significant when controlling for admission diagnosis group (coef. -2.200, 95% CI [-5.144, 0.743], p=0.142). Conclusions Rapid correction is not associated with shorter length of stay when controlling for admission diagnosis, suggesting that the disease state confounds this association. Findings from prior and future studies reporting this association should not drive clinical decision making if the confounding effect of hospital admission diagnosis and competing risk of death are not fully accounted for.

Evaluation and Management of Hyponatremia in Heart Failure

PURPOSE OF REVIEW

To provide a contemporary overview of the pathophysiology, evaluation, and treatment of hyponatremia in heart failure (HF).

RECENT FINDINGS

Potassium and magnesium losses due to poor nutritional intake and treatment with diuretics cause an intracellular sodium shift in HF that may contribute to hyponatremia. Impaired renal blood flow leading to a lower glomerular filtration rate and increased proximal tubular reabsorption lead to an impaired tubular flux through diluting distal segments of the nephron, compromising electrolyte-free water excretion. Hyponatremia in HF is typically a condition of impaired water excretion by the kidneys on a background of potassium and magnesium depletion. While those cations can and should be easily repleted, further treatment should mainly focus on improving the underlying HF and hemodynamics, while addressing congestion. For decongestive treatment, proximally acting diuretics such as sodium-glucose co-transporter-2 inhibitors, acetazolamide, and loop diuretics are the preferred options.

Morbidities and mortality among hospitalized patients with hypopituitarism: Prevalence, causes and management

Hypopituitarism is a highly heterogeneous multisystem disorder that can have a major impact on long-term morbidity and mortality, but even more so during acute medical conditions requiring hospitalization. Recent studies suggest a significant in-hospital burden with prolonged length of stay, increased rate of intensive care unit (ICU) admission, and initiation of mechanical ventilation - all of which may lead to an increased risk of in-hospital mortality. On the one hand, patients with hypopituitarism are often burdened by metabolic complications, including obesity, hypertension, dyslipidemia, and hyperglycemia, which alone, or in combination, are known to significantly alter relevant physiological mechanisms, including metabolism, innate and adaptive immune responses, coagulation, and wound healing, thereby contributing to adverse in-hospital outcomes. On the other hand, depending on the extent and the number of pituitary hormone deficiencies, early recognition of hormone deficiencies and appropriate management and replacement strategy within a well-organized multidisciplinary team are even stronger determinants of short-term outcomes during acute hospitalization in this vulnerable patient population. This review aims to provide an up-to-date summary of recent advances in pathophysiologic understanding, clinical implications, and recommendations for optimized multidisciplinary management of hospitalized patients with hypopituitarism.

Locked-in syndrome after central pontine myelinolysis, an outstanding outcome of two patients

OBJECTIVE

Central pontine myelinolysis (CPM) is a rare demyelinating disease that affects the pons and which can cause extreme disabilities such as locked-in syndrome (LIS) in the initial phase. The aim of the study was to describe the evolution over a 12-month period of two patients with CPM causing an initial LIS.

METHOD

We retrospectively report the unexpected clinical outcome of these two patients in relation with the anatomical damages documented by brain MRI, associated with diffusion tensor imaging and reconstruction of corticospinal tracts in tractography. The following clinical parameters systematically assessed at 3, 6, 9, and 12 months: muscle testing on 12 key muscles (Medical Research Council), prehension metrics (box and block test and purdue pegboard), and independence for acts of daily living (functional independence measure).

RESULTS

Both patients showed a progressive recovery beginning between 2 and 3 months after the onset of symptoms, leading to almost complete autonomy at 12 months (FIM > 110), with motor strength greater than 4/5 in all joint segments (MRC > 50/60). On brain MRI with tractography, CST appeared partially preserved at pons level.

INTERPRETATION

The possibility of a near-complete functional recovery at 12 months is important to consider given the ethical issues at stake and the discussions about limiting care that may take place initially. It seems to be the consequence of reversible myelin damage combined with partially preserved neurons. Development of collateral pathways or resolution of conduction block may explain this recovery. MRI comprising DTI and tractography could play a key role in the prognosis of motor recovery.

[Consensus recommendations on the diagnosis and treatment of hyponatremia from the Austrian Society for Nephrology 2024]

Hyponatremia is a disorder of water homeostasis. Water balance is maintained by the collaboration of renal function and cerebral structures, which regulate thirst mechanisms and secretion of the antidiuretic hormone. Measurement of serum-osmolality, urine osmolality and urine-sodium concentration help to diagnose the different reasons for hyponatremia. Hyponatremia induces cerebral edema and might lead to severe neurological symptoms, which need acute therapy. Also, mild forms of hyponatremia should be treated causally, or at least symptomatically. An inadequate fast increase of the serum sodium level should be avoided, because it raises the risk of cerebral osmotic demyelination. Basic pathophysiological knowledge is necessary to identify the different reasons for hyponatremia which need different therapeutic procedures.