Tonicity Balance in Patients With Hypernatremia Acquired in the Intensive Care Unit

Plasma sodium during the recovery of renal function in critically ill adult patients: Multicenter prospective cohort study

BACKGROUND

Sodium increases during acute kidney injury (AKI) recovery. Both hypernatremia and positive fluid balances are associated with increased mortality. We aimed to evaluate the association between daily fluid balance and daily plasma sodium during the recovery from AKI among critical patients.

METHODS

Adult patients with AKI were enrolled in four ICUs and followed up for four days or until ICU discharge or hemodialysis initiation. Day zero was the peak day of creatinine. The primary outcome was daily plasma sodium; the main exposure was daily fluid balance.

RESULTS

93 patients were included. The median age was 66 years; 68% were male. Plasma sodium increased in 79 patients (85%), and 52% presented hypernatremia. We found no effect of daily fluid balance on plasma sodium (β -0.26, IC95%: -0.63-0.13; p = 0.19). A higher total sodium variation was observed in patients with lower initial plasma sodium (β -0.40, IC95%: -0.53 to -0.27; p < 0.01), higher initial urea (β 0.07, IC95%: 0.04-0.01; p < 0.01), and higher net sodium balance (β 0.002, IC95%: 0.0001-0.01; p = 0.05).

CONCLUSIONS

The increase in plasma sodium is common during AKI recovery and can only partially be attributed to the water and electrolyte balances. The incidence of hypernatremia in this population of patients is higher than in the general critically ill patient population.

Enteral free water vs. parenteral dextrose 5% in water for the treatment of hypernatremia in the intensive care unit: a retrospective cohort study from a mixed ICU

PURPOSE

Effective treatment options for patients with hypernatremia are limited. Free water administration (parenterally or enterally) is the mainstay of treatment but the impact of each strategy on lowering serum sodium (Na) is not known. The purpose of the study was thus to assess the effectiveness of enteral free water vs. parenteral dextrose 5% in water (D5W) in treating ICU-acquired hypernatremia.

METHODS

An electronic medical record-based, retrospective cohort study was conducted in a 30-bed mixed medical-surgical intensive care unit (ICU) in Japan. All adult patients admitted to the ICU from August 2017 to July 2021 were reviewed. After a 2-step exclusion, patients who stayed in the ICU ≥ 24 h and received either or both treatments for ICU-acquired hypernatremia (Na ≥ 145 mEq/L) constituted the study cohort. The primary outcome was a change in serum Na during the 24 h before treatment each day (ΔNa); the secondary outcomes were gastrointestinal complications, serum glucose levels, ICU/hospital mortality, ICU/hospital length of stay, and the duration of mechanical ventilation. Repeated measurements on each patient were addressed using a generalized estimated equation (GEE) for multiple linear regression analysis. Analysis was conducted with R version 4.0.3.

RESULTS

In total, 256/6596 (131: D5W, 125: enteral free water) patients were analyzed. Median treatment lasted 6 days [3-17] for the D5W group vs 7 days [3-14] for the enteral free water group with a total median daily treatment volume of 799 [IQR 299-1221] mL vs. 400 [IQR 262-573] mL. GEE multiple linear regression analysis showed an estimated mean ΔNa per liter of treatment fluid of - 2.25 [95% CI - 2.76 to - 1.74] mEq/L per liter of parenteral D5W vs. - 1.91 mEq decrease [95% CI - 2.75 to - 1.07] per liter of enteral free water. Hydrochlorothiazide was the only medication associated with a statistically significant negative ΔNa by- 0.89 [- 1.57 to - 0.21] mEq/L. There were no significant inter-group differences for secondary outcomes.

CONCLUSIONS

These results suggest that both enteral free water and parenteral D5W are effective for treating ICU-acquired hypernatremia. Parenteral D5W was slightly more effective than enteral free water to lower serum Na levels in patients with ICU-acquired hypernatremia.

TRIAL REGISTRATION

Not applicable.

Hypernatremia at presentation to the emergency department: a case series

Disorders of serum sodium are common findings in patients presenting to the emergency department (ED). The aim of this study was to systematically investigate the prevalence, symptoms, etiology, treatment as well as the course of hypernatremia present on admission to the ED. All adult patients with measurements of serum sodium presenting to the ED between 01 January 2017 and 31 December 2020 were included in this retrospective cohort study. Chart reviews were performed for all patients with hypernatremia defined as serum sodium > 147 mmol/L. 376 patients (0.7%) had a serum sodium > 145 mmol/L on admission and 109 patients (0.2%) had clinically relevant hypernatremia > 147 mmol/L. Main symptoms included somnolence (42%) followed by disorientation (30%) and recent falls (17%). An impaired sense of thirst was the main cause of hypernatremia as present in 76 patients (70%), followed by a lack of free access to water in 50 patients (46%). Regarding treatment, only one patient received targeted oral hydration and 38 patients (35%) experienced inadequate correction of hypernatremia as defined as either a correction of < 2 mmol/L or further increasing sodium during the first 24 h. 25% of patients with hypernatremia died during the course of their hospital stay. Patients who died had significantly lower correction rates of serum sodium (0 mmol/L (-3 - 1.5) versus - 6 mmol/L (-10 - 0), p < 0.001). Hypernatremia is regularly encountered in the ED and patients present with unspecific neurologic symptoms. Initial treatment and correction of hypernatremia are frequently inadequate with no decrease or even increase in serum sodium during the first 24 h.

A Prospective Cohort Study on Serum Sodium and Clinical Outcome in Pediatric Nontraumatic Coma

OBJECTIVE

To study the serum sodium level and clinical outcome in pediatric nontraumatic coma.

METHODS

A prospective cohort study was conducted in a tertiary care pediatric intensive care unit (PICU) from September 2015 to June 2016. Children aged < 13 y with nontraumatic coma [modified-Glasgow Coma Scale (m-GCS) score ≤ 8 or fall of ≥ 3 from baseline within 24 h of admission] were included. Children who received intravenous fluids for > 24 h, those with developmental delay, or died within 24 h of admission were excluded. The serum sodium profile (mEq/L) in the first 72 h and clinical outcome [mortality, length of stay in mechanical ventilation, PICU, and hospital] were studied.

RESULTS

Eighty patients [Died n = 26 and Survived n = 54] were enrolled. Median [interquartile range (IQR)] age and m-GCS were 21 (4-78) mo and 9 (7-11), respectively. The mean [standard deviation (SD)] Pediatric Risk of Mortality-III (PRISM-III) was 17.7 (4). The most common etiology was acute central nervous system (CNS) infections (30%, n = 24) followed by an intracranial bleed (11.3%, n = 9). Mean (Standard error, SE) sodium levels and fluctuation of serum sodium from baseline up to 72 h were similar between nonsurvivors and survivors [140.8 (1.3) vs. 139.6 (0.8), p = 0.421] and [1.2 (0.3) vs. 0.8 (0.2), p = 0.307], respectively. On multivariate analysis, the need for vasoactive therapy was an independent predictor of mortality [adjusted odds ratio = 20.78, 95% CI 4.24-101.85, p = < 0.001, R² = 0.62].

CONCLUSION

Mean serum sodium within normal range and fluctuation of serum sodium of 0.8 to 1.2 mEq/L over 72 h was not associated with poor outcomes in pediatric nontraumatic coma. Vasoactive therapy was an independent predictor of mortality.

Sodium alterations impair the prognosis of hospitalized patients with COVID-19 pneumonia

OBJECTIVE

Dysnatremia is common in hospitalized patients, often worsening the prognosis in pneumopathies and critical illnesses. Information on coronavirus disease-19 (COVID-19)-related hyponatremia is partially conflicting, whereas data on hypernatremia in this context are scarce. We assessed, in a cohort of COVID-19 inpatients: the prevalence of sodium alterations at admission and throughout their hospitalization; their association with inflammation/organ damage indexes; their short-term prognostic impact.

STUDY DESIGN AND METHODS

117 patients (81 males, 64 ± 13 years) hospitalized for COVID-19 between 1 March and 30 April 2020 were retrospectively followed-up for their first 21 days of stay by collecting all serum sodium measurements, basal CRP and serum lactate levels, maximum IL-6 and information on care setting, required ventilation, length of hospitalization, in-hospital death.

RESULTS

At admission, 26.5% patients had hyponatremia, and 6.8% had hypernatremia. During their hospitalization, 13.7% patients experienced both disorders ('mixed dysnatremia'). Lower sodium levels at admission were correlated with higher C reactive protein (CRP) (P = 0.039) and serum lactate levels (P = 0.019), but not interleukin-6 (IL-6). Hypernatremia and a wider sodium variability were associated with maximum required ventilation, need for ICU assistance and duration of the hospitalization. Mean estimated time to Intensive Care Unit (ICU) admission was 20 days shorter in patients exposed to sodium alterations at any time of their hospital course (log-rank test P = 0.032).

CONCLUSIONS

Sodium alterations frequently affect hospitalized COVID-19 patients. Hyponatremia could indicate pulmonary involvement, whereas hypernatremia is associated to prolonged hospitalization and the need for intensive care/mechanical ventilation, particularly when resulting from prior hyponatremia. Optimizing in-hospital sodium balance is crucial to improve patients' prognosis.

Intravenous Infusion of Sterile Water for the Treatment of Hypernatraemia

Little research has been carried out into the infusion of intravenous sterile water for the treatment of hypernatraemia, and it remains a contentious issue. We conducted a review of the literature and extract results following an extensive search of Medline 1946, Embase 1974, ProQuest, evidence-based practice resources, national and international guideline sites and the publications of various professional bodies. The review is presented on the infusion of sterile water (hypotonic fluid) to lower serum sodium level in those circumstances when enteral supplementation of water is not possible, such as in postoperative patients or when other isotonic fluids (such as 5% dextrose in water infusion) are less than ideal—for example, hyperglycaemic patients on an insulin infusion. Absence of guidelines has limited the use of sterile water, even as an off-label drug when it can be administered relatively safely via a central line.

Polyuria in adults. A diagnostic approach based on pathophysiology

Polyuria is a common clinical condition characterized by a urine output that is inappropriately high (more than 3 L in 24 h) for the patient's blood pressure and plasma sodium levels. From a pathophysiological point of view, it is classified into two types: polyuria due to a greater excretion of solutes (urine osmolality >300 mOsm/L) or due to an inability to increase solute concentration (urine osmolality <150 mOsm/L). Sometimes both mechanisms can coexist (urine osmolality 150-300 mOsm/L). Polyuria is a diagnostic challenge and its proper treatment requires an evaluation of the medical record, determination of urine osmolality, estimation of free water clearance, use of water deprivation tests in aqueous polyuria, and measurement of electrolytes in blood and urine in the case of osmotic polyuria.

COVID-19 and endocrine and metabolic disorders: critical points and suggestions for a correct therapeutic management from a tertiary endocrine center in Italy

The Coronavirus-19 (COVID-19) pandemic, which began in December 2019 in Wuhan, China, has spread rapidly worldwide, affecting mostly frail individuals and resulting in high lethality among people with chronic conditions. The management of chronic endocrine disorders during the pandemic period proved particularly challenging, as they require close physician-patient contact for proper long-term management. In addition, acute endocrinologic conditions that presented during the COVID-19 period required timely management in an unusual clinical setting, providing an ongoing challenge for clinicians. This article summarizes the most recent guidance on the management and therapy of frequent conditions such as diabetes and osteoporosis and less common endocrine disorders (e.g., adrenal insufficiency) in this setting.

Early ICU-acquired hypernatraemia is associated with injury severity and preceded by reduced renal sodium and chloride excretion in polytrauma patients

PURPOSE

To further elucidate the origin of early ICU-acquired hypernatraemia.

MATERIAL AND METHODS

In this retrospective single-centre study, polytrauma patients requiring ICU treatment were analysed.

RESULTS

Forty-eight (47.5%) of 101 included polytrauma patients developed hypernatraemia within the first 7 days on ICU. They were more severely ill as described by higher SAPS III, ISS, daily SOFA scores and initial norepinephrine requirements as well as longer requirements of mechanical ventilation and ICU treatment in general. The development of hypernatraemia was neither attributable to fluid- or sodium-balances nor renal impairment. Although lower in the hypernatraemic group from day 4 onwards, median creatinine clearances were sufficiently high throughout the observation period. However, in the hypernatraemic group, urine sodium and chloride concentrations prior to the evolvement of hypernatraemia (56 (27-87) mmol/l and 39 (23-77) mmol/l) were significantly decreased when compared to i) the time after developing hypernatraemia (94 (58-134) mmol/l and 78 (36-115) mmol/l; p < 0.001) and ii) the non-hypernatraemic group in general (101 (66-143) mmol/l and 75 (47-109) mmol/l; p < 0.001).

CONCLUSIONS

Early ICU-acquired hypernatraemia is associated with injury severity and preceded by reduced renal sodium and chloride excretion in polytrauma patients.

Increased sodium intake and decreased sodium excretion in ICU-acquired hypernatremia: A prospective cohort study

PURPOSE

To provide more in-depth insight in the development of early ICU-acquired hypernatremia in critically ill patients based on detailed, longitudinal and quantitative data.

MATERIALS AND METHODS

A comparative analysis was performed using prospectively collected data of ICU patients. All patients requiring ICU admission for more than 48 h between April and December 2018 were included. For this study, urine samples were collected daily and analyzed for electrolytes and osmolality. Additionally, plasma osmolality analyses were performed. Further data collection consisted of routine laboratory results, detailed fluid balances and medication use.

RESULTS

A total of 183 patient were included for analysis, of whom 38% developed ICU-acquired hypernatremia. Whereas the hypernatremic group was similar to the non-hypernatremic group at baseline and during the first days, hypernatremic patients had a significantly higher sodium intake on day 2 to 5, a lower urine sodium concentration on day 3 and 4 and a worse kidney function (plasma creatinine 251 versus 71.9 μmol/L on day 5). Additionally, hypernatremic patients had higher APACHE IV scores (67 versus 49, p < 0.05) and higher ICU (23 versus 12%, p = 0.07) and 90-day mortality (33 versus 14%, p < 0.01).

CONCLUSIONS

Longitudinal analysis shows that the development of early ICU-acquired hypernatremia is preceded by increased sodium intake, decreased renal function and decreased sodium excretion.

ICU acquired hypernatremia treated by enteral free water - A retrospective cohort study

PURPOSE

ICU acquired hypernatremia (IAH) is associated with increased morbidity and mortality, however treatment remains controversial. This study aims to determine the effect of enteral free water suppletion in patients with IAH.

MATERIALS AND METHODS

Retrospective single center study in a tertiary ICU.

INCLUSION CRITERIA

patients with IAH and treatment with enteral free water.

EXCLUSION CRITERIA

patients with renal replacement therapy, diabetic ketoacidosis or hyperosmolar hyperglycaemic state.

PRIMARY OUTCOME

change in plasma sodium (in mmol/l) after 5 days treatment. Responders were defined as patients with a decrease in sodium level of 5 mmol/l or more.

RESULTS

In total 382 consecutive patients were included. The median sodium level at the start of water therapy was 149 mmol/l (IQR 147-150). The median volume of enteral water was 4423 ml (IQR 3349-5379 ml) after 5 days and mean sodium decrease was 1.87 mmol/l (SD 4.84). There was no significant correlation between the volume of enteral water and sodium decrease (r² = 0.01).

CONCLUSIONS

Treatment with enteral free water did not result in a clinically relevant decrease in serum sodium level in patients with IAH. In addition, the volume of enteral free water and the use of diuretics was unrelated with sodium change over 5 days.

Renal Function is a Major Determinant of ICU-acquired Hypernatremia: A Balance Study on Sodium Handling

Background and Objectives

The development of ICU-acquired hypernatremia (IAH) is almost exclusively attributed to ‘too much salt and too little water’. However, intrinsic mechanisms also have been suggested to play a role. To identify the determinants of IAH, we designed a prospective controlled study.

Methods

Patients with an anticipated length of stay ICU > 48 hours were included. Patients with hypernatremia on admission and/or on renal replacement therapy were excluded. Patients without IAH were compared with patients with borderline hypernatremia (≥ 143 mmol/L, IAH 143) and more severe hypernatremia (≥ 145 mmol/L, IAH 145).

Results

We included 89 patients, of which 51% developed IAH 143 and 29% IAH 145. Sodium intake was high in all patients. Fluid balances were slightly positive and comparable between the groups. Patients with IAH 145 were more severely ill on admission, and during admission, their sodium intake, cumulative sodium balances, serum creatinine and copeptin levels were higher. According to the free water clearance, all the patients conserved water. On multivariate analysis, the baseline serum creatinine was an independent risk factor for the development of IAH 143 and IAH 145. Also, the copeptin levels remained significant for IAH 143 and IAH 145. Sodium intake remained only significant for patients with IAH 145.

Conclusions

Our data support the hypothesis that IAH is due to the combination of higher sodium intake and a urinary concentration deficit, as a manifestation of the renal impairment elicited by severe illness.

Prevalence and Prognostic Impact of Hypernatremia in Sepsis and Septic Shock Patients in the Intensive Care Unit: A Single Centre Experience

Introduction

Hypernatremia is a commonly associated electrolyte disturbance in sepsis and septic shock patients in the ICU. The objective of this study was to identify the prognostic value of hypernatremia in sepsis and septic shock

Material and Methods

A prospective study conducted on sepsis and septic shock patients diagnosed prior to admission in the ICU in King Hamad University Hospital, Bahrain from January 1st 2017 to February 28th 2019. Data including age, sex, comorbidities, source of sepsis, sodium levels on days one, three, and seven. Data was correlated with the outcome (survival/death and the length of ICU stay).

Results

Patients included were 168, 110 survived, and 58 died. Hypernatraemia at day seven was associated with significantly higher mortality (P= 0.03). Hypernatraemia at Day1was associated with a significantly prolonged stay in the ICU (p= 0.039).Multivariate analysis to identify the independent predictors of mortality revealed that immunosuppression and hypernatraemia at Day7 proved to be independent predictors of mortality (P= 0.026 and 0.039 respectively).

Conclusion

Hypernatremia can be an independent predictor of poor outcome in septic and septic shock patients in the ICU.

Continuous veno-venous hemofiltration in the treatment of severely burned patients with acute hypernatremia: A retrospective study of 13 cases

OBJECTIVES

This study aimed to evaluate the clinical effects of continuous veno-venous hemofiltration in the treatment of severely burned patients with acute hypernatremia.

METHODS

A total of 13 severely burned patients with acute hypernatremia admitted to Xijing Hospital were included in this study. All patients received continuous veno-venous hemofiltration treatment in addition to conventional treatment. The original sodium level in the replacement fluid was set to be lower than the serum sodium level by 8 mmol/L and subsequently undergoes a reduction rate of 2.16 ± 0.18 mmol/L every 4 h. Patients' clinical features, serum laboratory tests, hemodynamic variables, changes in sodium levels in serum, and replacement fluid during continuous veno-venous hemofiltration treatment were monitored.

RESULTS

Patients had an average total burn surface area of 66.69% ± 20.28%. Two patients died of systematic Pseudomonas aeruginosa infections, and 11 patients survived. After continuous veno-venous hemofiltration treatment, patients showed a significant reduction in the serum sodium level (168.91 ± 4.88 mmol/L vs 144.62 ± 2.98 mmol/L, p < 0.01). Likewise, the serum levels of urea and creatinine decreased from 24.8 ± 6.5 mmol/L to 14.9 ± 8.3 mmol/L and from 278.6 ± 155.3 μmol/L to 152.6 ± 29.7 μmol/L, respectively (p < 0.05). The patients also displayed improvements in the Acute Physiology and Chronic Health Evaluation II and Glasgow scores (p < 0.05) and showed a significant reduction in hemoglobin and serum albumin levels (p < 0.05), but no obvious change in levels of platelets, alanine aminotransferase, and aspartate aminotransferase (p > 0.05).

CONCLUSION

Our results indicate that continuous veno-venous hemofiltration with gradient sodium replacement fluid is effective in treating hypernatremia in severely burned patients with the controllable sodium reduction rate and satisfactory clinical outcomes.

Regulation of Inflammatory Functions of Macrophages and T Lymphocytes by NFAT5

The transcription factor NFAT5, also known as TonEBP, belongs to the family of Rel homology domain-containing factors, which comprises the NF-κB proteins and the calcineurin-dependent NFAT1 to NFAT4. NFAT5 shares several structural and functional features with other Rel-family factors, for instance it recognizes DNA elements with the same core sequence as those bound by NFAT1 to 4, and like NF-κB it responds to Toll-like receptors (TLR) and activates macrophage responses to microbial products. On the other hand, NFAT5 is quite unique among Rel-family factors as it can be activated by hyperosmotic stress caused by elevated concentrations of extracellular sodium ions. NFAT5 regulates specific genes but also others that are inducible by NF-κB and NFAT1 to 4. The ability of NFAT5 to do so in response to hypertonicity, microbial products, and inflammatory stimuli may extend the capabilities of immune cells to mount effective anti-pathogen responses in diverse microenvironment and signaling conditions. Recent studies identifying osmostress-dependent and -independent functions of NFAT5 have broadened our understanding of how NFAT5 may modulate immune function. In this review we focus on the role of NFAT5 in macrophages and T cells in different contexts, discussing findings from in vivo mouse models of NFAT5 deficiency and reviewing current knowledge on its mechanisms of regulation. Finally, we propose several questions for future research.

ESPEN guideline on clinical nutrition and hydration in geriatrics

BACKGROUND

Malnutrition and dehydration are widespread in older people, and obesity is an increasing problem. In clinical practice, it is often unclear which strategies are suitable and effective in counteracting these key health threats.

AIM

To provide evidence-based recommendations for clinical nutrition and hydration in older persons in order to prevent and/or treat malnutrition and dehydration. Further, to address whether weight-reducing interventions are appropriate for overweight or obese older persons.

METHODS

This guideline was developed according to the standard operating procedure for ESPEN guidelines and consensus papers. A systematic literature search for systematic reviews and primary studies was performed based on 33 clinical questions in PICO format. Existing evidence was graded according to the SIGN grading system. Recommendations were developed and agreed in a multistage consensus process.

RESULTS

We provide eighty-two evidence-based recommendations for nutritional care in older persons, covering four main topics: Basic questions and general principles, recommendations for older persons with malnutrition or at risk of malnutrition, recommendations for older patients with specific diseases, and recommendations to prevent, identify and treat dehydration. Overall, we recommend that all older persons shall routinely be screened for malnutrition in order to identify an existing risk early. Oral nutrition can be supported by nursing interventions, education, nutritional counseling, food modification and oral nutritional supplements. Enteral nutrition should be initiated if oral, and parenteral if enteral nutrition is insufficient or impossible and the general prognosis is altogether favorable. Dietary restrictions should generally be avoided, and weight-reducing diets shall only be considered in obese older persons with weight-related health problems and combined with physical exercise. All older persons should be considered to be at risk of low-intake dehydration and encouraged to consume adequate amounts of drinks. Generally, interventions shall be individualized, comprehensive and part of a multimodal and multidisciplinary team approach.

CONCLUSION

A range of effective interventions is available to support adequate nutrition and hydration in older persons in order to maintain or improve nutritional status and improve clinical course and quality of life. These interventions should be implemented in clinical practice and routinely used.

Postoperative fluid retention after heart surgery is accompanied by a strongly positive sodium balance and a negative potassium balance

The conventional model on the distribution of electrolyte infusions states that water will distribute proportionally over both the intracellular (ICV) and extracellular (ECV) volumes, while potassium homes to the ICV and sodium to the ECV. Therefore, total body potassium is the most accurate measure of ICV and thus potassium balances can be used to quantify changes in ICV. In cardiothoracic patients admitted to the ICU we performed complementary balance studies to measure changes in ICV and ECV. In 39 patients, fluid, sodium, potassium, and electrolyte‐free water (EFW) balances were determined to detect changes in ICV and ECV. Cumulatively over 4 days, these patients received a mean ± SE infusion of 14.0 ± 0.6 L containing 1465 ± 79 mmol sodium, 196 ± 11 mmol potassium and 2.1 ± 0.1 L EFW. This resulted in strongly positive fluid (4.0 ± 0.6 L) and sodium (814 ± 75 mmol) balances but in negative potassium (−101 ± 14 mmol) and EFW (−1.1 ± 0.2 L) balances. We subsequently compared potassium balances (528 patients) and fluid balances (117 patients) between patients who were assigned to either a 4.0 or 4.5 mmol/L blood potassium target. Although fluid balances were similar in both groups, the additionally administered potassium (76 ± 23 mmol) in the higher target group was fully excreted by the kidneys (70 ± 23 mmol). These findings indicate that even in the context of rapid and profound volume expansion neither water nor potassium moves into the ICV.

The Development of Intensive Care Unit Acquired Hypernatremia Is Not Explained by Sodium Overload or Water Deficit: A Retrospective Cohort Study on Water Balance and Sodium Handling

Background. ICU acquired hypernatremia (IAH, serum sodium concentration (sNa) ≥ 143 mmol/L) is mainly considered iatrogenic, induced by sodium overload and water deficit. Main goal of the current paper was to answer the following questions: Can the development of IAH indeed be explained by sodium intake and water balance? Or can it be explained by renal cation excretion? Methods. Two retrospective studies were conducted: a balance study in 97 ICU patients with and without IAH and a survey on renal cation excretion in 115 patients with IAH. Results. Sodium intake within the first 48 hours of ICU admission was 12.5 [9.3-17.5] g in patients without IAH (n = 50) and 15.8 [9-21.9] g in patients with IAH (n = 47), p = 0.13. Fluid balance was 2.3 [1-3.7] L and 2.5 [0.8-4.2] L, respectively, p = 0.77. Urine cation excretion (urine Na + K) was < sNa in 99 out of 115 patients with IAH. Severity of illness was the only independent variable predicting development of IAH and low cation excretion, respectively. Conclusion. IAH is not explained by sodium intake or fluid balance. Patients with IAH are characterized by low urine cation excretion, despite positive fluid balances. The current paradigm does not seem to explain IAH to the full extent and warrants further studies on sodium handling in ICU patients.

Water-loss (intracellular) dehydration assessed using urinary tests: how well do they work? Diagnostic accuracy in older people

BACKGROUND

Water-loss dehydration (hypertonic, hyperosmotic, or intracellular dehydration) is due to insufficient fluid intake and is distinct from hypovolemia due to excess fluid losses. Water-loss dehydration is associated with poor health outcomes such as disability and mortality in older people. Urine specific gravity (USG), urine color, and urine osmolality have been widely advocated for screening for dehydration in older adults.

OBJECTIVE

We assessed the diagnostic accuracy of urinary measures to screen for water-loss dehydration in older people.

DESIGN

This was a diagnostic accuracy study of people aged ≥65 y taking part in the DRIE (Dehydration Recognition In our Elders; living in long-term care) or NU-AGE (Dietary Strategies for Healthy Ageing in Europe; living in the community) studies. The reference standard was serum osmolality, and index tests included USG, urine color, urine osmolality, urine cloudiness, additional dipstick measures, ability to provide a urine sample, and the volume of a random urine sample. Minimum useful diagnostic accuracy was set at sensitivity and specificity ≥70% or a receiver operating characteristic plot area under the curve ≥0.70.

RESULTS

DRIE participants (women: 67%; mean age: 86 y; n = 162) had more limited cognitive and functional abilities than did NU-AGE participants (women: 64%; mean age: 70 y; n = 151). Nineteen percent of DRIE participants and 22% of NU-AGE participants were dehydrated (serum osmolality >300 mOsm/kg). Neither USG nor any other potential urinary tests were usefully diagnostic for water-loss dehydration.

CONCLUSIONS

Although USG, urine color, and urinary osmolality have been widely advocated for screening for dehydration in older adults, we show, in the largest study to date to our knowledge, that their diagnostic accuracy is too low to be useful, and these measures should not be used to indicate hydration status in older people (either alone or as part of a wider tranche of tests). There is a need to develop simple, inexpensive, and noninvasive tools for the assessment of dehydration in older people. The DRIE study was registered at www.researchregister.org.uk as 122273. The NU-AGE trial was registered at clinicialtrials.gov as NCT01754012.

Basic concepts and practical equations on osmolality: Biochemical approach

The terms osmotic pressure, osmotic coefficient, osmole, osmolarity, osmolality, effective osmolality and delta osmolality are formally defined. Osmole is unit of the amount of substance, one mole of nonionized impermeant solute is one osmole. Assuming an ideal solution, osmotic pressure (π) in mmHg is 19.3 times the osmolarity. Osmolarity is defined as the number of milliosmoles of the solutes per liter of solution. Suitable equations are presented for the rapid calculation of the osmolarity of different solutions. The concentrations of electrolytes are expressed by mEq/L that is, equal to their osmolarity as mOsm/L. If the solute concentration (C) is expressed as mg/L, mg/dL and g%, osmolarity is calculated as: C.n' /MW, C.n' (10)/MW and C.n' (10(4))/MW respectively. Osmolality is milliosmoles of solutes per one kilogram (or liter) of water of solution (plasma) and is calculated by osmolarity divided to plasma water. The osmolal concentration is corrected to osmolal activity by using the osmotic coefficient, φ. The salts of sodium (choloride and bicarbonate) and nonelectrolyte glucose and urea are the major five osmoles of plasma. The equation: Posm =2 [Na(+)]+glucose (mg/dL)/18+BUN (mg/dL)//2.8 is also the simplest and best formula to calculate plasma osmolality. The concentration of only effective osmoles evaluates effective osmolality or tonicity as: Eosm =2 [Na(+)]+glucose/18. The normal range of plasma tonicity is 275-295mOsm/kg of water. The difference between the measured and calculated osmolality is called osmolal gap. It is recommended to withdraw the formula of Dorwart-Chalmers from the textbooks and autoanalyzers and to use the simplest equation of Worthley et al. as the best equation for calculating serum osmolality. Furthermore the normal ranges of osmolal gap also must be corrected to 0±2mOsm/L.

Incidence, severity and prognosis associated with hypernatremia in dogs and cats

Background

Hypernatremia has been associated with substantial morbidity and death in human patients. The incidence and importance of hypernatremia in dogs and cats has not been determined.

Hypothesis/Objectives

To describe the incidence of and prognosis associated with hypernatremia in dogs and cats at a university teaching hospital.

Animals

A total of 16,691 dogs and 4,211 cats with measured blood or serum sodium concentration.

Methods

Retrospective study. Medical records of animals with a blood or serum sodium concentration measured during a 60‐month period were reviewed to determine the severity of hypernatremia and its associated case fatality rate. Cases with moderate (11–15 mmol/L above the reference range) or severe hypernatremia (≥16 mmol/L above the reference range) were further reviewed.

Results

A total of 957 dogs (5.7%) and 338 cats (8.0%) were diagnosed with hypernatremia. Case fatality rates of dogs and cats with hypernatremia was 20.6 and 28.1%, respectively compared to 4.4 and 4.5% with a normal blood or serum sodium concentration (P < .0001). The magnitude of hypernatremia was linearly associated with a higher case fatality rate (P < .0001). Hypernatremia was associated with a higher case fatality rate than hyponatremia. Among the animals with moderate or severe hypernatremia, 50% of dogs and 38.5% of cats presented with community‐acquired hypernatremia, and 50% of dogs and 61.5% of cats developed hospital‐acquired hypernatremia.

Conclusions and clinical importance

Hypernatremia was found infrequently in this population but was associated with increased case fatality rates in dogs and cats. Presence and severity of hypernatremia might be useful as a prognostic indicator.

Preoperative abnormalities in serum sodium concentrations are associated with higher in-hospital mortality in patients undergoing major surgery

BACKGROUND

Abnormal serum sodium concentrations are common in patients presenting for surgery. It remains unclear whether these abnormalities are independent risk factors for postoperative mortality.

METHODS

This is a secondary analysis of the European Surgical Outcome Study (EuSOS) that provided data describing 46 539 patients undergoing inpatient non-cardiac surgery. Patients were included in this study if they had a recorded value of preoperative serum sodium within the 28 days immediately before surgery. Data describing preoperative risk factors and serum sodium concentrations were analysed to investigate the relationship with in-hospital mortality using univariate and multivariate logistic regression techniques.

RESULTS

Of 35 816 (77.0%) patients from the EuSOS database, 21 943 (61.3%) had normal values of serum sodium (138-142 mmol litre(-1)) before surgery, 8538 (23.8%) had hyponatraemia (serum sodium ≤137 mmol litre(-1)) and 5335 (14.9%) had hypernatraemia (serum sodium ≥143 mmol litre(-1)). After adjustment for potential confounding factors, moderate to severe hypernatraemia (serum sodium concentration ≥150 mmol litre(-1)) was independently associated with mortality [odds ratio 3.4 (95% confidence interval 2.0-6.0), P<0.0001]. Hyponatraemia was not associated with mortality.

CONCLUSIONS

Preoperative abnormalities in serum sodium concentrations are common, and hypernatraemia is associated with increased mortality after surgery. Abnormalities of serum sodium concentration may be an important biomarker of perioperative risk resulting from co-morbid disease.

Risk Factors and Outcomes in Patients With Hypernatremia and Sepsis

BACKGROUND

Hypernatremia is an uncommon but important electrolyte abnormality in intensive care unit patients. Sepsis is one of the most common causes of intensive care unit admission, but few studies about the role of hypernatremia in sepsis has been published yet. In this study, we aimed to explore the risk factors for developing hypernatremia in patients with sepsis, and the prognosis of patients with sepsis with or without hypernatremia was also assessed.

MATERIALS AND METHODS

In this retrospective cohort study of 51 septic intensive care unit patients at a single center, we examined the risk factors for the development of hypernatremia and the association of hypernatremia with clinical outcomes using univariate and multivariable analyses. Clinical outcomes such as mortality and hospital duration of patients with or without hypernatremia were also compared.

RESULTS

Acute Physiology and Chronic Health Evaluation II score (odds ratio = 1.15; 95% CI: 1.022-1.294) was found to be the only independent risk factor for hypernatremia in patients with sepsis. Moreover, patients developing hypernatremia during hospitalization showed significantly higher morbidity and mortality.

CONCLUSIONS

Acute Physiology and Chronic Health Evaluation II score may be an independent risk factor for hypernatremia in patients with sepsis. Moreover, hypernatremia is strongly associated with worse outcome in sepsis.

Addition of indapamide to frusemide increases natriuresis and creatinine clearance, but not diuresis, in fluid overloaded ICU patients

BACKGROUND

Fluid and sodium overload are a common problem in critically ill patients. Frusemide may result in diuresis in excess of natriuresis. The addition of indapamide may achieve a greater natriuresis, and also circumvent some of the problems associated with frusemide. The objective of this study was to examine the effect of adding indapamide to frusemide on diuresis, natriuresis, creatinine clearance and serum electrolytes.

METHODS

Fluid overloaded ICU patients were randomised to either intravenous frusemide (Group F) or intravenous frusemide and enteral indapamide (Group F + I). Comprehensive exclusion criteria were applied to address confounders. 24 hour urine was analysed for electrolytes and creatinine. Serum electrolytes were measured before and 24 hours after administration of diuretics.

RESULTS

Forty patients (20 in each group) were included in the study. The groups were similar in their baseline characteristics. Over the 24 h study period, patients in Group F + I, had a larger natriuresis (P = 0.01), chloride loss (P = 0.01) and kaliuresis (P = 0.047). Patients in Group F + I also had a greater 24 hour urinary creatinine clearance (P = 0.01). The 24 hour urine volume and fluid balance was similar between the groups. Patients in Group F had an increase in serum sodium (P = 0.04), while patients in Group F + I had a decrease in both serum chloride (P = 0.01) and peripheral oedema (P < 0.001) during the study duration.

CONCLUSION

In fluid overloaded ICU patients, addition of indapamide to frusemide led to a greater natriuresis and creatinine clearance. Such a strategy might be utilised in optimising sodium balance in ICU patients.

Acquired hypernatremia in a general surgical Intensive Care Unit: Incidence and prognosis

Purpose:

Intensive Care Unit (ICU)-acquired hypernatremia (IAH) is a serious electrolyte disturbance that recently was shown to present an independent risk factor for mortality in critically ill patients. IAH has not been widely investigated in Surgical ICU (SICU) patients. No study has specifically investigated IAH epidemiology in the Kingdome of Saudi Arabia (KSA) in general SICU. The objectives of this study are to assess the epidemiological characteristics and prognostic impact of IAH on SICU mortality and outcome in KSA and compare it with international figures.

Materials and Methods:

A retrospective observational study on a prospectively collected data of patients (14 years of age or older) admitted to SICU over 2 years, with normal serum sodium on admission and who developed IAH (serum sodium above 145 mmol/L) from day two of admission. Traumatic brain injury patients with therapeutic target sodium level above 145 mmol/L were excluded.

Results:

Over 2 years study period, 864 patients were admitted to SICU. A total of 50 (5.8%) developed IAH and were included in the study. Twenty-eight (56%) patients were male. The median age was 47 (14-84) years. The mean (± standard deviation) Acute Physiology and Chronic Health Evaluation II score was 17 ± 6.5. The incident density (the rate of occurrence of IAH per 100 days care for SICU admission for the first episode) was 0.71. Risk factors include mechanical ventilation, male sex, age ≥50 years, postgastrointestinal surgeries, weekend and night admission. SICU mortality was 40%. The SICU and hospital median (range) length of stay was 8.3 (2-53) and 28.8 (3-95), respectively.

Conclusions:

IAH is not uncommon in SICU patients and is associated with increased risk of SICU as well as hospital mortality.

Are the Dysnatremias a Permanent Threat to the Critically Ill Patients?

Backgroud

The dysnatremias (hyponatremia and hypernatremia) are relatively common findings on admission of intensive care unit (ICU) patients and may represent a major risk. The aim of the study was to assess the ability of serum sodium levels and the Acute Physiology and Chronic Health Evaluation II (APACHE II) to predict mortality of surgical critically ill patients.

Methods

One hundred and ninety-five surgical patients (62% males and 38% females; mean age of 51.8 ± 17.3 years) admitted to the ICU in the postoperative phase were retrospectively studied. The patients were divided into survivors (n = 152) and non-survivors (n = 43). APACHE II, and serum sodium levels at admission, 48 h and discharge were analyzed by generation of receiver operating characteristic (ROC) curves.

Results

The mean APACHE II was 16.3 ± 8.3 (13.6 ± 6.1 for survivors and 25.5 ± 8.5 for non-survivors). The area under the ROC curve for APACHE II was 0.841 (0.782 - 0.889) and 0.721 (0.653 - 0.783), 0.754 (0.653 - 0.783) and 0.720 (0.687 - 0.812) for serum sodium level at admission, 48 h and discharge, respectively.

Conclusion

Even though APACHE II scoring system was the most effective index to predict mortality in the surgical critically ill patients, the serum sodium levels on admission may also be used as an independent predictor of outcome.

Prevention of hospital-acquired hyponatraemia: individualised fluid therapy

BACKGROUND

Large amounts of fluids are daily prescribed to hospitalised patients across different medical specialities. Unfortunately, inappropriate fluid administration commonly causes iatrogenic hyponatraemia with associated increase in morbidity and mortality.

METHODS/RESULTS

Fundamental for prevention of hospital-acquired hyponatraemia is an understanding of what determines plasma sodium concentration (P-[Na(+) ]) in the individual patient. P-[Na(+) ] is determined by balances of water and cations according to Edelman. This paper discusses the mechanisms influencing water and cation balances. In the hospitalised patient, non-osmotic antidiuretic hormone secretion is frequent and results in a reduced renal electrolyte-free water clearance (EFWC). This condition puts the patient at risk of hyponatraemia upon infusion of fluids that are hypotonic such as 5% glucose, Darrow-glucose, NaKglucose and 0.45% NaCl in 5% glucose. It is suggested that individualised fluid therapy includes the following: Firstly, bolus therapy with Ringer-acetate/Ringer-lactate/0.9% NaCl in the hypovolaemic patient to minimise the risk of fluid under-/overload. Secondly, P-[Na(+) ] should be monitored together with the balances influencing P-[Na(+) ]. This may include EFWC in patients at additional risk of hyponatraemia. In patients with potentially reduced intracranial compliance (e.g. meningitis, intracranial bleeding, cerebral contusion and brain oedema), even a small decrease in P-[Na(+) ] induced by slightly hypotonic fluids like Ringer-acetate/Ringer-lactate can increase the intracranial pressure dramatically. Consequently, 0.9 % NaCl is recommended as first-line fluid for such patients.

CONCLUSIONS

The occurrence of hospital-acquired hyponatraemia may be reduced by prescribing fluids, type and amount, with the same dedication as shown for other drugs.

Clinical symptoms, signs and tests for identification of impending and current water-loss dehydration in older people

BACKGROUND

There is evidence that water-loss dehydration is common in older people and associated with many causes of morbidity and mortality. However, it is unclear what clinical symptoms, signs and tests may be used to identify early dehydration in older people, so that support can be mobilised to improve hydration before health and well-being are compromised.

OBJECTIVES

To determine the diagnostic accuracy of state (one time), minimally invasive clinical symptoms, signs and tests to be used as screening tests for detecting water-loss dehydration in older people by systematically reviewing studies that have measured a reference standard and at least one index test in people aged 65 years and over. Water-loss dehydration was defined primarily as including everyone with either impending or current water-loss dehydration (including all those with serum osmolality ≥ 295 mOsm/kg as being dehydrated).

SEARCH METHODS

Structured search strategies were developed for MEDLINE (OvidSP), EMBASE (OvidSP), CINAHL, LILACS, DARE and HTA databases (The Cochrane Library), and the International Clinical Trials Registry Platform (ICTRP). Reference lists of included studies and identified relevant reviews were checked. Authors of included studies were contacted for details of further studies.

SELECTION CRITERIA

Titles and abstracts were scanned and all potentially relevant studies obtained in full text. Inclusion of full text studies was assessed independently in duplicate, and disagreements resolved by a third author. We wrote to authors of all studies that appeared to have collected data on at least one reference standard and at least one index test, and in at least 10 people aged ≥ 65 years, even where no comparative analysis has been published, requesting original dataset so we could create 2 x 2 tables.

DATA COLLECTION AND ANALYSIS

Diagnostic accuracy of each test was assessed against the best available reference standard for water-loss dehydration (serum or plasma osmolality cut-off ≥ 295 mOsm/kg, serum osmolarity or weight change) within each study. For each index test study data were presented in forest plots of sensitivity and specificity. The primary target condition was water-loss dehydration (including either impending or current water-loss dehydration). Secondary target conditions were intended as current (> 300 mOsm/kg) and impending (295 to 300 mOsm/kg) water-loss dehydration, but restricted to current dehydration in the final review.We conducted bivariate random-effects meta-analyses (Stata/IC, StataCorp) for index tests where there were at least four studies and study datasets could be pooled to construct sensitivity and specificity summary estimates. We assigned the same approach for index tests with continuous outcome data for each of three pre-specified cut-off points investigated.Pre-set minimum sensitivity of a useful test was 60%, minimum specificity 75%. As pre-specifying three cut-offs for each continuous test may have led to missing a cut-off with useful sensitivity and specificity, we conducted post-hoc exploratory analyses to create receiver operating characteristic (ROC) curves where there appeared some possibility of a useful cut-off missed by the original three. These analyses enabled assessment of which tests may be worth assessing in further research. A further exploratory analysis assessed the value of combining the best two index tests where each had some individual predictive ability.

MAIN RESULTS

There were few published studies of the diagnostic accuracy of state (one time), minimally invasive clinical symptoms, signs or tests to be used as screening tests for detecting water-loss dehydration in older people. Therefore, to complete this review we sought, analysed and included raw datasets that included a reference standard and an index test in people aged ≥ 65 years.We included three studies with published diagnostic accuracy data and a further 21 studies provided datasets that we analysed. We assessed 67 tests (at three cut-offs for each continuous outcome) for diagnostic accuracy of water-loss dehydration (primary target condition) and of current dehydration (secondary target condition).Only three tests showed any ability to diagnose water-loss dehydration (including both impending and current water-loss dehydration) as stand-alone tests: expressing fatigue (sensitivity 0.71 (95% CI 0.29 to 0.96), specificity 0.75 (95% CI 0.63 to 0.85), in one study with 71 participants, but two additional studies had lower sensitivity); missing drinks between meals (sensitivity 1.00 (95% CI 0.59 to 1.00), specificity 0.77 (95% CI 0.64 to 0.86), in one study with 71 participants) and BIA resistance at 50 kHz (sensitivities 1.00 (95% CI 0.48 to 1.00) and 0.71 (95% CI 0.44 to 0.90) and specificities of 1.00 (95% CI 0.69 to 1.00) and 0.80 (95% CI 0.28 to 0.99) in 15 and 22 people respectively for two studies, but with sensitivities of 0.54 (95% CI 0.25 to 0.81) and 0.69 (95% CI 0.56 to 0.79) and specificities of 0.50 (95% CI 0.16 to 0.84) and 0.19 (95% CI 0.17 to 0.21) in 21 and 1947 people respectively in two other studies). In post-hoc ROC plots drinks intake, urine osmolality and axillial moisture also showed limited diagnostic accuracy. No test was consistently useful in more than one study.Combining two tests so that an individual both missed some drinks between meals and expressed fatigue was sensitive at 0.71 (95% CI 0.29 to 0.96) and specific at 0.92 (95% CI 0.83 to 0.97).There was sufficient evidence to suggest that several stand-alone tests often used to assess dehydration in older people (including fluid intake, urine specific gravity, urine colour, urine volume, heart rate, dry mouth, feeling thirsty and BIA assessment of intracellular water or extracellular water) are not useful, and should not be relied on individually as ways of assessing presence or absence of dehydration in older people.No tests were found consistently useful in diagnosing current water-loss dehydration.

AUTHORS' CONCLUSIONS

There is limited evidence of the diagnostic utility of any individual clinical symptom, sign or test or combination of tests to indicate water-loss dehydration in older people. Individual tests should not be used in this population to indicate dehydration; they miss a high proportion of people with dehydration, and wrongly label those who are adequately hydrated.Promising tests identified by this review need to be further assessed, as do new methods in development. Combining several tests may improve diagnostic accuracy.

Intravenous solutions in the care of patients with volume depletion and electrolyte abnormalities

Infusion fluids are often given to restore blood pressure (volume resuscitation), but may also be administered to replace ongoing losses, match insensible losses, correct electrolyte or acid-base disorders, or provide glucose. The development of new infusion fluids has provided clinicians with a wide range of products. Although the choice for a certain infusion fluid is often driven more by habit than by careful consideration, we believe it is useful to approach infusion fluids as drugs and consider their pharmacokinetic and pharmacodynamic characteristics. This approach not only explains why infusion fluids may cause electrolyte and acid-base disturbances, but also why they may compromise kidney function or coagulation. In this teaching case, we present a 19-year-old patient in whom severe hypernatremia developed as a result of normal saline solution infusion and explore the pharmacokinetic and pharmacodynamic effects of frequently used infusion fluids. We review clinical evidence to guide the selection of the optimal infusion fluid.

Incidence and mortality prognosis of dysnatremias in neurologic critically ill patients

BACKGROUND

Dysnatremia, which is associated with increased mortality in general intensive care units (ICU), has not been thoroughly studied in neurologic ICU (NICU).

METHODS

Prevalence of dysnatremia was retrospectively assessed. The multivariable binary logistic regression model was used to determine the influence of dysnatremia on mortality.

RESULTS

Of 519 patients, 106 (20.4%) were admitted with hyponatremia and 177 (34.10%) with hypernatremia. Hypernatremia was detected in 69 (13.29%) patients on admission to NICU and in 108 patients (20.81%) during the ICU stay. However, the incidence of dysnatremia did not differ across the neurological categories (p = 0.4690). ICU stay in patients with acquired hypernatremia (22.3 ± 25.35 days) was longer than those with admission hypernatremia (13.5 ± 12.8 days) or with consistent normonatremia (16.16 ± 20.06 days). The other indicators such as Acute Physiology and Chronic Health Evaluation II, Glasgow Coma Scale score, urinary catheterization, and incidence of pneumonia were also associated with the serum sodium concentrations. Hypernatremia both on admission and acquired in NICU could significantly differentiate between survivors and nonsurvivors (p = 0.002 and <0.0001). However, only NICU-acquired hypernatremia was the independent risk factor for mortality with high sensitivity (p = 0.000).

CONCLUSIONS

Dysnatremia is more common in NICU, whereas only acquired-hypernatremia was independently associated with outcome.

Disorders of sodium and water balance

Dysnatremias occur simultaneously with disorders in water balance. The first priority is to correct dehydration; once the patient is euvolemic, the sodium level can be reassessed. In unstable patients with hyponatremia, the clinician should rapidly administer hypertonic saline. In unstable patients with hypernatremia, the clinician should administer isotonic intravenous fluid. In stable patients with either hyponatremia or hypernatremia, the clinician should aim for correction over 24 to 48 hours, with the maximal change in serum sodium between 8 to 12 mEq/L over the first 24 hours. This rate of correction decreases the chances of cerebral edema or osmotic demyelination syndrome.

Normal saline to dilute parenteral drugs and to keep catheters open is a major and preventable source of hypernatremia acquired in the intensive care unit

PURPOSE

We wanted to identify modifiable risk factors for intensive care unit (ICU)-acquired hypernatremia.

MATERIALS AND METHODS

We retrospectively studied sodium and fluid loads and balances up to 7 days prior to the development of hypernatremia (first serum sodium concentration, [Na+], >150 mmol/L; H) vs control (maximum [Na+] ≤150 mmol/L; N), in consecutive patients admitted into the ICU with a normal serum sodium (<145 mmol/L) and without cerebral disease, within a period of 8 months.

RESULTS

There were 57 H and 150 N patients. Severity of disease and organ failure was greater, and length of stay and mechanical ventilation in the ICU were longer in H (P<.001), with a mortality rate of 28% vs 16% in N (P=.002). Sodium input was higher in H than in N, particularly from 0.9% saline to dissolve drugs for infusion and to keep catheters open during the week prior to the first day of hypernatremia (P<.001). Fluid balances were positive and did not differ from N on most days in the presence of slightly higher plasma creatinine and more frequent administration of furosemide, at higher doses, in H than in N.

CONCLUSIONS

High sodium input by 0.9% saline used to dilute drugs and keep catheters open is a modifiable risk factor for ICU-acquired H. Dissolving drugs in dextrose 5% may partially prevent potentially harmful sodium overloading and H.

Evaporation of free water causes concentrational alkalosis in vitro

BACKGROUND

The development of metabolic alkalosis was described recently in patients with hypernatremia. However, the causes for this remain unknown. The current study serves to clarify whether metabolic alkalosis develops in vitro after removal of free water from plasma and whether this can be predicted by a mathematical model.

MATERIALS AND METHODS

Ten serum samples of healthy humans were dehydrated by 29 % by vacuum centrifugation corresponding to an increase of the contained concentrations by 41 %. Constant partial pressure of carbon dioxide at 40 mmHg was simulated by mathematical correction of pH [pH(40)]. Metabolic acid-base state was assessed by Gilfix' base excess subsets. Changes of acid-base state were predicted by the physical-chemical model according to Watson.

RESULTS

Evaporation increased serum sodium from 141 (140-142) to 200 (197-203) mmol/L, i.e., severe hypernatremia developed. Acid-base analyses before and after serum concentration showed metabolic alkalosis with alkalemia: pH(40): 7.43 (7.41 to 7.45) vs 7.53 (7.51 to 7.55), p = 0.0051; base excess: 1.9 (0.7 to 3.6) vs 10.0 (8.2 to 11.8), p = 0.0051; base excess of free water: 0.0 (- 0.2 to 0.3) vs 17.7 (16.8 to 18.6), p = 0.0051. The acidifying effects of evaporation, including hyperalbuminemic acidosis, were beneath the alkalinizing ones. Measured and predicted acid-base changes due to serum evaporation agreed well.

CONCLUSIONS

Evaporation of water from serum causes concentrational alkalosis in vitro, with good agreement between measured and predicted acid-base values. At least part of the metabolic alkalosis accompanying hypernatremia is independent of renal function.

Hypernatremia severity and the risk of death after traumatic brain injury

PURPOSE

To investigate the relationship between severity of hypernatremia and the risk of death for patients with traumatic brain injury (TBI) who have been admitted to the neurosurgical intensive care unit (NICU).

METHODS

A total of 1044 patients with TBI were admitted to our NICU from January 2005 to January 2010. Of these patients, 881 were included in this study. Based on blood serum sodium level in the NICU the 881 patients were divided into four groups: 614 had normal serum sodium (Na<150mmol/L), 34 had mild hypernatremia (Na 150-<155mmol/L), 66 had moderate hypernatremia (Na 155-160mmol/L) and 167 had severe hypernatremia (Na≥160mmol/L).

RESULTS

The mortality rates for the mild, moderate, and severe hypernatremia groups were 20.6%, 42.4%, and 86.8%, respectively; the mortality rate for the normal group was 2.0%. In multivariable analysis, mild, moderate, and severe hypernatremia were independent risk factors for mortality; compared with the normal group the odds ratios of mild, moderate, and severe hypernatremia were 9.50, 4.34, and 29.35, respectively.

CONCLUSIONS

Severe hypernatremia is an independent risk factor with extremely high odds ratio for death in patients with TBI who are admitted to the NICU.

Body salt and water balances in cardiothoracic surgery patients with intensive care unit-acquired hyponatremia

PURPOSE

Hyponatremia is frequently observed in intensive care unit (ICU) patients, but there is still lack information on the physiological mechanisms of development.

MATERIALS AND METHODS

In this retrospective analysis we performed tonicity balances in 54 patients with ICU acquired hyponatremia. We calculated fluid and solute in and outputs during 24 hours in 106 patient days with decreasing serum-sodium levels.

RESULTS

We could observe a positive fluid balance as a single reason for hyponatremia in 25% of patients and a negative solute balance in 57%. In 18% both factors contributed to the decrease in serum-sodium. Hyponatremic patients had renal water retention, measured by electrolyte free water clearance calculation in 79% and positive input of free water in 67% as reasons for decline of serum-sodium. The theoretical change of serum sodium during 24 hours according to the calculations of measured balances correlated well with the real change of serum sodium (r = 0.78, P < .01).

CONCLUSIONS

Balance studies showed that renal water retention together with renal sodium loss and high electrolyte free water input are the major contributors to the development of hyponatremia. Control of renal water and sodium handling by urine analysis may contribute to a better fluid management in the ICU population.

Community-acquired hypernatremia in elderly and very elderly patients admitted to the hospital: clinical characteristics and outcomes

Background

The clinical features, outcome and cost burden of community-acquired hypernatremia (CAH) in elderly and very elderly patients are not well known. Our aim was to investigate the etiologies, reasons for admission, clinical courses, outcomes, complications, and cost assessments of the elderly patients with CAH.

Material/Methods

We conducted a retrospective study in our tertiary hospital. Elderly and very elderly patients evaluated in the emergency department (ED) from January 1, 2010 to December 31, 2010 (n=4960) were included. Totally, 102 patients older than 65 years and diagnosed with CAH were evaluated. The patients were divided into 2 main groups according to their age: elderly (65–74 years old) (group 1) (n=38), and very elderly (>74 years) (group 2) (n=64).

Results

Our overall observed prevalence of CAH was 2.0% (n=102, 102/4960). In particular, the prevalences of CAH in group 1 and group 2 were 1.0% (38/3651) and 4.8% (64/1309), respectively (p<0.001). Totally, 62 patients had been treated by renin-angiotensin system (RAS) blockers (ie, ACE-inhibitors). Alzheimer’s disease had been diagnosed in 46.1% of the subjects. The mean Katz scores at the time of admission were 2.4±1.9 and 1.1±1.0 in group 1 and 2, respectively (p<0.001). The mean cost was higher in group 2 than in group 1 (2407.13±734.54 USD, and 2141.12±1387.14 USD, respectively) (p<0.01). The need for intensive care was significantly greater in group 2 as compared to group 1.

Conclusions

The important determinants of “CAH” in elderly subjects are accompanying Alzheimer’s disease, oral intake impairment, and concomitant treatment with RAS blockers.

Clinical review: practical approach to hyponatraemia and hypernatraemia in critically ill patients

Disturbances in sodium concentration are common in the critically ill patient and associated with increased mortality. The key principle in treatment and prevention is that plasma [Na+] (P-[Na+]) is determined by external water and cation balances. P-[Na+] determines plasma tonicity. An important exception is hyperglycaemia, where P-[Na+] may be reduced despite plasma hypertonicity. The patient is first treated to secure airway, breathing and circulation to diminish secondary organ damage. Symptoms are critical when handling a patient with hyponatraemia. Severe symptoms are treated with 2 ml/kg 3% NaCl bolus infusions irrespective of the supposed duration of hyponatraemia. The goal is to reduce cerebral symptoms. The bolus therapy ensures an immediate and controllable rise in P-[Na+]. A maximum of three boluses are given (increases P-[Na+] about 6 mmol/l). In all patients with hyponatraemia, correction above 10 mmol/l/day must be avoided to reduce the risk of osmotic demyelination. Practical measures for handling a rapid rise in P-[Na+] are discussed. The risk of overcorrection is associated with the mechanisms that cause hyponatraemia. Traditional classifications according to volume status are notoriously difficult to handle in clinical practice. Moreover, multiple combined mechanisms are common. More than one mechanism must therefore be considered for safe and lasting correction. Hypernatraemia is less common than hyponatraemia, but implies that the patient is more ill and has a worse prognosis. A practical approach includes treatment of the underlying diseases and restoration of the distorted water and salt balances. Multiple combined mechanisms are common and must be searched for. Importantly, hypernatraemia is not only a matter of water deficit, and treatment of the critically ill patient with an accumulated fluid balance of 20 litres and corresponding weight gain should not comprise more water, but measures to invoke a negative cation balance. Reduction of hypernatraemia/hypertonicity is critical, but should not exceed 12 mmol/l/day in order to reduce the risk of rebounding brain oedema.

Intensive care unit-acquired hypernatremia is an independent predictor of increased mortality and length of stay

PURPOSE

The purpose of this study is to examine the impact of hypernatremia acquired after intensive care unit (ICU) admission on mortality and length of stay (LOS).

MATERIALS AND METHODS

Data for this observational study were collected from patients admitted between January 1, 2008, and September 30, 2010 to 344 ICUs in the eICU Research Institute.

RESULTS

Of the 207702 eligible patients, 8896 (4.3%) developed hypernatremia (serum Na >149 mEq/L). Hospital mortality was 32% for patients with hypernatremia and 11% for patients without hypernatremia (P < .0001). Intensive care unit LOS was 13.7 ± 9.7 days for patients with hypernatremia and 5.1 ± 4.6 for patients without hypernatremia (P < .0001). Multivariate analysis showed that hypernatremia was an independent risk factor for hospital mortality with a relative risk (RR) of 1.40 (95% confidence interval, 1.34-1.45) and ICU LOS with a rate ratio (RtR) of 1.28 (1.26-1.30). The RR for mortality and RtR for ICU LOS increased with increasing severity strata of hypernatremia, but the duration of hypernatremia was not associated with mortality.

CONCLUSIONS

Hypernatremia developed following ICU admission in 4.3% of patients. Hypernatremia was independently associated with a 40% increase in risk for hospital mortality and a 28% increase in ICU LOS. Severity, but not duration of ICU-acquired hypernatremia was associated with hospital mortality.

Prognostic consequences of borderline dysnatremia: pay attention to minimal serum sodium change

Introduction

To assess the prevalence of dysnatremia, including borderline changes in serum sodium concentration, and to estimate the impact of these dysnatremia on mortality after adjustment for confounders.

Methods

Observational study on a prospective database fed by 13 intensive care units (ICUs). Unselected patients with ICU stay longer than 48 h were enrolled over a 14-year period were included in this study. Mild to severe hyponatremia were defined as serum sodium concentration < 135, < 130, and < 125 mmol/L respectively. Mild to severe hypernatremia were defined as serum sodium concentration > 145, > 150, and > 155 mmol/L respectively. Borderline hyponatremia and hypernatremia were defined as serum sodium concentration between 135 and 137 mmol/L or 143 and 145 respectively.

Results

A total of 11,125 patients were included in this study. Among these patients, 3,047 (27.4%) had mild to severe hyponatremia at ICU admission, 2,258 (20.3%) had borderline hyponatremia at ICU admission, 1,078 (9.7%) had borderline hypernatremia and 877 (7.9%) had mild to severe hypernatremia. After adjustment for confounder, both moderate and severe hyponatremia (subdistribution hazard ratio (sHR) 1.82, 95% CI 1.002 to 1.395 and 1.27, 95% CI 1.01 to 1.60 respectively) were associated with day-30 mortality. Similarly, mild, moderate and severe hypernatremia (sHR 1.34, 95% CI 1.14 to 1.57; 1.51, 95% CI 1.15 to 1.99; and 2.64, 95% CI 2.00 to 3.81 respectively) were independently associated with day-30 mortality.

Conclusions

One-third of critically ill patients had a mild to moderate dysnatremia at ICU admission. Dysnatremia, including mild changes in serum sodium concentration, is an independent risk factor for hospital mortality and should not be neglected.

Rising serum sodium levels are associated with a concurrent development of metabolic alkalosis in critically ill patients

PURPOSE

Changes in electrolyte homeostasis are important causes of acid-base disorders. While the effects of chloride are well studied, only little is known of the potential contributions of sodium to metabolic acid-base state. Thus, we investigated the effects of intensive care unit (ICU)-acquired hypernatremia on acid-base state.

METHODS

We included critically ill patients who developed hypernatremia, defined as a serum sodium concentration exceeding 149 mmol/L, after ICU admission in this retrospective study. Data on electrolyte and acid-base state in all included patients were gathered in order to analyze the effects of hypernatremia on metabolic acid-base state by use of the physical-chemical approach.

RESULTS

A total of 51 patients were included in the study. The time of rising serum sodium and hypernatremia was accompanied by metabolic alkalosis. A transient increase in total base excess (standard base excess from 0.1 to 5.5 mmol/L) paralleled by a transient increase in the base excess due to sodium (base excess sodium from 0.7 to 4.1 mmol/L) could be observed. The other determinants of metabolic acid-base state remained stable. The increase in base excess was accompanied by a slight increase in overall pH (from 7.392 to 7.429, standard base excess from 0.1 to 5.5 mmol/L).

CONCLUSIONS

Hypernatremia is accompanied by metabolic alkalosis and an increase in pH. Given the high prevalence of hypernatremia, especially in critically ill patients, hypernatremic alkalosis should be part of the differential diagnosis of metabolic acid-base disorders.

Characteristics, symptoms, and outcome of severe dysnatremias present on hospital admission

OBJECTIVE

Dysnatremias are common in critically ill patients and associated with adverse outcomes, but their incidence, nature, and treatment rarely have been studied systematically in the population presenting to the emergency department. We conducted a study in patients presenting to the emergency department of the University of Bern.

METHODS

In this retrospective case series at a university hospital in Switzerland, 77,847 patients admitted to the emergency department between April 1, 2008, and March 31, 2011, were included. Serum sodium was measured in 43,911 of these patients. Severe hyponatremia was defined as less than 121 mmol/L, and severe hypernatremia was defined as less than 149 mmol/L.

RESULTS

Hypernatremia (sodium>145 mmol/L) was present in 2% of patients, and hyponatremia (sodium<135 mmol/L) was present in 10% of patients. A total of 74 patients had severe hypernatremia, and 168 patients had severe hyponatremia. Some 38% of patients with severe hypernatremia and 64% of patients with hyponatremia had neurologic symptoms. The occurrence of symptoms was related to the absolute elevation of serum sodium. Somnolence and disorientation were the leading symptoms in hypernatremic patients, and nausea, falls, and weakness were the leading symptoms in hyponatremic patients. The rate of correction did not differ between symptomatic and asymptomatic patients. Patients with symptomatic hypernatremia showed a further increase in serum sodium concentration during the first 24 hours after admission. Corrective measures were not taken in 18% of hypernatremic patients and 4% of hyponatremic patients.

CONCLUSIONS

Dysnatremias are common in the emergency department. Hyponatremia and hypernatremia have different symptoms. Contrary to recommendations, serum sodium is not corrected more rapidly in symptomatic patients.