Hypernatremia in the Critically Ill Is an Independent Risk Factor for Mortality

Outcome and frequency of sodium disturbances in neurocritically ill patients

Sodium disturbances are frequent and serious complications in neurocritically ill patients. Hyponatremia is more common than hypernatremia, which is, however, prognostically worse. The aim of this study was to analyse outcome and frequency of sodium disturbances in relation to measured serum osmolality in neurologic-neurosurgical critically ill patients. A 5-year retrospective collection of patients (pts) and laboratory data were made from the Laboratory Information System database in the Clinical Biochemistry Department. The criteria for patients' inclusion was acute brain disease and serum sodium (SNa(+)) <135 mmol/l (hyponatremia) or SNa(+) >150 mmol/l (hypernatremia). Hypoosmolality was defined as measured serum osmolality (SOsm) <275 mmol/kg, hyperosmolality as SOsm >295 mmol/kg. We performed analysis of differences between hyponatremia and hypernatremia and subanalysis of differences between hypoosmolal hyponatremia and hypernatremia. From 1,440 pts with acute brain diseases there were 251 (17 %) pts with hyponatremia (mean SNa(+) 131.78 ± 2.89 mmol/l, SOsm 279.46 ± 11.84 mmol/kg) and 75 (5 %) pts with hypernatremia (mean SNa(+) 154.38 ± 3.76 mmol/l, SOsm 326.07 ± 15.93 mmol/kg). Hypoosmolal hyponatremia occurred in 50 (20 % of hyponatremic patients) pts (mean SNa(+) 129.62 ± 4.15 mmol/l; mean SOsm 267.35 ± 6.28 mmol/kg). Multiple logistic regression analysis showed that hypernatremia is a significant predictor of mortality during neurologic-neurosurgical intensive care unit (NNICU) stay (OR 5.3, p = 0.002) but not a predictor of bad outcome upon discharge from NNICU, defined as Glasgow Coma Scale 1-3. These results showed that hypernatremia occurred less frequently than all hyponatremias, but more often than hypoosmolal hyponatremia. Hypernatremia was shown to be a significant predictor of NNICU mortality compared to hyponatremia.

Safety and efficacy of intravenous hypotonic 0.225% sodium chloride infusion for the treatment of hypernatremia in critically ill patients

BACKGROUND

The purpose of this study was to evaluate the safety and efficacy of central venous administration of a hypotonic 0.225% sodium chloride (one-quarter normal saline [¼ NS]) infusion for critically ill patients with hypernatremia.

METHODS

Critically ill, adult patients with traumatic injuries and hypernatremia (serum sodium [Na] >150 mEq/L) who were given ¼ NS were retrospectively studied. Serum sodium, fluid balance, free water intake, sodium intake, and plasma free hemoglobin concentration (fHgb) were assessed.

RESULTS

Twenty patients (age, 50 ± 18 years; Injury Severity Score, 29 ± 12) were evaluated. The ¼ NS infusion was given at 1.5 ± 1.0 L/d for 4.6 ± 1.6 days. Serum sodium concentration decreased from 156 ± 4 to 143 ± 6 mEq/L (P < .001) over 3-7 days. Total sodium intake was decreased from 210 ± 153 to 156 ± 112 mEq/d (P < .05). Daily net fluid balance was not significantly increased. Plasma fHgb increased from 4.9 ± 5.4 mg/dL preinfusion to 8.9 ± 7.4 mg/dL after 2.6 ± 1.3 days of continuous intravenous (IV) ¼ NS in 10 patients (P = .055). An additional 10 patients had a plasma fHgb of 10.2 ± 9.0 mg/dL during the infusion. Hematocrit and hemoglobin decreased (26% ± 3% to 24% ± 2%, P < .001 and 9.1 ± 1.1 to 8.2 ± 0.8 g/dL, P < .001, respectively).

CONCLUSIONS

Although IV ¼ NS was effective for decreasing serum sodium concentration, evidence for minor hemolysis warrants further research to establish its safety before its routine use can be recommended.

Impact of diuretic therapy-associated electrolyte disorders present on admission to the emergency department: a cross-sectional analysis

BACKGROUND

Diuretics are among the most commonly prescribed medications and, due to their mechanisms of action, electrolyte disorders are common side effects of their use. In the present work we investigated the associations between diuretics being taken and the prevalence of electrolyte disorders on admission as well as the impact of electrolyte disorders on patient outcome.

METHODS

In this cross sectional analysis, all patients presenting between 1 January 2010 and 31 December 2011 to the emergency room (ER) of the Inselspital, University Hospital Bern, Switzerland were included. Data on diuretic medication, baseline characteristics and laboratory data including electrolytes and renal function parameters were obtained from all patients. A multivariable logistic regression model was performed to assess the impact of factors on electrolyte disorders and patient outcome.

RESULTS

A total of 8.5% of patients presenting to the ER used one diuretic, 2.5% two, and 0.4% three or four. In all, 4% had hyponatremia on admission and 12% hypernatremia. Hypokalemia was present in 11% and hyperkalemia in 4%. All forms of dysnatremia and dyskalemia were more common in patients taking diuretics. Loop diuretics were an independent risk factor for hypernatremia and hypokalemia, while thiazide diuretics were associated with the presence of hyponatremia and hypokalemia. In the Cox regression model, all forms of dysnatremia and dyskalemia were independent risk factors for in hospital mortality.

CONCLUSIONS

Existing diuretic treatment on admission to the ER was associated with an increased prevalence of electrolyte disorders. Diuretic therapy itself and disorders of serum sodium and potassium were risk factors for an adverse outcome.

Acute kidney injury, sodium disorders, and hypercalcemia in the aging kidney: diagnostic and therapeutic management strategies in emergency medicine

This article summarizes the current literature regarding the structural and functional changes of the aging kidney and describes how these changes make the older patient more susceptible to acute kidney injury and fluid and electrolyte disorders. It discusses the clinical manifestations, evaluation, and management of hyponatremia and shows how the management of hypernatremia in geriatric patients involves addressing the underlying cause and safely correcting the hypernatremia. The current literature regarding evaluation and management of hypercalcemia in older patients is summarized. The management of severe hypercalcemia is discussed in detail. The evaluation and management of acute kidney injury is described.

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.

Hypernatremia is associated with increased risk of mortality in pediatric severe traumatic brain injury

Acquired hypernatremia in hospitalized patients is often associated with poorer outcomes. Our aim was to evaluate the relationship between acquired hypernatremia and outcome in children with severe traumatic brain injury (sTBI). We performed a retrospective cohort study of all severely injured trauma patients (Injury Severity Score ≥12) with sTBI (Glasgow Coma Scale [GCS] ≤8 and Maximum Abbreviated Injury Scale [MAIS] ≥4) admitted to a Pediatric Critical Care Unit ([PCCU]; 2000-2009). In a cohort of 165 patients, 76% had normonatremia (135-150 mmol/L), 18% had hypernatremia (151-160 mmol/L), and 6% had severe hypernatremia (>160 mmol/L). The groups were similar except for lower GCS (p=0.002) and increased incidence of fixed pupil(s) on admission in both hypernatremia groups (p<0.001). Mortality rate was four-fold and six-fold greater with hypernatremia and severe hypernatremia, respectively (p<0.001), and mortality rates were unchanged when patients with fixed pupils or those with central diabetes insipidus were excluded (p<0.001). Hypernatremic patients had fewer ventilator-free days (p<0.001). Survivors with hypernatremia had greater PCCU (p=0.001) and hospital (p=0.031) lengths of stays and were less frequently discharged home (p=0.008). Logistic regression analyses of patient characteristics and sTBI interventions demonstrated that hypernatremia was independently associated with the presence of fixed pupil(s) on admission (odds ratio [OR] 5.38; p=0.003); administration of thiopental (OR 8.64; p=0.014), and development of central diabetes insipidus (OR 5.66; p=0.005). Additional logistic regression analyses demonstrated a significant association between hypernatremia and mortality (OR 6.660; p=0.034). In summary, acquired hypernatremia appears to signal higher risk of mortality in pediatric sTBI and is associated with a higher discharge level of care in sTBI survivors.

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.

Plasma sodium and subclinical left atrial enlargement in chronic kidney disease

BACKGROUND

Left atrial enlargement (LAE) reflects diastolic dysfunction and predicts mortality in end-stage renal disease patients. However, little is known of its prevalence and factors associated with subclinical LAE in earlier stages of chronic kidney disease (CKD).

METHODS

We conducted a prospective, cross-sectional study in 261 Stage 3-5 non-dialysis CKD patients without symptomatic cardiovascular disease with two-dimensional echocardiography performed to estimate left atrial volume index and other cardiac parameters.

RESULTS

One hundred and nine (41.8%) patients had LAE. Mild and moderate/severe LAEs were observed in 22.9 and 41.3% of patients with left ventricular (LV) hypertrophy (n = 109) versus 13.2 and 12.5% of patients with no LV hypertrophy (n = 152), respectively (P < 0.001). On univariate analysis, plasma sodium concentration showed a significant association with LAE [odds ratio (OR) 1.22, 95% confidence interval (95% CI) 1.09-1.37; P = 0.001]. In the stepwise multiple logistic regression, plasma sodium concentration emerged as one of the most significant factors associated with LAE (adjusted OR 1.29, 95% CI 1.14-1.47; P < 0.001]. Its significance was well maintained (adjusted OR 1.23, 95% CI 1.07-1.43; P = 0.005) when including LV mass and volume index and N-terminal pro-brain natriuretic peptide in the model, while blood haemoglobin and systolic blood pressure were displaced.

CONCLUSIONS

This study for the first time alerted to a very high prevalence of subclinical LAE and reported a strong novel, independent relationship between plasma sodium concentration and subclinical LAE in Stage 3-5 CKD patients. Longitudinal studies are needed to establish causality between high plasma sodium concentration and LAE and their usefulness as therapeutic targets in CKD.

Dysnatremias and survival in adult burn patients: a retrospective analysis

BACKGROUND/AIMS

Dysnatremias have been evaluated in many populations and have been found to be significantly associated with mortality. However, this relationship has not been well described in the burn population.

METHODS

Admissions to the burn center at our institution from January 2003 to December 2008 were examined. Independent variables included gender, age, percentage total body surface area burned (%TBSA), percentage of third-degree burn, inhalation injury, injury severity score (ISS), Acute Kidney Injury Network (AKIN) stage, hypernatremia, and hyponatremia. They were examined via Cox proportional hazard regression models against death. Moderate to severe hypo- and hypernatremia were defined as serum sodium <130 and >150 mmol/l, respectively.

RESULTS

In 1,969 subjects with a mean age of 36.3 ± 16.4 years, a median %TBSA of 9 (interquartile range 4-20) and a median ISS of 5 (interquartile range 1-16) hypernatremia occurred in 9.9% (n = 194), while hyponatremia occurred in 6.8% (n = 134) with mortality rates of 33.5 and 13.8%, respectively. Patients without a dysnatremia had a mortality rate of 4.3%. On Cox proportional hazard regression age, %TBSA, ISS, and AKIN stage were found to be significant predictors of mortality. Hypernatremia (HR 2.00, 95% CI 1.212-3.31; p = 0.0066), but not hyponatremia (HR 1.72, 95% CI 0.89-3.34; p = 0.1068) was associated with mortality.

CONCLUSIONS

In the burn population, hypernatremia, but not hyponatremia, is an independent predictor of mortality.

[Severe hypernatremia. Case report, pathophysiology and therapy]

The case of a female patient with a suprasellar optic glioma is reported, who was admitted to the intensive care unit due to decompensated diabetes insipidus with hypernatremia of 194 mmol/l. The sodium concentration was reduced slowly over 4 days and the patient recovered without sequelae. Based on this case the article deals with the pathophysiology and therapy of hypernatremia. An increase in extracellular osmolarity leads to augmented production of intracellular osmolytes in order to maintain the cell volume constant. Due to this counterregulation correction of the sodium concentration must be done with caution.

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.

Electrolyte-free water clearance versus modified electrolyte-free water clearance: do the results justify the effort?

BACKGROUND

Calculation of electrolyte-free water clearance (EFWC) allows for quantification of renal losses of free water and was shown to be helpful in the differential diagnosis of dysnatremias and might help in the correction of the electrolyte disorders. A modified EFWC formula (MEFWC) was described to be more accurate than the conventional one; however, it has never been evaluated clinically.

METHODS

In order to evaluate the performance of MEFWC compared to EFWC under clinical circumstances, we gathered data from a total of 912 patient days of 138 critically ill patients. EFWC and MEFWC were calculated on the basis of these data. Additionally, from data of critically ill patients, we calculated a prediction of serum sodium based on the Edelman equation using either EFWC or MEFWC and compared results.

RESULTS

Altogether, 343 normonatremic, 124 hyponatremic and 445 hypernatremic days were analyzed. Results for EFWC and MEFWC correlated significantly (R = 0.98). In patients with hyponatremia, the absolute difference between EFWC and MEFWC was significantly larger than in patients with normonatremia (437 vs. 256 ml, p < 0.01). The absolute difference between EFWC and MEFWC correlated significantly with the level of serum sodium (R = -0.41). The mean difference in the prediction of serum sodium change as calculated based on the Edelman equation between the formula using EFWC and the formula using MEFWC was 0.7 mmol/l (SD 0.68) and was highest in hyponatremia and lowest in hypernatremia.

CONCLUSION

Results of EFWC and MEFWC were comparable in critically ill patients. Under normal circumstances, the use of the more complicated MEFWC is not justified. In hyponatremia, the difference between EFWC and MEFWC is larger and thus might justify the use of the more complicated formula.

Dysnatraemias in the emergency room: Undetected, untreated, unknown?

BACKGROUND

Hypo- and hypernatraemia are the most common electrolyte disorders in hospitalized patients and have been associated with increased mortality. However, data on the prevalence of dysnatraemias in the emergency room and the characteristics of patients presenting with them are rare.

METHODS

In this retrospective study, we analyzed data from patients who presented to the emergency department of a large tertiary university hospital between September 1st 2010 and November 30th 2010 and who received measurement of serum sodium.

RESULTS

3,182 patients received measurement of serum sodium during the three-month study period. 124 patients (4%) presented with hyponatraemia on admission to the emergency department while 400 patients (13%) presented with hypernatraemia. While there was no difference in age between patients with hypernatraemia and those who were normonatraemic, patients with hyponatraemia were significantly older.

CONCLUSION

Dysnatraemias are present in almost 1 in 5 patients who presented to the emergency department. Contrarily to patients who are already hospitalized, hypernatraemia was by far more common than hyponatraemia in patients at the emergency department. Surprisingly, patients with hyponatraemia were significantly older than normonatraemic patients while there was no age difference in hypernatraemic patients. Dysnatraemias are common in the emergency room and further studies are indicated to evaluate the causes and the impact on outcome of patients.

Study of outcomes associated with hyponatremia and hypernatremia in children

Sodium is usually included in hospitals' critical values lists; however, the values at which sodium is considered to be life threatening (critical) vary among hospitals. Studies of outcomes associated with hyponatremia and hypernatremia in pediatric patients have not been published. We performed a retrospective chart review of sodium values of <124 mmol/L and >155 mmol/L that occurred during a 6-month period. Univariate and multivariate analyses for mortality risk were performed with the different variables. A total of 702 (1.32%) sodium tests fell in the study reference range, with 166 being <124 mmol/L and 536 being >155 mmol/L. Although not statistically significant, mortality was higher (38.5%) in patients with sodium values ≤ 120 mmol/L than in those with values ≥ 170 mmol/L (25%) or in patients with other values (<14%). Underlying conditions prevented assessment of morbidity associated with hyponatremia or hypernatremia. Treatment was instituted within 4 hours in 80% of cases (50% within 1 hour). Multivariate analysis showed increased risk of death for hyponatremic patients if they were premature or had heart abnormalities, while for hypernatremic patients the risk increased when other critical values were present. In conclusion, sodium levels of ≤ 120 mmol/L and ≥ 170 mmol/L have increased mortality in children; however, the risk of death is not statistically different when compared to risk in patients with milder hyponatremia and hypernatremia. Risk factors for death in hyponatremic and hypernatremic patients may primarily reflect the severity of the underlying conditions present in these children, such as prematurity and heart abnormalities, rather than the sodium derangement.

Hypo- and hypernatraemia in surgical patients: is there room for improvement?

BACKGROUND

Up to 30% of surgical inpatients develop complications related to fluid and electrolyte therapy. We sought to study the occurrence of hypo- and hypernatraemia in these patients to inform current standards of care.

METHODS

This prospective audit took place over 80 days in a university hospital. Patients with a serum sodium concentration less than 130 or greater than 150 mmol/l were included. Daily intakes of Na(+), K(+) and Cl(-), and fluid balance were recorded before and after development of dysnatraemia. Fluid balance charts were assessed, as was the presence of documented patient weights. Patients were followed up until one of these milestones was reached: normonatraemia, death, or hospital discharge.

RESULTS

During the study period 55 (4%) of the 1,383 surgical admissions met the inclusion criteria. Fifteen patients had hypernatraemia, 13 (87%) of whom were identified on ICU/HDU. In the days preceding the hypernatraemia, patients received (in mmol/day) a median (IQR) of 157 (76-344) Na(+), 38 (6-65) K(+), 157 (72-310) Cl(-), and 1.96 (1.13-2.96) L water. In the days preceding the hyponatraemia, patients received 50 (0-189) Na(+), 0 (0-10) K(+), 56 (0-188) Cl(-), and 1.45 (0-2.60) L water. Before the dysnatraemias only 28% of fluid balance charts were completed accurately. During the audit 42% of patients were not weighed. Dysnatraemic patients had a higher hospital mortality rate than those who did not develop dysnatraemia (12.7 vs. 2.3%, P < 0.001).

CONCLUSIONS

Four percent of surgical inpatients developed dysnatraemias, which were associated with increased mortality. Fluid balance documentation was suboptimal and daily weights were not measured routinely, even in patients with severe electrolyte derangements.

Does hypernatremia impact mortality in Toxic Epidermal Necrolysis?

Introduction: In-hospital hypernatremia is associated with increased mortality rates. We want to elucidate the impact of in-hospital acquired hypernatremia in mortality of Toxic Epidermal Necrolysis (TEN).

Purpose: Is there an association between hypernatremia and mortality in patients with TEN?

Method: Retrospective study of 25 patients with TEN. Laboratory electrolyte results, diuresis and survival were analyzed. Patients were separated in two groups without (Group A) or with (Group B) hypernatremia.

Results: In Group A 10 patients with a TBSA of 74±25% (mean ± standard deviation), and a SCORTEN-Score of 2.7±0.9 were summarized. Diuresis within the first 10 days after admission was 1±0.3 ml/kg/hour. In Group B 15 patients with a TBSA of 76±19%, and a SCORTEN-Score of 3.5±1 were included. Diuresis within the first 10 days after admission was 1.4±0.4 ml/kg/hour. Hypernatremia occurred on day 3.3±2.4 after admission and persisted for 5.3±2.9 days. Statistical analysis showed a significantly higher diuresis (p=0.007) and SCORTEN-Score (p=0.04) in the hypernatremic patients. One normonatremic and 8 hypernatremic patients died during ICU-stay (overall mortality rate 36%). A significantly higher mortality rate was found in Group B (odds ratio: 13,5; 95% confidence interval: 1.34–135.98; p=0.01) during ICU-stay.

Conclusion: TEN patients with an in-hospital acquired hypernatremia have an increased mortality risk. Close electrolyte monitoring is advisable in these patients.

Electrolyte disturbances associated with commonly prescribed medications in the intensive care unit

Electrolyte imbalances are common in critically ill patients. Although multiple disease states typically encountered in the intensive care unit may be responsible for the development of electrolyte disorders, medications may contribute to these disturbances as well. Medications can interfere with the absorption of electrolytes, alter hormonal responses affecting homeostasis, as well as directly impact organ function responsible for maintaining electrolyte balance. The focus on this review is to identify commonly prescribed medications in the intensive care unit and potential electrolyte disturbances that may occur as a result of their use. This review will also discuss the postulated mechanisms associated with these drug-induced disorders. The specific drug-induced electrolyte disorders discussed in this review involve abnormalities in sodium, potassium, calcium, phosphate, and magnesium. Clinicians encountering electrolyte disturbances should be vigilant in monitoring the patient's medications as a potential etiology. Insight into these drug-induced disorders should allow the clinician to provide optimal medical management for the critically ill patient, thus improving overall healthcare outcomes.

Increased mortality in hypernatremic burned patients

Introduction: In-hospital hypernatremia develops usually iatrogenically from inadequate or inappropriate fluid prescription. In severely burned patient an extensive initial fluid resuscitation is necessary for burn shock survival. After recovering of cellular integrity the circulating volume has to be normalized. Hereby extensive water and electrolyte shifts can provoke hypernatremia.

Purpose: Is a hypernatremic state associated with increased mortality?

Method: Retrospective study for the incidence of hypernatremia and survival in 40 patients with a totally burned surface area (TBSA) >10%. Age, sex, TBSA, ABSI-Score and fluid resuscitation within the first 24 hours were analyzed. Patients were separated in two groups without (Group A) or with (Group B) hypernatremia.

Results: Hypernatremia occurred on day 5±1.4. No significant difference for age, sex, TBSA, ABSI-Score and fluid resuscitation within the first 24 hours were calculated. In Group A all patients survived, while 3 of the hypernatremic patient in Group B died during ICU-stay (Odds-ratio = 1.25; 95% CI 0.971–1.61; p=0.046).

Conclusion: Burned patients with an in-hospital acquired hypernatremia have an increased mortality risk. In case of a hypernatremic state early intervention is obligatory. There is a need of a fluid removal strategy in severely burned patient to avoid water imbalance.

Characterization of intensive care unit acquired hyponatremia and hypernatremia following cardiac surgery

PURPOSE

Although intensive care unit (ICU) acquired sodium disturbances are common in critically ill patients, few studies have examined sodium disturbances in patients following cardiac surgery. The objective of this study was to describe the epidemiology of ICU-acquired hyponatremia and hypernatremia in patients following cardiac surgery.

METHODS

We identified 6,727 adults (> or =18 yr) who were admitted consecutively to a regional cardiovascular intensive care unit (CVICU) from January 1, 2000 to December 31, 2006 and were documented as having normal serum sodium levels (133 to 145 mmol.L(-1)) during the first day of ICU admission. ICU-acquired hyponatremia and hypernatremia were defined as a change in serum sodium concentration to <133 mmol.L(-1) or >145 mmol.L(-1), respectively, following ICU day one.

RESULTS

A first episode of ICU-acquired hyponatremia and hypernatremia developed in 785 (12%) and 242 (4%) patients, respectively, (95% confidence interval [CI] 11-12% and 95% CI 3-4%, respectively), with a respective incidence density of 4.2 and 1.3 patients per 100 days of ICU admission (95% CI 4.0-4.5 and 95% CI 1.2-1.5). The incidence of ICU-acquired sodium disturbances varied according to the patients' demographic and clinical variables for both hyponatremia (age, diabetes, Acute Physiology and Chronic Health Evaluation [APACHE II] score, mechanical ventilation, length of ICU stay, serum glucose level, and serum potassium level) and hypernatremia (APACHE II score, mechanical ventilation, length of hospital stay prior to ICU admission, length of ICU stay, serum glucose level, and serum potassium level). Compared with patients with normal serum sodium levels, hospital mortality was increased in patients with ICU-acquired hyponatremia (1.6% vs 10%, respectively; P < 0.001) and ICU-acquired hypernatremia (1.6% vs 14%, respectively; P < 0.001).

CONCLUSION

ICU-acquired hyponatremia and hypernatremia are common complications in critically ill patients following cardiac surgery. They are associated with patient demographic and clinical characteristics and an increased risk of hospital mortality.

The relation between the incidence of hypernatremia and mortality in patients with severe traumatic brain injury

Introduction

The study was aimed at verifying whether the occurrence of hypernatremia during the intensive care unit (ICU) stay increases the risk of death in patients with severe traumatic brain injury (TBI). We performed a retrospective study on a prospectively collected database including all patients consecutively admitted over a 3-year period with a diagnosis of TBI (post-resuscitation Glasgow Coma Score ≤ 8) to a general/neurotrauma ICU of a university hospital, providing critical care services in a catchment area of about 1,200,000 inhabitants.

Methods

Demographic, clinical, and ICU laboratory data were prospectively collected; serum sodium was assessed an average of three times per day. Hypernatremia was defined as two daily values of serum sodium above 145 mmol/l. The major outcome was death in the ICU after 14 days. Cox proportional-hazards regression models were used, with time-dependent variates designed to reflect exposure over time during the ICU stay: hypernatremia, desmopressin acetate (DDAVP) administration as a surrogate marker for the presence of central diabetes insipidus, and urinary output. The same models were adjusted for potential confounding factors.

Results

We included in the study 130 TBI patients (mean age 52 years (standard deviation 23); males 74%; median Glasgow Coma Score 3 (range 3 to 8); mean Simplified Acute Physiology Score II 50 (standard deviation 15)); all were mechanically ventilated; 35 (26.9%) died within 14 days after ICU admission. Hypernatremia was detected in 51.5% of the patients and in 15.9% of the 1,103 patient-day ICU follow-up. In most instances hypernatremia was mild (mean 150 mmol/l, interquartile range 148 to 152). The occurrence of hypernatremia was highest (P = 0.003) in patients with suspected central diabetes insipidus (25/130, 19.2%), a condition that was associated with increased severity of brain injury and ICU mortality. After adjustment for the baseline risk, the incidence of hypernatremia over the course of the ICU stay was significantly related with increased mortality (hazard ratio 3.00 (95% confidence interval: 1.34 to 6.51; P = 0.003)). However, DDAVP use modified this relation (P = 0.06), hypernatremia providing no additional prognostic information in the instances of suspected central diabetes insipidus.

Conclusions

Mild hypernatremia is associated with an increased risk of death in patients with severe TBI. In a proportion of the patients the association between hypernatremia and death is accounted for by the presence of central diabetes insipidus.

Disorders of sodium and water balance in hospitalized patients

PURPOSE

To review and discuss the epidemiology, contributing factors, and approach to clinical management of disorders of sodium and water balance in hospitalized patients.

SOURCE

An electronic search of the MEDLINE, Embase, and Cochrane Central Register of Controlled Trials databases and a search of the bibliographies of all relevant studies and review articles for recent reports on hyponatremia and hypernatremia with a focus on critically ill patients.

PRINCIPAL FINDINGS

Disorders of sodium and water balance are exceedingly common in hospitalized patients, particularly those with critical illness and are often iatrogenic. These disorders are broadly categorized as hypo-osmolar or hyper-osmolar, depending on the balance (i.e., excess or deficit) of total body water relative to total body sodium content and are classically recognized as either hyponatremia or hypernatremia. These disorders may represent a surrogate for increased neurohormonal activation, organ dysfunction, worsening severity of illness, or progression of underlying chronic disease. Hyponatremic disorders may be caused by appropriately elevated (volume depletion) or inappropriately elevated (SIADH) arginine vasopressin levels, appropriately suppressed arginine vasopressin levels (kidney dysfunction), or alterations in plasma osmolality (drugs or body cavity irrigation with hypotonic solutions). Hypernatremia is most commonly due to unreplaced hypotonic water depletion (impaired mental status and/or access to free water), but it may also be caused by transient water shift into cells (from convulsive seizures) and iatrogenic sodium loading (from salt intake or administration of hypertonic solutions).

CONCLUSION

In hospitalized patients, hyponatremia and hypernatremia are often iatrogenic and may contribute to serious morbidity and increased risk of death. These disorders require timely recognition and can often be reversed with appropriate intervention and treatment of underlying predisposing factors.

The epidemiology of intensive care unit-acquired hyponatraemia and hypernatraemia in medical-surgical intensive care units

INTRODUCTION

Although sodium disturbances are common in hospitalised patients, few studies have specifically investigated the epidemiology of sodium disturbances in the intensive care unit (ICU). The objectives of this study were to describe the incidence of ICU-acquired hyponatraemia and hypernatraemia and assess their effects on outcome in the ICU.

METHODS

We identified 8142 consecutive adults (18 years of age or older) admitted to three medical-surgical ICUs between 1 January 2000 and 31 December 2006 who were documented to have normal serum sodium levels (133 to 145 mmol/L) during the first day of ICU admission. ICU acquired hyponatraemia and hypernatraemia were respectively defined as a change in serum sodium concentration to below 133 mmol/L or above 145 mmol/L following day one in the ICU.

RESULTS

A first episode of ICU-acquired hyponatraemia developed in 917 (11%) patients and hypernatraemia in 2157 (26%) patients with an incidence density of 3.1 and 7.4 per 100 days of ICU admission, respectively, during 29,142 ICU admission days. The incidence of both ICU-acquired hyponatraemia (age, admission diagnosis, Acute Physiology and Chronic Health Evaluation (APACHE) II score, length of ICU stay, level of consciousness, serum glucose level, body temperature, serum potassium level) and ICU-acquired hypernatraemia (baseline creatinine, APACHE II score, mechanical ventilation, length of ICU stay, body temperature, serum potassium level, level of care) varied according to patients' characteristics. Compared with patients with normal serum sodium levels, hospital mortality was increased in patients with ICU-acquired hyponatraemia (16% versus 28%, p < 0.001) and ICU-acquired hypernatraemia (16% versus 34%, p < 0.001).

CONCLUSIONS

ICU-acquired hyponatraemia and hypernatraemia are common in critically ill patients and are associated with increased risk of hospital mortality.