Gregor Lindner

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

BACKGROUND Hypernatremia is a serious electrolyte disturbance and an independent risk factor for mortality in critically ill patients. In many cases, hypernatremia is an iatrogenic problem that develops in the intensive care unit (ICU). STUDY DESIGN Case series. SETTING & PARTICIPANTS 45 patients were studied in a medical ICU. For inclusion in the study, patients needed to show an increase in serum sodium concentration to greater than 149 mEq/L from an initial concentration of less than 146 mEq/L. OUTCOMES Solute balance, fluid balance, and both. Causes of hypernatremia. MEASUREMENTS The daily mass balance of sodium, potassium, and water over 1- to 3-day intervals was measured while serum sodium levels were increasing. RESULTS During the study period, 69 of 981 patients (7%) acquired hypernatremia after admission to the ICU. Of these, 45 had sufficient data for evaluation. Maximum serum sodium levels were 150 to 164 mEq/L. The average duration of hypernatremia was 2 days (range, 1 to 10 days), with an average onset on day 5.9 +/- 4.3 of the ICU stay. Patients were classified as having a positive solute balance (n = 17; 38%), negative fluid balance (n = 20; 44%), or both (n = 8; 18%). The most important extrarenal factors contributing to hypernatremia were fever (45%) and diarrhea (18%). Polyuria was observed in 38% of patients and 35% had acute renal failure. Hypertonic solutions were administered to 27% of patients. LIMITATIONS Retrospective analysis; lack of daily measurement of body weight. CONCLUSION ICU-acquired hypernatremia is associated with multiple factors associated with negative fluid and positive solute balance.

Hypernatremia in critically ill patients

Hypernatremia is common in intensive care units. It has detrimental effects on various physiologic functions and was shown to be an independent risk factor for increased mortality in critically ill patients. Mechanisms of hypernatremia include sodium gain and/or loss of free water and can be discriminated by clinical assessment and urine electrolyte analysis. Because many critically ill patients have impaired levels of consciousness, their water balance can no longer be regulated by thirst and water uptake but is managed by the physician. Therefore, the intensivists should be very careful to provide the adequate sodium and water balance for them. Hypernatremia is treated by the administration of free water and/or diuretics, which promote renal excretion of sodium. The rate of correction is critical and must be adjusted to the rapidity of the development of hypernatremia.

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.

Acid–base disturbances in critically ill patients with cirrhosis

Background/Aims: The equilibrium of offsetting metabolic acid–base disorders in stable cirrhosis might be lost during episodes of hepatic decompensation, haemorrhage or sepsis. The purpose of this study was to determine whether the acid–base state is destabilized in critically ill patients with cirrhosis and whether this is associated with mortality.

Can we really predict the change in serum sodium levels? An analysis of currently proposed formulae in hypernatraemic patients

BACKGROUND Hypernatraemia is common in intensive care patients and may present an independent risk factor of mortality. Several formulae have been proposed to guide infusion therapy for correction of serum sodium. Unfortunately, these formulae have never been validated comparatively. We assessed the predictive potential of four different formulae (Adrogué-Madias, Barsoum-Levine, Kurtz-Nguyen and a simple formula based on electrolyte-free water clearance) in correction and maintenance of serum sodium in 66 hyper- and normonatraemic ICU patients. METHODS With daily measurements of sodium/potassium and fluid/electrolyte balances, a day-to-day prediction of serum sodium levels was calculated using the four formulae. This was compared to the measured changes in serum sodium. RESULTS Six hundred and eighty-one patient-days (194 hypernatraemic) in 66 patients were available for calculations. Prediction of serum sodium levels using all four formulae correlated significantly (P < 0.05) with measured changes in serum sodium. Individual variations were extreme, and the mean differences (+/-SD) for predicted versus measured serum sodium were within the range of 3.4-4.5 (+/-4.4-4.7) mmol/l similar for the Adrogué-Madias, Barsoum-Levine and Nguyen-Kurtz formulae. In comparison, our proposed formula underestimated the changes of serum sodium (mean +/- SD -1.5 +/- 5.3). During hypernatraemia, the differences between predicted and measured values were even greater (mean +/- SD 5.0-6.7 +/- 3.9-4.3) using the published formulae compared to our formula (mean +/- SD 0.2 +/- 4.0). CONCLUSIONS Currently available formulae to guide infusion therapy in hyper- and normonatraemic states do not accurately predict changes of serum sodium in the individual ICU patient. In clinical practice, infusion therapy should be based on the reasons for hypernatraemia and serial measurements of serum sodium to avoid evolution of derangements.

An acetate-buffered balanced crystalloid versus 0.9% saline in patients with end-stage renal disease undergoing cadaveric renal transplantation: a prospective randomized controlled trial.

BACKGROUND:Recent studies have shown a decline in glomerular filtration rate and increased renal vasoconstriction after administration of normal saline when compared with IV solutions with less chloride. In this study, we investigated the impact of normal saline versus a chloride-reduced, acetate-buffered crystalloid on the incidence of hyperkalemia during cadaveric renal transplantation. The incidence of metabolic acidosis and kidney function were secondary aims. METHODS:In this prospective randomized controlled trial, 150 patients received normal saline or an acetate-buffered balanced crystalloid during and after cadaveric renal transplantation. Venous blood gases were obtained at the start of anesthesia and every 30 minutes until discharge from the postoperative surveillance unit. Serum creatinine and 24-hour urine output were obtained on postoperative days 1, 3, and 7. RESULTS:Patients received a similar amount of fluid (median: 2625mL [interquartile range: 2000 to 3100] vs 2500 mL [2000 to 3050], P = 0.83). Hyperkalemia, defined as serum potassium >5.9 mmol/L, occurred in 13 patients (17%) in the saline and 15 (21%) in the balanced group (P = 0.56; difference between proportions −0.037 [−16.5% to 8.9%]). Minimum base excess was lower in the saline group compared with the balanced regimen (−4.5 mmol/L [−6 to −2.4] vs −2.6 mmol/L [−4 to −1], P < 0.001) and maximum chloride was significantly higher in the saline group (109 mmol/L [107 to 111] vs 107 mmol/L [105 to 109], P < 0.001). No difference in creatinine or urine output was seen postoperatively. Significantly more patients needed catecholamines in the saline group (30% vs 15%, P = 0.03). CONCLUSIONS:The incidence of hyperkalemia differed by less than 17% between groups. Use of balanced crystalloid resulted in less hyperchloremia and metabolic acidosis. Significantly more patients in the saline group required administration of catecholamines for circulatory support.

Osmotic diuresis due to urea as the cause of hypernatraemia in critically ill patients

BACKGROUND Hypernatraemia is common in critically ill patients and has been shown to be an independent predictor of mortality. Osmotic urea diuresis can cause hypernatraemia due to significant water losses but is often not diagnosed. Free water clearance (FWC) and electrolyte free water clearance (EFWC) were proposed to quantify renal water handling. We aimed to (i) identify patients with hypernatraemia due to osmotic urea diuresis and (ii) investigate whether FWC and EFWC are helpful in identifying renal loss of free water. METHODS In this retrospective study, we screened a registry for patients, who experienced intensive care unit (ICU)-acquired hypernatraemia. Among them, patients with hypernatraemia due to osmotic urea diuresis were detected by a case-by-case review. Total fluid and electrolyte balances together with FWC and EFWC were calculated for days of rising serum sodium and stable serum sodium. RESULTS We identified seven patients (10% of patients with ICU-acquired hypernatraemia) with osmotic diuresis due to urea. All patients were intubated during development of hypernatraemia and received enteral nutrition. The median highest serum sodium level of 153 mmol (Q1: 151-Q3: 155 mmol/L) was reached after a 5-day period of rise in serum sodium. During this period, FWC was -904 mL/day (Q1: -1574-Q3: -572), indicating renal water retention, while EFWC was 1419 mL/day (Q1: 1052-Q3: 1923), showing renal water loss. While FWC did not differ between time of stable serum sodium and development of hypernatraemia, EFWC was significantly higher during rise in serum sodium. CONCLUSION Osmotic urea diuresis is a common cause of hypernatraemia in the ICU. EFWC was useful in the differential diagnosis of polyuria during rising serum sodium levels, while FWC was misleading.

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

BackgroundDiuretics 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.MethodsIn 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.ResultsA 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.ConclusionsExisting 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.

Diuretic-induced hyponatremia and osteoporotic fractures in patients admitted to the emergency department

OBJECTIVE Hyponatremia is a complication of diuretic treatment and has been recently identified as a novel factor associated with osteoporosis and fractures. The impact of diuretic-associated electrolyte disorders on osteoporotic fractures (OF) has rarely been studied systematically. DESIGN AND SETTING We conducted a study in patients presenting to the emergency department at the University Hospital Bern. In this retrospective case series analysis of prospectively gathered data, over a 2-year period we identified 10,823 adult (≥50 years) outpatients with a measured baseline serum sodium, at admission to the hospital. OF patients were compared to a control group without fractures using standard statistical methods. RESULTS Four hundred and eighty (5%) patients had 547 OF. The OF group had a higher mean age (73 vs. 68 years, p<0.0001), smaller proportion of men (37% vs. 58%, p<0.0001), higher hospitalisation rate (83% vs. 62%, p<0.0001) and longer hospital stay (8 vs. 6 days, p<0.0001). Any diuretic agent (p<0.0001), loop diurietics (p=0.02), spironolactone (p=0.02) and amiloride (p<0.01) were used significantly more in OF patients, but not thiazides (p=0.68). The prevalence of hyponatremia increased significantly (p<0.0001) with the number of diuretics taken. Advanced age (odds ratio [OR] 1.04, p<0.0001), hyponatremia (OR 1.46, p=0.011) higher serum creatinine (OR 1.53, p=0.0001), furosemide use alone (OR 1.40, p=0.01) and co-treatment with amiloride (OR 2.22, p=0.02) were associated with a higher risk for OF. CONCLUSIONS This study highlights the clinical association of hyponatremia during the use of certain diuretics (i.e. furosemide or in combination, i.e. amiloride) with an increased risk of osteoporosis associated fractures. Although evidence-based data is currently lacking a pragmatic approach concerning hyponatremia monitoring and correction appears reasonable in selected groups of patients.

Hypercalcemia in the ED: prevalence, etiology, and outcome

PURPOSES The aim of the study was to describe the prevalence, demographic, and clinical characteristics and etiologies of hypercalcemia in emergency department patients. BASIC PROCEDURES In this retrospective cross-sectional descriptive study, all patients admitted between April 1, 2008, and March 31, 2011, to the emergency department of Inselspital, University Hospital Bern, were screened for the presence of hypercalcemia, defined as a serum calcium exceeding 2.55 mmol/L after correction for serum albumin. Demographic, laboratory, and outcome data were gathered. A detailed medical record review was performed to identify causes of hypercalcemia. MAIN FINDINGS During the study period, 14 984 patients (19% of all admitted patients) received a measurement of serum calcium. Of these, 116 patients (0.7%) presented with hypercalcemia. Median serum calcium was 2.72 mmol/L (first quartile, 2.64; third quartile, 2.88), with 4.3 mmol/L being the maximum serum calcium value observed. Underlying malignancy in 44% of patients and hyperparathyroidism in 20% (12% secondary and 8% primary) were the leading causes of hypercalcemia. Twenty-six percent of patients presented with symptomatic hypercalcemia. Weakness was the most common symptom of hypercalcemia, followed by nausea and disorientation. PRINCIPAL CONCLUSIONS Hypercalcemia is a rare but harmful electrolyte disorder in emergency department patients. Unspecific symptoms such as a change in mental state, weakness, or gastrointestinal symptoms should prompt physicians to order serum calcium measurements, at least in patients with known malignancy or renal insufficiency.