Clinical PotpourriPatterns of treatment and correction of hyponatremia in intensive care unit patients
Introduction
Hyponatremia is the most common electrolyte disorder in hospitalized patients, with the prevalence in intensive care unit (ICU) patients as high as 30% to 40%, highlighting hyponatremia as a common and important clinical condition that adds complexity to the care of the ICU patient population [1], [2], [3], [4]. Hyponatremia is an independent predictor of increased hospitalization cost and length of stay (LOS) and of ICU admissions and cost [5]; hyponatremia, especially in patients with heart failure and cirrhosis, is associated with increased healthcare costs [6], [7].
Hyponatremia, even when mild, is independently associated with increased risk of death in hospitalized individuals [8], [9] and in those with critical illness [10], [11], [12], suggesting that correction of hyponatremia may be important. However, diagnosis and treatment of hyponatremia have not been standardized, and although European clinical guidelines exist, there are no official US guidelines [3], [13], [14]. Therefore, no consensus exists among clinicians on the optimal diagnostic and therapeutic approach to hyponatremia in the critically ill, thus increasing the difficulty of treating these patients.
The management and epidemiology of hyponatremia in critically ill patients are important to investigate due to the higher severity of illness, hemodynamic instability, and numerous comorbid conditions (eg, heart failure and respiratory failure) and medications [15], [16], [17]. Intensive care unit patients may be treated differently due to the individual clinical characteristics of these patients and, therefore, may have an altered response to hyponatremia treatment than general hospital patients [18], [19]. Even minimal changes in serum sodium concentration could be important in these patients [15], [20]. However, many previous studies that have assessed hyponatremia in ICU patients used administrative or billing databases as the primary source of information, which can be prone to coding and billing errors [5], [6], [7], [11].
The goal of this study was to examine the real-world patterns of care and interventions among ICU patients with hyponatremia using a large clinical database. Because hypovolemic hyponatremia generally responds readily to treatment with intravenous fluids, this study focused on patients with euvolemic and hypervolemic hyponatremia—who typically receive numerous interventions and treatments—by excluding those patients with hypovolemic hyponatremia, as noted in the electronic chart.
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Study design
To investigate hyponatremia treatment patterns and trends, mortality, and ICU and hospital LOS, this study used a large clinical database from the Phillips eICU Research Institute that captures nearly all components of the medical chart for approximately 10% of ICU admissions in the United States, including detailed clinical and outcomes-related variables [21], [22]. The Phillips eICU Research Institute database aggregates ICU data from more than 400 teaching and nonteaching hospitals and
Patients
From the database, 77 214 ICU admissions were identified by the hyponatremia criteria (Fig. 1). Following the exclusion criteria for the study, 7445 ICU admissions were included. Patients were assigned to one of the following study groups according to the designated hierarchal order: heart failure (1164; 15.6%), cirrhosis (213; 2.9%), liver failure (733; 9.8%), SIADH (57; 0.8%), and not otherwise specified (5567; 74.8%). Of note, because SIADH is a diagnosis of exclusion and may not be diagnosed
Discussion
The primary results of this study show that euvolemic and hypervolemic hyponatremia is common in the ICU population and that hyponatremia is often not corrected by the end of the ICU stay.
Using a more strict correction definition, 48% of patients did not have their serum sodium concentration corrected, and using a less strict definition, 24% were not corrected. Using either definition of correction, patients with serum sodium correction had lower mortality and longer survival than did patients
Conclusion
Critically ill patients with hyponatremia who have their serum sodium corrected have lower mortality and longer survival. In addition, a significant proportion of hyponatremia is not corrected during an ICU stay. Furthermore, it appears that many patients received drugs associated with increasing the risk of hyponatremia. Collectively, these results highlight the need for more attention to hyponatremia and its correction in critically ill patients.
Conflict of interest statement
Joseph Dasta has served as a consultant for AbbVie, AcelRx, Janssen Scientific Affairs, LLC, Hospira, Mallinckrodt, Otsuka America Pharmaceuticals, Pacira Pharmaceuticals, Phillips-VISICU, and The Medicines Company and owns stock in Abbott, Abbvie, Merck, and Pfizer. Sushrut Waikar has served as a consultant for Otsuka America Pharmaceutical, Inc, and has served on an advisory board for AbbVie and data safety monitoring boards for HCRI and Takeda. Susan Boklage and Joseph Chiodo are employees
Acknowledgments
This study was sponsored by Otsuka America Pharmaceutical, Inc, Princeton, NJ. Medical writing and editorial support for the preparation of this manuscript was provided by Scientific Connexions, Lyndhurst, NJ, USA, an Ashfield Company, part of UDG Healthcare plc, and funded by Otsuka America Pharmaceutical, Inc.
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