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  • Barbiturates May Falsely Increase Serum Sodium Levels

    Final Number:

    Bart F.E. Feyen MD; Dries Coenen; Philippe G Jorens; Kristien Wouters; Andrew Ian Ramsay Maas MD, PhD; Viviane Van Hoof; Walter Verbrugghe

    Study Design:

    Subject Category:

    Meeting: Congress of Neurological Surgeons 2013 Annual Meeting

    Introduction: Barbiturates are used as a third tear therapy in intracranial hypertension refractory to medical treatment. In our center we observed a high percentage of hypernatremia in patients treated with barbiturates.

    Methods: We performed a retrospective study of 53 patients treated with barbiturates (thiopental) in our intensive care unit between 2007 and 2011 and evaluated electrolyte changes. Standardized in vitro laboratory tests were performed to study the effect of thiopental on sodium analysis. We further compared the values obtained on the central laboratory (CL) device versus the bedside point-of-care (POC) device.

    Results: The sodium levels were much higher on the CL device than on the POC device (+11.57 mmol/L, P < .0001) (figure 1). In the standardized in vitro tests thiopental induced a dose-dependent false hypernatremia (P = .002). Further exploration revealed that these erroneous values were related to the Siemens Dimension Vista 1500 central lab auto-analyzer.

    Conclusions: Barbiturates may cause false hypernatremia when assayed with a particular CL device. Clinicians treating patients with intracranial hypertension should be aware of this possible interference. Otherwise, the risk exists that elevated sodium levels may result in withholding essential treatments with hypertonic saline or mannitol for raised ICP.

    Patient Care: This paper warns clinicians about possible barbiturate interference in sodium assays since a false assumption of hypernatremia may result in withholding essential treatments.

    Learning Objectives: understand that barbiturates may cause false hypernatremia which may result in withholding essential treatments for raised ICP


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