Hyponatremia in an Intensive Care Unit: Biological, Epidemiological, and Prognostic Patterns

Abstract

Hyponatremia is an electrolyte balance disorder frequently encountered in the intensive care setting. Its prevalence is high but not well known. Its clinical expression varies and its management depends on the mechanisms related to its installation. The prognosis of hyponatremia may be severe, and this severity may be due to underlying conditions, treatment related complications and time lapse before treatment is initiated. This is a prospective, descriptive, analytic, prognostic study. Patients admitted to the ICU with hyponatremia lower than 135mmol / l were included over a period of thirteen months. Several parameters were identified (demographic, anamnestic, clinical, biological, therapeutic, progression and severity scores) and compared between patients with or without hyponatremia. During the study period, 84 patients (32.60%) had hyponatremia out of the 258 who were included in our study. Hyponatremia was hypervolemic in 27.72%, normovolemic in 19.28%, hypovolemic in 51% of patients. The median duration of onset of hyponatremia acquired in the intensive care unit is 5.79 days. The mortality rate was 56% and the predicted mortality was 44% according to the APACHE II score. Some variables were significantly associated with hyponatremia: age (p <0.005), comorbidities (p = 0.02), tumor history (p = 0.001), metabolic history (p = 0.003), diabetes (p = 0.008), recent surgical history (p = 0.002), previous hepato-gastroenterological history (p = 0.017). Four variables were significantly associated with ICU-acquired hyponatremia: shock (p = 0.008), consciousness disorders (p = 0.008), APACHE II (p <0.001). In conclusion, hyponatremia is quite common in intensive care patients. Management must be rapid and include symptomatic as well as etiological treatment. Mortality is largely related to other factors and not to hyponatremia itself.