Management of severe hyponatremia: infusion of hypertonic saline and desmopressin or infusion of vasopressin inhibitors?

Abstract

Rapid correction of severe hyponatremia carries the risk of osmotic demyelination. Two recently introduced methods of correction of hyponatremia have diametrically opposite effects on aquaresis. Inhibitors of vasopressin V2 receptor (vaptans) lead to the production of dilute urine, whereas infusion of desmopressin causes urinary concentration. Identification of the category of hyponatremia that will benefit from one or the other treatment is critical. In general, vaptans are effective in hyponatremias presenting with concentrated urine and, with the exception of hypovolemic hyponatremia, can be used as their primary treatment. Desmopressin is effective in hyponatremias presenting with dilute urine or developing urinary dilution after saline infusion. In this setting, desmopressin infusion helps prevent overcorrection of the hyponatremia. Monitoring of the changes in serum sodium concentration as a guide to treatment changes is imperative regardless of the initial treatment of severe hyponatremia.

FIGURE 1

Simulations of the response of [Na]_s depending on urine flow and electrolyte content as well as infusate composition and volume. We began with a 70-kg man (42 L TBW_Ini) and a [Na]_Ini of 125 mEq/L. Simulations are shown in 4 circumstances. Top left panel: no infusate. Top right panel: 2 L of 5% dextrose in water. Bottom left panel: 2 L of 0.9% saline. Bottom right panel: 2 L of 3% saline. Urine volume and electrolyte content were allowed to range in the x and y axes between 0 and 10 L and 25 and 300 mEq/L, respectively. We present simulations as if these occurred after 24 hours and color-coded rates of correction exceeding 20 mEq/L per 24 hours as red with lesser rates of correction having hues moving toward the blue end of the color spectrum.

FIGURE 2

Initial management of severe hyponatremia.