Pass the salt: indications for and implications of using hypertonic saline.

Sodium is the most abundant extracellular ion. Historically, therapy with hypertonic saline was widely used for a variety of conditions. Currently, there are 3 primary indications for its use in critical care: hyponatremia, volume resuscitation, and brain injury. SIADH and CSW syndrome may require sodium replacement, but most cases of hyponatremia can be managed without administration of hypertonic saline. Studies of use of hypertonic saline in hypovolemia and brain injury are promising, but additional research is needed to better define optimal dosing regimens and to determine the relative risks associated with hypertonic saline versus conventional treatment for the management of patients with head injuries and for volume resuscitation in shock states.