A word on Sodium Correction....

In patients who are truly hypo-osmolar and hypovolemic and have symptoms of hyponatremia and/or hypovolemia, a careful correction must be made. These patients must be in a closely supervised setting like an intensive care unit or step-up unit where frequent blood work and monitoring can occur. The rapid correction of sodium can be dangerous - leading to permanent neurologic deficits including central pontine myelinolysis - a spastic quadriplegia and pseudobulbar palsy resulting from pontine demyelination of corticospinal and corticobulbar tracts.

Normal saline can be used to correct hypovolemia in most cases: it will raise the plasma sodium a bit as well as it has 154 mEq of Na in it. Remember, we want to raise the sodium up to a level where patients are not seizing or at risk of seizing. We not targeting normal sodium levels here - essentially, we do not want to raise the serum sodium more than 8 mmol/L per day. Hypovolemic patients will have a lot of ADH released - sucking up every drop of water through the cortical collecting ducts. When volume is restored, the stimulus for ADH will be turned off and patients may start to diurese. This can cause an unintentional and overly rapid correction of serum sodium and can lead to neurologic injury. We can be prevent this overly rapid correction by giving DDAVP (desmopressin, a synthetic version of ADH) back to the patient.

Finally, if patients are profoundly hyponatremic and symtomatic, hypertonic (3%) saline can be administered in emergency situations. This is usually done in an acute setting to stop or prevent seizure activity. Again, these patients will need very close monitoring of their neurologic status and electrolytes - and this is best done in an intensive care unit.

This equation can be used to predict the rise in sodium based on the fluids being administered:

Increase in PNa = (Infusate [Na] - PNa) ÷ (Total Body Water + 1)

(TBW is the estimated by: lean body weight times 0.5 for women, or 0.6 for men)

A great review article HERE