On the basis of the available information, hypertonic saline should be reserved for a previously well individual who is symptomatic with seizures, coma, or new focal neurologic findings and whose serum sodium level is less than 120 mEq/L. (Some experts argue that 110 mEq/L is the limit.)
I recommend that this very select group of patients receive 1.5 mL/kg of 3% hypertonic saline in less than an hour, and have this regimen supplemented with a small dose (20 mg) of intravenous furosemide to facilitate free water diuresis and block ADH secretion from the hypertonic saline infusion. This will raise the serum sodium level by 1-2 mEq/L within 1 hour. A second infusion can be given over another hour if the patient is still symptomatic. Seizures can also be treated aggressively in this routine manner with intravenous benzodiazepines.
This is consistent with what most text books and reviews recommend for the acute situation. One review to which I previously linked suggested a more aggressive approach, in which the hypertonic saline is bolused over 10 minutes, in patients who are actively seizing. (That is more aggressive than other recommendations I’ve seen but, after all, the patient is about to herniate). Those with a single resolved seizure and other milder neurologic symptoms, according to that review, were to be treated with the more traditional hypertonic saline infusion.