HS reduces the volume of intravenous fluid required to maintain patients undergoing surgery but transiently increases serum sodium. It is not known if HS effects patient survival and morbidity but it should be tested in randomized clinical trials that are designed and powered to test these outcomes.
Intravenous pretreatment of hypertonic saline can prevent systemic hypotension induced by spinal anesthesia.
Hypertonic saline improves organ perfusion and patient survival during hemorrhagic shock because it expands plasma volume and increases tissue oxygenation. Its beneficial results have been reported in patients suffering from hypotension during spinal anesthesia. The purpose of this study was to compare the influence between prehydration with 3% hypertonic saline and with isotonic lactated Ringer's solution on the hemodynamic changes and serum electrolyte concentrations in patients undergoing spinal anesthesia.
                Sixty ASA class I patients scheduled for herniorrhapy under spinal anesthesia were assigned randomly into two groups. Group 1 = patients were prehydrated with isotonic lactated Ringer's solution at 7 mg/kg (n = 30); Group 2 = patients were given prehydration with 3% hypertonic saline at 7 ml/kg (n = 30). Following prehydration, arterial blood pressure and heart rate were recorded and serum electrolyte concentrations were measured.
                The incidence of hypotension was 17/30 (57%) in the isotonic lactated Ringer's solution group as against 7/30 (23%) in the hypertonic saline group (p < 0.05). There was no significant difference between two groups in relation to the level of anesthesia or maximal heart rate, and electrolyte imbalance did not occur in either group.
                Prior to spinal anesthesia, hydration with small amount of hypertonic saline is effective to minimize hypotension associated with spinal anesthesia. If so administered it would not increase bodily sodium load and unlike isotonic crystalloid solution it dose not cause accumulation of water in the body on equipollent basis.