The comparison of hypertonic saline (7.5%) and normal saline (0.9%) for initial fluid administration before spinal anesthesia

Hypertonic saline can be used for initial fluid administration before spina l anesthesia. It is effective in small-volume fluid resuscitation. This ran domized double-blinded study compared the effects of 7.5% hypertonic saline (HS) and 0.9% normal saline (NS) in doses containing 2 mmol/kg of sodium i n 40 ASA physical status I-II patients undergoing arthroscopy or other lowe r limb surgery under spinal anesthesia. We infused 1.6 mL/kg of HS or 13 mL /kg of NS for initial fluid administration before spinal anesthesia induced with a 10-mg dose of 0.5% hyperbaric bupivacaine. Etilefrine was administe red to maintain mean arterial pressure at greater than or equal to 80% of i ts control value. Systolic and diastolic blood pressure, heart rate, and ca rdiac index did not differ between the groups, and the amount of etilefrine administered was similar in the treatment groups. In all our patients, the plasma sodium concentrations were within the normal range after surgery an d serum osmolality was within the normal range after spinal anesthesia. The time and the volume of the first micturition were similar in both groups, despite the much smaller amount of infused free water in the HS group. We c onclude that 7.5% HS was as good as NS for the initial fluid administration before spinal anesthesia when the amount of sodium was kept unchanged.