[The effect of hypertonic saline infusion on lumbar epidural anesthesia]

The author compared hemodynamic effects of fluid loading during epidural anesthesia with 7.2% hypertonic saline (HS), lactate Ringer's (LR) or isotonic saline solutions in 24 ASA 1 patients undergoing elective lower abdominal or pelvic surgery, allocated randomly into three groups. The first two groups, patients received equal amounts of sodium (2.2 mmol.kg-1), and the latter group, isotonic saline solutions for 1-2 ml.kg-1.h-1 as control. After epidural injection (2%mepivacaine 0.1 ml.cm(Height)-1), fluid loading was performed for 20 minutes. The volume of fluid loading was significantly larger in group LR (979.3 +/- 154.7 ml) than the other two groups (HS: 104.5 +/- 20.0 ml, NS: 48.8 +/- 8.3 ml) (P < 0.05). The number of blocked segments was similar in three groups. Magnitude of hypotension was no significantly different among the groups 20 minutes after fluid loading, but recovered to the control level in group HS. In all groups heart rate decreased but the decrease was significant only in group HS. But, in group HS, stroke index increased after fluid loading and remained elevated. Increase of extracellular volume in group HS was observed by bioelectrical impedance analysis as in group LR. The author concludes that HS may be useful especially in the case not requiring a large volume of fluid loading. Finding ideal concentration, volume, and speed of infusion of intravenous fluids would be clinically useful.