The aim was to determine the equivalence or otherwise of Normal Saline in comparison to Plasmalyte for intra-operative fluid replacement in elective, adult open abdominal surgery on serum chloride level using a restrictive fluid therapy algorithm. 

 Previous studies had reported a difference of approximately 6 mEq/l in the chloride levels when saline was used in comparison to Plasmalyte at the volumes infused in the study. We hypothesized that the difference would be much smaller (<3 mEq/L) when smaller volumes ( 2ml/kg/hr + urine output + blood loss every hour ) of fluid were infused using a dynamic index to titrate fluid therapy and that both fluids would be demonstrated to be equivalent.

  SUMMARY and RESULTS:1) Restrictive fluid regimen shows equivalence in the choice of crystalloid fluid ( Plasmalyte versus Normal saline) used for intraoperative fluid therapy. 

2) Infusing fluids according to the algorithm lead to a decrease in pH but not significant acidosis (pH< 7.35) in both the groups even at postoperative day one.

3)The constituents of crystalloids have an impact on the acid-base balance as seen with changes in independent parameters of Stewart. These changes may become significant if fluids are given in larger volume for a longer duration. 

4) Normal saline has an obvious impact on urine output even when given in restricted amounts but these did not amount to renal injury. 

5) In surgeries of prolonged duration with a restrictive regimen, a close watch on lactate to prevent tissue hypoperfusion is necessary which shows a trend of increase with duration of surgery in our study. 

6) Dynamic indices like PPV are effective in guiding fluid therapy intraoperatively.