the effect of intra-operative plethysmography variability index-guided fluid therapy on serum lactate levels: a randomized double-blinded clinical trial

Background: goal-directed fluid therapy may improve perioperative fluid management. this study aimed to evaluate the effects of pleth variability index (pvi)-guided fluid therapy on changes in intraoperative serum lactate levels in comparison with liberal fluid therapy. methods: this study was a randomized double-blinded clinical trial that was conducted in the operating room of a university hospital. inclusion criteria comprised patients aged 18–60 years and classified as american society of anesthesiologists physical status class i and ii, who were candidates for elective thyroidectomy. in total, 44 patients meeting the inclusion criteria were enrolled in the study and randomly assigned to two groups: the liberal and pvi groups. in both groups, 5 ml/kg bolus of normal saline was infused prior to the anesthesia induction. in the pvi group, 100 ml bolus of normal saline was administered every 5 min if the pvi remained >13% during the operation. in the liberal group, continuous crystalloid infusion (5–6 ml/kg/h) was administered throughout the surgery. arterial blood samples were taken, and serum lactate levels were measured following anesthesia induction and just before tracheal extubation. results: in the pvi group, mean serum lactate decreased at the end of the surgery, with a difference of −0.6 ± 0.13 mmol/l, whereas it increased in the liberal group (0.070 ± 0.3, p<0.05). conclusion: in conclusion, we found that using intraoperative pvi-guided fluid therapy could decrease serum lactate levels and total fluid administration compared to the liberal method.