Plethysmography Variability Index as a Guidance for Intraoperative Fluid Management in Cesarean Section Delivery under Spinal Anesthesia: A Pilot Study

Abstract

Background: Plethysmography variability index (PVI) is a measure of the dynamic changes in the perfusion index (PI) that occur during one or more complete respiratory cycles. This study was designed to investigate the accuracy of PVI in guidance of fluid management in parturient undergoing cesarean section surgery under spinal anesthesia.
Methods: This randomized clinical trial was performed on 21 consecutive patients who were candidate for cesarean section surgery under spinal anesthesia at Shariati Hospital in Tehran, Iran, between April 2015 and April 2016. The patients were randomly assigned to one of the PVI or conventional group. In all patients, serum level of lactate, mean arterial pressure (MAP), total amount of infused intraoperative fluids, urine output, and duration of surgery were recorded.
Results: In total, 21 patients (10 in PVI group and 11 in control group) were assessed. The trend of the change in MAP was significantly different between the two groups with a downward trend in PVI group and a fluctuated trend in the conventional group (P = 0.003). The mean amount of infused fluid was 2565.00 ± 563.74 ml in PVI group that was significantly lower than control group (3122.73 ± 321.99 ml) (P = 0.011). Although urine output was numerically higher in PVI than in control group (425.00 ± 274.12 ml vs. 322.00 ± 121.82 ml), it was not statistically significant (P = 0.292). In PVI group, the primary value of PVI was 23.80 ± 6.93 that reached to 12.20 ± 1.75 at the end of surgery indicating a significant reduction (P < 0.001).
Conclusions: Regarding clinical and hemodynamic stability as well as fluid therapy responsiveness (less requiring fluids within surgery), PVI monitoring seems to be superior to the conventional method.