# O2C-Based Evaluation of Microperfusion During Dialysis Fistula Creation

## TL;DR

This study uses O2C to evaluate microcirculation during dialysis fistula surgery, showing how regional anesthesia affects blood flow and oxygen levels.

## Contribution

First study to objectively assess microcirculatory changes during AVF surgery using non-invasive O2C technology.

## Key findings

- Plexus anesthesia significantly increased tissue oxygen saturation, flow, and velocity (p < 0.0001).
- Microcirculatory parameters declined after AVF creation compared to values under regional anesthesia.
- Weak correlation was found between O2C values and ultrasound-measured shunt flow on the first postoperative day.

## Abstract

Background: Regional anesthesia during arteriovenous fistula (AVF) creation increases arterial and venous diameters and intraoperative flow through sympathetic blockade and vasodilation. These changes are associated with improved short- and medium-term AVF patency. However, their impact on long-term outcomes remains unclear. While current assessments focus on macrocirculatory parameters, no objective method exists to evaluate microcirculatory changes perioperatively. The use of non-invasive optical devices such as the O2C remains investigational in this context. Methods: This single-center prospective observational study enrolled 31 patients aged ≥18 years undergoing AVF surgery. Microcirculatory parameters—including tissue oxygen saturation (SO2), flow, velocity, and relative hemoglobin concentration (rHb)—were recorded using the non-invasive O2C spectrophotometer (LEA Medizintechnik, Germany). Measurements were performed at the thenar and hypothenar regions at five defined time points, before and after surgery. Where applicable, O2C parameters were compared with shunt flow volumes measured by duplex ultrasonography. Results: Plexus anesthesia led to a significant increase in SO2, flow, and velocity (p < 0.0001). After AVF creation, these parameters declined compared to values under functional regional anesthesia. Correlation between O2C values and ultrasound-measured shunt flow on the first postoperative day was weak (r = 0.40 for flow at M1). Conclusions: This is the first study to objectively demonstrate the effects of plexus anesthesia on microcirculation during AVF surgery. O2C may serve as a valuable non-invasive tool to assess perioperative microcirculatory changes.