# Monitoring of Venous and Arterial Occlusion With Remote Interstitial Tissue Glucose Measurement Systems in a Rabbit Free Flap Model

## TL;DR

This study shows that remote glucose monitoring can detect blood flow issues in tissue transplants in rabbits, offering a potential new tool for post-surgery monitoring.

## Contribution

The study introduces long-term interstitial glucose monitoring as a novel method for detecting vascular occlusion in free tissue transfers.

## Key findings

- Venous occlusion caused a 47.8% increase in interstitial glucose levels within 15 minutes.
- Arterial occlusion led to a 56% decrease in glucose levels within 15 minutes and total flap necrosis.
- Glucose levels dropped significantly during venous decongestion, showing dynamic changes in perfusion.

## Abstract

Free tissue transfer requires meticulous postoperative monitoring to detect vascular occlusion. Although experimental studies have explored the relationship between interstitial glucose levels and tissue perfusion, long‐term evaluation of glucose levels during and after occlusion‐reperfusion has not been thoroughly investigated. The study objective was to investigate the correlation between controlled venous and arterial occlusion and changes in interstitial tissue glucose, using a remote interstitial glucose monitoring device.

This experimental study was conducted on eight New Zealand White rabbits, each weighing between 3.2 and 3.8 kg, under general anesthesia, utilizing a 4 × 8 cm perforator flap supplied by skin perforators originating from the thoracodorsal artery. Interstitial glucose levels within the flaps were continuously monitored using FreeStyle Libre flash glucose monitoring system. Baseline glucose levels were recorded 1 day prior to vascular occlusion, followed by monitoring between 15 min intervals during experimental clamping of both venous ischemia (75 min), venous decongestion (75 min), and arterial occlusion (45 min). Criteria for detecting vessel occlusion were established based on changes in interstitial glucose concentration.

Venous occlusion was associated with a significant increase in interstitial glucose levels. At 15 min post‐occlusion, interstitial glucose increased by 47.8%, which was significantly higher than baseline (p = 0.018). However, at 30 min post‐unclamping, interstitial glucose declined by 18.3% (p = 0.028) and by 57.4% over 75 min. In contrast, arterial occlusion was associated with a rapid decline in glucose levels. At 15 min post‐occlusion, interstitial glucose decreased by 56% (p = 0.018). Total necrosis was observed in all flaps followed by arterial occlusion.

Interstitial glucose monitoring appears to be a reliable method for detecting vascular occlusion in free tissue transfers within this experimental model. This technique may offer a rapid, minimally invasive, and cost‐effective approach for postoperative vascular monitoring of free flaps. Further investigation in human trials is warranted to confirm these findings and assess clinical utility.