American Society of Hirudotherapy

Prospective Trial of Near-Infrared Spectroscopy for Continuous Noninvasive Monitoring of Free Fibular Flaps

Research article published in Annals of plastic surgery (2021)

Last Updated: June 18, 2026Reviewed by: ASH Editorial Board
Research article — evidence reviewArticle reference
Evidence: Research reportClinical TrialsOuyang SY et al. · Annals of plastic surgery, 2021

Abstract

INTRODUCTION: Some free flaps develop postoperative vessel thrombosis, which influences the flap survival rate. Early discovery and identification of vascular crisis are critical to the success rate of flap salvage. The primary aims of this study were to determine the features of postoperative blood supply changes in fibular flaps with normal and abnormal blood flow, using near-infrared spectroscopy (NIRS), to monitor oxygenation and blood flow, and to characterize the probable risk factors for vascular crisis. METHODS: Sixty-three consecutive patients undergoing reconstruction of unilateral mandibular defects with free fibular flaps at the Peking University School of Stomatology were included. Patients were divided into 2 groups, A (n = 38) and B (n = 25); fibular flaps in group A underwent continuous NIRS monitoring from immediately postoperatively until 7 days postoperatively (approximately 150 hours), whereas fibular flaps and opposite mandibles in group B underwent intermittent monitoring: once every 4 hours during the first 24 hours postoperatively and once every 12 hours from 24 to 168 hours postoperatively. RESULTS: Six fibular flaps developed vascular thromboses: 4 were venous thromboses and 2 were arterial thromboses; 5 were rescued after exploration. Of 6 regional oxygen saturation (rSO2) values in the continuous monitoring group, 4 showed no significant differences at any time point compared with the intermittent monitoring group (P > 0.05). The rSO2 of the fibular flap was significantly different from that in the opposite mandible in the first 36 hours postoperatively (P < 0.05). This difference decreased over time. During the initial period of venous thrombosis, rSO2, deoxyhemoglobin, and oxygenated hemoglobin all rose slightly, then showed simultaneous rapid reduction. However, the magnitude of reduction was smaller for deoxyhemoglobin than for oxygenated hemoglobin. CONCLUSIONS: Near-infrared spectroscopy can be used for noninvasive and reliable assessment of oxygenation and blood flow in free flaps through continuous, real-time monitoring. It is also portable, inexpensive, and simple to operate. In addition, the detection depth of NIRS is up to 2.0 cm, so it can be used to monitor buried flaps with depths <2.0 cm.

Abstract sourced from PubMed (NCBI) for the cited record. See the original publication for the authoritative version.

Publication typeJournal Article
Indexed MeSH termsFree Tissue FlapsHumansMandibleOxyhemoglobinsProspective StudiesSpectroscopy, Near-Infrared

Summary

Some free flaps develop postoperative vessel thrombosis, which influences the flap survival rate.

Why This Matters for Hirudotherapy

This study evaluated the use of near-infrared spectroscopy (NIRS) for continuous, noninvasive postoperative monitoring of blood supply and oxygenation in free fibular flaps. The researchers characterized patterns of regional oxygen saturation associated with vascular thrombosis in a sample of consecutive patients undergoing mandibular reconstruction. While early detection of vascular compromise is critical in reconstructive surgery, this research is strictly diagnostic in nature and focuses entirely on evaluating the reliability of a monitoring technology. The provided abstract contains absolutely no mention of leeches, hirudotherapy, or the leech secretome, nor does it propose any related therapeutic interventions for flap salvage. Consequently, its relevance to the American Society of Hirudotherapy is nonexistent based solely on the provided text, serving only as general background on flap monitoring technologies.

Citation

Prospective Trial of Near-Infrared Spectroscopy for Continuous Noninvasive Monitoring of Free Fibular Flaps

Ouyang SY et al. · Annals of plastic surgery, 2021

Added to ASH library: May 27, 2026 · Site last updated: June 18, 2026

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