Tissue Oximetry Changes during Postoperative Dangling in Lower Extremity Free Flap Reconstruction: A Pilot Study

Area of Science:

• Microsurgery
• Tissue engineering
• Physiology

Background:

• Lower extremity free flap dangling protocols lack strong evidence but are common practice.
• Investigating the physiological impact of postoperative dangling is crucial for optimizing patient care.

Purpose of the Study:

• To utilize tissue oximetry to assess the physiological effects of postoperative dangling in lower limb free flap transfers.
• To gain insights into microcirculatory function during dangling protocols.

Main Methods:

• Pilot study involving 10 patients undergoing lower extremity free flap reconstruction.
• Continuous non-invasive near-infrared spectroscopy measurement of tissue oxygen saturation (StO2) in the free flap and contralateral limb.
• Measurements taken from postoperative day 7 to 11 during the dangling protocol.

Main Results:

• Free flap StO2 decreased to 70 ± 13.7% during dangling.
• Microvascular reactivity improved over the study period, indicated by delayed StO2 nadir and larger area under the curve on postoperative day 11 vs. day 7.
• Smokers exhibited significantly lower tissue oximetry values compared to non-smokers.

Conclusions:

• Tissue oximetry provides valuable physiological insights into the microcirculatory effects of dangling in lower extremity free flaps.
• Findings may inform decisions to revise or discontinue current dangling protocols.
• Smoking history is associated with reduced tissue oxygen saturation in free flaps.