Wound Healing Society

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Detection Of Acute Vascular Occlusion Using Oxygen Monitoring In Myocutaneous Flaps
Mohamed M. Ibrahim1, Jennifer S. Chien1, Mahmoud M. Mohammed1, Timothy King2, Bruce Klitzman1.
1Duke University Medical Center, Durham, NC, USA, 2University of Alabama, Birmingham, AL, USA.

PURPOSE:
Vascular-compromise occurs in immediate-postoperative period due to failure of micro-vascular-anastomosis. It is estimated that 6-25% of skin flaps require secondary-surgical re-exploration and ~10% of flaps fail. Currently, all monitoring methods have limitations because they require an experience, calibration-difficulties and expensive. Furthermore, these methods impose significant delay between time of vessel-occlusion and detection. We introduce implantable-oxygen-sensors as new method to detect vascular-occlusion.
METHODS:
Experimental-sensors were made by incorporating benzo-porphyrin into matrix of biocompatible-hydrogel. Sensors were approximately 3mm-long1.5mm-wide,0.5mm-thick. Sprague-Dawley rats were used throughout study. Sensors were implanted intradermally in impending flap site. Inspired oxygen was modulated between 100%-12% to qualitatively confirm sensor sensitivity. Superficial inferior epigastric artery(SIEA) myocutaneous-flaps were surgically elevated. Vessels were carefully dissected to create 3×5cm-island-flap containing skin, subcutaneous-fat. Tissue-oxygen tension(TOT) readings obtained from implanted-sensors both at baseline and during vascular-clamping of feeding-blood-vessels.
RESULTS:
TOT-measurements from sensors were observed to modulate correlating with changes in inspired-oxygen levels. Clinical-observation of flaps did not show any significant change in color and temperature of flaps during or immediately after clamping of feeding-blood-vessels. Real-time-analysis of sensors implanted in myocutaneous-flaps has demonstrated that acute-vascular-clamping of feeding-blood-vessels in pedicle were immediately detected within 70sec (*p<0.05).
CONCLUSION:
Oxygen-monitoring in tissues is highly-sensitive and can be specific for detection of acute-vascular-occlusion. This is superior to clinical observation, faster than current standard-of-care methods and offers cost-effective, and accurate-means of monitoring free-tissue-transfers.


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