Background: Free tissue transfer necessitates vigilant postoperative monitoring for vessel occlusion. Unfortunately, most monitoring methods require experienced personnel and are expensive to use. Furthermore, many tests have low sensitivity, low specificity, or significant delay between vessel occlusion and detection. The authors report on a novel method of tissue monitoring that avoids these limitations by tracking interstitial glucose concentration.
Methods: Vertical rectus abdominis myocutaneous flaps were elevated in adult rats based on the superior epigastric vessels. Interstitial glucose within the flaps was monitored using a transcutaneous sensor. Interstitial glucose was recorded following arterial occlusion in 10 flaps and venous occlusion was recorded in eight flaps. Criteria for detecting vessel occlusion were developed based on interstitial glucose concentration and rate of change.
Results: Occlusion of the flap's arterial supply led to a rapid decline in interstitial glucose. Within 15 minutes of arterial occlusion, the interstitial glucose in occluded flaps was significantly lower than in viable flaps (p = 0.0003). Occlusion of venous outflow resulted in a similar decline of interstitial glucose. Interstitial glucose below the animal's euglycemic range was 100 percent sensitive (95 percent confidence interval, 78.1 to 100 percent) and 95.2 percent specific (95 percent confidence interval, 74.1 to 99.8 percent) for vessel occlusion. A fall in interstitial glucose greater than or equal to 7 mg/dl per minute was 100 percent sensitive (95 percent confidence interval, 78.1 to 100 percent) and 100 percent specific (95 percent confidence interval, 80.8 to 100 percent) for vessel occlusion. The delay between occlusion and detection was less than 30 minutes for all flaps.
Conclusions: Interstitial glucose monitoring is highly sensitive and specific for vessel occlusion. This technology offers a rapid, inexpensive, and accurate method of monitoring free tissue transfers.
Madison, Wis.; and Evanston, Ill.
From the Division of Plastic and Reconstructive Surgery, University of Wisconsin School of Medicine and Public Health, and the Division of Plastic Surgery, NorthShore University HealthSystem.
Received for publication October 16, 2009; accepted December 11, 2009.
Presented at the 54th Annual Meeting of the Plastic Surgery Research Council, in Pittsburgh, Pennsylvania, May 27 through 30, 2009.
Disclosures: This work was funded by a Pilot Research Grant from the Plastic Surgery Educational Foundation (to T.W.K and T.J.S). All intellectual property for the monitoring of tissue perfusion by means of interstitial glucose is owned by the Wisconsin Alumni Research Foundation. As inventors of this technology, Drs. Sitzman and Gutowski may someday receive royalties if a product is ever developed. Drs. Sitzman and Gutowski have no real or deferred equity interests in this technology. The authors hereby declare that they have no other financial interest(s) in the material presented within.
Thomas J. Sitzman, M.D. Division of Plastic and Reconstructive Surgery, University of Wisconsin School of Medicine and Public Health, G5/361 Clinical Sciences Center, 600 Highland Avenue, Madison, Wis. 53792, firstname.lastname@example.org