Title: Comparing Non-Invasive Perfusion Measuring Modalities in Predicting Skin Injury Following Flap Creation

 

Authors: David A. Febre-Alemañy^1,2,6,Shreeniket Pawar^3,4,Bijay Ghimirey^3,4,Ji Ho Park^1,2,Neekita Jikaria^1,2 ,Anilchandra Attaluri^3,4,Mohammad-Reza Tofighi^3,4 ,Dino Ravnic^1,2,5

 

 

Affiliations:

¹Irvin S. Zubar Plastic Surgery Research Laboratory, Penn State College of Medicine, Hershey, Pennsylvania, USA.

²Department of Surgery, Penn State Health Milton S. Hershey Medical Center, Hershey, Pennsylvania, USA.

³Department of Mechanical Engineering, School of Science, Engineering, and Technology, The Pennsylvania State University Harrisburg, Harrisburg , Pennsylvania, USA.

⁴Department of Electrical Engineering, School of Science, Engineering, and Technology, The Pennsylvania State University Harrisburg, Harrisburg Pennsylvania, USA.

⁵Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, State College, Pennsylvania, USA.

⁶San Juan Bautista School of Medicine, Caguas, Puerto Rico, USA.

 

Purpose:

Flaps are crucial in reconstructive surgery, but inadequate perfusion can lead to necrosis and compromise outcomes. Multiple non-invasive modalities have been developed for assessing perfusion intraoperatively during flap elevation, but the optimal modality to predict necrosis progression remains unclear.

Methods:

Six random pattern skin-flaps were created on the dorsum of four domestic pigs, with each flap having a contralateral non-flap control. Both sides were divided into six smaller zones for analysis, with zone 1 being the most proximal and zone 6 being most distal. Oxygen saturation, temperature, and total hemoglobin index (THI) were measured in all zones immediately following flap creation. At Day 7, animals were euthanized and skin thickness was quantified in each zone using hematoxylin and eosin staining. Statistical analysis was performed using unpaired t-tests (α = 0.05).

Results:

Only THI showed a predictable linear decrease in flap perfusion from proximal to distal compared to controls at Day 0. Oxygen saturation and thermal imaging appeared unpredictable. At Day 7, there was a progression in skin thickness from proximal to distal, suggesting edema and injury evolution. Results are summarized in Figure 1.

Conclusion:

THI appears to correlate best with impending skin injury following flap creation. Further studies are needed to assess whether THI can be used to formulate an actual positive predictive value that could guide surgeons in taking immediate corrective action.