I Spy Without My Little Eye: Preventing Wound Complications Quantitatively with SPY-PHI QP 

 

Introduction: The SPY Fluorescence Imaging system with quantitative perfusion (QP) software allows surgeons to assess relative perfusion quantitatively. However, its ability to predict wound development remains unclear, as there is no consensus on a perfusion value at or below which one should be concerned about wound healing compromise.

Methods: Patients who underwent staged breast reconstruction with tissue expander placement at the time of mastectomy followed by exchange for an implant or flap were included. Images using SPY-PHI QP® were captured prospectively. Using the SPY-PHI QP® values in concert with an intraoperative clinical assessment, the senior author determined management. SAS v9.4 (SAS, Cary, NC) was used to perform logistic regression analyses. A validated cut-off value for relative tissue perfusion has yet to be identified; therefore, the following cut-off values were used: 33% as suggested by Moyer et. al. and 30.015% as calculated with the Youden index.

Results: Twenty-four patients with 34 total breasts underwent staged reconstruction with tissue expander placement at the time of a mastectomy. Four breasts developed wounds in areas where SPY-PHI QP® values were ≤30% (9.0-30.0%). With a 33% cut-off, the SPY-PHI QP® yielded a nonsignificant odds ratio (OR) of 20 (95% CI, 0.9-450.7) for wound development. With a 30.015% cut-off, the SPY-PHI QP® yielded a sensitivity of 100%, specificity of 76.7%, PPV of 36.4%, NPV of 100%, accuracy of 79.4%, and OR of 28.2 (95% CI, 1.3-632.8) for wound development. When adjusted for nitroglycerin ointment usage, the OR was 16.8 (95% CI, 0.8-363.0), suggesting that it may prevent wound development.

Conclusions: SPY-PHI QP® can be used in real time to better predict wound development in breast reconstruction patients with low perfusion values and guide breast reconstruction approach. Based on our data, we recommend using a cut-off value of 30.015%.