Using quantitative imaging, investigators identified a potential cutoff that could help surgeons assess mastectomy skin flap viability and determine when additional interventions may be needed.

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By Alyx Arnett

Inadequate blood flow to mastectomy skin flaps can lead to tissue necrosis, wound complications, and reconstructive failure. Although surgeons can use intraoperative imaging to assess tissue viability, specific perfusion thresholds that reliably predict complications have not been well established.

A prospective study involving 58 patients undergoing staged breast reconstruction with tissue expanders sought to establish a perfusion threshold that could help predict wound complications. Researchers used the SPY Portable Handheld Imager with Quantitative Perfusion software (SPY-PHI QP), which uses indocyanine green angiography to visualize blood flow and provide numerical measurements of tissue perfusion during surgery.

“Indocyanine green angiography is a widely utilized modality to assess perfusion of mastectomy skin flaps intraoperatively,” says study co-author George Kokosis, MD, FACS, associate professor and director of surgical AI and innovation in the Division of Plastic and Reconstructive Surgery at Rush University Medical Center. “It is also well known that angiography-guided management of mastectomy flaps decreases complication rates. However, what is not well studied is specific perfusion thresholds.”

Kokosis spoke with Plastic Surgery Practice about the potential perfusion threshold identified, how nitroglycerin use affects the interpretation of measurements, and what the findings could mean for surgical decision-making.

[Editor’s note: Read the study, “Establishing a predictive perfusion threshold using SPY-PHI QP in staged breast reconstruction: A prospective evaluation with nitroglycerin adjustment” in Aesthetic Surgery Journal.]

PSP: What were your key findings?

Kokosis: SPY-PHI QP offers real-time insight into tissue viability during breast reconstruction and can be used in real time to help guide surgeons in their breast reconstruction approach. In our cohort, a perfusion threshold of 30% in patients not treated with nitroglycerin may be predictive of wound complications.

PSP: What is the significance of this finding?

Kokosis: When a plastic surgeon utilizes perfusion thresholds intraoperatively, having a number to guide them as to what next steps are indicated is paramount in decreasing mastectomy skin flap necrosis and potentially reconstructive failure. A threshold below 30% will guide them to take additional measures (debride the hypo-perfused area if possible, use nitroglycerin or hyperbaric treatments, or not offer reconstruction with a device if there is significant concern for postoperative complications).

PSP: Were any of the findings surprising?

Kokosis: Not surprising. We were able, however, to confirm thresholds below which the user needs to be aware of increased chances of complications, therefore creating a roadmap of addressing intraoperative flap perfusion variability.

PSP: How did nitroglycerin use affect the results, and what does this suggest about interpreting perfusion measurements?

Kokosis: Nitroglycerin has a vasodilatory effect, and therefore its use can potentially improve suboptimal perfusion. Although the thresholds for perfusion interpretation may change in the setting of nitroglycerin use, the main point is that a skin flap that requires nitroglycerin use is already deemed to have suboptimal perfusion and may lead to complications as nitroglycerin use is not a panacea.

PSP: How might quantitative perfusion measurements help surgeons assess tissue viability and make decisions during breast reconstruction?

Kokosis: This is the whole point of this study: to identify thresholds below which additional measures need to be taken to minimize chances of complications. In this era of breast reconstruction where adjunct technology exists that can inform and guide, we should be able to harness it and improve outcomes for the vulnerable reconstructive population.

PSP: What are the key takeaways for plastic surgeons?

Kokosis: If possible, use indocyanine green angiography, and utilize the perfusion thresholds to guide intra- and post-operative management of hypo-perfused mastectomy skin flaps. This can help minimize postoperative wound complications and ultimately reconstructive failure.

PSP: What additional research is needed before specific perfusion thresholds can be more widely adopted in breast reconstruction?

Kokosis: Randomized controlled studies would be the most appropriate method to study this further and add high level data to what we already know.

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