New aspects in free flap surgery: Mini-perforator flaps and extracorporeal flap perfusion

Imaging Photoplethysmography (iPPG) in Head and Neck Reconstructive Surgery: A Novel Technique for Noninvasive Flap Perfusion Monitoring

BACKGROUND

Evaluate imaging photoplethysmography (iPPG) as a novel noninvasive technique to assess flap perfusion in head and neck free flap reconstructive (FFR) surgeries.

METHODS

Intraoperative iPPG was performed in 17 patients undergoing FFR surgery. Imaging consisted of a 30-s video from which perfusion maps were extracted, providing detailed information about blood flow and pulsatility in the flap microvasculature. During each procedure, iPPG acquisitions were acquired representing distinct perfusion conditions of the flap (fully perfused/ischemic/reperfused). When possible, postoperative measurements were performed to assess flap recovery during the critical time period (3 days) and long-term follow-up (30 days).

RESULTS

Perfusion maps, displaying iPPG amplitude and delay times, correlated strongly (p < 0.001) with the perfusion status of the tissue. One case of postoperative thrombosis, leading to flap failure, was identified with iPPG. After surgical revision in this case, flap perfusion was restored and confirmed by iPPG. Postoperative follow-up imaging allowed for objective visualization of flap recovery short term (3 days) and up to 30 days after the surgical procedure.

CONCLUSIONS

This study shows that iPPG is suitable for objective and noninvasive assessment of flap perfusion in head and neck FFR surgery. In addition, postoperative monitoring shows potential for assessing flap perfusion in patients with increased risk of postoperative complications.

Continuous oxygen monitoring to enhance ex-vivo organ machine perfusion and reconstructive surgery

Continuous oxygenation monitoring of machine-perfused organs or transposed autologous tissue is not currently implemented in clinical practice. Oxygenation is a critical parameter that could be used to verify tissue viability and guide corrective interventions, such as perfusion machine parameters or surgical revision. This work presents an innovative technology based on oxygen-sensitive, phosphorescent metalloporphyrin allowing continuous and non-invasive oxygen monitoring of ex-vivo perfused vascularized fasciocutaneous flaps. The method comprises a small, low-energy optical transcutaneous oxygen sensor applied on the flap's skin paddle as well as oxygen sensing devices placed into the tubing. An intermittent perfusion setting was designed to study the response time and accuracy of this technology over a total of 54 perfusion cycles. We further evaluated correlation between the continuous oxygen measurements and gold-standard perfusion viability metrics such as vascular resistance, with good agreement suggesting potential to monitor graft viability at high frequency, opening the possibility to employ feedback control algorithms in the future. This proof-of-concept study opens a range of research and clinical applications in reconstructive surgery and transplantation at a time when perfusion machines undergo rapid clinical adoption with potential to improve outcomes across a variety of surgical procedures and dramatically increase access to transplant medicine.

The Future of Microsurgery: Vascularized Composite Allotransplantation and Engineering Vascularized Tissue

Background

Microsurgical techniques have revolutionized the field of reconstructive surgery and are the mainstay for complex soft tissue reconstruction. However, their limitations have promoted the development of viable alternatives. This article seeks to explore technologies that have the potential of revolutionizing microsurgical reconstruction as it is currently known, reflect on current and future vascularized composite allotransplantation (VCA) practices, as well as describe the basic science within emerging technologies and their potential translational applications.

Methods

A literature review was performed of the technologies that may represent the future of microsurgery: vascularized tissue engineering (VCA) and flap-specific tissue engineering.

Results

VCA has shown great promise and has already been employed in the clinical setting (especially in face and limb transplantation). Immunosuppression, logistics, cost, and regulatory pathways remain barriers to overcome to make it freely available. Vascularized and flap-specific tissue engineering remain a laboratory reality but have the potential to supersede VCA. The capability of creating an off-the-shelf free flap matching the required tissue, size, and shape is a significant advantage. However, these technologies are still at the early stage and require significant advancement before they can be translated into the clinical setting.

Conclusion

VCA, vascularized tissue engineering, and flap-specific bioengineering represent possible avenues for the evolution of current microsurgical techniques. The next decade will elucidate which of these three strategies will evolve into a tangible translational option and hopefully bring a paradigm shift of reconstructive surgery.

A Guide to Perforator Flap Selection for Buttock Pressure Sore Reconstruction

ABSTRACT

Perforator flaps have been increasingly used to repair stage IV buttock pressure ulcers. However, no one has proposed an approach for stage IV buttock pressure ulcers repairing based on the subregion of buttock pressure ulcers. This study aims to evaluate the effect of perforator flaps in the repair of stage IV buttock pressure ulcers, and flap selection was based on the location of the pressure ulcers. Over the past 5 years, we evaluated 65 cases of stage IV buttock pressure ulcers repaired using perforator flaps. Flap selection was based on the subregion of each buttock pressure ulcer, following our approach. A total of 87 perforator flaps were used for 65 cases, including 42 superior gluteal artery perforator flaps, 19 fourth lumbar artery perforator flaps, and 26 descending inferior gluteal artery perforator flaps. All patients showed satisfactory reconstruction. The authors' approach can support surgeons in selecting the appropriate flaps to repair stage IV buttock pressure ulcers and achieve excellent reconstructive outcomes. This method makes the selection of flaps for pressure ulcer repair systematic, simple, and highly feasible and thus is worthy of promotion.

The Autonomization Principle in Vascularized Flaps: An Alternative Strategy for Composite Tissue Scaffold In Vivo Revascularization

Autonomization is a physiological process allowing a flap to develop neo-vascularization from the reconstructed wound bed. This phenomenon has been used since the early application of flap surgeries but still remains poorly understood. Reconstructive strategies have greatly evolved since, and fasciocutaneous flaps have progressively replaced muscle-based reconstructions, ensuring better functional outcomes with great reliability. However, plastic surgeons still encounter challenges in complex cases where conventional flap reconstruction reaches its limitations. Furthermore, emerging bioengineering applications, such as decellularized scaffolds allowing a complex extracellular matrix to be repopulated with autologous cells, also face the complexity of revascularization. The objective of this article is to gather evidence of autonomization phenomena. A systematic review of flap autonomization is then performed to document the minimum delay allowing this process. Finally, past and potential applications in bio- and tissue-engineering approaches are discussed, highlighting the potential for in vivo revascularization of acellular scaffolds.

Towards Optimizing Sub-Normothermic Machine Perfusion in Fasciocutaneous Flaps: A Large Animal Study

Machine perfusion has developed rapidly since its first use in solid organ transplantation. Likewise, reconstructive surgery has kept pace, and ex vivo perfusion appears as a new trend in vascularized composite allotransplants preservation. In autologous reconstruction, fasciocutaneous flaps are now the gold standard due to their low morbidity (muscle sparing) and favorable functional and cosmetic results. However, failures still occasionally arise due to difficulties encountered with the vessels during free flap transfer. The development of machine perfusion procedures would make it possible to temporarily substitute or even avoid microsurgical anastomoses in certain complex cases. We performed oxygenated acellular sub-normothermic perfusions of fasciocutaneous flaps for 24 and 48 h in a porcine model and compared continuous and intermittent perfusion regimens. The monitored metrics included vascular resistance, edema, arteriovenous oxygen gas differentials, and metabolic parameters. A final histological assessment was performed. Porcine flaps which underwent successful oxygenated perfusion showed minimal or no signs of cell necrosis at the end of the perfusion. Intermittent perfusion allowed overall better results to be obtained at 24 h and extended perfusion duration. This work provides a strong foundation for further research and could lead to new and reliable reconstructive techniques.

Microvascular reconstructions in oral and maxillofacial surgery - Results of a survey among oral and maxillofacial surgeons in Germany, Austria, and Switzerland

This study aimed to evaluate the use of microvascular free flaps (MFF) in oral and maxillofacial surgery (OMFS) in Germany, Austria, and Switzerland. A dynamic online questionnaire, using 42-46 questions, was sent to OMF surgeons based in hospitals in Germany, Austria, and Switzerland. The questionnaire was evaluated internally and externally. Aside from general information, data were collected on organizational aspects, approaches, MFF types and frequency, presurgical planning, intraoperative procedures, perioperative medications, flap monitoring, and patient management. Participants mostly performed 30-40 MFF each year (11/53). Most stated that the COVID-19 pandemic did influence MFF frequency (25/53) to varying extents. Radial forearm flap was most frequently used (37/53), followed by ALT (5/53), and fibula flap (5/53). Primary reconstruction was performed by most participants (35/48). Irradiated bony transplants were mostly used for implant placement after 12 months (23/48). Most participants (38/48) used reconstruction plates, followed by miniplates (36/48), PSI reconstruction (31/48), and PSI miniplates (10/48). Regarding the postoperative use of anticoagulants, low-molecular-weight (37/48) and unfractioned heparins (15/48) were widely used, most often for 3-7 days (26/48). Clinical evaluation was mostly preferred for flap monitoring (47/48), usually every 2 h (34/48), for at least 48 h (19/48). Strong heterogeneity in MFF reconstructions in OMFS was found, especially regarding the timepoints of reconstruction, types of osteosynthesis, and postoperative MFF management. These findings provide the chance to further compare the different treatment algorithms regarding relevant MFF aspects, such as postoperative management. This could create evidence-based treatment algorithms that will further improve the clinical outcomes in MFF reconstructions.

Pedicled buccal flaps as a backup procedure for intraoral reconstruction

BACKGROUND

Intraoral soft tissue deficiency and impaired wound beds are common problems after cleft and tumour surgery or after dental trauma. Frequently, limited defects are overtreated with extensive microvascular reconstruction procedures, but pedicled flaps remain useful, as they are simple to harvest, and they provide a reliable outcome. The buccal flap, first described in the 1970s, has been used for palatine lengthening in cleft patients over decades. In the following, we present an expanded indication in cases of palatal fistula, complex vestibulum, exposed bone in orthognathic surgery, and osteoradionecrosis.

METHODS

We conducted a retrospective chart review and report on all buccal flaps harvested in our department within the last 3 years with a follow-up period of at least half a year after flap surgery. Patients of all age groups and treatment indications in which a buccal flap was used were implicated in the evaluation.

RESULTS

Sixteen buccal flaps were performed in 10 patients. The median age at the time of surgery was 42 years, reaching from 12 up to 66 years. Fourteen buccal flaps were used for upper jaw or palatal coverage; two buccal flaps were used in the mandible. In terms of complications (four flaps; 25%), there were two partial flap failures, one wound dehiscence and one wound dehiscence. There were no failures of the remaining mucosal flap islands after pedicle dissection.

CONCLUSION

The buccal flap is a reliable and straightforward approach to challenging intraoral wound beds with soft tissue deficiency. We thoroughly discuss the additional indications for buccal flap surgery, describe the harvest technique, and provide strategies to prevent intra- and postoperative complications.

Objective Skin Quality Assessment after Reconstructive Procedures for Facial Skin Defects

Local random skin flaps and skin grafts are everyday surgical techniques used to reconstruct skin defects. Although their clinical advantages and disadvantages are well known, there are still uncertainties with respect to their long-term results. Hence, the aim of this study was to evaluate outcomes more than one-year post operatively using objective measurement devices. The study included 31 facial defects reconstructed with local random flap, 30 facial defects reconstructed with split-thickness skin grafts (STSGs) and 30 facial defects reconstructed with full-thickness skin grafts (FTSGs). Skin quality was objectively evaluated using MP6 noninvasive probes (Courage + Khazaka GmbH, Cologne, Germany), which measure melanin count, erythema, hydration, sebum, friction and transepidermal water loss. The results showed that there were no significant differences in melanin count, erythema, hydration, sebum level, friction value and transepidermal water loss (TEWL) between the site reconstructed with random local flaps and the same site on the healthy contralateral side of the face. However, both FTSGs and STSGs showed significantly higher levels in terms of TEWL and erythema, whereas the levels of hydration, sebum and friction were significantly lower compared to the healthy contralateral side. Moreover, STSGs resulted in a significant difference in melanin count. These findings imply that the complex pathophysiology of the wound-healing process possibly results in better skin-quality outcomes for random local flaps than skin autografts. Consequently, this suggests that random local flaps should be implemented whenever possible for the reconstruction of facial region defects.

Recipient bed perfusion as a predictor for postoperative complications in irradiated patients with microvascular free tissue transfer of the head and neck area: a clinical analysis of 191 microvascular free flaps

PURPOSE

Despite microvascular free tissue transfer being the mainstay of care in the reconstruction of larger maxillofacial defects, a significant number of patients experience postoperative complications due to impaired blood supply of the flap. In this context, the early influence of recipient bed perfusion remains unclear, but there is evidence that it is associated with free flap viability immediately after surgery.

METHODS

We analyzed flap and recipient bed perfusion within the first 2 weeks after surgery by using the oxygen-to-see device. One hundred ninety-one patients who underwent free flap surgery in our department were included.

RESULTS

Flow parameters were higher and postoperative complications were less frequent in radial forearm free flaps compared to any other type of flap. Flow parameters of the recipient bed were higher than transferred tissue at all times, implicating flap autonomization is not completed within 2 weeks. Previous radiotherapy significantly decreased flow parameters of the recipient bed but not of the flaps. Furthermore, irradiated patients with postoperative complications were found to have reduced flow parameters of their recipient bed compared to non-irradiated patients with postoperative complications.

CONCLUSION

We conclude that monitoring of recipient bed perfusion is useful for detecting flap compromise of irradiated patients in the early postoperative period.

Head and Neck Reconstruction of the Vessel-Depleted Neck: A Systematic Review of the Literature

BACKGROUND

Damage of the vascular system secondary to radical neck dissection and/or radiotherapy or other treatments has a negative impact on microsurgical reconstruction. The search for adequate recipient vessels is hindered by the complexity of previous procedures.

METHODS

A systematic review of microsurgical head and neck reconstruction in the vessel-depleted neck was performed. The issues analyzed were indications for surgery, more frequently performed flaps, vascular systems used as recipient vessels, outcomes, and complications.

RESULTS

The eligibility criteria were fulfilled by 57 studies published between September 1993 and January 2020. In 8235 patients, 8694 flaps were performed, 925 of which were for a vessel-depleted neck. The most commonly used flap was the anterolateral thigh flap, used in 195 cases (30%), followed by the radial forearm free flap, used in 157 cases (24%). The potential recipient vessels were numerous for arteries (26 options) and veins (31 options). For the 712 flaps with an identifiable recipient artery, the superficial temporal artery was the most commonly used vessel (n = 142, 20%). The superficial temporal vein was the most commonly used vessel for 639 flaps with an identifiable recipient vein (n = 118, 18.5%). Complications amounted to 11%; 80 out of 716 flaps in papers that reported them. Flap losses were reported in 2% of cases.

CONCLUSIONS

Major microsurgical head and neck reconstruction for postoncologic defects depends on appropriate recipient vessels. Vein availability is paramount. Understanding the complexity of this problem is useful for preoperative planning, precise decision-making, and an accurate surgical approach.

A decade of reconstructive surgery: outcome and perspectives of free tissue transfer in the head and neck. Experience of a single center institution

PURPOSE

Free flaps have become the standard option in reconstructive surgery of the head and neck. Even though many authors have outlined the reliability of free transplants, there is an ongoing discussion about treatment options for patients bearing particular risks as previous irradiation treatment. In this analysis, we aim to address these patients with particular risk profiles by comparing different flap entity outcome parameters.

METHODS

We retrospectively analyzed a cohort of 494 patients who underwent flap surgery between 2009 and 2018 in our department. Focusing on free microvascular transplants, we additionally analyzed the pectoralis major myocutaneous flap as the most frequently used vascular pedicled flap. Data analysis was performed by uni- and multivariate statistics.

RESULTS

Overall flap success rate was 90%, with the radial forearm flap occurring to be most reliable (93%) in head and neck reconstruction. Previous radiation therapy (RT) and intraoperative revision of vascular anastomosis during primary surgery significantly resulted in impaired transplant outcome with a success rate of 91.8% (no RT) vs. 83.7% (RT), respectively. There was a negative linear correlation between incision to suture time and number of flaps per year (R² = 0.67).

CONCLUSIONS

Preoperative radiation therapy and intraoperative revision of anastomosis significantly impair outcome of microvascular flaps in the head and neck and oral cavity, whereas patient's age is not a predictor of flap failure. Increasing case number and experience reduces time of flap surgery as well as rate of complications and flap failure.

In vivo perfusion of free skin flaps using extracorporeal membrane oxygenation

BACKGROUND

The vessel-depleted, irradiated, and frozen neck, as well as severe atherosclerosis of recipient vessels represent challenging problems in free flap transfer. Extracorporeal free flap perfusion theoretically allows free flap reconstructions in the absence of local donor vessels, but is associated with a number of technical issues. In this study, a novel technique is presented using a commercially available system for extracorporeal membrane oxygenation (ECMO), modified for small blood volumes.

METHODS

After preclinical testing, an ECMO system certified for lung support was used to establish blood flow through the flap's artery with oxygenation, decarboxylation and warming of diluted packed blood cells. Venous blood was allowed to flow passively into a separate container. Perfusion was performed for 15 min at intervals of 4 h over 4-6 days.

RESULTS

Five patients with soft tissue defects requiring free flap reconstruction were included. Either primarily thinned anterolateral thigh (ALT) flaps (n = 3) or radial forearm flaps (n = 2) were used. We observed infection of the perfusate, with consequent subtotal flap loss, in one patient, complete epithelial loss in two patients, venous congestion in one case, and almost uneventful healing in the fifth patient. With conservative wound care and a split thickness skin graft in one case, stable wound coverage was achieved in all patients except one, who had secondary healing. None of the patients required a second flap for sufficient coverage.

CONCLUSIONS

The technique described is associated with the risks of infection, flap congestion, nutritive hypoperfusion, and consequent tissue loss. Nevertheless, stable defect closure seems to be achievable even in patients with depleted recipient vessels.

Extracorporeal Free Flap Perfusion Using Extracorporeal Membrane Oxygenation Device: An Experimental Model

Extracorporeal perfusion of organs has a wide range of clinical applications like prolonged vital storage of organs, isolated applications of drugs, bridging time to transplant, and free composite tissue transfer without anastomosis, but there are a limited number of experimental models on this topic.This study aimed to develop and evaluate a human extracorporeal free flap perfusion model using an extracorporeal membrane oxygenation device. Five patients undergoing esthetic abdominoplasty participated in this study. Deep inferior epigastric artery perforator flaps were obtained abdominoplasty flaps, which are normally medical waste, used in this model. Deep inferior epigastric artery perforator flaps were extracorporeally perfused with a mean of 6 days. The biochemical and pathological evaluations of the perfusions were discussed in the article.

Rerouting the internal thoracic pedicle: a novel solution for maxillofacial reconstruction in vessel-depleted situations? A preliminary anatomic study

PURPOSE

Microsurgical reconstruction in a vessel-depleted neck is a challenge due to the lack of reliable vessels in or nearby the host site. The use of the internal thoracic pedicle (ITP) by rib section or sparring is a limited option due to the small length of the pedicle of some flaps. However, in cardiac surgery, the internal thoracic artery (ITA) is widely used for myocardial revascularization, providing a long and versatile pedicle. We aimed at determining precise anatomical bases for the use of the ITP, approached by sternotomy and rerouted in the neck, as recipient vessels for free-flap facial reconstructions.

METHODS

We performed a descriptive single centre anatomical study on 20 formalin-embalmed cadavers. The ITP was harvested on both sides from the emergence of the artery under the brachiocephalic vein to its terminal division. The level reached by the ITP in the cervicofacial area was described. Distal arterial and venous diameters, pedicle length and other parameters were measured.

RESULTS

In at least 85% of the cases, the ITP reached the mandibular angle. The mean diameter at the distal extremity for the ITA was 2.36 ± 0.15, and 2.48 ± 0.19 mm for the committing vein. The mean length of the ITP was 177.3 mm.

CONCLUSION

Rerouting the ITP towards the cervicofacial area could provide a reliable pedicle for free-flap reconstructions in patients with a vessel-depleted neck but it should be limited to selected patients. This novel solution for situations where current techniques are unfeasible warrants further clinical research.