Perioperative factors that influence the outcome of microsurgical reconstructions in craniomaxillofacial surgery

Does the Anastomosis Recipient Vessel Have an Influence on Free Flap Perfusion in Microvascular Head and Neck Reconstruction-A Retrospective Analysis of 338 Cases with Comparison of Flap Perfusion between Different Arterial and Venous Recipient Vessels in Radial Free Forearm Flaps, Anterolateral Thigh Flaps, and Fibula Free Flaps

Background: Flap perfusion is a prerequisite for microvascular free flap survival and a parameter routinely used for flap monitoring. The aim of this study was to investigate the influence of the anastomosis recipient vessel on flap perfusion. Methods: Flap perfusion was retrospectively analyzed in 338 patients who underwent head and neck reconstruction with microvascular free flaps between 2011 and 2020. The Oxygen-to-see tissue oxygen analysis system measurements for intraoperative and postoperative flap blood flow, hemoglobin concentration, and hemoglobin oxygen saturation at 8 and 2 mm tissue depths were compared between arterial anastomosis recipient vessels (external carotid artery [ECA], facial artery [FAA], lingual artery [LIA], and superior thyroid artery [STA]) and venous anastomosis recipient vessels (internal jugular vein [IJV], combination of IJV and IJV branches, IJV branches, and external jugular vein). Results: The postoperative hemoglobin concentration at 2 mm tissue depth differed significantly between arterial anastomosis recipient vessels (ECA, 41.0 arbitrary units [AU]; FAA, 59.0 AU; LIA, 51.5 AU; STA, 59.0 AU; p = 0.029). This difference did not persist in the multivariable testing (p = 0.342). No other differences in flap blood flow, hemoglobin concentration, or hemoglobin oxygen saturation were observed between the arterial and venous anastomosis recipient vessels (p > 0.05 for all). Conclusions: The arterial and venous recipient vessels used for anastomosis did not influence microvascular free flap perfusion. This underlines the capability of the studied recipient vessels to adequately perfuse free flaps, may explain the observed indifferent flap survival rates between commonly used anastomosis recipient vessels, and implies that the recipient vessel is not a confounding variable for flap monitoring with the Oxygen-to-see tissue oxygen analysis system. Further prospective studies are needed to confirm the findings.

Outcomes of Head and Neck Free Tissue Transfer Requiring Vein Grafting: Systematic Review and Meta-analysis

OBJECTIVE

To systematically review the literature to determine the prevalence of free flap failure in head and neck free flaps requiring vein grafting.

DATA SOURCES

Search strategies created in collaboration with a medical librarian were implemented using PubMed, Cochrane, Scopus, Web of Science, and Google Scholar from inception to August 2022.

REVIEW METHODS

The population of interest included adult and pediatric patients undergoing reconstruction of oncologic or traumatic head and neck defects with a free flap requiring a vein graft that presents the success/failure rate. The primary outcome was the flap failure rate, and the secondary outcome was the flap compromise/revision rate. Inclusion and exclusion criteria were designed to capture all study designs. Initially, 2778 articles were identified by the search strategy. Two reviewers independently performed the review, data extraction for analysis, and a quality assessment. Primary Reporting Items for Systematic Reviews and Meta-analyses guidelines were followed. Meta-analysis was performed using a random effects model.

RESULTS

Eleven studies of 789 flaps were included for data extraction. Random effects meta-analysis resulted in an estimated prevalence of free flap failure of 12.30% (95% confidence interval: 6.39%-19.49%, I2 = 77.4%).

CONCLUSION

Taking into account that head and neck free tissue transfers that require a vein graft are typically associated with more challenging reconstructions and the lack of a suitable alternative, vein grafts appear to be a reliable method for bridging the gap between the flap and recipient vessels in head and neck free tissue transfer when indicated.

Risk Factors for Flap Loss: Analysis of Donor and Recipient Vessel Morphology in Patients Undergoing Microvascular Head and Neck Reconstructions

In microvascular head and neck reconstruction, various factors such as diabetes, alcohol consumption, and preoperative radiation hold a risk for flap loss. The primary objective of this study was to examine the vessel morphology of both recipient and donor vessels and to identify predictors for changes in the diameters of H.E.-stained specimens associated with flap loss in a prospective setting. Artery and vein samples (N = 191) were collected from patients (N = 100), with sampling from the recipient vessels in the neck area and the donor vessels prior to anastomosis. External vessel diameter transverse (ED), inner vessel diameter transverse (ID), thickness vessel intima (TI), thickness vessel media (TM), thickness vessel wall (TVW), and intima-media ratio (IMR) for the recipient (R) and transplant site (T) in arteries (A) and veins (V) were evaluated using H.E. staining. Flap loss (3%) was associated with increased ARED (p = 0.004) and ARID (p = 0.004). Preoperative radiotherapy led to a significant reduction in the outer diameter of the recipient vein in the neck (p = 0.018). Alcohol consumption (p = 0.05), previous thrombosis (p = 0.007), and diabetes (p = 0.002) were associated with an increase in the total thickness of venous recipient veins in the neck. Diabetes was also found to be associated with dilation of the venous media in the neck vessels (p = 0.007). The presence of cardiovascular disease (CVD) was associated with reduced intimal thickness (p = 0.016) and increased total venous vessel wall thickness (p = 0.017) at the transplant site. Revision surgeries were linked to increased internal and external diameters of the graft artery (p = 0.04 and p = 0.003, respectively), while patients with flap loss showed significantly increased artery diameters (p = 0.004). At the transplant site, alcohol influenced the enlargement of arm artery diameters (p = 0.03) and the intima-media ratio in the radial forearm flap (p = 0.013). In the anterolateral thigh, CVD significantly increased the intimal thickness and the intima-media ratio of the graft artery (p = 0.01 and p = 0.02, respectively). Patients with myocardial infarction displayed increased thickness in the A. thyroidea and artery media (p = 0.003). Facial arteries exhibited larger total vessel diameters in patients with CVD (p = 0.03), while facial arteries in patients with previous thrombosis had larger diameters and thicker media (p = 0.01). The presence of diabetes was associated with a reduced intima-media ratio (p < 0.001). Although the presence of diabetes, irradiation, and cardiovascular disease causes changes in vessel thickness in connecting vessels, these alterations did not adversely affect the overall success of the flap.

Effect of preoperative radiation on free flap outcomes for head and neck reconstruction: An updated systematic review and meta-analysis

BACKGROUND

There is an ongoing debate about whether neoadjuvant radiation therapy is associated with higher rates of postoperative complications after head and neck reconstruction. Herle et al. conducted a systematic review in 2014 of 24 studies, finding higher complication rates in irradiated fields. We sought to perform an exhaustive updated systematic review and meta-analysis.

METHODS

We conducted an updated systematic review of the literature, as outlined in our protocol, which was registered on PROSPERO. Databases included Medline, Embase, Cochrane Central, and Web of Science. There were no limits placed on the date range, place of publication, or origin. Exclusion criteria included patients less than 18 years of age, studies with less than 20 participants (n < 20), case studies, skull base reconstructions, and local tissue rearrangements. The combined results of the studies and relative risks (RR) were calculated.

RESULTS

53 studies were included for analysis, including 5,086 free flaps in an irradiated field, and 9,110 free flaps in a non-irradiated field. Of the 53 studies, 21 studies overlapped with those discussed in Herle et al.'s study, with a total of 32 additional studies. Neoadjuvant radiation was found to be a statistically significant risk factor for postoperative complications (RR 1.579, P < 0.001), total flap failure (RR, 1.565; P < 0.001), and fistula (RR, 1.810; P < 0.001). Our work reaffirmed the findings of the Herle et al.

STUDY

CONCLUSION

Preoperative radiation was associated with a statistically significant increase in the risk of total flap failure, fistula, and total complications but not partial flap failure. These high-morbidity complications must be taken into consideration when determining which patients should receive neoadjuvant radiation therapy.

Endothelial inflammatory and thrombogenic expression changes in microvascular anastomoses - An immunohistochemical analysis

The aim of this study was to investigate intraluminal vessel diameters and endothelial expression levels of pro-inflammatory and -thrombotic mediators in patent and non-patent microvascular anastomoses. Endothelial expression of CD31, VCAM-1, E- and P-Selectin, eNOS, iNOS and PAI-1 was evaluated by immunohistochemistry and compared to non-anastomosed arteries as controls. Intraluminal diameters were determined via H.E.-staining. In 20 human anastomoses (8 patent, 12 non-patent) neither the analysis of endoluminal de-endothelialization (p = 0.966) nor luminal narrowing (p = 0.750) revealed any significant differences between patent and non-patent microanastomoses. Expressions of pro-inflammatory mediators were significantly higher in patent anastomoses compared to controls but did not show any difference compared to non-patent anastomoses (p > 0.050). iNOS was higher in non-patent compared to patent anastomoses (p = 0.030) and controls (p = 0.001), whereas eNOS did not reveal any differences between these groups (p = 0.611 and p = 0.130). In non-patent anastomoses PAI-1 was expressed higher compared to patent anastomoses and controls (p = 0.021 and p < 0.001). Irrespective of their patency, anastomoses are characterized by endothelial dysfunction with a pro-inflammatory and pro-thrombotic milieu. Avoiding endothelial trauma during suturing is essential in order not to aggravate existing endothelial dysfunction in microanastomoses. Additionally, the influence of medication-related changes on anastomoses should be investigated as this is still an indistinctive topic.

A Standard Algorithm for Reconstruction of Scalp Defects With Simultaneous Free Flaps in an Interdisciplinary Two-Team Approach

Reconstructions of complex scalp after ablative resection or by post-traumatic tissue loss, can present difficulties regarding recipient vessel selection, functional, and aesthetic outcome. The harvesting method for many microvascular free flaps requires a need for changing patients position during surgery and makes a simultaneous interdisciplinary two-team approach complicated, which is a major disadvantage regarding safety and operation time. The ideal flap for scalp reconstruction has yet to be described, although the microvascular latissimus dorsi flap is frequently referred to as the first choice in this context, especially after resection of large defects. The purpose of this study is to compare two different microvascular free flaps for a simultaneous scalp reconstruction in an interdisciplinary two-team approach applying a standardized algorithm. All consecutively operated complex scalp defects after ablative surgery from April 2017 until August 2018 were included in this retrospective study. The indications were divided into neoplasm or wound healing disorder. Two microvascular flaps (latissimus dorsi or parascapular flap) were used to cover the soft tissue component of the resulting defects. Seventeen patients met the inclusion criterion and were treated in an interdisciplinary two-team approach. Skull reconstruction with a CAD/CAM implant was performed in 10 cases of which four were in a secondary stage. Nine patients received a parascapular flap and eight patients were treated with latissimus dorsi flap with split thickness skin graft. Anastomosis was performed with no exception to the temporal vessels. One parascapular flap had venous insufficiency after 1 week followed by flap loss. One latissimus dorsi flap had necrosis of the serratus part of the flap. All other flaps healed uneventful and could be further treated with adjuvant therapy or CAD/CAM calvarial implants. Regarding overall complications, flap related complications, flap loss, and inpatient stay no statistical differences were seen between the diagnosis or type of reconstruction. The parascapular flap seems to be a good alternative for reconstruction of complex tumor defects of the scalp besides the latissimus dorsi flap. Stable long-term results and little donor site morbidity are enabled with good aesthetic outcomes and shorter operation time in an interdisciplinary two-team approach.