Free Flap Monitoring, Salvage, and Failure Timing: A Systematic Review

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.

Advancing indocyanine green fluorescence flap perfusion assessment via near infrared signal quantification

Introduction

Intraoperative indocyanine green fluorescence angiography (ICGFA) perfusion assessment has been demonstrated to reduce complications in reconstructive surgery. This study sought to advance ICGFA flap perfusion assessment via quantification methodologies.

Method

Patients undergoing pedicled and free flap reconstruction were subjected to intraoperative ICGFA flap perfusion assessment using either an open or endoscopic system. Patient demographics, clinical impact of ICGFA and outcomes were documented. From the ICGFA recordings, fluorescence signal quality, as well as inflow/outflow milestones for the flap and surrounding (control) tissue were computationally quantified post hoc and compared on a region of interest (ROI) level. Further software development intended full flap quantification, metric computation and heatmap generation.

Results

Fifteen patients underwent ICGFA assessment at reconstruction (8 head and neck, 6 breast and 1 perineum) including 10 free and 5 pedicled flaps. Visual ICGFA interpretation altered on-table management in 33.3% of cases, with flap edges trimmed in 4 and a re-anastomosis in 1 patient. One patient suffered post-operative flap dehiscence. Laparoscopic camera use proved feasible but recorded a lower quality signal than the open system.Using established and novel metrics, objective ICGFA signal ROI quantification permitted perfusion comparisons between the flap and surrounding tissue. Full flap assessment feasibility was demonstrated by computing all pixels and subsequent outputs summarisation as heatmaps.

Conclusion

This trial demonstrated the feasibility and potential for ICGFA with operator based and quantitative flap perfusion assessment across several reconstructive applications. Further development and implementation of these computational methods requires technique and device standardisation.

Tissue perfusion in DIEP flaps using Indocyanine Green Fluorescence Angiography, Hyperspectral imaging, and Thermal imaging

Flap necrosis continues to occur in skin free flap autologous breast reconstruction. Therefore, we investigated the benefits of indocyanine green angiography (ICGA) using quantitative parameters for the objective, perioperative evaluation of flap perfusion. In addition, we investigated the feasibility of hyperspectral (HSI) and thermal imaging (TI) for postoperative flap monitoring. A single-center, prospective observational study was performed on 15 patients who underwent deep inferior epigastric perforator (DIEP) flap breast reconstruction (n=21). DIEP-flap perfusion was evaluated using ICGA, HSI, and TI using a standardized imaging protocol. The ICGA perfusion curves and derived parameters, HSI extracted oxyhemoglobin (oxyHb) and deoxyhemoglobin (deoxyHb) values, and flap temperatures from TI were analyzed and correlated to the clinical outcomes. Post-hoc quantitative analysis of intraoperatively collected data of ICGA application accurately distinguished between adequately and insufficiently perfused DIEP flaps. ICG perfusion curves identified the lack of arterial inflow (n=2) and occlusion of the venous outflow (n=1). In addition, a postoperatively detected partial flap epidermolysis could have been predicted based on intraoperative quantitative ICGA data. During postoperative monitoring, HSI was used to identify impaired perfusion areas within the DIEP flap based on deoxyHb levels. The results of this study showed a limited added value of TI. Quantitative, post-hoc analysis of ICGA data produced objective and reproducible parameters that enabled the intraoperative detection of arterial and venous congested DIEP flaps. HSI appeared to be a promising technique for postoperative flap perfusion assessment. A diagnostic accuracy study is needed to investigate ICGA and HSI parameters in real-time and demonstrate their clinical benefit.

An Experimental and Clinical Study of Flap Monitoring with an Analysis of the Clinical Course of the Flap Using an Infrared Thermal Camera

Flap surgery is a common method used to cover defects following tumor ablation, trauma, or infection. However, insufficient vascularity in the transferred flap can lead to flap necrosis and failure. Proper postoperative monitoring is essential to prevent these complications. Recently, research has explored the use of infrared thermal imaging in plastic surgery, leading to its clinical application. This study comprises two separate parts: an in vivo experimental study and a clinical study. In this study, 28 rats underwent reverse McFarlane flap surgery, and their flaps were analyzed using a FLIR thermal imaging camera seven days post-surgery. Additionally, thermal images of flaps were taken on postoperative days 0, 1, 2, 3, and 7 in 22 patients. This study focused on temperature differences between normal skin and the perforator compared to the average flap temperature. Results showed that the temperature difference was higher in the necrosis group and increased over time in cases of total necrosis. A lower perforator temperature compared to the flap's average indicated vascular compromise, potentially leading to flap failure. The FLIR camera, being contact-free and convenient, shows promise for understanding and inferring the clinical progression of flaps in postoperative monitoring.

Development of an Automated Free Flap Monitoring System Based on Artificial Intelligence

Importance

Meticulous postoperative flap monitoring is essential for preventing flap failure and achieving optimal results in free flap operations, for which physical examination has remained the criterion standard. Despite the high reliability of physical examination, the requirement of excessive use of clinician time has been considered a main drawback.

Objective

To develop an automated free flap monitoring system using artificial intelligence (AI), minimizing human involvement while maintaining efficiency.

Design, Setting, and Participants

In this prognostic study, the designed system involves a smartphone camera installed in a location with optimal flap visibility to capture photographs at regular intervals. The automated program identifies the flap area, checks for notable abnormalities in its appearance, and notifies medical staff if abnormalities are detected. Implementation requires 2 AI-based models: a segmentation model for automatic flap recognition in photographs and a grading model for evaluating the perfusion status of the identified flap. To develop this system, flap photographs captured for monitoring were collected from patients who underwent free flap-based reconstruction from March 1, 2020, to August 31, 2023. After the 2 models were developed, they were integrated to construct the system, which was applied in a clinical setting in November 2023.

Exposure

Conducting the developed automated AI-based flap monitoring system.

Main Outcomes and Measures

Accuracy of the developed models and feasibility of clinical application of the system.

Results

Photographs were obtained from 305 patients (median age, 62 years [range, 8-86 years]; 178 [58.4%] were male). Based on 2068 photographs, the FS-net program (a customized model) was developed for flap segmentation, demonstrating a mean (SD) Dice similarity coefficient of 0.970 (0.001) with 5-fold cross-validation. For the flap grading system, 11 112 photographs from the 305 patients were used, encompassing 10 115 photographs with normal features and 997 with abnormal features. Tested on 5506 photographs, the DenseNet121 model demonstrated the highest performance with an area under the receiver operating characteristic curve of 0.960 (95% CI, 0.951-0.969). The sensitivity for detecting venous insufficiency was 97.5% and for arterial insufficiency was 92.8%. When applied to 10 patients, the system successfully conducted 143 automated monitoring sessions without significant issues.

Conclusions and Relevance

The findings of this study suggest that a novel automated system may enable efficient flap monitoring with minimal use of clinician time. It may be anticipated to serve as an effective surveillance tool for postoperative free flap monitoring. Further studies are required to verify its reliability.

An Institutional Analysis of Early Postoperative Free Tissue Transfer Takeback Procedures

BACKGROUND

 Postoperative free tissue transfer reexploration procedures are relatively infrequent but associated with increased overall failure rates. This study examines the differences between flaps requiring takeback versus no takeback, as well as trends in reexploration techniques that may increase the odds of successful salvage.

METHODS

 A retrospective review was conducted on all free tissue transfers performed at our institution from 2011 to 2022. Patients who underwent flap reexploration within 30 days of the original procedure were compared with a randomly selected control group who underwent free flap procedures without reexploration (1:2 cases to controls). Univariate and multivariate logistic regression analyses were performed.

RESULTS

 From 1,213 free tissue transfers performed in the study period, 187 patients were included in the analysis. Of the total flaps performed, 62 (0.05%) required takeback, and 125 were randomly selected as a control group. Free flap indication, flap type, reconstruction location, and number of venous anastomoses differed significantly between the two groups. Among the reexplored flaps, 8 (4.3% of the total) had a subsequent failure while 54 (87.10%) were salvaged, with significant differences in cause of initial flap failure, affected vessel type, and salvage technique.

CONCLUSION

 Free tissue transfers least prone to reexploration involved breast reconstruction in patients without predisposition to hypercoagulability or reconstruction history. When takeback operations were required, salvage was more likely in those without microvascular compromise or with an isolated venous injury who required a single exploratory operation.

Catastrophic complications following microvascular free tissue transfer: A 10-year review of NSQIP data

INTRODUCTION

There is an absence of literature regarding the risks of catastrophic medical outcomes (CMOs) such as stroke, cardiac arrest, and pulmonary embolism in microvascular free tissue transfer. This study aims to determine the CMO and mortality rates, as well as risk factors, associated with microvascular reconstruction of the head and neck, extremity, and breast.

METHODS

This study uses data from the American College of Surgeons National Surgical Quality Improvement Program. Cases of microvascular free tissue transfer from 2012 to 2021 were analyzed to assess the 30-day rates of CMOs, including death, as well as associated risk factors.

RESULTS

Of the 22,839 included patients, 785 (3.44%) experienced 1043 CMOs, including 99 (0.43%) deaths. Pulmonary complications of prolonged respiratory failure and pulmonary embolism were the most common. Independent risk factors included age, male sex, underweight status, longer operation times, American Society of Anesthesiologists (ASA) class of III or above, wound classification other than clean, and underlying conditions such as diabetes, hypertension, chronic obstructive pulmonary disorder, dyspnea, metastatic cancer, and ventilator dependence. CMOs were associated with an average 10-day delay in hospital discharge. Multivariate regression analysis revealed that head and neck reconstructions were associated with increased risk of CMO (OR 4.96; p < 0.0001).

CONCLUSION

This is the largest study to examine CMOs following microvascular free tissue transfer. Compared to previous literature spanning the period between 2006 and 2011, we observed a decreased rate of CMOs but a slight increase in 30-day mortality. Our data provide updated and comprehensive criteria for risk stratification and patient counseling. The modifiable risk factors reported in our study should be considered in elective, non-urgent cases of microvascular reconstruction.

No Skin Paddle, No Problem: Burying Deep Inferior Epigastric Artery Flaps in the Immediate Setting is Safe in Select Patient Populations

BACKGROUND

 In appropriately selected patients, it may be possible to fully bury breast free flaps deep to the mastectomy skin flaps. Because this practice forgoes the incorporation of a monitoring skin paddle for the flap, and thus limits the ability for physical exam, it may be associated with an increased risk of flap loss or other perfusion-related complications, such as fat necrosis. We hypothesized that fully de-epithelialized breast free flaps were not associated with an increased complication rate and reduced the need for future revision surgery.

METHODS

 A single-institution retrospective review of 206 deep inferior epigastric artery (DIEP) flaps in 142 patients was performed between June 2016 and September 2021. Flaps were grouped into buried or nonburied categories based on the absence or presence of a monitoring paddle. Patient-reported outcomes were assessed postoperatively using the BREAST-Q breast reconstruction module. Electronic medical record data included demographics, comorbidities, flap characteristics, complications, and revision surgery.

RESULTS

 The buried flap patients (N = 46) had a lower median body mass index (26.9 vs 30.3, p = 0.04) and a lower rate of hypertension (19.5 vs. 37.5%, p = 0.04) compared with nonburied flap patients (N = 160). Burying flaps was more likely to be adopted in skin-sparing mastectomy or nipple-sparing mastectomy (p = 0.001) and in an immediate or a delayed-immediate fashion (p = 0.009). There was one flap loss in the nonburied group; complication rates were similar. There was a significantly greater revision rate in the nonburied flap patients (92 vs. 70%; p = 0.002). Buried flap patients exhibited a greater satisfaction with breasts (84.5 ± 13.4 vs. 73.9 ± 21.4; p = 0.04) and sexual satisfaction (73.1 ± 22.4 vs. 53.7 ± 29.7; p = 0.01) compared with nonburied flap patients.

CONCLUSION

 Burying breast free flaps in appropriately selected patients does not appear to have a higher complication rate when compared with flaps with an externalized monitoring paddle. Furthermore, this modification may be associated with a better immediate aesthetic outcome and improved patient satisfaction, as evidenced by a lower rate of revision surgery and superior BREAST-Q scores among buried DIEP flaps.

Impact of Gabapentin on Postoperative Hypotension in Enhanced Recovery after Surgery Protocols for Microvascular Breast Reconstruction

Background

Enhanced recovery after surgery (ERAS) protocols have been associated with hypotensive episodes after autologous breast reconstruction. Gabapentin (Gaba), a nonopioid analgesic used in ERAS, has been shown to attenuate postoperative hemodynamic responses. This study assesses ERAS's impact, with and without Gaba, on postoperative hypotension after microvascular breast reconstruction.

Methods

Three cohorts were studied: traditional pathway, ERAS + Gaba, and ERAS no-Gaba. We evaluated length of stay, inpatient narcotic use [morphine milligram equivalents (MME)], mean systolic blood pressure, hypotension incidence, and complications. The traditional cohort was retrospectively reviewed, whereas the ERAS groups were enrolled prospectively after the initiation of the protocol in April 2019 (inclusive of Gaba until October 2022).

Results

In total, 441 patients were analyzed. The three cohorts, in the order mentioned above, were similar in age and bilateral reconstruction rates (57% versus 61% versus 60%). The ERAS cohorts, both with and without Gaba, had shorter stays (P < 0.01). Inpatient MME was significantly less in the ERAS + Gaba cohort than the traditional or ERAS no-Gaba cohorts (medians: 112 versus 178 versus 158 MME, P < 0.01). ERAS + Gaba significantly increased postoperative hypotensive events on postoperative day (POD) 1 and 2, with notable reduction after Gaba removal (P < 0.05). Across PODs 0-2, mean systolic blood pressure was highest in the traditional cohort, followed by ERAS no-Gaba, then the ERAS + Gaba cohort (P < 0.05). Complication rates were similar across all cohorts.

Conclusions

Postmicrovascular breast reconstruction, ERAS + Gaba reduced overall inpatient narcotic usage, but increased hypotension incidence. Gaba removal from the ERAS protocol reduced postoperative hypotension incidence while maintaining similar stay lengths and complication rates.

Buried Autologous Breast Reconstruction: Outcomes and Technical Considerations

The purpose of this study is to compare outcomes in patients undergoing buried and non-buried free flaps for breast reconstruction, in addition to evaluating the safety and reliability of venous flow couplers. A retrospective review was performed of all patients undergoing free flap breast reconstruction between 2013 and 2023. The primary outcomes were free flap failure, complications and the number of procedures required to complete the reconstructive journey. A total of 322 flaps were performed in 254 consecutive patients, with 47.5% (n = 153) being buried and 52.0% (n = 169) being non-buried reconstructions. The most common flap of choice being deep inferior epigastric artery perforator flaps (81.9%) followed by profunda artery perforator flaps (14.3%). There was no significant difference between the two groups in complications, including flap failure (buried 2.0% vs. non-buried 1.8% p = 0.902). There was a significant reduction in the number of procedures required to complete the reconstructive journey, with 52.2% (n = 59) of patients undergoing single-stage breast reconstruction in the buried group compared with only 25.5% (n = 36) in the non-buried group (p < 0.001). Two (0.6%) patients experienced a false negative in which the signal of the flow coupler was lost but the flap was perfused during re-exploration. No flap losses occurred without being identified in advance by a loss of audible venous flow signal. Buried free flap breast reconstruction is safe and requires fewer operations to complete patients' reconstructive journey. Flow couplers are a safe and effective method of monitoring buried free flaps in breast reconstruction.

Continuous Monitoring of Buried Free Bone Flap Microcirculation Using a Near-Infrared Spectroscopy System

SUMMARY

Postoperative evaluation of free flaps remains a challenging task. The current accepted standard for diagnosis of vascular compromise remains clinical observation. In recent years, near-infrared spectroscopy (NIRS) has been widely used as a noninvasive objective monitoring tool for postoperative evaluation of soft-tissue flaps. However, methods for monitoring bone flaps remain inadequate. In this study, NIRS was applied for the first time to monitor free buried bone flaps that were used for mandibular reconstruction. The penetrating property of NIRS was used to measure the tissue oxygenation index (TOI) of deep tissues, which reflected the microcirculatory status of the tissues. Changes in TOI values were monitored continuously in 59 cases of free bone flaps up to 72 hours after surgery. Five cases of vascular compromise were noted by clinical observation. Two fibula flaps were total failures, one of which showed a sharp decrease in TOI value to 45% in a short period of time; the other showed a continual gradual decrease to 55%. The observed sudden (<50%) and continuous (>10%) decreases in TOI values suggest that more attention should be paid to revision surgical procedures. The authors conclude that NIRS holds promise as an objective and valid method for clinical evaluation of buried bone flaps.

Predictors, management and prognosis of initial hyperemia of free flap

In free flap operation, temporary hyperemia of the transferred flaps can often be encountered in the early postoperative period, appearing reddish and rapid capillary refilling time, which mimics venous congestion. This study aimed to investigate the factors associated with the development of hyperemia and evaluate clinical course. Consecutive patients who underwent free flap-based reconstruction between December 2019 and October 2021 were reviewed. Independent risk factors associated with its development were assessed. Flap showing initial hyperemic features were assessed using flap blood glucose measurement (BGM). If it showed over 60 mg/dL, they were closely observed without management. Their clinical outcomes were evaluated. In total, 204 cases were analyzed, of which 35 (17.2%) showed initial hyperemia. Multivariable analyses showed that using thoracodorsal artery perforator flaps and muscle containing flaps (musculocutaneous/muscle-chimeric flaps) and conducting end-to-end arterial anastomosis (vs. end-to-side) were independent predictors. All cases with initial hyperemia showed over 60 mg/dL in BGM. The phenomenon resolved spontaneously within 6.9 h averagely. Overall perfusion-related complications developed in 10 (4.9%) cases, which rate did not differ between the two groups. Several factors might be associated with the development of initial hyperemia after free flap surgery. With proper assessment, this condition can be successfully managed without unnecessary intervention.

Reevaluating Thrombocytosis as a Risk Factor in Free Flap Surgery: Does Timing Matter?

INTRODUCTION

Thrombocytosis, defined as a platelet count >400,000, has been implicated as a risk factor in free flap failure. Despite proposed mechanisms of pedicle thrombosis, recent studies have suggested that thrombocytosis has no effect on free tissue transfer viability. Risk factors that may compromise successful free tissue transfer should be understood and elucidated, with particular attention to thrombocytosis and its conflicting evidence in the literature. We hypothesize that thrombocytosis has no bearing on free flap success or the rates of pedicle thrombosis.

METHODS

Our institution performed a retrospective chart review on all patients who underwent free flap reconstruction over the past 6 years. Patient demographics, medical history, type and location of free tissue transfer, preoperative platelets, postoperative platelets, and flap outcomes and complications (wound dehiscence, infection, hematoma, seroma, and need for blood transfusion) were recorded. Independent t test, Mann-Whitney U tests, χ2 test, and Fisher exact tests were used to determine P values to compare flap outcomes in patients with thrombocytosis (platelet count >400,000) and those with platelet counts less than 400,000.

RESULTS

In our 502-patient cohort, 71 were found to have a platelet count >400,000 (35 preoperatively and 36 postoperatively) and 431 patients had platelet counts <400,000. There were 42 reconstructive failures (flap success rate of 91.6%) and 111 returns to the operating room (OR). For patients with postoperative thrombocytosis, 24 flaps returned to the OR (44.4%), whereas in patients without thrombocytosis, 87 flaps returned to the OR (19.4%; P < 0.001). In patients with postoperative thrombocytosis, 10 OR returns were due to pedicle venous thrombosis (18.5%), in comparison to 10 returns for venous thrombosis in those with normal platelets (2.2%; P < 0.001). There was a small difference in free flap success rates between those with postoperative thrombocytosis and normal platelets, 88.7% versus 92.11%; however, this was not statistically significant ( P = 0.71). The thrombocytosis group had a higher incidence of overall postoperative complications ( P = 0.002).

CONCLUSIONS

Thrombocytosis has historically been cited as a risk factor for free flap reconstruction failure with recent conflicting evidence in the literature. In patients with postoperative thrombocytosis, we found an increased risk of venous thrombosis; however, this did not result in increased flap failure. There was an increase in postoperative complications, which corresponds with National Surgical Quality Improvement Program data reported in the literature. We suspect that thrombocytosis is not a harbinger of free flap failure but rather a marker for overall inflammation, which may confer a higher rate of venous thrombosis requiring reoperation and postoperative complications.

The volume-outcome relationship in free-flap reconstruction: A nationwide study based on the Clinical Database

BACKGROUND

The association between successful reconstructive surgery with a free flap and hospital volume has not been well established. This study was designed to retrospectively analyze the outcome of free-flap surgery registered in a nationwide surgical registration system in Japan to clarify the relationship between free-flap survival and facilities' average annual number of free-flap surgeries.

METHODS

We analyzed data from 19,482 free flaps performed during 2017-2020 at 407 facilities throughout Japan. After adjusting for sex, age, and disease classification that differ between the groups, we examined the differences in the flap survival rates among the different facilities in terms of the average number of free-flap surgeries performed annually.

RESULTS

The total overall necrosis rate was 2.8%. Of all procedures, 14.9%, 12.9%, 33.4%, and 38.8% were performed at facilities with an average number of free-flap procedures <10, 10-19, 20-49, and ≥ 50 per year, respectively, and the respective rates of total necrosis were 6.0%, 3.8%, 2.1%, and 1.7%, respectively. The odds ratios and 95% confidence intervals of flap necrosis for facilities with ≥ 50 cases per year relative to those <10 were 2.70 (1.98-3.68) for nonbreast reconstruction cases and 5.72 (2.77-11.8) for breast reconstruction cases.

CONCLUSION

This analysis of a nationwide plastic surgery database showed that free-flap surgeries in institutions with a low average annual number of free-flap surgeries had a higher risk of total necrosis. Measures should be taken to either aggregate cases into high-volume centers or improve management at low-volume centers.

Attached compared with unattached surface probes for monitoring flap perfusion in microvascular head and neck reconstruction: a feasibility study

Unattached surface probes are commonly used with the O2C analysis system (LEA Medizintechnik, Germany) to monitor microvascular free flap perfusion. This study compared attached and unattached surface probes for extraoral free flaps. The study included 34 patients who underwent extraoral microvascular head and neck reconstruction between 2020 and 2022. Flap perfusion was monitored postoperatively using the O2C analysis system at 0, 12, 24, 36, and 48 h, with an attached surface probe at 3 mm tissue depth and an unattached surface probe at 2 mm and 8 mm tissue depths. Clinical complications, technical errors, and perfusion measurement values were compared. No clinical complications (attachment suture infections) or technical errors (probe detachment) occurred. Flap blood flow values of the probes were partially different (3 mm vs. 2 and 8 mm: p < 0.001; p = 0.308) and moderately correlated (3 mm with 2 and 8 mm: r = 0.670, p < 0.001; r = 0.638, p < 0.001). Hemoglobin concentration and oxygen saturation values were generally different (3 mm vs. 2 and 8 mm: all p < 0.001) and variably correlated (3 mm with 2 and 8 mm: r = 0.756, r = 0.645; r = 0.633, r = 0.307; all p < 0.001). Both probes are comparable in terms of technical feasibility and patient safety, with flap perfusion values dependent on tissue measurement depth.

Flap perfusion monitoring with an attached surface probe in microvascular reconstruction of the oral cavity

OBJECTIVES

Postoperative flap monitoring is essential in oral microvascular reconstruction for timely detection of vascular compromise. This study investigated the use of attached surface probes for the oxygen-2-see (O2C) analysis system (LEA Medizintechnik, Germany) for intraoral flap perfusion monitoring.

MATERIALS AND METHODS

The study included 30 patients who underwent oral reconstruction with a microvascular radial-free forearm flap (RFFF) or anterolateral thigh flap (ALTF) between 2020 and 2022. Flap perfusion was measured with attached (3-mm measurement depth) and unattached surface probes (2- and 8-mm measurement depths) for the O2C analysis system at 0, 12, 24, 36, and 48 h postoperatively. Flap perfusion monitoring with attached surface probes was evaluated for cut-off values for flap blood flow, hemoglobin concentration, and hemoglobin oxygen saturation indicative of vascular compromise and for accuracy and concordance with unattached surface probes.

RESULTS

Three RFFFs were successfully revised, and one ALTF was unsuccessfully revised. The cut-off values indicative of vascular compromise for flap perfusion monitoring with attached surface probes were for RFFF and ALTF: blood flow < 60 arbitrary units (AU) and < 40AU, hemoglobin concentration > 100AU and > 80AU (both > 10% increase), and hemoglobin oxygen saturation < 40% and < 30%. Flap perfusion monitoring with attached surface probes yielded a 97.1% accuracy and a Cohen's kappa of 0.653 (p < 0.001).

CONCLUSIONS

Flap perfusion monitoring with attached surface probes for the O2C analysis system detected vascular compromise accurately and concordantly with unattached surface probes.

CLINICAL RELEVANCE

Attached surface probes for the O2C analysis system are a feasible option for intraoral flap perfusion monitoring.

Improving Quality and Value in Head and Neck Reconstruction

Multiple advances in surgical techniques, technology, and perioperative patient care have revolutionized head and neck reconstruction over the last 40 years. Concurrent with these advances, health systems, patients, and payers have become increasingly focused on value and quality, owing in part to rapidly increasing health care costs. However, there is no consensus on how to define value and quality in the realm of head and neck reconstruction. This review focuses on the past, present, and future of quality improvement efforts in head and neck reconstruction.

Negative Pressure Wound Therapy (NPWT) after Hybrid Reconstruction of Occipital Pressure Sore Using Local Flap and Skin Graft

Background and objectives: Pressure sores are a common medical burden among patients, particularly those who are bedridden or frail. Surgical management of occipital pressure sores poses unique challenges due to limited elasticity and the spherical shape of the scalp. This study aims to evaluate the efficacy and safety of a novel reconstruction method utilizing a local transpositional flap and split-thickness skin graft with negative pressure wound therapy (NPWT) for occipital pressure sore treatment. Material and methods: A retrospective analysis was performed on patients with occipital pressure sores who underwent hybrid reconstructions using a local flap and split-thickness skin graft in conjunction with NPWT. Surgical outcomes, including flap survival rate, graft take percentage, and complications, were assessed. A comparative analysis was performed between the NPWT group and the conventional dressing group. Results: The NPWT group (n = 24) demonstrated a significantly higher mean graft take percentage at postoperative day 14 compared with the conventional dressing group (n = 22) (98.2% vs. 81.2%, p < 0.05). No significant difference in flap survival rate was observed between the two groups. Conclusions: As the aging population continues to grow, occipital pressure sores have gained significant attention as a crucial medical condition. The innovative surgical method incorporating NPWT offers an efficient and safe treatment option for patients with occipital pressure sores, potentially establishing itself as the future gold standard for managing this condition.

Postoperative Day 1 Discharge in Deep Inferior Epigastric Artery Perforator Flap Breast Reconstruction

With high success rates of autologous breast reconstruction, the focus has shifted from flap survival to improved patient outcomes. Historically, a criticism of autologous breast reconstruction has been the length of hospital stay. Our institution has progressively shortened the length of stay after deep inferior epigastric artery perforator (DIEP) flap reconstruction and began discharging select patients on postoperative day 1 (POD1). The purpose of this study was to document our experience with POD1 discharges and to identify preoperative and intraoperative factors that may identify patients as candidates for earlier discharge.

Methods

An institutional review board-approved, retrospective chart review of patients undergoing DIEP flap breast reconstruction from January 2019 to March 2022 at Atrium Health was completed, consisting of 510 patients and 846 DIEP flaps. Patient demographics, medical history, operative course, and postoperative complications were collected.

Results

Twenty-three patients totaling 33 DIEP flaps were discharged on POD1. The POD1 group and the group of all other patients (POD2+) had no difference in age, ASA score, or comorbidities. BMI was significantly lower in the POD1 group (P = 0.039). Overall operative time was significantly lower in the POD1 group, and this remained true when differentiating into unilateral operations (P = 0.023) and bilateral operations (P = 0.01). No major complications occurred in those discharged on POD1.

Conclusions

POD1 discharge after DIEP flap breast reconstruction is safe for select patients. Lower BMI and shorter operative times may be predictive in identifying patients as candidates for earlier discharge.

Quantization of extraoral free flap monitoring for venous congestion with deep learning integrated iOS applications on smartphones: a diagnostic study

BACKGROUND

Free flap monitoring is essential for postmicrosurgical management and outcomes but traditionally relies on human observers; the process is subjective and qualitative and imposes a heavy burden on staffing. To scientifically monitor and quantify the condition of free flaps in a clinical scenario, we developed and validated a successful clinical transitional deep learning (DL) model integrated application.

MATERIAL AND METHODS

Patients from a single microsurgical intensive care unit between 1 April 2021 and 31 March 2022, were retrospectively analyzed for DL model development, validation, clinical transition, and quantification of free flap monitoring. An iOS application that predicted the probability of flap congestion based on computer vision was developed. The application calculated probability distribution that indicates the flap congestion risks. Accuracy, discrimination, and calibration tests were assessed for model performance evaluations.

RESULTS

From a total of 1761 photographs of 642 patients, 122 patients were included during the clinical application period. Development (photographs =328), external validation (photographs =512), and clinical application (photographs =921) cohorts were assigned to corresponding time periods. The performance measurements of the DL model indicate a 92.2% training and a 92.3% validation accuracy. The discrimination (area under the receiver operating characteristic curve) was 0.99 (95% CI: 0.98-1.0) during internal validation and 0.98 (95% CI: 0.97-0.99) under external validation. Among clinical application periods, the application demonstrates 95.3% accuracy, 95.2% sensitivity, and 95.3% specificity. The probabilities of flap congestion were significantly higher in the congested group than in the normal group (78.3 (17.1)% versus 13.2 (18.1)%; 0.8%; 95% CI, P <0.001).

CONCLUSION

The DL integrated smartphone application can accurately reflect and quantify flap condition; it is a convenient, accurate, and economical device that can improve patient safety and management and assist in monitoring flap physiology.

Selective Application of Blood Glucose Monitoring After Free Flap Surgery: Potential Indications in Real-World Practice

BACKGROUND

For free-flap monitoring, physical examination still serves as the criterion standard. Blood glucose measurement (BGM) has been suggested to be useful in identifying flap perfusion status. Nonetheless, its routine use may not be cost-effective in real-world settings. This study aimed to share the experiences of using BGM for flap monitoring and suggest its potential indications.

METHODS

Of cases of free flap reconstruction conducted between March 2017 and May 2021, those using BGM for flap monitoring were reviewed. Blood glucose measurement was selectively conducted for the following specific situations, which included encountering a flap showing a reddish discoloration and/or rapid capillary refilling time in the immediate postoperative period, monitoring discolored flaps after conducting a salvage operation, and conducting bloodletting therapy for salvaging congestive flaps. The clinical course and outcomes were evaluated.

RESULTS

Of a total of 203 cases, 35 used BGM for flap monitoring in addition to clinical examination. In 29 cases, BGM was performed to distinguish early hyperemia from true venous insufficiency. All flaps showed BGM greater than 60 mg/dL with a mean value of 115.42, suggesting early hyperemia, and had uneventful postoperative courses. In 3 cases with already discolored flaps after a salvage operation, BGM was conducted 4 times serially every 3 hours and showed a mean value of 81.6 mg/dL with increasing trends. The flaps recovered completely. In the other 3 cases requiring bloodletting therapy, BGM was conducted an average of 11 times at a median interval of 7 hours. The bloodletting therapy was terminated with reference to the value of BGM when it showed greater than 60 mg/dL while the therapy was on hold. All flaps were successfully salvaged except one showing partial necrosis.

CONCLUSIONS

Blood glucose measurement may be helpful in assessing flap perfusion and decision making in certain clinical situations and may be useful as an ancillary tool for flap monitoring. Selective application of BGM may contribute to achieving optimal outcomes.

Practice Trends and Evidence-Based Practice in Microvascular Reconstruction

Microvascular and free flap reconstruction are important to the otolaryngology-head and neck surgery practice. Herein, the reader will find an up-to-date discussion of various evidence-based practice trends related to microvascular surgery, including surgical techniques, anesthetic and airway considerations, free flap monitoring and troubleshooting, surgical efficiency, and both patient-related and surgeon-related risk factors that may affect outcomes.

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.

Surgical and demographic predictors of free flap salvage after takeback: A systematic review

BACKGROUND

Microsurgical free tissue transfer (FTT) is a widely employed surgical modality utilized for reconstruction of a broad range of defects, including head and neck, extremity, and breast. Flap survival is reported to be 90%-95%. When FTT fails, salvage procedures aim at establishing reperfusion while limiting ischemia time-with salvage rates between 22% and 67%. There are limited data-driven predictors of successful salvage present in the literature. This systematic review aims to identify predictors of flap salvage.

METHODS

A systematic literature review was conducted per PRISMA guidelines. Articles included in the final analysis were limited to those investigating FTT salvage procedures and included factors impacting outcomes. Cohort and case series (>5 flaps) studies up until March 2021 were included. Chi-square tests and linear regression modeling was completed for analysis.

RESULTS

The patient-specific factors significantly associated with salvage included the absence of hypercoagulability (p < .00001) and no previous salvage attempts (p < .00001). Case-specific factors significantly associated with salvage included trunk/breast flaps (p < .00001), fasciocutaneous/osteocutaneous flaps (p = .006), venous compromise (p < .00001), and shorter time from index procedure to salvage attempt (R = .746). Radiation in the head and neck population was significantly associated with flap salvage failure.

CONCLUSIONS

Given the complexity and challenges surrounding free flap salvage procedures, the goal of this manuscript was to present data helping guide surgical decision-making. Based on our findings, patients without documented hypercoagulability, no previous salvage attempts, fasciocutaneous/osteocutaneous flaps, trunk/breast flaps, and a shorter time interval post-index operation are the best candidates for a salvage attempt.

Simple and Easily Interpretable Flap Monitoring Method Using a Commercial Pulse Oximeter and a Widely Used Bedside Patient Monitor

Background  Various methods for monitoring after free flap surgery have been reported in the literature. Among them, pulse oximetry shows a sensitive reaction to vascular issues, and it is easy to interpret visually. However, previous reports used special equipment that was less commonly used and difficult to generalize. In this study, we used a commercial pulse oximeter and a widely used bedside patient monitor to monitor transplanted free tissue and lower extremities of healthy subjects with impaired circulation. Methods  A reflectance pulse oximeter sensor was attached on the flap after free tissue transplantation. The sensor was connected to a bedside patient monitor, and the flap oxygen saturation (SpO₂) levels and arterial waveforms were continuously monitored. Additionally, blood circulation disorder was induced in the lower limbs of healthy volunteers using pressure cuff inflation on the thigh, and the waveform and SpO₂ levels on the pulse oximeter attached to the lower leg were monitored. Results  Twenty-two patients were included in this study. No postoperative vascular issues were observed in any case. Pulse oximeters showed normal rhythmic wavelengths, and the flap SpO₂ level ranged approximately >90%. The pulse oximeter waveform rapidly disappeared during arterial occlusion in the thigh pressure cuff inflation test, and the waveform flattened and the SpO₂ level decreased slightly during venous congestion. Conclusion  Flap monitoring using a commercially available pulse oximeter and a bedside patient monitor is a versatile, easy-to-interpret, and useful method. Changes in waveform and SpO₂ levels appear during arterial and venous circulation disorders, and these changes can be differentiated.

Clinical application and outcomes of reconstructive microsurgery in Africa: A systematic review and meta-analysis

BACKGROUND

Reconstructive microsurgical free flap techniques are often the treatment of choice for a variety of complex tissue defects across multiple surgical specialties. However, the practice is underdeveloped in low- and middle-income countries. The aim of this systematic review was to evaluate the clinical application and outcomes of reconstructive microsurgery performed in Africa.

METHODS

Seven databases (PubMed, Web of Science, MEDLINE, CINAHL, Academic Search Complete, Embase, and Google Scholar) were searched for studies reporting microsurgical procedures performed in Africa. The risk of bias was assessed using the Joanna Briggs Institute Critical Appraisal Tools and quality of evidence using the GRADE approach. Meta-analysis was performed using a random effects model to estimate the pooled proportion of events with 95% confidence intervals. The primary outcome was free flap success rate, and the secondary outcomes were the complication and flap salvage rates.

RESULTS

Ninety-two studies were included in the narrative synthesis and nine in the pooled meta-analysis. In total, 1376 free flaps in 1327 patients from 1976 to 2020 were analyzed. Head and neck oncologic reconstruction made up 30% of cases, while breast reconstruction comprised 2%. The pooled flap survival rate was 89% (95% CI: 0.84, 0.93), complication rate 51% (95% CI: 0.36, 0.65), and free flap salvage rate was 45% (95% CI: 0.08, 0.84).

CONCLUSION

This meta-analysis showed that the free flap success rates in Africa are high and comparable to those reported in high-income countries. However, the comparatively higher complication rate and lower salvage rate suggest a need for improved perioperative care.

REVIEW REGISTRATION

Registered with the International Prospective Register of Systematic Reviews (PROSPERO) on 25th September 2020, ID: CRD42020192344.

Infrared Thermography in Wound Care, Surgery, and Sports Medicine: A Review

For many years, the role of thermometry was limited to systemic (core body temperature) measurements (e.g., pulmonary catheter) or its approximation using skin/mucosa (e.g., axillary, oral, or rectal) temperature measurements. With recent advances in material science and technology, thermal measurements went beyond core body temperature measurements and found their way in many medical specialties. The article consists of two primary parts. In the first part we overviewed current clinical thermal measurement technologies across two dimensions: (a) direct vs. indirect and (b) single-point vs. multiple-point temperature measurements. In the second part, we focus primarily on clinical applications in wound care, surgery, and sports medicine. The primary focus here is the thermographic imaging modality. However, other thermal modalities are included where relevant for these clinical applications. The literature review identified two primary use scenarios for thermographic imaging: inflammation-based and perfusion-based. These scenarios rely on local (topical) temperature measurements, which are different from systemic (core body temperature) measurements. Quantifying these types of diseases benefits from thermographic imaging of an area in contrast to single-point measurements. The wide adoption of the technology would be accelerated by larger studies supporting the clinical utility of thermography.

Head and Neck Free Flap Reconstruction in an Academic versus a Community Setting

BACKGROUND

 Head and neck free flap reconstructions are complex procedures requiring extensive resources, and have the potential to be highly morbid. As such, it is imperative that they should be performed in an appropriate setting, optimizing outcomes while limiting morbidity. The aim of this study is to identify any disparities in the treatment outcomes of patients undergoing head and neck free flap reconstruction by a single surgeon in an academic versus a community hospital setting.

METHODS

 A retrospective review of all patients who underwent head and neck free flap reconstruction for any indication by a single surgeon from 2009 to 2019 was conducted. All surgeries were performed at one of two hospitals: one academic medical center and one community hospital. Demographics and rates of partial or complete flap failure, medical complications, surgical complications, mortality, and other secondary outcomes were compared between the two settings.

RESULTS

 Ninety-two patients who underwent head and neck free flap reconstruction were included. Fifty-seven (62%) of free flap reconstructions were performed in the academic medical center, while 35 (38%) were performed in the community hospital. There were no significant differences in complete flap loss, either intraoperative or postoperative (p = 0.5060), partial flap loss (p = 0.5827), postoperative surgical complications (p = 0.2930), or medical complications (p = 0.7960) between groups. The in-hospital mortality rate was 0% (n = 0) at the university hospital as compared with 5.7% at the community hospital (p = 0.0681). The mean operative time was 702.3 minutes at the university hospital and 606.3 minutes at the community hospital (p = 0.0080).

CONCLUSION

 Head and neck free flap surgery can be performed safely in either an academic or a community setting, with no difference in primary outcomes of surgery. Preferential selection of either treatment setting should be based on consideration of patient needs and availability of auxiliary specialty services.

Macrophage Migration Inhibitory Factor-An Innovative Indicator for Free Flap Ischemia after Microsurgical Reconstruction

(1) Background: Nowadays, the use of microsurgical free flaps is a standard operative procedure in reconstructive surgery. Still, thrombosis of the microanastomosis is one of the most fatal postoperative complications. Clinical evaluation, different technical devices and laboratory markers are used to monitor critical flap perfusion. Macrophage migration inhibitory factor (MIF), a structurally unique cytokine with chemokine-like characteristics, could play a role in predicting vascular problems and the failure of flap perfusion. (2) Methods: In this prospective observational study, 26 subjects that underwent microsurgical reconstruction were observed. Besides clinical data, the number of blood leukocytes, CRP and MIF were monitored. (3) Results: Blood levels of MIF, C-reactive protein (CRP) and leukocytes increased directly after surgery. Subjects that needed surgical revision due to thrombosis of the microanastomosis showed significantly higher blood levels of MIF than subjects without revision. (4) Conclusion: We conclude that MIF is a potential and innovative indicator for thrombosis of the microanastomosis after free flap surgery. Since it is easy to obtain diagnostically, MIF could be an additional tool to monitor flap perfusion besides clinical and technical assessments.