Regional Oxygen Saturation Index: A Novel Criterion for Free Flap Assessment Using Tissue Oximetry

Diluted Indocyanine Green Angiography: A Novel Approach to Free Flap Perfusion Evaluation in Reconstructive Microsurgery

Background

Assessing perfusion in free flaps is crucial in clinical practice. Indocyanine green (ICG) angiography offers a more objective and reproducible method, utilizing near-infrared imaging to monitor flap vascularization. This study aims to evaluate the efficacy of diluted ICG as a tool for assessing free flap perfusion.

Methods

This pilot randomized clinical trial compares the fluorescence concentrations of ICG at 3 different dilutions: 5 mg/mL (standard concentration), 2.5 mg/mL (half the standard concentration), and 0.5 mg/mL (one-tenth of the standard concentration). Inclusion criteria required participants to have serum albumin levels above 3 g/dL, hemoglobin levels over 10 g/dL, and no comorbidities. Participants were randomized into 3 groups based on ICG concentration. Fluorescence analysis was performed using ImageJ software to determine mean gray values. Both surgeons and data analysts were blinded to the ICG concentrations administered, ensuring unbiased evaluation.

Results

Forty-five patients undergoing free flap surgery, predominantly male (60%) with a mean age of 37.76 ± 19.79 years and a mean body mass index of 21.23 ± 4.49 kg/m², primarily received osteoseptocutaneous fibular free flaps (46.67%), with an average skin flap area of 66.07 ± 46.94 cm². The primary etiology was underlying tumors (84.4%), with the head and neck as the most common reconstruction site (82.2%). The superior thyroid artery was the most frequently used recipient vessel (37.78%). Analysis revealed mean gray values of 64.10 ± 8.27 (5 mg/mL), 79.03 ± 2.7 (2.5 mg/mL), and 33.56 ± 3.47 (0.5 mg/mL), with 2.5 mg/mL yielding the highest value (P < 0.001).

Conclusions

Findings suggest using 2.5 mg/mL concentration enhances fluorescence emission, offering a dosage alternative in clinical practice.

NIRO200NX: Reliable Monitoring System for Buried Deep Inferior Epigastric Perforator Flap

Background

The deep inferior epigastric perforator (DIEP) flap is a useful tool for breast reconstruction and tends to be transferred into the breast envelope as the buried flap from an aesthetic point of view. However, it is difficult to monitor the blood flow in the buried DIEP flap after reconstructive microsurgery. Near-infrared spectroscopy devices have recently been used for monitoring the blood flow of various organs. NIRO200NX (Hamamatsu Photonics) continuously measures the tissue oxygen index (TOI) and quickly reflects changes in flap blood flow. In this study, we investigated whether and how much the NIRO200NX applies to monitoring the blood flow of the buried flap.

Methods

We included 156 patients who underwent breast reconstruction using a DIEP flap from October 2013 to May 2022, comprising 57 exposed and 99 buried-type DIEP flap cases. We measured TOI using NIRO200NX, in combination with conventional evaluation methods, including color check, pinprick test, and Doppler sound.

Results

A criterion of TOI 50 gave the best evaluations. All the 57 exposed-type flap cases showed no false evaluations, and NIRO200NX performed precise judgment. In 99 buried-type flap cases, NIRO200NX correctly evaluated 96 cases. For those buried-type cases, we found only two false-positive and one false-negative case. The misjudgments by NIRO200NX were likely caused by hematoma.

Conclusion

We propose NIRO200NX as a reliable device for monitoring the blood flow of the DIEP flap and predicting the outcomes of breast reconstruction by the DIEP flap transfer.

Near-Infrared Spectroscopy for Continuous Noninvasive Monitoring of Free Flap in Head and Neck Reconstruction: Systematic Review of the Literature and Personal Experience

BACKGROUND

Buried free flaps represent a reconstructive challenge concerning monitoring of vitality, which is fundamental for an early detection of flap failure and prompt surgical salvage. Many flap monitoring techniques have been developed over time, and there is still no consensus concerning the best monitoring technique for buried reconstructions.

METHODS

We performed a systematic review of the literature on NIRS monitoring for head and neck free flaps. Moreover, we presented a case of orbital reconstruction through a buried free myo-fascial anterolateral tight flap (ALTF) in which postoperative monitoring was performed by means of NIRS.

RESULTS

Four studies were included with a total of 200 monitored head and neck free flap reconstructions. Flap survival was reported in 96.5% of studies (n = 193/200) with a 3.5% of total flap failure rate (n = 7/200). We monitored the buried myo-fascial ALTF for 7 post-operative days measuring a regional oxygen saturation (rSO2) ranging from 55% to 72% (mean = 66%).

CONCLUSIONS

This device appeared to be an efficient choice for monitoring buried flaps, thanks to its ability to measure tissue perfusion deep under the skin, to the continuous availability of recorded data on the monitor, and to its low impact on the patient. Further prospective studies are advised in order to standardize this monitoring technique and define warning values.

An Updated Systematic Review and Meta-Analysis of Tissue Oximetry Versus Conventional Methods for Postoperative Monitoring of Autologous Breast Reconstruction

BACKGROUND

Tissue oximetry monitoring has shown superior outcomes to conventional monitoring methods for autologous breast reconstruction in retrospective studies with consecutive cohorts. A recent study used consecutive cohorts with tissue oximetry as the earlier cohort and found that tissue oximetry was nonsuperior. We hypothesize that improvement in microsurgical outcomes with institutional experience confounds the superiority of tissue oximetry demonstrated in prior studies. This study aimed to perform a systematic review and meta-analysis of the outcomes of tissue oximetry monitoring compared with conventional monitoring.

METHODS

Relevant studies were found using PubMed, Embase, and Web of Science searches for keywords such as near-infrared spectroscopy or tissue oximetry and microsurgery. Studies included compared tissue oximetry and conventional monitoring in autologous breast reconstruction patients. Studies were excluded if they did not contain a comparison group. Random-effective models were used to analyze early returns to the operating room, the total number of partial or complete flap loss, and late fat necrosis.

RESULTS

Six hundred sixty-nine studies were identified; 3 retrospective cohort studies met the inclusion criteria. A total of 1644 flaps were in the tissue oximetry cohort, and 1387 flaps were in the control cohort. One study contained tissue oximetry as the former cohort; 2 had tissue oximetry as the latter. Neither technique was superior for any measured outcomes. The estimated mean differences between tissue oximetry and conventional monitoring method were early returns, -0.06 (95% confidence interval [CI], -0.52 to 0.410; P = 0.82); partial flap loss, -0.04 (95% CI, -0.86 to 0.79; P = 0.93); complete flap loss, -1.29 (95% CI, -3.45 to 0.87; P = 0.24); and late fat necrosis -0.02 (95% CI, -0.42 to, 0.39; P = 0.94).

CONCLUSIONS

In a systematic review and meta-analysis of mixed timeline retrospective cohort studies, tissue oximetry does not provide superior patient outcomes and shifts our current understanding of postoperative breast reconstruction monitoring. Prospective studies and randomized trials comparing monitoring methods need to be included in the existing literature.

Lymphatic Function Decreases over Time in the Arms of Breast Cancer Patients following Treatment

In patients with breast cancer-related lymphedema, distinct lymphatic patterns and changed lymphatic contractile function have been described, but it is unknown how these characteristics change over time and to what extent they appear before clinical edema is detectable. Recently, we described the lymphatic morphology and function in a cohort of breast cancer patients shortly after radiation therapy (RT). In the current study, we investigate lymphatic function and morphology in the same cohort after 1 year of follow-up.

Methods

The study population consisted of 28 breast cancer patients investigated 12 months after adjuvant locoregional RT. Lymphatic contraction frequency (CF), propulsion velocity, and the morphology of lymphatic vessels in the upper extremities were described in vivo using near-infrared fluorescence imaging. Lymphatic stress test was performed using hyperthermia.

Results

At 1 year after RT, (n = 28) 46% of the patients presented with lymphatic morphological abnormalities with a degree of dermal backflow and 21% had developed clinical breast cancer-related lymphedema. In the ipsilateral arm, CF was 23% lower than in the contralateral arm (P = 0.04). Since primary examination, CF in the ipsilateral arm decreased by 40% (P = 0.03), whereas no change was observed in the contralateral arm. During hyperthermia, the ipsilateral arms with lymphatic complications were not able to increase CF as the remaining subgroups.

Conclusions

Lymphatic function in the ipsilateral arm deteriorated over time after adjuvant breast cancer therapy. Furthermore, the presence of abnormal torturous lymphatic vessels in asymptomatic arms appeared to be associated with weak lymphatic reserve pumping capacity.

Clinical and Histological Effects of Partial Blood Flow Impairment in Vascularized Lymph Node Transfer

Regarding vascularized lymph node transfer (VLNT) for lymphedema, partial blood flow impairment in transferred lymph node (LN) flaps may adversely affect the therapeutic results. We investigated the clinical and histological effects of partial blood flow impairment in LN flaps. In upper extremity lymphedema cases, based on ultrasonographic examination at 2 weeks after VLNT, we compared the treatment results depending on whether the postoperative blood flow in transferred LNs was good (Group G) or poor (Group P). Novel partial ischemia and congestion of LN flap mouse models were developed to determine their histological features. In 42 cases, significant differences were observed between Group G (n = 37) and Group P (n = 5) based on the amount of volume reduction (136.7 ± 91.7 mL and 55.4 ± 60.4 mL, respectively; p = 0.04) and lymph flow recanalization rate in indocyanine green fluorescent lymphography (67.6% and 0%, respectively; p = 0.0007). In mouse models, thrombi formation in the marginal sinus and numerous Myl9/12-positive immunocompetent cells in follicles were observed in congested LNs. Blood flow maintenance in the transferred LNs is an essential factor influencing the therapeutic effect of VLNT. Postoperatively, surgeons should closely monitor blood flow in the transferred LNs, particularly in cases of congestion.

Intraoperative Blood Flow Analysis of DIEP vs. ms-TRAM Flap Breast Reconstruction Combining Transit-Time Flowmetry and Microvascular Indocyanine Green Angiography

Background: Vascular patency is the key element for high flap survival rates. The purpose of this study was to assess and compare the blood flow characteristics of deep inferior epigastric perforator (DIEP) and muscle-sparing transverse rectus abdominis musculocutaneous (ms-TRAM) flaps for autologous breast reconstruction. Methods: This prospective clinical study combined Transit-Time Flowmetry and microvascular Indocyanine Green Angiography for the measurement of blood flow volume, vascular resistance, and intrinsic transit time. Results: Twenty female patients (mean age, 52 years) received 24 free flaps (14 DIEP and 10 ms-TRAM flaps). The mean arterial blood flow of the flap in situ was 7.2 ± 1.9 mL/min in DIEP flaps and 11.5 ± 4.8 mL/min in ms-TRAM flaps (p < 0.05). After anastomosis, the mean arterial blood flow was 9.7 ± 5.6 mL/min in DIEP flaps and 13.5 ± 4.2 mL/min in ms-TRAM flaps (p = 0.07). The arterial vascular resistance of DIEP flaps was significantly higher than that of ms-TRAM flaps. The intrinsic transit time of DIEP flaps was 52 ± 18 s, and that of ms-TRAM flaps was 33 ± 11 s (p < 0.05). The flap survival rate was 100%. One DIEP flap with the highest intrinsic transit time (77 s) required surgical revision due to arterial thrombosis. Conclusion: In this study, we established the blood flow characteristics of free DIEP and ms-TRAM flaps showing different blood flow rates, vascular resistances, and intrinsic transit times. These standard values will help to determine the predictive values for vascular compromise, hence improving the safety of autologous breast reconstruction procedures.

Intraflap Vascular Catheterization Method for Monitoring, Prevention, and Intervention of Thrombogenesis in Free-Flap Surgery

BACKGROUND

Thrombosis at the anastomotic site is a significant problem in free tissue transfer with microvascular anastomosis. We report a newly developed intraflap vascular catheterization (IFVC) technique for monitoring hemodynamics, prevention of thrombogenesis, and transcatheter intervention of free-flap thrombosis.

METHODS

We performed a hospital-based, prospective study. Ninety-three patients underwent free tissue transfer by a single surgeon in a single hospital. In the IFVC group (n = 40), catheters were inserted into the arterial and venous branches of the flap main pedicle vessels near the anastomoses. The catheters were connected to the pressure monitor. A bolus injection of urokinase was administered every hour to the artery, and a continuous infusion of saline was initiated to the vein. The bolus injection of urokinase solution reached the arterial anastomosis by the retrograde flow. During the postoperative period, rapid injection of urokinase or saline was performed according to the pressure monitor. Intraflap vascular catheterization monitoring was performed postoperatively for 72 hours.

RESULTS

The overall flap survival rate in the IFVC group was 100% (40 of 40), whereas the overall flap survival rate in the non-IFVC group was 96% (51 of 53). In a subgroup analysis of lower extremity reconstruction, the flap survival rate was 100% (22 of 22) with no cases of reanastomosis requiring a return to the operation room in the IFVC group. By contrast, the flap survival rate was 92% (22 of 24), with 6 cases of reanastomosis requiring a return to the operation room in the non-IFVC group (P = 0.04).

CONCLUSIONS

The IFVC method enables monitoring, prevention, and intervention of thrombi at anastomotic sites of the free flap. Intraflap vascular catheterization may increase free tissue transfer success rate, especially in high-risk cases, such as free-flap reconstruction after the lower extremity trauma or venous leg ulcer.

Flap Monitoring Using Transcutaneous Oxygen or Carbon Dioxide Measurements

Free tissue transfer is a cornerstone of complex reconstruction. In many cases, it represents the last option available for a patient and their reconstruction. At high-volume centers, the risk of free flap failure is low but its occurrence can be devastating. Currently, the mainstay for flap monitoring is the clinical examination. Though reliable when performed by experienced clinicians, the flap exam is largely subjective, is performed discontinuously, and often results in significant time delay between detection of flap compromise and intervention. Among emerging flap monitoring technologies, the most promising appear to be those that rely on noninvasive transcutaneous oxygen and carbon dioxide measurements, which provide information regarding flap perfusion. In this article, we review and summarize the literature on various techniques but primarily emphasizing those technologies that rely on transcutaneous gas measurements. We also define characteristics for the ideal flap monitoring tool and discuss critical barriers, predominantly cost, preventing more widespread utilization of adjunct monitoring technologies, and their implications.

Imaging for thinned perforator flap harvest: current status and future perspectives

With advances in anatomical knowledge and technology, increased interest has been directed towards reconstruction with enhanced aesthetic and functional outcomes. A myriad of thinned perforator flap harvest approaches have been developed for this purpose; however, concerns about jeopardizing their vascularity remain. To ensure optimum reconstructive outcome without hampering the flap's microcirculation, it is important to make good use of the existing advanced imaging modalities that can provide clear visualization of perforator branches, particularly in the adipose layer, and an accurate assessment of flap perfusion. Therefore, this review will highlight the imaging modalities that have been utilized for harvesting a thinned perforator flap from these two perspectives, along with future insights into creating both functionally and aesthetically satisfying, yet simultaneously safe, thinned perforator flaps for the best reconstructive outcomes for patients.

The usefulness of a free thinned deep inferior epigastric artery perforator flap and measurement of the vascular pedicle length: A thin flap with a long pedicle

BACKGROUND

The thinned deep inferior epigastric perforator (DIEP) flap branching from the main trunk to the superolateral direction may be useful because of its long vascular pedicle. DIEP flap is used as an axial-pattern adipose flap. The vascular pedicle length of the thinned DIEP flap was investigated using originally developed software. The clinical application of the thinned DIEP flap was verified in a case series.

METHODS

In 40 patients with enhanced computed tomography (CT) data, the vascular pedicle length of the longest thinned DIEP flap was simulated using the software. A free thinned DIEP flap was used in 10 clinical cases of facial or breast reconstruction.

RESULTS

In all simulated cases, the vascular pedicle of the DIEP branching to the superolateral direction was the longest, and the vascular pedicle could be lengthened up to 34.8% by dissecting the vessels on the fascia as a vascular pedicle. In all the clinical cases, the reconstruction of a complex form defect or reconstruction requiring a long vascular pedicle could be achieved in one stage without any perioperative complications. The intraclass correlation coefficient between simulated pedicle length and dissected pedicle length was 0.99.

CONCLUSION

Thinned DIEP flaps with long vascular pedicles could be elevated safely. Multiple adipose or muscle flaps could be combined without complications. The length of the winding vascular pedicle could be measured using imaging data using the software first developed in the present study. This software would be useful in the planning of a thinned DIEP flap and other free flaps.

Potential role of artificial intelligence in craniofacial surgery

The field of artificial intelligence (AI) is rapidly advancing, and AI models are increasingly applied in the medical field, especially in medical imaging, pathology, natural language processing, and biosignal analysis. On the basis of these advances, telemedicine, which allows people to receive medical services outside of hospitals or clinics, is also developing in many countries. The mechanisms of deep learning used in medical AI include convolutional neural networks, residual neural networks, and generative adversarial networks. Herein, we investigate the possibility of using these AI methods in the field of craniofacial surgery, with potential applications including craniofacial trauma, congenital anomalies, and cosmetic surgery.

Early detection onset of flap failure using near infrared spectroscopy

BACKGROUND

Near-infrared spectroscopy (NIRS) is widely used to assess flap perfusions by measuring tissue oxygen saturation (StO₂). However, the StO₂ level for the onset of perfusion failure is still a controversial issue.

AIM

This study proposes a new threshold of StO₂ level for detecting the onset of perfusion failure as early as possible to increase flap salvage rates.

METHODS

Twenty patients undergoing flap surgery were included in this study - 13 flaps were implemented to cover defects that occurred due to trauma and 7 flaps to hide imperfections that occurred after cancer treatment. Thirteen flaps were in the lower extremity, six in the mandible, and one in the breast. NIRS was used to measure StO₂ in 240 flap regions of the 20 patients to determine flap viability using descriptive statistics.

RESULTS

The mean StO₂ values from healthy flap and control regions were obtained as 81.6% ± 0.36 and 82% ± 0.18, respectively. The lowest StO₂ value of 77.2% was defined as the onset of a vascular complication at a probability of 99.74% by subtracting three times the standard deviation from the mean StO₂ of healthy flaps. Vascular complications were observed from 21 regions in the four flaps with StO₂ values lower than 77.2%, but only one was lost.

CONCLUSION

The threshold value for the onset of perfusion failure was a 5% decrease from the expected value, much lower than previously described thresholds that may facilitate the detection of perfusion failure in the early stage and increase salvage rates in flap revisions.

[Prosthetics after construction of the outer genitalia for transmen]

BACKGROUND

Growing awareness of gender identity issues and a rising prevalence of female-to-male transsexualism is increasing demand for surgical solutions that deliver both aesthetically and functionally satisfying outer genitalia for transmen.

OBJECTIVE

This article summarizes the available prosthetic options, describes different surgical approaches and reviews the outcome of prosthetics for transmen with a focus on penile prosthesis in phalloplasty.

METHODS

Current international standards of care, reviews and original publications are critically reviewed and correlated with our own experience with more than 400 transmen at two interdisciplinary referral centres in Frankfurt, Germany and London, UK.

RESULTS

Despite of a wide range of different phalloplasty techniques and prosthetic types, the currently most used technique is implantation of a three-piece, inflatable penile prosthesis in a radial-free-flap phalloplasty. There is still an ongoing debate about the number of implanted penile prosthesis cylinders, the use of customised corporoplasty-windsocks for the cylinder(s), and the location for the placement of the reservoir. At present there is only one penile prosthesis design for use in phalloplasties and long-term results are still pending.

CONCLUSION

There is still no ideal implant available for the use in phalloplasties. The current literature does not provide evidence-based treatment algorithms, which is also due to a lack of prospective randomised studies and validated measurement tools for the postoperative outcome. Initial data for the first transmen-specific penile prosthesis as well as an increase of transgender studies might lead to an improvement of treatment and the quality-of-life of the affected transmen.

[Gender reassignment from female to male : Phalloplasty]

BACKGROUND

The increasing prevalence of gender dysphoria necessitates an evaluation of the literature of phalloplasty techniques for female to male transgender individuals.

OBJECTIVE

The following article provides an overview of the current surgical concepts and complications of phalloplasty, associated urethrogenitoplasty and the implantation of prostheses in phalloplasty.

MATERIAL AND METHODS

Current international reviews and original publications from 2010 to 2020 were reviewed and correlated with our referral center experience with more than 350 female to male transgender patients over the last 25 years.

RESULTS

Free radial forearm flap phalloplasty is the most widely used technique, followed by an anterolateral thigh flap (ALT flap) and pedicled or microsurgical transplantation. Hydraulic multicomponent prostheses are given preference and supplementary surgical techniques, such as scrotoplasty and glans sculpturing can make sense or be necessary. The complication rates after phalloplasty and after insertion of penile prostheses are substantial. Nevertheless, the overall patient reported satisfaction rate in the majority of studies is often over 80%.

CONCLUSION

Due to the increasing prevalence of gender dysphoria there is currently a need for interdisciplinary referral centers for gender reassignment surgery. A certain standardization of surgical techniques and timing would be desirable but a review of the current literature shows a high heterogeneity so that this cannot be derived from the currently available literature. It is hoped that the recently founded S2K guideline committee on operative treatment of gender dysphoria under the auspices of the German Society for Urology and the Society for Plastic and Reconstructive Surgery can report an initial collection of experiences in 2021.

A comparative analysis using flowmeter, laser-Doppler |spectrophotometry, and indocyanine green-videoangiography for detection of vascular stenosis in free flaps

The effects of gradual vascular occlusion on the blood supply of perfused areas are poorly described. Information relating to the comparison of flap monitoring techniques is lacking. Varying stenotic conditions (0%, 25%, 50%, 75% and 100%) were generated on purpose at the A. and V. femoralis in the rat model. Analyses included flowmeter, simultaneous laser-Doppler flowmetry and tissue spectrophotometry (O2C) and indocyanine green- (ICG-) videoangiography with integrated FLOW 800 tool. A Random Forests prediction model was used to analyse the importance of each method to diagnose the stenotic conditions. The ability to discriminate and to accurately estimate the probability of stenosis was assessed by Receiver Operating Characteristic (ROC) curves and calibration plots. Blood flow changes for all modalities were described in detail. Flowmeter displayed earliest a linear decrease as a result of increasing stenosis. A stenosis of 50% degrees was most difficult to detect correctly. The combination of flowmeter and ICG-videoangiography showed high diagnostic power for each stenotic situation (area under the ROC > 0.79). Flowmeter and ICG-videoangiography showed to be most relevant in detection of varying stenotic conditions and may change the clinical outcome. The O2C showed less effect on varying stenotic situations as the only surface monitoring device.

Optimizing Indocyanine Green Fluorescence Angiography in Reconstructive Flap Surgery: A Systematic Review and Ex Vivo Experiments

Background. Indocyanine green angiography (ICGA) offers the potential to provide objective data for evaluating tissue perfusion of flaps and reduce the incidence of postoperative necrosis. Consensus on ICGA protocols and information on factors that have an influence on fluorescence intensity is lacking. The aim of this article is to provide a comprehensive insight of in vivo and ex vivo evaluation of factors influencing the fluorescence intensity when using ICGA during reconstructive flap surgery. Methods. A systematic literature search was conducted to provide a comprehensive overview of currently used ICGA protocols in reconstructive flap surgery. Additionally, ex vivo experiments were performed to further investigate the practical influence of potentially relevant factors. Results. Factors that are considered important in ICGA protocols, as well as factors that might influence fluorescence intensity are scarcely reported. The ex vivo experiments demonstrated that fluorescence intensity was significantly related to dose, working distance, angle, penetration depth, and ambient light. Conclusions. This study identified factors that significantly influence the fluorescence intensity of ICGA. Applying a weight-adjusted ICG dose seems preferable over a fixed dose, recommended working distances are advocated, and the imaging head during ICGA should be positioned in an angle of 60° to 90° without significantly influencing the fluorescence intensity. All of these factors should be considered and reported when using ICGA for tissue perfusion assessment during reconstructive flap surgery.

Effectiveness of small monitoring skin paddle in free muscle flap for scalp reconstruction

BACKGROUND

Monitoring free muscle flaps with skin grafts is difficult. To intensify the monitoring process for this type of flap, a small skin paddle was included in the flap and analyzed its effects.

METHODS

A retrospective analysis of all patients who underwent scalp reconstruction with a free latissimus dorsi flap and skin graft between 1994 and 2016 was conducted. Flap monitoring was proceeded using a combination of clinical examination and handheld Doppler for both types of flaps.

RESULTS

A total of 71 patients were included in this study and were divided into a study group (skin paddle included; n = 30) and a control group (conventional method; n = 41). The time between initial surgery to pedicle exploration was significantly shorter in the study group (11.3 ± 2.5 vs 79.8 ± 42.6 hours; P = .024). The flap salvage rate was significantly higher in the study group (100% vs 16.7%; P = .048).

CONCLUSION

The efficacy of flap monitoring and flap salvage outcomes were improved by including a small monitoring skin flap.

Glucose level evaluation in monopedicled rectus abdominis myocutaneous flap after venous occlusion: experimental study in rats

OBJECTIVE

to validate an experimental model for the measurement of glycemic levels in surgical flaps with the use of common glucometers, and to analyze the diagnostic criteria for hypoperfusion of such flaps.

METHODS

we performed vertical myocutaneous rectus abdominis flaps with upper pedicles bilaterally in 20 male Wistar rats, divided into two groups: with and without venous occlusion of the pedicle. We measured glucose levels in the flaps and in the systemic circulation with standard glucometers. We tested the accuracy of alternative diagnostic criteria for the detection of hypoperfusion.

RESULTS

from 15 minutes of venous occlusion on, there was a significant reduction in glucose levels measured in the congested flap (p<0.001). Using a minimum difference of 20mg/dl in the glycemic levels between the flap and systemic blood, 30 minutes after occlusion, as a diagnostic criterion, the sensitivity was 100% (95% CI 83.99-100%) and specificity of 90% (95% CI 69.90-97.21%) for the diagnosis of flap congestion.

CONCLUSION

It is possible to measure glucose levels in vertical myocutaneous rectus abdominis flaps of Wistar rats, perfused or congested, using a common glucometer. The diagnostic criteria that compare the glucose levels in the flaps with the systemic ones were more accurate in the evaluation of tissue perfusion.

[Progress of monitoring methods and preventions of disorder of blood supplying of expanded flaps]

Objective

To summarize the monitoring methods and preventions of the disorder of blood supplying of expanded flaps, so as to provide some references for improving the survival of expanded flaps.

Methods

The domestic and abroad related literature about the disorder of blood supplying of expanded flaps was reviewed and analyzed.

Results

Handheld Doppler, digital subtraction angiography, computer tomographic angiography, magnetic resonance angiography, and fluorescein angiography can be used as reliable preoperative imaging methods in designing expanded flaps with rich blood supply. Several techniques can be used for monitoring the blood supply of expanded flaps during the early postoperative period including traditional monitoring via physical examination, monitoring via dynamic infrared thermography, near-infrared spectroscopy tissue oximeter, external and implantable Doppler, and more recently developed diffuse correlation spectroscopy. Surgical delay, bloodletting, leech therapy, hyperbaric oxygen, and so on can decrease the risk of necrosis in expanded flaps.

Conclusion

The survival of expanded flap is influenced by many factors. Preoperative design by using handheld Doppler and new imaging technology and postoperative early detection of blood supply can provide references of timely intervention, so that ischemic necrosis of the flaps can be reduced, and the success rate of surgery can be improved.

A systematic review of near-infrared spectroscopy in flap monitoring: Current basic and clinical evidence and prospects

BACKGROUND

Near-infrared spectroscopy (NIRS) has been reported to be a reliable non-invasive modality for free flap monitoring; however, the history of its application in flap monitoring is short, and there is no definite consensus regarding its use at present.

OBJECTIVES

The aim of this review is to clarify the evidence related to post-operative flap monitoring using NIRS and examine its appropriateness and usability.

MATERIALS AND METHODS

The PubMed and Web of Science databases were searched using the strings "flap monitoring AND near-infrared spectroscopy" and "flap monitoring AND tissue oxygen saturation," with a study period from inception to December 31, 2016. Two authors independently extracted articles and assessed the quality of the studies. Articles related to NIRS for flap perfusion monitoring were classified and selected regardless of study type.

RESULTS

A total of 15 clinical studies and 8 animal studies were identified and reviewed. The evidence and information on various aspects of NIRS flap monitoring were summarized. The overall flap success rate was 99.5%, and the flap salvage rate was 91.1%, when measuring StO₂ at intervals of every 2 h or sooner. Single StO₂ monitoring was able to detect vascular compromise with 99.1% sensitivity and 99.9% specificity, and earlier than other monitoring methods, but additional Hb concentration monitoring was useful for avoiding false negatives and differentiating arterial and venous occlusion.

CONCLUSIONS

NIRS can be used for flap monitoring and displays high accuracy in various situations; however, further studies are needed to take full advantage of the potential of NIRS.