Adjunctive technologies in postoperative free-flap monitoring: a systematic review

Ischemic preconditioning in arterialized venous flap: Temperature effects and monitoring

INTRODUCTION

Arterialized venous flap, like any other flap, will undergo an ischemic reperfusion injury during its transfer process. To overcome this, ischemic preconditioning can be done to provide protection and enhanced flap survival. One of the reliable parameters of flap survival is its temperature. However, there was no recorded data regarding AVF's temperature or its monitoring. This research aimed to demonstrate the temperature effect of ischemic preconditioning on arterialized venous flap.

METHOD

Male Wistar Rats were randomly divided into 4 groups, consisting of 6 negative control groups, 8 positive control group (PS) rats that underwent an anastomosis of the superficial epigastric artery to the superficial epigastric vein, 8 experimental rat group 1 (EX1) that underwent 3 cycles of 5 minutes pre-anastomosis clamping with 3 cycles of 5 minutes each, and 8 experimental rats' group 2 (EX2) with 3 cycles of 10 minutes. Flap's temperature was observed preoperatively and postoperatively from day 1 to day 7, day 14, and day 21 with an android-based thermal camera and recorded in Celsius degrees.

RESULTS

All the flaps (N= 26) were vital. The temperature drop was seen in all anastomosed flaps compared to the negative control (30.37 vs. 25.08 vs. 23.77 vs. 25.27, p<0.05). A significant increase in temperature occurred on days 4 to 6 in Ex1 (33.62±1.820, 33.62±1.820, 32.40±1.627; p<0.05). As in the temperature trend, Ex2 is shown to have a stable temperature from day 2 until 21.

CONCLUSION

This study has recorded an increase in temperature in the early days of the creation of the arterialized venous flap at various timings of ischemic preconditioning. The flap's monitoring was easily observed with a thermal camera that can be implemented in humans.

Laser Speckle Flowgraphy Can Support Intraoperative Assessment of Deep Inferior Epigastric Perforator Flap Blood Flow With Indocyanine Green

Background

Accurately evaluating cutaneous blood flow during the elevation of a deep inferior epigastric perforator (DIEP) flap may reduce postoperative complications in breast reconstruction surgery. This study examined whether laser speckle flowgraphy (LSFG) could be used to help objectively identify the safe areas of DIEP flaps.

Methods

Forty-eight patients who underwent unilateral breast reconstruction with a DIEP flap at Shinshu University Hospital between 2020 and 2024 were prospectively studied. During flap elevation, skin blood flow throughout the flap was measured using LSFG and compared with results obtained by indocyanine green (ICG) angiography. The cohort was also divided according to the number and location of perforators, and an intergroup comparison was performed according to LSFG readings.

Results

In all subjects, relative LSFG blood flow in zones 2 (89.1%) and 3 (87.9%) was comparable, whereas blood flow in zone 4 (72.8%) was significantly lower than in those areas (both P < 0.001). In the lateral row group, blood flow in zone 2 tended to be lower and in zone 3 tended to be higher than in the medial row group (zone 2: 82.6% versus 89.5%, zone 3: 93.6% versus 86.8%). LSFG values did not differ significantly in relation to perforator number. LSFG-determined blood flow in the stained side of the ICG-determined staining border was significantly higher than in the nonstained side (80.6% versus 71.4%, P < 0.001).

Conclusions

LSFG enables objective, noninvasive evaluation of safety margins in DIEP flaps that may support ICG angiography. Safe zones may vary depending on the location of the selected perforator.

Could Periodic Laser Doppler Imaging Monitoring Enhance Insights Into Perfusion Challenges in Anterolateral Thigh Flaps? A 5-Year Retrospective Analysis

BACKGROUND

Postoperative monitoring after free flap transfer is challenging, and clinical observation alone remains subjective and unquantifiable. Furthermore, re-explored flaps often have a poor appearance, making it challenging for surgeons to decide whether further aggressive treatments are necessary. Laser Doppler (LD) imaging can provide noninvasive, real-time, and quantifiable monitoring for flap perfusion. This study aimed to utilize fixed-timing LD to assist in postoperative free flap monitoring, especially in re-explored flaps.

MATERIAL AND METHODS

We retrospectively analyzed free anterolateral thigh (ALT) flap transfers with at least 1 re-exploration surgery from 2018 to 2022. Fixed-timing LD scans were conducted once a day on weekdays, and the flux mean of the flap and its adjacent reference healthy skin was obtained via an LD imager. The perfusion index (PI) was calculated as the percentage difference of flux mean between the flap and the reference. Timing of compromise, surgical findings and flap outcomes were recorded. Re-explored cases were matched with non-re-explored cases by propensity score matching for age, sex, and recipient site. Receiver operating characteristic curves and Youden's index were used to identify a PI cutoff value to define flap compromise. Post re-exploration outcomes were categorized into flap survival, partial necrosis, and failure. Post re-exploration LD data were analyzed with the Wilcoxon test.

RESULTS

Forty-seven re-explored free ALT flaps were included. Ten re-explored cases with LD scans before compromise on postoperative day 1 were matched with 20 nonreopened cases. A PI threshold value < -0.62 could identify flap compromise with 80% sensitivity and 70% specificity. In the flap survival group, the mean PI mean was -0.61 ± 0.03 in 32 cases within 24 hours after re-exploration, which was higher than the PI threshold. A significant difference in PI mean was found between the survival and partial necrosis groups (-0.61 ± 0.03 vs -0.86 ± 0.02, P = 0.034).

CONCLUSIONS

When facing uncertain circulation after free flap transfers, LD imaging can provide reliable and objective method for postoperative monitoring. A PI value ≤ -0.62 could identify free ALT flap compromise. This PI threshold value could be applied to re-explored flaps, providing an option to evaluate those in which compromise is suspected.

Free Flap Enhanced Recovery Protocols in Head and Neck Surgery

Enhanced recovery after surgery (ERAS) protocols facilitates a standardized patient care regimen with a goal of reducing the metabolic stress of surgery. Adapted to head and neck free flap reconstructive surgery in 2017, these protocols focused on several key domains such as perioperative nutritional optimization, multimodal pain control, and early mobilization. Studies have shown that in addition to ERAS implementation, the maintenance and improvement of ERAS protocol compliance rates improve perioperative outcomes such as hospital length of stay and decrease major postoperative complications.

Prompt, Objective, and Accurate Measurement of Rat Abdominal Flap Blood Flow Using Laser Speckle Flowgraphy

Background

The indications for free flap procedures have expanded, with recent technical advances enhancing procedural safety. However, few objective indicators exist to monitor flap status during and after the operation. This experimental study assessed laser speckle flowgraphy (LSFG) as a prompt and accurate indicator of free flap blood flow.

Methods

After elevating bilateral lower abdomen flaps with superficial inferior epigastric artery (SIEA) and superficial inferior epigastric vein vasculature in Wistar rats, the right flap with the SIEA was cut (ischemic group) or the superficial inferior epigastric vein was cut (congestive group), and the unaltered left flaps were monitored using LSFG every 5 minutes for a 30-minute period. Flap survival or necrosis was assessed after 7 days.

Results

In the ischemic group, LSFG measurements were significantly lower after cutting the SIEA than beforehand (74% at 5 minutes and 72% at 30 minutes). Similar findings were seen in the congestive group (63% at 5 minutes and 55% at 30 minutes). LSFG measurements were significantly lower in the congestive group than in the ischemic group. Seven days afterward, whereas all right-side flaps with cut vessels were necrotic, all unaltered left-side flaps had survived.

Conclusions

Our preliminary results demonstrated that LSFG could objectively identify abnormal blood flow in skin flaps as early as 5 minutes into surgery and predict graft survival. LSFG may potentially enable quick and objective assessment of flap blood flow and reduce the risk of complications and flap loss.

Recent Trends in Plastic Surgery: A Network Analysis of the Abstract Titles of the Largest German Plastic Surgery Congress 2023

BACKGROUND

Every year, German-speaking experts in plastic, reconstructive, and aesthetic surgery gather to discuss the latest developments at Germany's largest conference for plastic surgery, the joint annual meeting of the German Society of Plastic, Reconstructive and Aesthetic Surgery (DGPRÄC) and the Association of German Aesthetic Plastic Surgeons (VDÄPC). Since the topics of the conference have a lasting impact on the practice and research of plastic surgery, an examination of the presented content provides insight into the driving developments in plastic surgery in Germany.

MATERIALS AND METHODS

We conducted a retrospective network analysis of all abstract titles from the DGPRÄC and VDÄPC annual meeting in 2023. Data were extracted regarding titles, language, author, and place of origin, and the titles were categorized into the four pillars of the specialty. The titles were standardized and subjected to network analysis.

RESULTS

A total of 299 titles from 281 lectures and 18 instructional courses were analyzed. After preprocessing the data, 2463 words with 9384 connections qualified for network analysis. The most frequently mentioned keywords throughout the congress were 'Surgery', 'Breast', 'Reconstruction', 'Flap', 'Patient', 'Tissue', and 'Therapy'. Locations contributing the highest number of abstracts were Ludwigshafen, Hanover, Leipzig, and Munich.

CONCLUSION

In the era of big data, network analysis provides the ability to identify underlying structures and nodes in multidimensional, complex datasets. This study demonstrates the useful application of network analysis to identify thematic focuses and connections at the current DGPRÄC and VDÄPC annual meeting. Sites of intensified research could thus be identified.