Perfusion dynamics in lower limb reconstruction: Investigating postoperative recovery and training using combined white light photospectroscopy and laser Doppler (O2C®)

Negative Pressure Wound Therapy in Free Muscle Flaps-Risk or Benefit?

BACKGROUND

 Application of negative pressure wound therapy (NPWT) on free flaps not only reduces edema but also increases the pressure from outside. The impact of these opposite effects on flap perfusion remains elusive. This study evaluates the NPWT system's influence on macro- and microcirculation of free flaps and edema reduction to better assess the clinical value of this therapy in microsurgical reconstructions.

METHODS

 In this open-label, prospective cohort study, a total of 26 patients with free gracilis muscle flaps for distal lower extremity reconstruction were included. Flaps were covered with an NPWT (13 patients) or a conventional, fatty gauze dressing (13 patients) for 5 postoperative days (PODs). Changes in flap perfusion were analyzed by laser Doppler flowmetry, remission spectroscopy, and an implanted Doppler probe. Flap volume as a surrogate parameter for flap edema was evaluated by three-dimensional (3D) scans.

RESULTS

 No flap showed clinical evidence of circulatory disturbances. The groups showed significant differences in the dynamic of macrocirculatory blood flow velocity with an increase in the NPWT group and a decelerated flow in the control group from PODs 0 to 3 and PODs 3 to 5. No significant differences in microcirculation parameters were observed. 3D scans for estimation of edema development demonstrated significant differences in volume dynamics between the groups. Flap volume of the controls increased, while the volume in the NPWT group decreased during the first 5 PODs. The volume of NPWT-treated flaps decreased even further after NPWT removal from PODs 5 to 14 and significantly more than the flap volume in the control group.

CONCLUSION

 NPWT is a safe form of dressing for free muscle flaps that enhances blood flow and results in a sustainable edema reduction. The use of NPWT dressings for free flaps should therefore be considered not only as a pure wound covering but also as a supportive therapy for free tissue transfer.

Influence of VAC Therapy on Perfusion and Edema of Gracilis Flaps: Prospective Case-control Study

The gracilis muscle flap is a popular choice in reconstructive surgery to repair soft tissue defects or for functional restoration. Little is known on the influence of postoperative application of VAC (vacuum-assisted closure; Kinetic Concepts Inc., San Antonio, Tex.) therapy on perfusion and postoperative flap edema of free gracilis muscle flaps.

Methods

In total, 26 patients with soft tissue defects of lower extremity underwent gracilis muscle flap reconstruction. The study group (VAC, n = 13) was supplied with postoperative negative pressure therapy as a dressing; the control group (NVAC, n = 13) was supplied with conventional fat gauze dressing. Postoperative measurements of micro- and macroperfusion were performed intraoperatively, on postoperative day (POD) 3 and POD 5. Flap edema measurement was performed intraoperatively, on POD 5 and 2 weeks after operation.

Results

The VAC group showed significantly better macroflow during intraoperative VAC treatment, as well on POD 3 and POD 5. Venous outflow was also better with lower hemoglobin levels. Microflow was better in the NVAC group with higher measured oxygen levels. All gracilis muscle flaps of the VAC group showed significantly less flap edema compared with the control group.

Conclusions

VAC application on free gracilis muscle flaps leads to significantly less postoperative flap edema, improved arterial macroflow, and improved venous outflow. VAC therapy can be used without any danger for patient's safety, as flap survival is not endangered, and presents an easy to handle and pleasant dressing regimen for nursing staff and patients.

Canadian Trends in Free Flap Management for Microsurgical Lower Limb Reconstruction

Introduction: Free tissue transfers have become a mainstay in lower limb salvage, allowing safe and reliable reconstruction after trauma, tumor extirpation, and complex wounds. The optimal perioperative (PO) management of these flaps remains controversial. This study aims to assess the current state of practice among Canadian microsurgeons. Methods: Sixty-four Canadian microsurgeons were approached to complete an online questionnaire regarding their PO management of fasciocutaneous free flaps used for lower limb reconstruction. Trends in dangling timing and duration, use of venous couplers, compressive garments, thromboprophylaxis, and surgeons' satisfaction with their protocol were assessed. Results: Twenty-eight surgeons responded. Fifty-seven percent did not have a specific mobilization protocol. Dangling was mainly initiated on postoperative days 5 to 6 (44%). The most common protocol duration was 5 to 6 days (43%). The concern for prolonged venous pooling was the main reason for delay of dangling (71%). Compressive garments were placed routinely by 12 surgeons (43%) with 20% starting before dangling, 46% with dangling, and 33% after dangling. Venous couplers were routinely used by 24 surgeons (85.7%). Trends in management were influenced by previous training in 53.6% of cases (vs evidence-based medicine 7.1%). Although 89.3% were satisfied with their approach, 92.8% would consider changing practice if higher-level evidence was available. Conclusions: The majority of Canadian microsurgeons initiate dangling early and utilize venous couplers. However, the use of compressive garments is limited. Trends in management are largely based on personal experience. Nearly all surgeons would consider changing their practice if higher-level evidence was available.

Influence of high-energy laser therapy to the patellar tendon on its ligamentous microcirculation: An experimental intervention study

Laser therapeutic applications, such as the use of high energy lasers (HILT), are widely used in physical therapy, but basic studies on the mechanisms of action of HILT on tendinous/ligamentous tissue are largely lacking. The aim of this study was to investigate microcirculatory changes of the patellar tendon by HILT. 21 healthy volunteers were included in the present investigation. Before and after HILT, as well as 10 minutes later, the microcirculation was measured by noninvasive laser Doppler and white light spectroscopy (O2C device). Tissue temperature was recorded at the measurement time points using thermography. Blood flow increased significantly by 86.38 arbitrary units (AU; p < 0.001) after the intervention and by 25.76 AU (p < 0.001) at follow-up. Oxygen saturation increased by 20.14% (p < 0.001) and 13.48%, respectively (p < 0.001), whereas relative hemoglobin decreased by 6.67 AU and 7.90 AU, respectively. Tendon temperature increased by 9.45° and 1.94° Celsius, respectively. Acceleration of blood flow by improving the flow properties of erythrocytes and platelets may have caused the results. HILT could be a therapeutic perspective for tendon pathologies with impaired microcirculation, although further studies are needed to validate the experimental results.

Analysis of Factors Determining Patient Survival after Receiving Free-Flap Reconstruction at a Single Center-A Retrospective Cohort Study

BACKGROUND

Microsurgical tissue transfer revolutionized reconstructive surgery after extensive trauma, oncological resections, and severe infections. Complex soft tissue reconstructions are increasingly performed in multimorbid and elderly patients. Therefore, it is crucial to investigate whether these patients benefit from these complex procedures.

OBJECTIVE

To evaluate the outcome for multimorbid patients who underwent microsurgical soft tissue reconstruction and to identify potential risk factors that may increase mortality.

METHODS

This single-center study retrospectively analyzed prospectively collected data of patients receiving free gracilis (GM) or latissimus dorsi muscle (LDM) flap reconstruction between September 2017 and December 2021. Cases were divided into two groups (dead vs. alive), depending on patient survival. Patient demographics, comorbidities and medication, perioperative details, free flap outcome, as well as microcirculation were determined.

RESULTS

A total of 151 flaps (LDM, n = 67; GM, n = 84) performed in 147 patients with a mean age of 61.15 ± 17.5 (range 19-94) years were included. A total of 33 patients (22.45%) passed away during the study period. Deceased patients were significantly older (Alive: 58.28 ± 17.91 vs. Dead: 71.39 ± 11.13; p = 0.001), were hospitalized significantly longer (Alive: 29.66 ± 26.97 vs. Dead: 36.88 ± 15.04 days; p = 0.046) and suffered from cardiovascular (Alive: 36.40% vs. Dead: 66.70%; p = 0.002) and metabolic diseases (Alive: 33.90% vs. Dead: 54.50%; p = 0.031) more frequently, which corresponded to a significantly higher ASA Score (p = 0.004). Revision rates (Alive: 11.00% vs. Dead: 18.20%; p = 0.371) and flap loss (Alive: 3.39% vs. Dead: 12.12%; p = 0.069) were higher in patients that died by the end of the study period.

CONCLUSIONS

Free flap transfer is safe and effective, even in multimorbid patients. However, patient age, comorbidities, preoperative ASA status, and medication significantly impact postoperative patient survival in the short- and mid-term and must, therefore, be taken into account in preoperative decision-making and informed consent.

Evaluation of Scar Quality after Treatment of Superficial Burns with Dressilk® and Suprathel®-In an Intraindividual Clinical Setting

Background: Various synthetic and biological wound dressings are available for the treatment of superficial burns, and standard care differs among hospitals. Nevertheless, the search for an ideal wound dressing offering a safe healing environment as well as optimal scar quality while being economically attractive is a continuing process. In recent years, Dressilk^®, which consists of pure silk, has become the standard of care for the treatment of superficial burns in our hospital. However, no long-term scar-evaluation studies have been performed to compare Dressilk^® with the often-used and more expensive Suprathel^® in the treatment of superficial burns. Methods: Subjective and objective scar evaluations were performed three, six, and twelve months after treatment in patients who received simultaneous treatment of 20 superficial burn wounds with both Suprathel^® and Dressilk^®. The evaluations were performed using the Vancouver Scar Scale, the Cutometer^®, Mexameter^®, Tewameter^®, and the O2C^®. Results: Both dressings showed mostly equivalent results in subjective scar evaluations. In the objective scar evaluations, the wounds treated with Dressilk^® showed a faster return to the qualities of non-injured skin. Wound areas treated with the two dressings showed no significant differences in elasticity and transepidermal water loss after 12 months. Only oxygen saturation was significantly lower in wound areas treated with Suprathel^® (p = 0.008). Subjectively, wound areas treated with Dressilk^® showed significantly higher pigmentation after six months, which was not apparent after 12 months. Conclusion: Both wound dressings led to esthetically satisfying scar recovery without significant differences from normal uninjured skin after 12 months. Therefore, Dressilk^® remains an economically and clinically interesting alternative to Suprathel^® for the treatment of superficial burns.

Dangle Protocols in Lower Extremity Reconstruction

INTRODUCTION

Dangling protocols are known to vary by surgeon and center, and their specific regimen is often largely based on single surgeon or institutional experience. A systematic review was conducted to derive evidence-based recommendations for dangling protocols according to patient-specific and flap-specific considerations.

METHODS

A systematic review was performed using PubMed, Embase-OVID and Cochrane-CENTRAL. Study design, patient and flap characteristics, protocol details, dangling-related complications, and flap success rate were recorded. Studies were graded using the Oxford Center for Evidence-Based Medicine Levels of Evidence Scale. Data heterogeneity precluded quantitative analysis.

RESULTS

Eleven articles were included (level of evidence (range):IIb-IV; N (range):8-150; age (range):6-89). Dangling initiation, time, and frequency varied considerably. Flap success rate ranged from 94 to 100%. Active smoking, diabetes, and hypertension are associated with characteristic physiologic changes that require vigilance and potential protocol modification. Early dangling appears to be safe across a variety of free flap locations, sizes, and indications. Axial fasciocutaneous flaps may tolerate more aggressive protocols than muscular flaps. While flaps with single venous anastomosis tolerate dangling, double venous or flow-through anastomoses may provide additional benefit. Major limitations included small sample sizes, uncontrolled study designs, and heterogeneous patient selection, dangling practices, monitoring methods, and outcome measures.

CONCLUSIONS

Significant heterogeneity persists in postoperative dangling protocols after lower extremity microvascular reconstruction. Patient comorbidities and flap characteristics appear to affect tolerance to dangling. We propose two different standardized pathways based on risk factors. Clinical vigilance should be exercised in tailoring lower extremity protocols to patients' individual characteristics and postoperative course.

The Influence of Topically Administered Heparin on Peripheral Microcirculation of the Skin: A Double-Blind, Randomized, Controlled Preliminary Study on 50 Healthy Subjects

BACKGROUND

 Venous thrombosis is the most common cause of flap failure in the first days after surgery. Although heparin is one of the most important antithrombotic substances and is implemented in the therapy of various diseases, there are only a few studies addressing its topical administration in the field of flap surgery. Especially, very little is known about the effects of topical heparin and its impact on microcirculation. In this study we evaluated to what extent topically administered heparin influences skin microcirculation (capillary venous oxygen saturation SO2, blood filling of microvessels, blood flow, and velocity) in healthy subjects.

METHODS

 Skin perfusion parameters on the forearm were measured with the O2C device in a double-blinded, controlled, and randomized study with 50 healthy subjects after administration of heparin ointment in three different concentrations and a control ointment (dexpanthenol).

RESULTS

 Topically administrated heparin slightly increased SO2 (max. 187 ± 285 SD or standard deviation % vs. 145 ± 129 SD %), flow (max. 264 ± 427 SD % vs. 151.74 ± 111 SD %), and velocity (max. 153 ± 149 SD % vs. 122 ± 56 SD %) after an incubation time of 60 minutes in comparison to control. No statistically significant difference could be detected regarding heparin concentration.

CONCLUSION

 As a first important step in possible future implementing of heparin as a topical administration in flap surgery, our data-although not statistically significant-indicate that heparin can improve microcirculation (SO2, flow) in healthy subjects. Nevertheless, further research in subjects with impaired microcirculation is necessary.

Canadian Postoperative Dependency Protocols Following Lower Limb Microvascular Reconstruction: A National Survey and Literature Review

Introduction

Microsurgical free tissue transfer for lower limb reconstruction presents unique challenges in the postoperative period where dependency promotes interstitial fluid diffusion and reduced tissue perfusion. Management of flap edema, venous congestion, and ischaemic conditioning is critical for flap survival. Little evidence exists to guide postoperative protocols in the initiation and progression of lower extremity dangle, monitoring, and anticoagulation. We aim to describe current trends for postoperative dependency protocols by surveying Canadian microsurgeons.

Methods

Plastic surgeons performing lower limb microvascular reconstruction at Fellow of The Royal College of Surgeons of Canada approved teaching institutions were administered a 17-question anonymous electronic survey. A literature review was conducted to identify protocols and consensus opinions in other jurisdictions.

Results

All respondents (n = 16) monitored flaps clinically, with conventional Doppler used by 13 respondents. Anticoagulation was employed by 15 of 16 respondents, and 9 of 16 used 2 or more agents. The most common agents were aspirin, followed by low-molecular-weight heparin. Significant variability existed in dangling protocols. Dependency was initiated at postoperative day (POD) 3 to 10 (mean POD: 6 ± 1.64 standard deviation), with intervals ranging from 5 to 20 minutes and frequencies ranging from 1 to 6 times per day. Nearly half allowed both increasing duration and frequency of dependency. Flap success rates were above 90%, and the median length of stay was 10 to 12 days.

Conclusion

While flap success rates across the country are similar, no consensus exists for postoperative dependency protocols amongst Canadian microsurgeons. Prospective randomised controlled trials are warranted to evaluate early aggressive dependency protocols to reduce length of stay and cost.

Safety and effectiveness of early compression of free flaps following lower limb reconstruction: A systematic review

INTRODUCTION

Early postoperative compression of free flaps for lower limb reconstruction remains controversial. It may reduce venous congestion and promote the resolution of oedema. However, concerns remain regarding inadvertent pedicle compression, which may lead to flap failure. The aim of this systematic review was to determine the safety and effectiveness of this intervention.

METHODS

A systematic review was designed in compliance with PRISMA. MEDLINE and EMBASE databases were searched. Parallel screening, selection of eligible studies, and data gathering were carried out by two independent authors. A formal risk of bias assessment was included along with the appraisal of outcomes.

RESULTS

A total of 847 abstracts were retrieved and 262 free flaps for lower limb reconstruction were identified in ten eligible articles. The overall flap failure rate for patients who underwent early postoperative compression was 1.6%. Apart from flap failure rates, there were no other outcomes consistently reported and none of the studies included a no-compression group for comparison.

DISCUSSION

All included studies had methodological flaws, resulting in a high risk of bias. Nevertheless, there was consistent reporting of flap failure as a postoperative outcome. Compression of free flaps in the context of lower limb reconstruction does not appear to be associated with a higher flap failure rate compared with other series. Compression bandages may reduce the pain associated with dangling regimes. However, there is no evidence to support that free flap compression in the context of lower limb reconstruction is associated with any other clinical benefit.

Investigating Lower Limb Hemodynamics during Flap Training Regimens and Patient-led Isometric Contraction Protocols

Supplemental Digital Content is available in the text.

The evidence for lower limb flap (LLF) training regimens is equivocal. The commonest cause of LLF failure is venous congestion. The aim of this study was to investigate whether venous congestion could be reduced by patient-led isometric calf contractions during flap training. A prospective clinical study was conducted using photospectroscopy and laser Doppler (Oxygen to See) to assess healthy limbs and LLF characteristics during flap training and isometric calf contractions. Tissue oxygen saturation, venous congestion, and blood flow were measured at rest, as well as during and after limb dangling and calf contraction exercises. In the acute postoperative period following LLF surgery, dependency markedly reduced superficial flow (−55.20% ± 19.17%), with a concurrent increase in venous congestion (33.80% ± 28.80%); supine isometric contractions improved superficial flow and reduced venous congestion from postoperative day 5. Contractions cause a significant increase in blood flow in the outpatient cohort (+84.40% ± 7.86%, P = 0.009), with a mean time since discharge of 14 weeks. Our data suggest patient-led isometric calf exercises are well tolerated and may reduce venous congestion in the acute phase. Progressive changes toward normal physiological function were demonstrated in the outpatient rehabilitation period. Incorporating calf exercises into LLF rehabilitation may allow longer periods of leg dependency, quicker recovery from surgery, and ultimately improve outcomes.

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.

Acute Effects of Lateral Thigh Foam Rolling on Arterial Tissue Perfusion Determined by Spectral Doppler and Power Doppler Ultrasound

Hotfiel, T, Swoboda, B, Krinner, S, Grim, C, Engelhardt, M, Uder, M, and Heiss, R. Acute effects of lateral thigh foam rolling on arterial tissue perfusion determined by spectral Doppler and power Doppler ultrasound. J Strength Cond Res 31(4): 893-900, 2017-Foam rolling has been developed as a popular intervention in training and rehabilitation. However, evidence on its effects on the cellular and physiological level is lacking. The aim of this study was to assess the effect of foam rolling on arterial blood flow of the lateral thigh. Twenty-one healthy participants (age, 25 ± 2 years; height, 177 ± 9 cm; body weight, 74 ± 9 kg) were recruited from the medical and sports faculty. Arterial tissue perfusion was determined by spectral Doppler and power Doppler ultrasound, represented as peak flow (Vmax), time average velocity maximum (TAMx), time average velocity mean (TAMn), and resistive index (RI), and with semiquantitative grading that was assessed by 4 blindfolded investigators. Measurement values were assessed under resting conditions and twice after foam rolling exercises of the lateral thigh (0 and 30 minutes after intervention). The trochanteric region, mid portion, and distal tibial insertion of the lateral thigh were representative for data analysis. Arterial blood flow of the lateral thigh increased significantly after foam rolling exercises compared with baseline (p ≤ 0.05). We detected a relative increase in Vmax of 73.6% (0 minutes) and 52.7% (30 minutes) (p < 0.001), in TAMx of 53.2% (p < 0.001) and 38.3% (p = 0.002), and in TAMn of 84.4% (p < 0.001) and 68.2% (p < 0.001). Semiquantitative power Doppler scores at all portions revealed increased average grading of 1.96 after intervention and 2.04 after 30 minutes compared with 0.75 at baseline. Our results may contribute to the understanding of local physiological reactions to self-myofascial release.

Analysis of the microcirculation after soft tissue reconstruction of the outer ear with burns in patients with severe burn injuries

Reconstruction of soft tissue defects of the ear with burns remains one of the most difficult tasks for the reconstructive surgeon. Although numerous reconstructive options are available, the results are often unpredictable and worse than expected. Besides full and split skin grafting, local random pattern flaps and pedicled flaps are frequently utilized to cover soft tissue defects of the outer auricle. Because of the difficulty and unpredictable nature of outer ear reconstruction after burn injury, a case-control study was conducted to determine the best reconstructive approach. The microcirculatory properties of different types of soft tissue reconstruction of the outer ear with burns in six severely burned Caucasian patients (three men and three women; mean age, 46 years (range, 22-70)) were compared to those in the healthy tissue of the outer ear using the O2C device (Oxygen to See; LEA Medizintechnik, Gießen, Germany). The results of this study revealed that the investigated microcirculation parameters such as the median values of blood flow (control group: 126 AU), relative amount of hemoglobin (control group: 59.5 AU), and tissue oxygen saturation (control group: 73%) are most similar to those of normal ear tissue when pedicled flaps based on the superficial temporal artery were used. These findings suggest that this type of reconstruction is superior for soft tissue reconstruction of the outer ear with burns in contrast to random pattern flaps and full skin grafts regarding the microcirculatory aspects. These findings may improve the knowledge on soft tissue viability and facilitate the exceptional and delicate process of planning the reconstruction of the auricle with burns.

Assessment of sural flap microcirculation: Which position maintains the optimal perfusion?

BACKGROUND

Limb elevation is a commonly used approach for reducing edema and increasing venous drainage. Considering the anatomy of the sural flap with retrograde perfusion and hence potentially difficult blood outflow, the best angle for positioning the leg following operation is not yet known.

METHODS

A total of 14 patients undergoing sural flap lower limb reconstruction were enrolled in the study. We assessed the perfusion dynamics of the flaps using the oxygen-to-see (O2C) device that combines laser light, to determine blood flow, and white light to determine the relative amount of hemoglobin and oxygen saturation. Three different positions were evaluated: 45° angle downward, the horizontal position, and 45° angle upward.

RESULTS

The blood flow was significantly higher in the 45° upward position compared to the 45° downward position. The relative amount of hemoglobin was significantly lower in the 45° upward position compared to the 45° downward position. No significant differences with regard to oxygen saturation were observed.

CONCLUSION

The results of this study show a more precise pattern of perfusion due to different positioning. The 45° upward position of the leg generally maintains the best blood flow and venous drainage. However, compared to horizontal positioning, these differences were not statistically significant. As an elevation of 45° can be uncomfortable for patients, we recommend an elevation of the leg which approximates the 45° upward position but is still comfortable.