Portable duplex ultrasonography: A diagnostic and decision-making tool in reconstructive microsurgery

A new protocol for improving immediate monitoring of skin-island free flap with near-infrared spectroscopy and ultrasound

BACKGROUND

Postoperative monitoring is essential for detecting early complications and improving the salvage rate of free flaps. We propose a new protocol for free flap monitoring based on the combination of near-infrared spectroscopy (NIRS) and ultrasound.

METHODS

All free flaps with a skin paddle were included and divided into two groups according to the immediate postoperative monitoring method used: ultrasound examination (control group) or those monitored using our protocol (study group). The number of surgical revisions, intraoperative findings, immediate flap failure, sensitivity, and specificity were compared between the two groups.

RESULTS

A total of 221 free flaps performed in 209 patients were included. The NIRS automatically detected vascular compromise in 21.8% of cases. A complication was confirmed in half of these cases by ultrasound examination, and surgical reintervention was indicated (10.9%), even in the absence of clinical changes in the skin paddle. In all the surgical revisions, the complication was confirmed, and there was no flap necrosis in the non-revised cases. The salvage rate for revised flaps and the flap survival rate were higher in the study group (salvage rate: 25% vs 72.7%; survival rate: 92.5% vs 97%). A sensitivity of 100% and a specificity of 100% were found for the combination of both monitoring methods.

CONCLUSION

The proposed protocol is a non-invasive and reliable method for early identification of postoperative complications of free flaps that allows higher rates of salvage rate and reduces the need for specific staff with continuous on-site presence for flap monitoring.

An algorithmic approach to soft-tissue reconstruction around the knee using anterolateral thigh perforator flap in patients with post-traumatic knee osteomyelitis

Background

Free tissue transfer to the knee region in patients with chronic post-traumatic knee osteomyelitis (CTKOM) poses a great challenge to surgeons because the remaining soft tissues adjacent to defects, including vascular structures, are usually damaged by chronic inflammation and multiple debridements. Thus, we developed an algorithm to help select the optimal recipient vessels and appropriate anterolateral thigh perforator (ALTP) flap type. In addition, we performed surgery using this algorithm and achieved successful reconstructions. This study aims to review our experiences in algorithmic reconstruction and assess its efficacy.

Methods

According to the defect size and location, our algorithm suggested the use of various-shaped ALTP flaps with centrally located perforators (Cen-ALTP flap) or eccentrically located perforators (Ecc-ALTP flap). Besides, through the algorithm, one recipient vessel was selected among three candidates, including descending branch of the lateral circumflex femoral artery (DB-LCFA), anterior tibial artery (ATA), and posterior tibial artery (PTA). Based on this algorithmic decision, we performed individualized soft tissue reconstructions of the knee in 21 patients with CTKOM, between March 2013 and June 2021. The medical records of the patients were retrospectively reviewed.

Results

The Cen-ALTP flap (n = 15) and ATA (n = 9) were the most commonly used for reconstruction. The Cen-ALTP flap anastomosed to the ATA was most commonly selected (n = 7) using the algorithm, followed by the Cen-ALTP flap anastomosed to the DB-LCFA (n = 5), and the Cen-ALTP flap anastomosed to the PTA (n = 3). All transferred ALTP flaps survived the follow-up period. Postoperative venous congestion in two patients and hematoma in one patient were resolved by immediate treatment. The postoperative course was uneventful.

Conclusion

During free ALTP flap transfer to CTKOM-related knee defects, we could select the optimal recipient vessel and appropriate flap type using our algorithm and obtain excellent reconstructive outcomes. Therefore, we believe that our algorithm could provide helpful guidance to reconstructive surgeons on free ALTP flap transfer to reconstruct CTKOM-related soft tissue defects.

Duplex echography as an adjuvant tool to clinical examination to detect early postoperative free flap vascular compromise

BACKGROUND

Clinical examination remains the cornerstone for postoperative monitoring of free flaps but is highly dependent on the surgeon's ability and experience. Duplex echography provides a noninvasive objective evaluation of tissue perfusion. The authors hypothesized that duplex echography may be a more sensitive and specific monitoring method for early detection of postoperative flap compromise compared to clinical examination alone. The goal was to evaluate any differences between combined duplex echography and clinical examination flap monitoring versus isolated clinical evaluation.

METHODS

A total of 730 free flaps in 700 patients were included in the study. We conducted an intra-subject prospective study of a cohort of patients who underwent free flap reconstruction in our unit to compare clinical examination with duplex echography for postoperative monitoring. An inter-subject study was also undertaken comparing the prospective cohort with a historical control group of patients in whom free flap monitoring was made using clinical examination alone. The patency flow and velocities through the artery and vein of the flap were measured at the donor and recipient vessels of every anastomosis by duplex scanning, by the same plastic surgeon every 4 hr, during the first 18 hr after surgery.

RESULTS

Duplex echography and clinical evaluation were used in 175 patients. The historical cohort included a total of 525 flaps. Every patient with suspicion of vascular compromise based on duplex echography was taken back for surgical re-exploration. There were no cases of overdiagnosis using duplex echography (Sensitivity 100%, Specificity 100%). Clinical evaluation detected issues with the vascularan astomoses in 23/175 flaps. However, it failed to detect 12/22 cases which presented with vascular complications and gave a false indication of possible complications in 13 flaps (Sensitivity 45%, Specificity 92%).

CONCLUSION

In our practice, duplex echography is considered a useful adjunct monitoring tool for early detection of postoperative flap compromise, which compliments clinical evaluation. It provides anatomic and hemodynamic information of the vascular status and may therefore increase survival of flaps by allowing earlier detection of vascular compromise, compared to clinical examination alone, in postoperative monitoring of free flaps.

Feasibility study of preoperative microvessel evaluation and characterization in perforator flaps using various modes of color-coded duplex sonography (CCDS)

BACKGROUND

Color-coded duplex sonography (CCDS) is useful for perforator flap design showing the highest sensitivity in identifying microvessels. This prospective study evaluates the feasibility of different ultrasound (US) modes applied by the microsurgeon in daily practice suggesting quantifiable reference values.

METHODS

Twenty-four patients aged between 17 and 68 years (mean 43.3 ± 14.2 years) with 18 anterolateral thigh (ALT) and 6 superficial circumflex iliac artery (SCIP) flaps were included. Indications were traumatic (n = 12), infectious (n = 6), ischemic (n = 4), or tumor-associated defects (n = 2). Different US modes were evaluated regarding applicability using multifrequency linear probes (5-15 MHz). Vessels diameter, peak systolic velocity (PSV), end diastolic velocity (EDV), and resistance index (RI) were measured. Preoperative results were correlated to intraoperative findings.

RESULTS

In the examined patient group with 24 perforator flaps a 100% correlation was seen when comparing perforators detected with CCDS/PD with intraoperative findings using optimized US settings. Sensitivity, PPV, and accuracy of CCDS were 100% respectively. Mean PSV of 16.99 ± 6.07 cm/s, mean EDV of 5.01 ± 1.84 cm/s and RI of 0.7 ± 0.07 were measured in microvessels (PW-mode). CCDS proved to be superior compared to PD in correct diameter assessment showing a mean diameter of 1.65 ± 0.45 mm, compared to PD-mode 1.31 ± 0.24 mm. Mean PSV and EDV were higher in ALT than in SCIP flaps, RI was slightly higher in SCIP flaps (p > .05). There were no significant differences in size of different flaps' perforators (p > .05).

CONCLUSION

CCDS represents a highly valuable tool in the daily practice of free flap reconstructions using optimized low flow US settings and multifrequency linear probes.

Preoperative Vascular Planning of Free Flaps: Comparative Study of Computed Tomographic Angiography, Color Doppler Ultrasonography, and Hand-Held Doppler

BACKGROUND

Preoperative planning of microsurgical perforator free flaps continues to be a discussion topic among microsurgeons. The purpose of this study was to compare the ability of three methods of preoperative vascular mapping-hand-held Doppler imaging, color Doppler ultrasonography, and computed tomographic angiography-to detect perforators and their concordance with surgical findings.

METHODS

A prospective study was performed to evaluate the sensitivity, specificity, and accuracy of hand-held Doppler imaging, color Doppler ultrasonography, and computed tomographic angiography to detect free flap perforators. Each patient undergoing a free flap reconstruction was studied preoperatively with the three methods, and the results were compared to the intraoperative findings.

RESULTS

Fifty-three patients undergoing autologous tissue reconstruction were included. Most reconstructions (71.7 percent) were performed with anterolateral thigh flaps. The positive predictive value (color Doppler ultrasonography, 100 percent; computed tomographic angiography, 100 percent; hand-held Doppler imaging, 88.6 percent) and negative predictive value (color Doppler ultrasonography, 100 percent; computed tomographic angiography, 94.3 percent; hand-held Doppler imaging, 90.5 percent) rates were significantly different between methods. The high resolution of the color Doppler ultrasonography probe provided a direct vision of the vasculature arborization and efficiently detected vessels with diameters of less than 0.5 mm. The sensitivity, specificity, and accuracy of color Doppler ultrasonography were greater than those of both computed tomographic angiography and hand-held Doppler imaging. There was 100 percent concordance between color Doppler ultrasonography perforators and the surgical findings.

CONCLUSIONS

Color Doppler ultrasonography provides a reproducible, harmless, and accurate way to visualize vascular anatomy. It has a high correlation with the surgical findings, signifying advantages over hand-held Doppler and computed tomographic angiography in sensitivity, specificity, and accuracy.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Diagnostic, II.

High-Resolution Ultrasound-Guided Perforator Mapping and Characterization by the Microsurgeon in Lower Limb Reconstruction

BACKGROUND

 Preoperative ultrasound (US)-guided perforator mapping has immensely simplified perforator flap planning. It may be executed by the microsurgeon. Device settings and selection of ultrasound modes are of utmost significance for detection of low-flow microvessels. The following study evaluates different US modes.

METHODS

 A prospective complete data acquisition was performed from July 2018 to June 2019 in a subset of patients who underwent US-guided flap planning. Multifrequency linear transducers were used applying five US modes. Brightness (B)-mode, color flow (CF), power Doppler (PD), pulse wave (PW), and B-flow modes were evaluated regarding applicability by microsurgeons. Peak systolic velocity (PSV), end diastolic velocity (EDV), and resistance index (RI) were chosen to evaluate flow characteristics. US results were correlated to intraoperative findings.

RESULTS

 A total number of eight patients (six males and two females) undergoing anterolateral thigh (ALT) or superficial circumflex iliac artery perforator (SCIP) flap surgery received an extensive standardized US-guided perforator characterization. Qualitative evaluation was performed in B-mode, color-coded duplex sonography (CCDS), PD, and B-flow mode. Quantitative assessment was executed using PW-mode and CCDS measuring the microvessels' diameter (mm) and flow characteristics (PSV, EDV, and RI). CCDS provided a mean diameter of 1.93 mm (range: 1.2-2.8 ± 0.51), a mean systolic peak of 16.9 cm/s (range: 9.9-33.4 ± 7.79), and mean RI of 0.71 (range: 0.55-0.87 ± 0.09) for lower limb perforators. All perforators located with US were verified by intraoperative findings. An optimized, time-effective US mapping algorithm was derived. Qualitative parameters may be evaluated with B-mode, CF, or B-flow. Smallest microvessels may be assessed in PD-mode. Lowering pulse-repetition frequency (PRF)/scale is mandatory to image low-flow microvessels as perforators. Quantitative information may be obtained using PW-mode and the distance-measuring tool in CF-mode. Image and video materials are provided.

CONCLUSION

 CCDS proved to be a powerful tool for preoperative perforator characterization when using a structured approach and mapping algorithm. Different techniques may be applied for specific visualizations and performed by the microsurgeon.

Step-by-step guide to ultrasound-based design of alt flaps by the microsurgeon - Basic and advanced applications and device settings

BACKGROUND

The anterolateral thigh (ALT) perforator flap is a popular reconstructive tissue transfer. Consistent with the "hot/cold zone" concept for rapid dissection and thin flap harvest, reliable preoperative perforator mapping is mandatory. Color-coded duplex sonography (CCDS) has been shown to have the highest pooled sensitivity and positive predictive value to identify ALT perforating vessels. By reviewing this guide, the reader should learn: 1. Probe selection and basic/advanced device settings 2. Interpreting tissue morphology 3. Structured mapping approach 4. Pedicle position planning 5. Safe flap design 6. Assess subcutaneous course and flap's thickness for subfascial/epifascial/suprafascial harvest 7. Implement perforators identified into a tailor-made flap design including chimeric flaps.

METHODS

Experiences with ultrasound-guided flap design gained from 125 ALT perforator flap free tissue transfers performed in two reconstructive centers was the basis of our guide. Our structured method comprises standardized markings, patient positioning, and simple ergonomics. Basic and advanced CCDS settings, selection, and conventional probe guidance are outlined for the microsurgeon.

RESULTS

Linear multifrequency probes (6-15 MHz) were used. Best preset programs were breast, thyroid, and vascular. Favorable device properties were depth focused to 2-5 cm, pulse repetition frequency (PRF/Scale) set low to 0.5-1.5 kHz/3-10 cm/s, color gain high, and wall filter (WF) low/off (< 50 Hz). Additional parameters were discussed. A 100% concordance rate was seen comparing preoperative perforator visualization with CCDS and intraoperative findings. Detailed picture and video material were demonstrated.

CONCLUSION

CCDS is a powerful tool for preoperative perforator mapping in perforator flaps such as the ALT.

Flap reconstruction of the knee: A review of current concepts and a proposed algorithm

A literature search focusing on flap knee reconstruction revealed much controversy regarding the optimal management of around the knee defects. Muscle flaps are the preferred option, mainly in infected wounds. Perforator flaps have recently been introduced in knee coverage with significant advantages due to low donor morbidity and long pedicles with wide arc of rotation. In the case of free flap the choice of recipient vessels is the key point to the reconstruction. Taking the published experience into account, a reconstructive algorithm is proposed according to the size and location of the wound, the presence of infection and/or 3-dimensional defect.