Reducing the Learning Curve of Color Doppler Ultrasound for Perforator Flap Design

INTRODUCTION Color Doppler ultrasound (CDUS) is an emerging modality for perforator flap planning. Compared with conventional computed tomography angiography (CTA), CDUS offers the advantage of nontoxic, noninvasive, and real-time high-resolution imaging. Prior reports have demonstrated that incorporating ultrasound into clinical practice can minimize surgical complications, improve comprehensive patient follow-up, and improve patients’ experience.1 Specifically for microsurgeons, CDUS imaging has proven useful in perforator mapping.2 A major barrier to the widespread adoption of CDUS for perforator flap planning is the practitioner learning curve. This study aimed to address this barrier through a brief CDUS perforator mapping curriculum. METHODS An institutional review board–approved CDUS training curriculum was developed and administered to trainees (plastic and reconstructive surgery residents and medical students) at a single institution. Curriculum consisted of 2 video modules: a 9-minute, 45-second primer lecture covering ultrasound basics and a 26-minute 3-second lecture on ultrasound use for perforator flap localization. (See Video 1 [online], which shows trainees the basic principles of ultrasound.) (See Video 2 [online], which orients trainees to basic point-of-care ultrasound use.) (See Video 3 [online], which demonstrates the process of locating an anterolateral thigh [ALT] perforator flap using ultrasound.) {"href":"Single Video Player","role":"media-player-id","content-type":"play-in-place","position":"float","orientation":"portrait","label":"Video 1","caption":"shows trainees the basic principles of ultrasound.","object-id":[{"pub-id-type":"doi","id":""},{"pub-id-type":"other","content-type":"media-stream-id","id":"1_79iacmla"},{"pub-id-type":"other","content-type":"media-source","id":"Kaltura"}]} {"href":"Single Video Player","role":"media-player-id","content-type":"play-in-place","position":"float","orientation":"portrait","label":"Video 2","caption":"orients trainees to basic point-of-care ultrasound use.","object-id":[{"pub-id-type":"doi","id":""},{"pub-id-type":"other","content-type":"media-stream-id","id":"1_mz063svc"},{"pub-id-type":"other","content-type":"media-source","id":"Kaltura"}]} {"href":"Single Video Player","role":"media-player-id","content-type":"play-in-place","position":"float","orientation":"portrait","label":"Video 3","caption":"demonstrates the process of locating an anterolateral thigh (ALT) perforator flap using ultrasound.","object-id":[{"pub-id-type":"doi","id":""},{"pub-id-type":"other","content-type":"media-stream-id","id":"1_v2omdxdp"},{"pub-id-type":"other","content-type":"media-source","id":"Kaltura"}]} The first practical demonstration provided basic ultrasound use information, including how to hold and orient an ultrasound probe, adjust settings (scanning depth, gain, color gain, Doppler velocity), interpret color Doppler mode, and measure distances within an ultrasound image (Videos 1 and 2 [online]). The second practical demonstration was oriented toward identifying perforators for an ALT flap, specifically, demonstrations of the following (Video 3 [online]): How to mark anatomic landmarks of the ALT flap, (midpoint of the line between anterior superior iliac spine and superolateral patella, 3 cm proximal and distal). Using sufficient ultrasound gel, initial scanning depth 4–5 cm. Using ultrasound perpendicular to lateral intermuscular septum, identifying femur, rectus femoris, vastus lateralis, vastus intermedius. Scanning along the lateral intermuscular septum from distal to proximal, going more slowly at the “hot zone” identified by anatomic markings. Microfanning once the perforator is seen to determine if it is septocutaneous or musculocutaneous. Identifying a perforator exit point into skin. Using the freeze feature to measure skin distance from perforator exit point to skin (flap thickness). Scanning proximally to trace the main pedicle from perforator to main pedicle origin. Before training module exposure, all trainees completed a written examination establishing a baseline of their factual and conceptual knowledge of the course material. All trainees then watched the primer module. At this point, the trainees were separated into 2 different groups within the study—residents were placed within the “control” group, and were not provided any additional training, and medical students were placed within the “treatment” group and were provided additional training by watching the second video module. A detailed lesson plan was provided to all participants, relevant to their assigned study group. All trainees then completed a timed practical skills examination, which consisted of a CDUS examination on a standardized patient, using a point-of-care ultrasound machine (FUJIFILM Sonosite, Bothell, WA). This practical skills examination scored trainees by ability to identify relevant ALT anatomy, identify cutaneous perforators, describe perforator course (musculocutaneous or septocutaneous), measure vessel caliber, and trace the course of the main vascular pedicle. Medical student ultrasound proficiency on written examination and technical scores was compared with that of training-naive plastic and reconstructive surgery (PRS) residents using Mann-Whitney U tests (alpha 0.05). RESULTS Thirty-six participants (9 residents and 27 medical students) completed the training module and practical test. Of these, 8 residents and 17 medical students completed both a written pretest and posttest. Following completion of the module, 8 (89%) residents and 22 (81%) students correctly identified relevant anatomy. Nine (100%) PRS residents and 23 (86%) trained medical students were able to identify a perforator exit point. After 1 training session, there was no difference between medical students and training-naive PRS residents in terms of written examination scores (P = 0.99) or technical examination scores (P = 0.79). DISCUSSION Results suggest that a virtual training tool may provide effective education on CDUS use, with participants of varying experience levels performing similarly well in practice. This is significant for several reasons. CDUS has been shown to have equivalent or superior vessel identification accuracy compared with conventional CTA for perforator flap planning.3 Furthermore, CDUS provides demonstrated advantages over CTA, including real-time image processing and quantitative data, such as intravascular flow velocity measurements, all without subjecting patients to ionizing radiation or intravenous contrast agents. It can be particularly useful for patients with allergies to contrast agents, renal insufficiency, or metal implants.4 Additionally, CDUS examination can be performed by the surgical team immediately before flap harvest, which can allow interpreting surgeons to “preselect” perforators before surgical exploration is performed. Despite these advantages, the steep learning curve and user-dependency associated with CDUS employment have often been cited as a barrier to its widespread adoption in microsurgical practice.5 A recent study suggests that users take 3 months to increase efficiency with ultrasound and 6 months to improve timing.6 Study limitations include a small sample size recruited from a single institution, lacking control arms consisting of students not exposed to the training videos and trained plastic surgeons. This training module and study show promise for overcoming these hurdles, suggesting that brief training periods can rapidly improve trainee fidelity with CDUS for perforator characterization. CONCLUSIONS This module has demonstrated value as an educational tool for achieving basic proficiency among users with varying experience levels. Upscaling this reproducible training model via more widespread distribution may prove useful in plastic surgery education and help further the employment of CDUS in microsurgical practice. This may be particularly valuable for those practicing in resource-constrained environments, facilitating free flap planning without access to CTA. Cost remains a consideration, as pricing for machines and gel/probe covers may vary widely by brand, model, specifications and contract pricing. Future directions may involve adapting this module for use in various anatomical regions, enabling trainees to confidently utilize CDUS for perforator mapping across the entire body. It is the authors’ hope that sharing this module will provide educational benefit and make perforator mapping more accessible. DISCLOSURE The authors have no financial interest to declare in relation to the content of this article.