A New Supermicrosurgery Training Model of Saphenous Artery and Great Saphenous Vein Anastomosis for Development of Advanced Microsurgical Skills

Traumatic vessel injuries initiating hemostasis generate high shear conditions

Various types of lesions in small and large mouse and human vessels result in high shear rates and elongational flows.

The relative hydrodynamic resistance of the vessel and wound explains a decrease in shear rate with increase in injury size.

Blood flow is a major regulator of hemostasis and arterial thrombosis. The current view is that low and intermediate flows occur in intact healthy vessels, whereas high shear levels (>2000 s⁻¹) are reached in stenosed arteries, notably during thrombosis. To date, the shear rates occurring at the edge of a lesion in an otherwise healthy vessel are nevertheless unknown. The aim of this work was to measure the shear rates prevailing in wounds in a context relevant to hemostasis. Three models of vessel puncture and transection were developed and characterized for a study that was implemented in mice and humans. Doppler probe measurements supplemented by a computational model revealed that shear rates at the edge of a wound reached high values, with medians of 22 000 s⁻¹, 25 000 s⁻¹, and 7000 s⁻¹ after puncture of the murine carotid artery, aorta, or saphenous vein, respectively. Similar shear levels were observed after transection of the mouse spermatic artery. These results were confirmed in a human venous puncture model, where shear rates in a catheter implanted in the cubital vein reached 2000 to 27 000 s⁻¹. In all models, the high shear conditions were accompanied by elevated levels of elongational flow exceeding 1000 s⁻¹. In the puncture model, the shear rates decreased steeply with increasing injury size. This phenomenon could be explained by the low hydrodynamic resistance of the injuries as compared with that of the downstream vessel network. These findings show that high shear rates (>3000 s⁻¹) are relevant to hemostasis and not exclusive to arterial thrombosis.

Training model for the intraluminal continuous suturing technique for microvascular anastomosis

Microvascular anastomosis is a critical procedure in cerebral bypass surgeries. In some rare cases, the extraluminal interrupted technique is not optimal because the vessels are immobile and cannot be rotated, and anastomosis can be performed effectively through the intraluminal continuous suturing technique. The authors reported the application of the intraluminal continuous suturing technique in microanastomosis training with silicone tube, rat’s common iliac arteries and abdominal aorta. A silicone tube with a diameter of 1.5 mm was used to practice microanastomosis in intraluminal continuous suturing technique. Then the technique was applied in side-to-side, end-to-side anastomoses of common iliac arteries and the end-to-end abdominal aorta anastomoses of rat. The suturing time and patency rates were compared with an alternative intraluminal continuous suturing technique and one-way-up interrupted suturing technique in silicone tube and rat vessel anastomoses. The intraluminal continuous suturing technique could be gained through practicing with silicone tube, and the technique has also been demonstrated effective in side-to-side, end-to-side anastomoses of common iliac arteries of rat and the abdominal aorta end-to-end anastomoses. In all the animal experimental groups with different suturing techniques, there was no difference between the patency rates, all the immediate patency rate was 100%. There was no significant suturing time difference between the two intraluminal continuous suturing techniques, but the two intraluminal continuous suturing techniques were faster than the interrupted technique. The intraluminal continuous suturing technique described in the study could be used as an efficient method for side-to-side, end-to-side and end-to-end anastomosis, especially under the situation the posterior wall of the anastomosis could not be rotated. Proficiency of the technique could be achieved through practicing in laboratory with silicone tube and live animals.

Superiority of living animal models in microsurgical training: beyond technical expertise

Background

Many studies are investigating the role of living and nonliving models to train microsurgeons. There is controversy around which modalities account for the best microsurgical training. In this study, we aim to provide a systematic literature review of the practical modalities in microsurgery training and compare the living and nonliving models, emphasizing the superiority of the former. We introduce the concept of non-technical skill acquisition in microsurgical training with the use of living laboratory animals in the context of a novel proposed curriculum.

Methods

A literature search was conducted on PubMed/Medline and Scopus within the past 11 years based on a combination of the following keywords: “microsurgery,” “training,” “skills,” and “models.” The online screening process was performed by two independent reviewers with the Covidence tool. A total of 101 papers was identified as relevant to our study. The protocol was reported in line with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement.

Results

Living models offer the chance to develop both technical and non-technical competencies (i.e., leadership, situation awareness, decision-making, communication, and teamwork). Prior experience with ex vivo tissues helps residents consolidate basic skills prior to performing more advanced techniques in the living tissues. Trainees reported a higher satisfaction rate with the living models.

Conclusions

The combination of living and nonliving training microsurgical models leads to superior results; however, the gold standard remains the living model. The validity of the hypothesis that living models enhance non-technical skills remains to be confirmed.

Level of evidence: Not ratable.

Vein Graft Interposition: A Training Model Using Gradually Thawed Cryopreserved Vessels

INTRODUCTION

Microsurgical interposition of vein grafts is an extraordinarily filigree surgical technique, which requires both sound theoretical knowledge and solid manual skills. Although there are a large number of training models, the majority of these are either relatively expensive, technically complex, or employ synthetic materials with poor resemblance to human tissue. The authors' model allows training of ex vivo vein graft interposition on gradually thawed cryopreserved vessels and it, therefore, is cost-efficient and readily available when needed. Furthermore, it respects the 3R-principle (Reduce-Refine-Replace), as it is based on rat cadaveric vessels.

METHODS

Three trainees with basic microsurgical experience, but without prior performance of vein graft interpositioning, were chosen to perform 20 femoral vein graft (5 mm) interpositions into femoral artery defects. The patency and leakage rate served as qualitative variable and operation time as a quantitative variable for efficiency control.

RESULTS

For the first half of trials, the trainees had a patency failure rate of 50% and for the second half a rate of 13.3%. The leakage rate noticeably decreased from 44.4% in the first half of trials to 10% in the second half. Although the trainees needed 60 minutes on average for their first 10 trials, they improved to 51 minutes for their last 10 anastomoses.

CONCLUSION

The authors' microsurgical model offers a simple, low-cost simulation training, specifically designed for learning of vein graft interposition into arterial defects. The model is associated with a high learning curve, based on an objective control of the anastomoses by assessment of the patency, leakage, and operation time.

Epineurial Nerve Coaptation: A Biological Nonliving Training Model Using Gradually Thawed Cryopreserved Sciatic Nerves

The authors present a novel biological nonliving epineurial nerve coaptation training model, which allows cost-efficient practicing on organic mammal nerves and offers an objective performance control on the basis of successful suturing and respecting the 3R model.Anatomic dissection of 40 rat cadavers was performed. Four residents without prior microneurosurgical experience were included. Each trainee performed 20 epineurial nerve coaptations. The number of successful sutures served as qualitative variable and operation time as a quantitative variable for efficiency control.The rate for successful sutures was 51.9% in the first half of trials and improved to 94.4% in the second half. Whereas, the trainees needed a mean time of 34 minutes for the first 10 coaptations, the last 10 coaptations were performed within 24.5 minutes.The authors' presented model is an easily accessible, low-cost microneurosurgical simulation model, allowing a realistic and instructive performance of epineurial nerve coaptation. Because cadaveric nerves are used, an approval of the local ethics committee is not needed. Furthermore, anatomic knowledge about the topography related to the harvest of the sciatic nerve of rats is provided in this study.

Evolution of an evidence-based supermicrosurgery simulation training curriculum: A systematic review

BACKGROUND

Supermicrosurgery (SM) involves operating on vessels with calibers from 0.3-0.8 mm. SM requires skills beyond those of conventional microsurgery. Current microsurgery courses do not prepare a junior surgeon for such a challenge. Several models have been developed to assist in the early learning curve, but their true purpose, benefit, and validation have not been addressed. This systematic literature review summarizes the existing SM simulation models, and their likely impact on microsurgery training for small-caliber vessel-based procedures is assessed.

METHODS

An electronic literature search was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. From the literature search, 90 potential articles from MEDLINE and 300 articles from other databases were identified and screened. Twenty-five studies were screened against the inclusion criteria by two independent reviewers for a final critical analysis.

RESULTS

Thirty-six articles were included in the reviewing process, and 15 SM simulation training models were identified. The simulation models were classified as nonbiological or biological and as ex vivo or in vivo. None of these models demonstrated validity. However, critical analysis of the full-text articles established the clinical correlation of each model along with the specific skill demonstrated. A novel ladder-based curriculum was established. Further, an expert's questionnaire generated a Likert scale and the clinical impact of each SM simulation training model.

CONCLUSION

This is the first review to highlight the clinical relevance of SM models and the need for validation. Currently, a variety of training models in SM appear to enable the acquisition of specific skills, and the clinical impact of a selection is recognized in a proposed SM simulation training curriculum.

Supermicrosurgery: History, Applications, Training and the Future

Supermicrosurgery, a technique of dissection and anastomosis of small vessels ranging from 0.3 to 0.8 mm, has revolutionized the fields of lymphedema treatment and soft tissue reconstruction. The technique offers several distinct benefits to microsurgeons, including the ability to manipulate small vessels that were previously inaccessible, and to minimize donor-site morbidity by dissecting short pedicles in a suprafascial plane. Thus, supermicrosurgery has become increasingly popular in recent years, and its applications have greatly expanded since it was first introduced 20 years ago. While supermicrosurgery was originally developed for procedures involving salvage of the digit tip, the technique is now routinely used in a wide variety of microsurgical cases, including lymphovenous anastomoses, vascularized lymph node transfers and perforator-to-perforator anastomoses. With continued experimentation, standardization of supermicrosurgical training, and high quality studies focusing on the outcomes of these novel procedures, supermicrosurgery can become a routine and valuable component of every microsurgeon's practice.

A New Synthetic Model for Microvascular Anastomosis Training? A Randomized Comparative Study Between Silicone and Polyvinyl Alcohol Gelatin Tubes

INTRODUCTION

Assessment of a resident's microsurgical competency with the rodent model remains the current gold standard. However, cost and ethical issues related to animal welfare may limit training opportunities. Therefore, synthetic alternatives such as silicone tubes have been developed to provide easy access to training, shorten the learning curve, and have been incorporated into microsurgical courses as a low-fidelity model for basic skills acquisition. This study compares the use of polyvinyl alcohol (PVA) gelatin tubes with silicone for resident microsurgical training.

MATERIAL AND METHODS

Residents were randomized into silicone (S) or PVA (P) groups and underwent the same training. Following basic instruction, microsurgical anastomoses were performed with the rat's aorta or carotid artery or both. Performance was assessed using the Objective Structured Assessment of Technical Skills (OSATS) score and 5 different items to assess the quality of the anastomosis. Posttest questionnaires were also conducted for qualitative assessment of both students' and trainers' experience with silicone and PVA in comparison with rat vessels.

RESULTS

OSATS score in Group P was higher than Group S (18.2 ± 2.6 vs 16.6 ± 2.5, p = 0.015). Results of anastomoses were similarly better in Group P based on OSATS score (19.3 ± 1.2 vs 17.7 ± 0.7, p = 0.027). Subjectively, both students and trainers found that PVA tubes resembled the rat aorta more closely than silicone. The number of rats used was also significantly lower in Group P than Group S (65 vs 75 total, p = 0.023).

CONCLUSION

PVA gelatin tubes may be a viable alternative to silicone for microsurgical training because this synthetic model mirrors better rat vessels and can improve training performance based on objective assessment while using less animals overall.