Waste Intercostal Neurovascular Bundles Used for Microsurgical Skills Training: Beneficial Inspiration?

Microsurgical techniques are becoming more and more important to modern surgery. Microsurgery constitutes the basis of many surgical specialties, such as hand surgery, transplantation surgery, plastic surgery, and neurosurgery, among others. To an increasing extent, junior surgeons need to acquire microsurgical skills to pursue their surgical careers. However, factors such as law, time, and cost can limit the opportunity for or access to microsurgical skills training. Ilie and Chan et al[1] [2] conducted a review of the literature, summed up several nonliving training models, and pointed out that none of the models are sufficiently integrative. An optimal model closely simulates real-life conditions so as to facilitate skills transfer, and it is also cost-effective.

In this context, we explored the waste intercostal neurovascular bundles of common adult dogs to be used for microsurgical skills training. These dog “spare ribs” came from common dogs that had been used for other scientific research without biohazard and that had to be sacrificed because of specimen collection (Animal protection approval was granted by the Institutional Animal Care Committee). It was attempted to convert the waste into an optimal training resource to reduce expenditure and to reduce the number of animals used for microsurgical skills training. The training model conformed to the 3 R's principle of experimental animals used (3 R's: reduce the number of animals used, replace as many as possible with model, and refine the experimental design).[3] The training strategy has been confirmed to be effective through practice. The main aim of the article is to offer a beneficial inspiration: how to convert some waste experimental animal carcasses into teaching and learning resources. It must be emphasized here that large animals used specially for microsurgical skills training are not advocated absolutely.

First, we researched the intercostal anatomy of common adult dogs and found that the anatomical features of intercostal spaces are very similar to those of intercostal spaces in a human body. There is a neurovascular bundle in each intercostal space, which has a strict order: vein-artery-nerve from superior to inferior. The internal intercostal muscles in dogs are smaller than those in human bodies. The parietal pleura cover the inside. The neurovascular bundles can be revealed after the parietal pleura have been incised on the inferior border of the rib and after some connective tissues have been dissected. The diameter of the intercostal arteries, veins, and nerves is approximately 0.4 to 0.6 mm, 0.5 to 0.7 mm, and 0.9 to 2 mm, respectively, which is suitable for training microsurgical skills. The rib, including the neurovascular bundles and the part of the intercostal muscles, was cut into segments of about 5 to 7 cm, wrapped by cling film, and preserved under the condition of -20°C for training microsurgical skills. Of course, the fresh intercostal neurovascular bundles, providing better structure texture of the anatomy, were optimal materials on which to practice microsurgical skills. However, it was difficult to set a training schedule at the same time when animals were sacrificed for the sake of specimen collection. Therefore, it was essential to preserve the rib segments under conditions of low temperature. According to our observation, if they were preserved at -20°C for 3 to 4 months, the rib segments still retained basic texture of anatomy and could still be used for practicing microsutures. Some blood coagulation might exist in the venous lumen, which did not affect usability because the coagulation was easily cleaned out. It was noticed that the wall of the vein collapsed markedly owing to the thin wall and decreased flexibility after cryopreservation, and that the artery and nerve remained little changed under surgical microscope.

The Training Program

The novices with no previous exposure to microsurgery started to practice their microsurgical skills on the intercostal neurovascular bundles when they had acclimatized themselves to the proper use of the micro instruments and performed microsutures on medical gauze under a surgical microscope.[4] First, the trainees trained on intercostal nerve sutures because of their thicker diameter, and then they trained on intercostal artery anastomosis when they had acquired basic microsurgical techniques and better hand-eye coordination under the microscope. Intercostal vein anastomosis training was undertaken last because of the thin wall, which presented the greatest challenge. When the trainees achieved better proficiency, they might suture vein, artery, and nerve one after another at the same time. In this way, trainees' performance was similar to the manipulation procedures of replantation of amputated finger. In other words, every step of a clinical micro-operation (e.g., macrodissection, microdissection, adventitial stripping, approximator placement, etc.) was simulated against a background of real biological tissues. Self-evidently, this training model provided a high-fidelity simulation that contributed to a high degree of transferability of microsurgical skills. In addition, the anastomosis satisfaction (patency and leakage) could be verified by injecting dye solution into a vessel lumen from the end of the rib segment. Of course, there were some imperfections in the present training model, one of which was neither blood ejection nor risk control of thrombosis, and another of which was the changes of vein wall after cryopreservation. In fact, the behavioral skills of trainees were required to be more workmanlike for vein anastomosis owing to the decreased flexibility after cryopreservation. That is, the collapse of venous wall compelled trainees to improve their manipulation skills rapidly.

To summarize, the intercostal neurovascular bundles of larger animals used for other research offer a convenient alternative for basic microsurgical skills training that is feasible, reliable, repeatable, and cost-effective.

• References

• 1 Ilie VG, Ilie VI, Dobreanu C, Ghetu N, Luchian S, Pieptu D. Training of microsurgical skills on nonliving models. Microsurgery 2008; 28: 571-577
• 2 Chan WY, Matteucci P, Southern SJ. Validation of microsurgical models in microsurgery training and competence: a review. Microsurgery 2007; 27: 494-499
• 3 Kroeger M. How omics technologies can contribute to the ‘3R’ principles by introducing new strategies in animal testing. Trends Biotech 2006; 24: 343-346
• 4 Demirseren ME, Tosa Y, Hosaka Y. Microsurgical training with surgical gauze: the first step. J Reconstr Microsurg 2003; 19: 385-386