Video-assisted thoracic surgery lobectomy simulation and training with a new human cadaver model

Video-assisted thoracic surgery (VATS) lobectomy is the gold standard for the treatment of early-stage lung cancer. The use of surgical models for training and simulation in minimally invasive surgery simulation is an integral part of surgical education and skills acquisition for residents, and also for more experienced surgeons. Live animals are still the most frequently used realistic surgical models. 

In this video tutorial, we demonstrate the use of a new human cadaver model with the aim of replacing the live animal model without compromising the fidelity of the simulation. 

To prepare the cadaver, selective cannulation of the heart was performed to fill the pulmonary vessels with a gel used to improve the visibility and tactile feed-back of the vessels, and to simulate any bleeding complications. The complete cadaver was then used for the simulation, with all the same instruments and devices required in normal clinical practice, to demonstrate and practice both surgical and non-surgical skills for VATS lobectomy.

In our opinion this model provides most of the features necessary for a valid surgical simulator and allows realistic training for VATS lobectomy. We believe that the cadaver model can be an effective alternative to anesthetized animals for VATS lobectomy training and simulation.

In recent years VATS lobectomy has increasingly replaced the open approach as a gold standard technique for lobectomy [1, 2]. Different models have been used to simulate VATS lobectomy for training purposes. The most frequently used model is a live anesthetized animal [1, 2, 3, 4]. However, ethical concerns about using animals for surgical simulation are becoming more widespread, and regulations governing their use are increasingly stringent, leading many institutions to adopt the 3Rs principle (reduction, refinement and replacement) [5]. 

The 3Rs support the development of realistic non-animal-based training models to address the ‘replacement’ principle. Very complex synthetic models with or without blood-like active perfusion have been used to simulate VATS lobectomies, but obviously the realistic nature of these models is highly questionable [1,4]. Learning from our academic experience in surgical training, we have tried to create a simulator model that is effective for teaching and practicing VATS lobectomy skills, for both surgical residents and medical students, and that does not depend on the use of live animals.

The day before the VATS simulation the cadaver was prepared with selective cannulation of the main pulmonary artery and left atrium using standard aortic extracorporeal circulation cannulas. Through the cannulas a colored gel was used to fill the pulmonary vessels, which would then be prepared and sutured the following day during lobectomy simulation (Figures 1 and 2). 

On the day of surgery the cadaver was placed in a standard lateral decubitus position (Figure 3) and draped as in standard clinical practice, simulating both surgical and non-surgical skills, such as surgical field preparation, instrument and device placement, operator positioning, and instrument handling (Figure 4). 

For each cadaver we simulate one lobectomy on the left side and two lobectomies on the right side (middle lobe + upper lobe or middle lobe + lower lobe). In this way at least two surgeons are able to perform a VATS lobectomy as the first operator. All the steps of the procedure were performed as in standard clinical practice.

Recently, Tong et al [4] described in detail all the features that must be respected by a simulation model when it comes to teaching a particular skill. Specifically, they outlined a series of validation parameters, namely fidelity (how the simulator feels to the student), content validity (accuracy of the steps performed), construct validity (ability to discriminate between learners of different levels), and predictive validity (correlation between the skills-level achieved with the simulator and the skills-level achieved performing the same procedure on a real patient). 

For VATS lobectomy simulation and training we decided to use a cadaver for several reasons. First of all, we wanted to respect the replacement principle about animal models. In addition, it is clear that a human cadaver is the most realistic model for simulating patient positioning, trocar placement, and anatomy correspondence. In the past, human cadaver torsos were used for VATS simulation, but there were several reported drawbacks, including the absence of vascular distension with difficult identification of the operative landmarks and the often poor preservation of the cadaver, with compromised tissue quality [1, 3, 4]. 

We have tried to address the vascular problem by using selective cannulation of the main pulmonary artery and  the left atrium, before injecting the gel, and in this way we were able to maintain fully filled pulmonary vessels, without parenchymal extravasation. This technique makes the lobar and segmental arterial and venous vessels clearly visible and distinguishable during all the procedures. The gel we used was colored and clearly visible in the surgical field in cases of vascular injuries. The simulator assistant could increase pressure selectively on the arterial or venous side to make the extravasation of the colored gel from the vascular lesion more evident, and better simulate the bleeding. 

In our model the trachea was intubated with the aim of simulating pulmonary inflation during the procedure, in particular to check correct bronchial closure and stump control. 

During the simulation we used the same surgical instruments that are used in the clinical setting. 

This human model allows learners to also simulate lymphadenectomy, which represents one of the most critical issues for inexperienced surgeons. Importantly, we set up the model to simulate also the “non-technical skills” that in a normal operating room are considered crucial, alongside their surgical counterparts. Using a standard surgical bed and a full human cadaver we simulate realistically the patient positioning, the surgical field dress-up, the video-column and devices positioning, and the back table preparation. 

A further advantage of our model is the possibility of using the same cadaver to perform more than one VATS procedure. And after completion of the VATS procedure training, the same cadaver can be used to teach thoracotomy to young residents and medical students or simulate an emergency thoracotomy during VATS conversion in a major bleeding scenario. 

In conclusion, we find our model to be a very accurate way to simulate all the aspects of a VATS lobectomy necessary to prepare for the real surgical procedure. Our cannulation technique gave us a realistic surgical field with well-filled vessels that allowed us to perform a truly realistic VATS lobectomy step by step. Of course, the preparation of this model can be time-consuming and it is organizationally complex, but on the other hand it is efficient because the same cadaver can be used for many procedures and purposes. In our opinion, this model can be a good alternative to live anesthetized animals. 

Fresh frozen cadavers provided by the Body Donation Program “Donation to Science” of Padua University [5] were used for our study. All the procedures performed in this study involved human bodies from the Veneto Region Reference Center for the preservation and use of gifted cadavers (DGR-Veneto-Region n.245, March 8th,2019; N°389897), in full compliance with national laws and with the ethical standards of the regional/national research committees.

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The authors express their deepest gratitude to the people and families whose support for the Body Donation Program “Donation to Science”, at the University of Padova, made this research possible. They hope that the results of this study are useful to the whole scientific community, and in this way truly honor the legacy of the body donors.

None declared.

Authors
Andrea Dell’Amore^a, Marco Schiavon^a, Rafael Boscolo Berto^b, Alessandro Pangoni^a, Raffaele De Caro^b, Federico Rea^a, 

Author Affiliations
^aThoracic Surgery Unit, Department of Cardiac, Thoracic and Vascular Sciences, University of Padova, Via Giustiniani 2, 35128, Padova, Italy.
^bDepartment of Neurosciences, Institute of Human Anatomy, University of Padova, Via Giustiniani 2, 35128, Padova, Italy.

Corresponding Author 
Andrea Dell’Amore MD
Department of Cardio-Thoracic and Vascular Sciences,
University of Padova, Via Giustiniani 2, 35128, Padova, Italy. 

Phone: +39-0498212237
Email: dellamore76@libero.it