Interactive Cardiovascular and Thoracic Surgery 2:697-701(2003)
© 2003 European Association of Cardio-Thoracic Surgery
A model to assist training in thoracoscopic surgery
Akinori Iwasaki*,
Kan Okabayashi and
Takayuki Shirakusa
Second Department of Surgery, School of Medicine, Fukuoka University, Jonan-ku, Nanakuma 7 chome 45-1, 814-0180 Fukuoka, Japan
* Corresponding author. Tel.: +81-92-8011011; fax: +81-92-8618271
akinori{at}fukuoka-u.ac.jp
Received April 2, 2003;
received in revised form August 1, 2003;
accepted August 26, 2003
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Abstract
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VATS is a relatively new technology that has become the standard for therapy and diagnosis of lung disease. However, there are few detailed descriptions of VATS education and training in the available literature. We have thus made a thoracoscopic trainer that is very helpful and practical for refining thoracoscopic skills. The mechanism of this trainer is based on circulating vessels in a lung, which were covered with a plastic replica of the human body. A thoracoscope and minimally invasive instruments are able to access the lung from the trocar in a replica that is life sized. The trainer consists of three disposable components: artificial pulmonary vessels, the lung, and parts connecting to the heart pump. The model was tested in a seminar of minimally invasive lung surgery, and compared to the Wet-Lab. The model was shown to reproduce the human anatomical situation in a video assisted thoracic lobectomy. Due to its perfect simulation, quality, simple handling, and economic benefits, this trainer serves to enhance the training of thoracic surgeons, simultaneously decreasing the number of animal experiments. It is recommended for all surgeons, students, and medical assistant trainees embarking on thoracoscopic work.
Key Words: Thoracoscopic surgery; Training; Pulsatile model
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1. Introduction
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Video-assisted thoracoscopic surgery (VATS) is a relatively new technology that has become the standard for treatment and diagnosis in thoracic surgery [1–3]. In spite of the validity and encouraging results of this approach, this technique is complicated compared to standard thoracotomy. One reason for difficulties and greater risk is that anatomic lung resection requires resection of hilus vessels and bronchus with an indirect view of the operative field. However, we believe that these procedures will prove safer and easier if the practitioners are well trained, with sufficient experience. Surgical techniques for laparoscopy can be studied using animal laboratories or training models [4–6]. But until today, there have been few detailed descriptions of a thoracoscopic training model. Therefore, it is important to develop a realistic artificial model for anatomical lung resection. This article presents the first new artificial training system for major VATS resection, with an emphasis on development and results.
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2. Material and methods
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The right upper lobectomy is thought to be a good standard and a good case for an example. First, we plan a complete VATS right upper lobectomy using our trainer. The main components of our model consisted of a blood flow source, vessels, bronchus, lung, and a human hemi-body (Fig. 1): this body is a replica of the human hemi thorax, and was made of plastic. Ten holes (1.5 cm in diameter) located in each antero-axillar, mid-axillar, retro-axillar line, were available for the thoracoscope and for thoracoscopic instruments, clamps, scissors, vascular or lung staplers, loop wires, and other devices. When this body was closed to contain the system components, the inner cavity blocks external light. It can be visible only on insertion of the thoracoscope. However, the model was not air-tight. Each hole sealed out light through an entrance valve. After setup of the inner components using the basic equipment, the covering body could be quickly and easily placed down from the foot side (Fig. 2a).
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Fig. 1 Schema of total model. (A) Pump; (B) pulmonary artery inflow to the lung; (C) blood reservoir; (D) lungs, featuring a hollow configuration; (E) pulmonary vein outflow from the lung.
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Fig. 2 (a) Before covering the body, inner components consisting of the lung and pulmonary vessels, which circulate and connect to the heart pump. (b) Before circulation. (c) V, pulmonary vein; A, pulmonary artery; T, trachea; B, upper bronchus. (d) Monitor and thoracoscope were set near the model used in the seminar.
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2.1. Lung components
This right model had two separate lungs, upper lobes, and middle and lower lobes. These lungs were made of polyurethane. After performing a right pneumonectomy, we measured and rescaled for adult right-lung tissue. According to the procedure, we first made a replica of the entire right lung using dry clay. Second, we made casts of two different sizes by these different sizes induce to lung lumen. Lung volume was constant at 1800 ml and the thickness of the lung wall is 5 mm. The lung can be kept inflating naturally. Because of the thin wall and lumen, it would be easy to grasp, resect, or implant circulatory vessels in the lung. The right upper mediastinal side has a slit for entry and exit vessels and bronchus (Fig. 2b).
2.2. Vessels
The artificial pulmonary vessels are made of polyvinyl chloride (PVC) and designed from a mold; these vessels were connected to the heart pump. Artificial vessels consist of two pulmonary arteries and veins. The wall thickness was 0.1 mm and the diameter tapers from 12 to 5 mm. These are easily attached to the bronchus. Artificial blood flow can be circulated into the pulmonary artery and back to the pulmonary vein (Fig. 2c). In accordance with the actual human anatomy, simulated blood flow is readily fed from the beating pump to accumulate in the lung component. A reservoir was located peripherally between the artery and vein to prevent collapse of the vessels. Furthermore, there are two bypass circuits between reservoir and after the pump, which released the pressure when the vessels were closed by ligature or stapling (Fig. 2d).
A bronchus made of plastic was fixed to the base of the body. A peripheral bronchus made of PVC can be connected to the plastic parts. It is useful for a bronchial approach of a suture or stapler (Fig. 2c).
2.3. Pump
The beating blood pump, which had a unidirectional valve and chamber, can reproduce human pulmonary circulation. Stroke volume can be selected from 0 to 80 beats/min, with blood flow of 0–6400 ml/m, at approximately 50–70 ml per beat. It has the same circulatory dynamics as the human body, including blood flow and blood pressure, and can reproduce pulmonary circulatory blood flow. Inflow takes place through the artificial pulmonary artery and outflow is through the vein. This enabled us to reproduce the human anatomical situation for a right upper lobectomy. Overall configuration of each part is shown in Fig. 2d.
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3. Results
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The surgeon in our training seminar tested the trainers. At first we showed videotaped demonstrations of the trainers used in typical cases of lung cancer. Thirty thoracic surgeons and five chest specialists attended the seminar at the 43rd meeting of the Japan Lung Cancer Society.
Five monitors and thoracoscopes were set up at different tables, each with one of our trainers (Fig. 3a). Each of the four groups (one setup was for backup) began a right upper lobectomy, following an explanation of the structure of this model and its similarity to the human anatomy.
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Fig. 3 (a) Set up of meeting place for training; (b) VATS view for training bullaectomy (arrow indicate the artificial bullae).
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Twenty surgeons also attended the thoracoscopic seminar at the 103rd meeting of the Japan Surgical Society. They have carried out lobectomies shorter than before the seminar. Each group has trained in lobectomy with this model at 1.5 h.
The vessels in this case could accurately reproduce clinical operations due to the pulsation of artificial blood flow. All doctors testing the models experienced the actual results and tension resulting from injury to vessels. When a vessel was damaged, massive bleeding occurred. This was a good experience, however, in terms of demonstrating how hemostasis occurs. The injury was controllable. This model was thus useful in training for ligation and dissection of the vessels. We suggested 2-0 silk and one extra-corporeal knot should be tied and sutured with a thoracoscopic instrument (Fig. 4a). After this procedure, there was no leakage of blood from the distal or proximal edge. Furthermore, one more advantage of these vessels is that they can be easily accessed with an endoscopic vascular stapler (Fig. 4b).
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Fig. 4 VATS view for right upper lobectomy. (a) Pulmonary vein which was sutured with thread; (b) with stapler; (c) clinical view of approach for pulmonary artery; (d) just before upper lobectomy; RUL, right upper lobe; RLL, right lower lobectomy.
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VATS insertion in actual clinical practice is shown in Fig. 4c. This automatic closure and suture proved to be of sufficient durability. Briefly, the pulmonary veins were first dissected, the branch of the pulmonary artery was dissected by the ligature or vascular stapler, and the next step was the upper bronchus. After performing serial movement and maneuver, the inter lobar connection was divided and finally can take out this upper lobe (Fig. 4d). As a reference we show one of the other training views, which was stapling bullaectomy (Fig. 3b).
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4. Discussion
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VATS is a relatively new technology that has become the basic standard of care for lung disease. This approach causes less inflammatory reaction and pain, and also offers cosmetic benefits [7,8]. It presents significant advantages to the patient and reduces overall costs. However, the value of this approach aside, the problem of education must be considered. Today, training in the basic skills of minimally invasive surgery is performed using expensive animal models or in operating rooms. We made the vessels from PCV because of the cost benefit and ease of manufacture. The cost of the disposable vessels was $200 and re-usable bronchus or lung is $100, respectively, when performing a lobectomy. If the other training, i.e. management of pleural adhesion, treatment of bullae, diagnostic procedure, it can be made cheaper. Our training models were designed to facilitate the acquisition of skills in the performance of VATS lobectomy. One of the most challenging aspects of thoracoscopic surgery is intracorporeal suturing and knot tying with pulmonary arteries and veins leading to and from the heart. We designed our model with this in mind; i.e. as one ideally suited for educational purposes. We suggest that the trainer is the most suitable for the surgeon who passed for graduation 4 years or more. Due to the perfect level of surgical simulation, the trainer serves to enhance the training of surgeons, while simultaneously decreasing the number of animal experiments and surgical errors. Because our model is easily mobile, surgeons can practice their thoracoscopic skills at convenient times and locations. Previously, no training models were available with pulsatile lungs to facilitate the acquisition of greater skill. Now, however, residents and students can practice these operative procedures whenever they need to. Also, in addition to surgeons, nurses and their assistant can also receive feedback using this system. It is difficult to analyze an objective test and preciseness of the procedure. Now we are evaluating the objective data from our model. In order to teach the proper response to hemostasis, the educator must instruct students on how to overcome this complication. With the disposable vascular and lung model housed in a compact model, thoracoscope and endoscopic instruments can easily be inserted from each point of access (each available trocar). A computer-based minimally invasive surgery trainer also may improve surgical skills [9,10]. We believe that the combined use of our model and computer-based trainers (i.e. ‘virtual reality’ trainers) will represent the ideal clinical approach. Robotic systems for cardiac surgery and for thoracoscopic lobectomies have now been introduced in clinical trials to facilitate minimally invasive techniques [11,12]. In such robotic surgery, education and training of surgeons will prove critical. Other VATS procedures, including lung cancer staging, wedge resections, the diagnosis and treatment of pleural diseases, the treatment of pneumothorax (as Fig. 3b), giant bullae, lung volume reduction surgery (LVRS) for emphysema, the diagnosis and treatment of mediastinal diseases, and various other procedures can also be addressed using our models (data not shown in this paper). Furthermore, it is possible to establish similar training programs for thoracic surgeons in every hospital.
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Acknowledgements
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The authors are very thankful to Mr Numazawa and Mr Honda from Senko Medical Co. (Japan) for their technical assistance.
doi:10.1016/S1569-9293(03)00198-1
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Abstract
1. Introduction