A Novel Training Model For Internal Mammary Artery Preparation In Breast Reconstruction: The Infused Pig Chest Wall "Sandwich"
Weifeng Zeng, MD, Ruston J Sanchez, MD, Kirsten A Gunderson, MS, Nicholas J Albano, MD, Aaron M Dingle, PhD, Samuel O Poore, MD, PhD.
University of Wisconsin-Madison, Madison, WI, USA.
PURPOSE: Preparation of the internal mammary artery (IMA) as a recipient vessel is crucial in free flap breast reconstruction. For surgical residents, there is a lack of opportunity for practicing this skill intraoperatively. Practicing the procedure using live laboratory pigs reportedly provides realistic simulation, but is expensive and inconvenient. We aimed to develop a simple, inexpensive, and effective simulator for IMA preparation.
METHODS: Chest walls were harvested from adult Wisconsin mini pigs at the termination of other projects at UW- Madison. This included the sternum and 15 centimeters of each side of the first through seventh ribs bilaterally. Skin and fat above the pectoralis muscle were removed. The proximal and distal ends of the IMA were cannulated with angiocatheters. The proximal IMA was attached with tubing to a "blue blood" infusion bag (500mL fluids mixed with 1cc blue food dye) and placed at gravity to mimic real-time blood flow. A collection bag was placed below the field and connected with tubing to the distal IMA. The complete model consists of four layers. The chest wall is first mounted to the surface of one mannequin, covered with a layer of yellow sponge which mimics human subcutaneous fat and adds realistic depth to the model. The final layer on the top is a second plastic mannequin shell with a window exposing the area of third, fourth, and fifth ribs. And then it is sandwiched by a second identical mannequin shell with cut out windows exposing the parasternal area of ribs 3, 4, and 5 bilaterally. To perfuse, running the drip at approximately ten drops per minute was efficacious.
RESULTS: This infused pig chest wall "sandwich" IMA preparation simulator could be set-up in any microsurgical suite. Residents can practice IMA preparation including elevating the perichondria, removing cartilage, dissecting the IMA, and anastomosing the IMA. With the perfusion of "blue-blood", the model provides immediate feedback on the quality of anastomosis.
CONCLUSIONS: This novel model can provide highly realistic simulation of IMA preparation. The effect of applying this model on improving the proficiency and confidence of plastic surgery residents will be studied in the upcoming educational study.
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