Practice makes perfect, but if you're a surgeon, truly realistic practice also means doing so at the patient's risk. To provide surgeons and students with an alternative to a living human being to work on, a pair of physicians at the University of Rochester Medical Center (URMC) have developed a way to use 3D printing to create artificial organs that look, feel, and even bleed like the real thing.

Mastering surgery means constant practice – not just by students learning the basics of how to stitch a wound, but also for even the most advanced surgeons to study and practice for a complex operation. Robots, models, and other simulators have been available in one form or another for over 50 years. For the most part, these simulators have been aimed at dealing with one part of an operation, such as anesthesia, using robotic surgeons, or the detailed study of an individual's anatomy for heart surgery or other intricate procedures, but none of them can simulate a surgical operation from beginning to end.


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The Simulated Inanimate Model for a Physical Learning Experience (SIMPLE) project looks to bridge that gap with artificial organs that can be used to construct entire artificial patients – or as much of one as is needed to practice operations. The invention of assistant professor in the Department of Urology, Ahmed Ghazi, and neurosurgery resident Jonathan Stone, SIMPLE was developed over a two-year period involving a great deal of trial and error.

The SIMPLE organs are made by using CAT scans or ultrasound images to produce digital models, which guide a 3D printer to form a solid model of the organ. This is used to make a mold, which is then fitted out with various soft plastic tubes and capillaries as needed, then filled with hydrogel. Since hydrogel is 70 percent water (the same as human tissue) it recreates a realistic heft and feel to the organs once they solidify.

In addition, color can be added and the hydrogel mixture customized to simulate the particular tissue of an organ, like a liver or muscle, or even lesions like tumors, while the organ can include ventricles, airways, and even blood vessels connected to bags of dye to simulate bleeding when cut. Hard plastic is also used for printing artificial bones and even skulls for a more realistic look and feel. And the inventors, in collaboration with University of Rochester Department of Biomedical Engineering have run the synthetic organs through a battery of tests to make sure that they have the same mechanical properties as living tissue.

URMC says that, at its simplest, these organs can be tailor made, so surgeons can study the anatomy of an organ to be operated on until they are completely familiar with its layout, arteries, veins, lesions, and all other relevant data before beginning. This way, surgeons can not only study surface features, but also slice open the artificial organs to examine cross sections or practice preliminary surgical ideas.

Another application of the organs is in student training. Instead of just watching operations, students can be presented with a complete torso filled with realistic organs that they can operate on themselves from first incision to final sutures. This way they can learn the practical problems of not only working on a particular organ, but also cutting through fat and muscle, finding it in the confusion of a body cavity, and clearing things away so work can begin. According to Stone, this approach is not only useful for future surgeons, but for other medical students who may need a hands-on appreciation of what surgery involves.

The assembled artificial patient can even be used in operating rooms equipped with robotic surgeons. According to the inventors, when set up, the practice operations often confuse passersby as being a real one on a real patient, and can even confuse surgeons looking through the robot's eyepieces at the artificial organs.

One area where Ghazi and Stone see SIMPLE as having important applications is to help surgeons not only hone their skills, but also to plan and rehearse delicate operations with a precision and realism not previously available. The surgeon can even have model organs made up to copy the anatomy and pathology of their patient in a realistic torso, so they can do detailed dry runs to make sure that everything runs as planned and in as little time as possible. Though doing this sort of practice is still a thing of the future, Ghazi is already using the technique for kidney surgery and sees it as having general applications.

"Surgery is often like a Pandora's Box," says Ghazi. "You don't know what is inside until you open it up. The fact that we could someday have surgeons practice procedures on these models before going to the operating room helps eliminate the unknown, increases safety, and improves the quality of care. Patients can, in turn, reassure themselves by asking their surgeons, 'how did the rehearsal go yesterday?' That is going to be the future of surgery."

The video below discusses SIMPLE.

Source: University of Rochester Medical Center
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