Artery and colon Project swith Scaffold

Discussion in 'Show off' started by Henry feldman, Mar 24, 2017.

  1. Henry feldman

    Henry feldman Well-Known Member

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    Sorry about the super long post, but it was a busy maker day!

    So some major updates this week, as my "real job" of software development and being a doctor had a slight lull, so did a huge amount of medical printing and molding this week. This post will be an update on the artery molding project and the colon project. I had to laugh that E3D had this big post about using scaffold for mold making, since I've now been doing that for many, many months, but yep, works great. All the printing for both projects is on the BigBox.

    So first off if you recall we have blood vessels 3D reconstructed from CT scans (angiograms) which I print in Scaffold to form the lumen (inside) of the arteries and veins. Our intention was to be able to ultrasound and use fluoroscopy on these blood vessels inside various body parts to perform procedures in training situations. So this week we decided to make it happen; we failed by learned a lot, and have a new offshoot that works even better:

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    Mold outer box in PLA (just a test block) and the distal iliac and femoral arteries in PVA. You can see I have gotten really good at super clean scaffold mold cores! Very smooth (the bumps are cholesterol plaques and offshoot arteries I cut off the model)

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    We coated the vessels in platinum cured mold making silicon from Reynolds Advance (Smooth On Silicones). Took multiple dripped on coats over multiple days. It's blue at baseline, so we couldn't color it...

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    Then we hot-glued the coated artery in the mold box so it was sealed against the edges. And then poured in our standard 50-weight silicone with skin color dye.

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    We picked the ends off the Scaffold so that the water could attack the PVA core (very optimistic of us). So over 36 hours we hit it with our high-pressure hot water hose repeatedly, which certainly blew a lot of PVA gunk out, but it never really got totally clear.

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    Then my colleague Jeff from interventional radiology tried ultra sounding it with, which never quite worked, as the 50 silicone just is too dense, so we are trying other silicone for the body tissue. But he was able to successfully insert a needle under guidance into the lumen but it was a battle.

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    We were able to snake a bronchoscope up there (it's like a $20000 bore scope) and there is our needle (and lots of little bits of PVA on the walls)

    Luckily Jeff said, hey let's try it under fluoroscopy (x-ray camera) and see if we can use it to practice a totally different procedure which is a blind inserted billiary drain. It's clearly the wrong shape (it's a large artery, but could we see and inject dye in a realistic manner).

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    So with a surgery resident in tow who wanted to play with the fluoroscopy (and it's perfect since he's a noob at fluoroscopy guided procedures since that is not his specialty), we ran upstairs and threw it on the table.

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    You can see the needle coming in on the left into the branch of the artery (which is showing up clearly as it is full of air right now) and injecting dye (black). You can also tell that the artery is clogged with PVA since it is a narrow little section. But we did do a pretend billiary drain insertion which worked out great. So while we research silicones (it's quite complicated as they also have to be chemically compatible with our other components) we are making the easy part (haha) which is a practice billiary drain kit. And that was just one of the projects mostly done today!

    Believe it or not, we did a second molding project at the same time as the above (pretty sure I am going to die of some exotic cancer due to all the silicone that got splashed on my skin despite gloves, etc)... So if you recall way back, we were also working on a molded colon. Well that got a lot of attention this week. First off I tromped off the OR with my colleague Tom (one of our colorectal surgeons) to look at the much more closely than in prior cases at a colon.

    since the case was not a cancer case, I could actually examine and cut into the specimen after removal (still can't "lose" any part, but can at least examine it). And after measuring the thickness, color and consistency of each layer (super important to the structure), off to CAD/printing and the sim center for some molding.

    First step was to see if we could make the colon suturable, and in the colon only the submucosa can hold a stitch. So it is important as a training aid, that any other layer tear, and that the submucosa be absolutely correct. So in case you are wondering what simulates tough connective tissue? It is power mesh. That is the fabric used in the crotch of women's bathing suits. Totally amazing stuff, which is almost untearable, incredibly fine weave mesh, super thin, flexible beyond belief and has other interesting mechanical properties. And it bonds great to 50 weight silicone.

    So first we made a big colon (like horse sized) to see how it would work (same mold as before):
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    So we laid out the power mesh first, and pour out some silicone.This actually turned out to be too much, but this was a quick test

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    It needs to be stippled in to make best contact

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    Skim coat on the mold core

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    Powermesh rolled over the mold core, now your colon has a connective tissue stripe called the Tinea Coli which is way, way less stretchy, so we rolled the power mesh around an endotracheal tube stylet and then flattened that out. Worked amazingly well

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    Into the mold for another 40 minutes

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    Sutures hold perfectly, and you can do full and half-thickness sutures, but super shallow tear out (as they should). Everyone commented how realistic the suturing experience was (other than this being huge)

    So now to produce a small segment of proper size colon, we used a real anatomic model of the colon to scale, with the core printed in PVA again

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    Mold core and power mesh

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    Waiting for final coat

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    Final coat with snazzy color scheme (looks sort of like colon, plan a different color technique with a better mold later)

    Soon to make a better outer mold (meshmixer keeps crashing on this model), and onto the full size colon. But in the mean time. this is super quick to make and the residents can practice anastomosis (attaching the ends together). This also holds staples, so they can use an endo-stapler, but those are insanely expensive compared to expired suture material. We hope to get these down to around $1 per practice.
     
  2. jfb

    jfb Well-Known Member

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    Great write up Henry. Thanks.
     
  3. mike01hu

    mike01hu Well-Known Member

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  4. Spoon Unit

    Spoon Unit Well-Known Member

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  5. Jasons_BigBox

    Jasons_BigBox Well-Known Member

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    Incredible work Henry, always interesting to see real applications.
     

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