Homemade simulators

SOFsono dedicationFridge

Don’t we all love homemade food? Nothing like all kinds of yummy stuff in the fridge! But wait a minute? Fake bones in Jell-O? Cords and tubes sticking out of bologna roll? 5 boxes of dark blue gelatin? Modelling balloon wrapped in chicken breast and clingy plastic? And what is that zip-locked goo? None looks quite that edible, but the concept is brilliant IMHO! Just as brilliant and amazing as bedside ultrasonography itself.

Who on earth needs the expensive simulators?! Let alone affording them… I’m telling you – the magic you can whip up with some gelatin and related ingredients is pretty exciting. To be honest, I don’t think there is enough evidence that high-fidelity (meaning pricey) phantoms perform any better when it comes to transfer of simulation-learned skills into clinical practice.

SOFsono page banners homemade simI did some digging around the net and I came up with quite a few gelatinous or meaty inspirations for your ultrasound sim lab needs. Some are quite ballistic! Let me show you what’s out there! Please refer to the individual links for detailed recipes and tips, and let me know if you have any trouble getting to any particular phantom.

I’d say the biggest benefit comes with the models that help you hone some PROCEDURAL SKiLLS. The further the more I am convinced that familiarization with pathology can be achieved by scanning normal patients, while the abnormal images or clips are shown on a simple tablet or a laptop screen. I’ll cover this cheapest yet effective ultrasound sim lab some other time.

SOFsono gel

Whether training or working with real patients, there is no scanning without ultrasound gel! In the worst case-scenario you can always use spit (just imagine the looks 😉 you’d get), water, water-filled glove or a saline bag (as stand-off cushions), petroleum jelly or even lotion (your transducer won’t like it though).

However, you can also prep your own gel. Guar gum powder is much lighter than bottles of gel, and it is one less object that screams “Look, I’m a Medic!” Here is an awesome guar gum recipe, which is super easy to make! Now, if you’re operating on the African continent, you can also resource to bula, sorghum or cassava root flour for your sono-goo production.

SOFsono vascular access

I get it, you’re tough, and it’s best to train as you fight! But… Just in case you got bored with poking each other while practicing ultrasound-guided vascular access, there are some cool phantoms you could easily make.Vascular chicken devollaie1

My personal favorite is the chicken breast phantom. It takes 5 minutes to prep and it seems like a great model for group training sessions as it lasts for any 20 to 50 uses… If you stick with edible liquids inside those fake vessels and use new needles, you could possibly grill your models for lunch ;-). Don’t forget to remove the inedible parts prior to the cook-out!

Your other options are:

SOFsono nerve blocksHomemade tastes better - pork loin nerve block phantomUltrasound-guided regional anesthesia is a great addition to your pain management plan in prolonged field care. And that is why you should become a master of this skill. No need to get on each other’s nerves (with needles), though! Nerve block phantomYou can practice the sonographic neuroanatomy on your buddies, but keep it to meat and tofu blocks when training how to drive the needle, hydro-localize the “nerves” and inject the local anesthetic (use water if you plan on grilling your phantom 🙂 for dinner). The “meaty” models can be made with pork loin, pork roast, poultry breast or bologna (= polony) roll. No matter what material you use as your nerve bundle (wood, cable, cord, wet yarn or even cherry pull-n-peel Twizzlers), expect some posterior acoustic shadowing (as in the model here). It’s no big deal, and it doesn’t prevent you from practicing the procedure. Also, in order to create a more sturdy model, it’s probably better to take a whole block of meat and use a fillet knife to cut through it prior to nerve phantom insertion, rather than wrapping the meat around it.

SOFsono abscess drainageIf you rely on your clinical skills only, you might as well flip a coin when trying to distinguish every cellulitis from an abscess with surrounding cellulitis. It’s been shown that even seasoned clinicians are wrong in pretty much 50% of the cases. That’s why you should practice abscess recognition and drainage under ultrasound guidance:

As another alternative you could sandwich some pudding-filled small balloons between two pieces of poultry breast and wrap it in clingy plastic, just like the vascular access phantom.

SOFsono other phantomsTo be honest, we can build homemade phantoms for any kind of “needling” procedures, yet it always comes down to ultrasound-guided needle-work training. It’s all about improving hand-eye coordination, while watching the screen and not the hands… Frankly, I am yet to meet a SOF Medic with any shortcomings in this particular department! It’s not like you look at your hands when you shoot, so I think you’re better off running some case-based sim with real images of pathology! Focus on the diagnostic pattern recognition in pericardial effusion, tamponade, pneumothorax or pleural fluid – you already got the needle-probe-screen business… I just don’t see how such primitive pedicardiocentesis or thoracentesis models can help you get any better. Simply look at the picture in this thoracentesis simulation article. I cannot imagine that you’d put your screen (target) off to the side rather than in straight line of view… That hand-eye coordination in ultrasound-guided procedures is your second nature! That’s where you, Guys, rock!

And last 🙂 I am throwing in 2 nerdy ocular phantoms. Those might be worth the trouble, as repetitive and prolonged scanning of normal eyeballs is probably best avoided:

SOFsono cadaver lab

Whenever you have a chance to practice procedures in the cadaver lab, I’d encourage you to ask their staff to prep for ultrasound-guided pericardiocentesis. Here is a really good description on how to set it up. I must say that trying to perform a “reverse pericardiocentesis” by injecting fluid into the stiff cadaveric pericardium is like an exercise in futility, so use the above recipe for success ;-).

Performing a few ultrasound-guided endotracheal intubations, and confirming tube placement by temporary injection of saline into the cuff, are both opportunities too good to pass up. Make sure to get a few proximal nerve blocks and access some central vessels under real-time ultrasound guidance.

SOFsono tips & tricks

  • Being military and all – you shouldn’t have much trouble finding some ballistic gel for your phantom creations
  • Ballistic gel model is more durable, you can melt it down, and re-use it
  • Most phantoms can be made with readily available food and household items
  • If using food items, consider adding chlorhexidine or EDTA for bacteriostatic properties
  • Gelatin blocks made at a lower temperature result in a more durable phantom (if water is too hot – it can burn gelatin when added)
  • Use 10% (100 mg per cc of liquid) solution of gelatin (e.g. 100 g or gelatin per 1 L of water – do the math for the amount you need)
  • In theory you could also re-melt and re-use the gelatin blocks, but it doesn’t work as well as the ballistic gel
  • Gelatin is clear – use food dyes
  • Layered production process is advised for any kind of inclusions such as vessels, foreign bodies or cysts
  • Cysts can be simulated with water-filled balloons, tips of examining gloves, grapes, or glycerine suppositories – though models need to be reconstructed after drainage
  • Pipette bulb clipped with kitchen clip can be used to simulate a cyst – place it on the bottom – it will self-seal even after multiple needle punctures – can be drained and refilled multiple times
  • Masses can be simulated with carrot pieces, macaroni, olives or hot dog pieces
  • Latex tubes (Penrose drains) or modelling balloons can be used to simulate vessels
  • Refrigerate the gelatin models when not in use to extend their durability (but don’t freeze them, or they’ll crack)
  • Models should be kept in airtight containers when not in use
  • Use clear adhesive plastic or strip of gelatin impregnated gauze on top of your gelatinous phantoms to protect them from pressure damage
  • Re-usable latex coating can increase durability
  • Hydrocolloid skin dressings can be used to protect the gelatinous phantom surface – increase durability
  • Electric mixer, handheld drill, stove and refrigerator are the major appliances used

SOFsono4

I am hoping you’ll find this overview useful. Check out the public SOFsono HOMEMADE PHANTOMS collection on PubMed for the additional references.

Don’t hesitate to contact us if you have any questions, concerns or educational needs!