Thursday, July 26, 2012

DIY Ultrasound Phantoms

I've got a lot of projects kicking around. This one kinda got pushed to the front because one of my colleagues said "We need to be able to perform this skill, but we don't have the resources to develop our techniques". Ordinarily, this would warrant some kind of project, slow and methodical like. However, I'm now one of the guys that responsible for fixing problems like this. It's not just an issue, it's "my" issue. The glove was thrown down, so to speak. The issue is that we need to place IV (intravenous) lines in our patients. It seems pretty simple: you come to the ER, sick/broken/in pain, and we need to take care of you. One of the ways that we address this is by starting an IV line and drawing blood. If you are going to do either of those things, you can do them both (in theory). Most of the time, this is a simple matter of getting a skilled provider, with the right equipment, to the bedside. Veins are typically pretty easy to find (it helps if you have sensitive fingertips, not sensitive eyes), and then it's just a matter of a quick poke. The complicating factor is the condition of the patient. Some folks don't have great veins (for that matter, some folks don't have shallow veins, demonstrated sonographically). If you can't find a shallow vein, you need to find a deep one. Beyond a few millimeters, you simply can't feel a deep vein. You need some way to visualize those deep veins. Enter in the bedside ultrasound system. We use these during traumas to examine patients for internal bleeding. Occasionally we use it to check on pregnant women and the health of the fetus. Other than that (this comprises maybe an hour or two a day, at most) our bedside sono units are dormant. They're like any other medical imager: not cheap. A couple of docs figured out that we can use these things to visualize deeper veins (and arteries). From there it was a simple trick to guide an angiocath (an IV needle) into one of these veins. It's a pretty cool solution. It's not as invasive as a PICC Line (Peripherally Inserted Central Catheter), or other central line (subclavian, femoral, etc), and it's more comfortable than a jugular line. It's also a guided solution. No blind sticking, and you can see the structures in the patient's arm to avoid complications (inadvertent arterial puncture). However, it's also a bigger deal than a simple IV stick. You're taking an angiocath that you would normally poke a couple of millimeters down, and going 10-20 millimeters down into someone's arm. You're asking more of your patient. More to the point, if all you have done, to date, is a standard IV placement, you're asking a lot of yourself. I know that the folks that I work with care for their patients. Or they're crazy. No one would work under these conditions (low pay, constant threat of bodily harm, verbally abusive clients, incredible work loads) for years. They all seem highly functional, so I'm going to stick with "Compassionate". I think my colleagues generally care for their patients, like they would care for their own family. So it's a lot to ask them to jam a needle two to three inches into someone's arm, using a technique they're uncertain of. In fact, it's just wrong. We have ultrasound simulators, called phantoms, that we borrow from the medical school. They're around $300-$400 dollars, and they're simple blocks of gel (silicone? dunno) with vessels suspended within them. The sonographic image looks pretty nice: a couple of straight vessels a couple of centimeters deep. It's not what a patient's arm looks like: vessels that are all over the place, twisting and turning, with various inclusions scattered through the arm. We needed to come up with a way to transition from the perfection of the standard ultrasound phantom to the reality of patient care. Oh yeah, one more thing: No budget. Solutions will start in the next post. (I'm going to try out a cliffhanger ending for this one)