Starting off with a beat up old ultrasound machine that I had to clean the blood and hair off of before placing it in service on the ambulance, I didn’t know what we were getting in to. But over the next couple years we found out one thing. Ultrasound is awesome. Seriously, it’s the future of EMS. I’ve been preaching this since 2009 to anyone that will listen. Ultrasound is the only imaging modality small enough and safe enough to be put into an ambulance. Sure there are a couple CT ambulances around the world 1, 2. for specialized stroke teams, but these aren’t real everyday, every call ambulances. Ultrasound could theoretically be everywhere. It’s even starting to pop up in EMS training programs 3. But just because I believe in this, doesn’t mean you do. Well, you at least kind of do if you came to this website voluntarily, but theoretically I still have to finish selling you on it. So to start off my first post on this blog I’m going to share with you some of my frequently asked questions and hopefully answer a couple of yours along the way.
I’m a paramedic, do you think I will be able to read an ultrasound? In a simple answer, yes. Ultrasound is not like x-ray. In ultrasound you have your hand on the patient and are viewing a real-time image. This makes confirmation of landmarks very easy and thus identification easy as well. It’s more like exploring than it is imaging. I liken ultrasound more to surgery than to true imaging because you can always go back and look at something again, plus you’re seeing it in real-time. If you’ve got even a basic understanding of anatomy and physiology then it’s generally pretty easy to identify when something isn’t normal. When I teach classes on ultrasound I say this and normally get blank stares, and then I play a video of a normal heart and one with an acute MI and everyone’s eyes get big, because they could instantly tell which one wasn’t beating right. That’s really all EMS ultrasound is about, we don’t have to diagnose an acute papillary muscle rupture with subsequent mitral regurgitation, we just have to look at it and go, “I know normal, and that aint it!” I know I’m simplifying things but that’s the reality of what we do, we’re not performing a sonographic evaluation of the heart, we’re doing a focused ultrasound examination which means we are asking a handful of questions like “does the ventricular wall motion look normal? Yes or no.”. So seeing things that aren’t normal and simply being able to tell the doc, “hey this lady looks sick and her LV wall motion is abnormal on echo” will be enough to actually improve her care by directing the ED workup. And as you gain skill with ultrasound, which comes quickly, you will begin to start picking up more and more things. But right out of the gate and for the things we care about, yes, I do think most paramedics can easily read an ultrasound.
How does it work and is it safe? Ultrasound works by bouncing high frequency sound waves off of structures within the body, similar to a fish finder. This works because humans are mostly made of water and is also why you must use lots of ultrasound coupling gel. This also makes it difficult (but not impossible) to ultrasound the lungs directly. Safety wise, because it is only producing sound waves and no radiation, there is no risk or danger posed by using or performing ultrasound. The energy produced is mostly thermal in nature, which can be evidenced by the probes getting a little bit warmer after extended use, but nowhere near enough to ever burn someone. Many studies have been done and, in the frequencies and power levels used in diagnostic ultrasound machines, no harm has ever been found. You may have heard about celebrities buying ultrasound machines to check their babies daily and how this isn’t recommended, it’s simply because that hasn’t been studied. I don’t personally think it’s smart to do that, but I really doubt it would ever hurt anything. I have heard recommendations from some OB/GYN’s against using the doppler mode on ultrasound machines (we’ll talk about modes more in-depth in a later post) as it’s the highest energy setting on the machine. Yet this is the same thing as a fetal heart monitor and no-one seems to be scared to use those. So in short, ultrasound is by far the safest means of imaging we have.
What can ultrasound do for me in the ambulance? That’s actually a pretty big question and will be addressed many times over the life of this blog. In short though, there are a ton of things ultrasound can be used for if you are willing to learn how. Most services use it simply for detecting bleeding around the heart and abdomen for trauma. But as we get to talk more over the coming months you will learn that this is but a fraction of what ultrasound can do for you. It can also be used to for pulse checks in cardiac arrest, finding causes of hypotension, identifying a pneumothorax, broken bones, finding a cardiac tamponade and guiding the needle in for pericentesis, pregnancies, AAA’s, preventative screenings, getting a difficult IV or central line, even nerve blocks and detecting (and potentially even treating) strokes are within the realm of prehospital ultrasound.
Can it work while bouncing down the road in an ambulance? Absolutely. In fact the protocols I wrote specifically say that unless you’re using it to start an IV, on an MCI or to determine the transport facility, you must only use ultrasound during transport so as not to delay scene time. This will make sense pretty quickly once you start using ultrasound, you move your probe all over the place and interestingly, the sloshing motion from the road will actually make any bleeding show up easier. So yes, ultrasound works great in the ambulance!
What are transducers and why do we need more than one of them? The transducer is actually the heart of the machine and is what transmits and receives the sound waves. Made up of arrays of piezoelectric crystals, each transducer is designed for a specific task. While it is true that you may use them for overlapping purposes this does not always give you a useable image. Our two main probes in emergency ultrasound are the phased array and linear probes, though the curved array is also sometimes used. This is discussed further in the course but the basic idea is that the phased array probe is designed to be able to go deep through normal and even obese individual’s abdomens to image their organs. To gain this penetration ability it sacrifices some image quality. The linear probe does not go as deep but will return a much clearer image and is used for starting IV’s.
How much does it cost? The cost of a used system starts around $5,000, while the cost of a new system is generally between $15,000 – $60,000. Because of the delicate crystal array, the probe is the most sensitive part of an ultrasound system and is unfortunately also the most likely to be dropped. Probes generally cost around $5000. I strongly recommend budgeting for a linear and phased array probe. But if you’re strapped for cash a phased or a curved array alone may be used in a pinch. There are some newer systems coming to market over the next few years that promise to be significantly cheaper (potentially in the $500-1000 range) but as of yet there isn’t really anything I would say is ready for primetime on the ambulance that I’m aware of. This is probably the biggest hurdle preventing EMS from using ultrasound more readily, it’s hard for EMS managers to justify buying something that may potentially cost more than the heart monitor and potentially be used less. But don’t worry, this is something we will be discussing more in the future.
Will this stuff hold up in the back of an ambulance? I have only ever used Sonosite units in an ambulance so that is where my experience is. Sonosite units are drop tested to a height of 3 feet without any damage. Sonosite’s newer units are built on a magnesium metal frame making them very sturdy. Sonosite units have been used by the military in the warzones of Iraq and Afghanistan as well. So while we don’t want to start throwing them on the ground just yet, you can rest assured these units are pretty durable. In my opinion Sonosite makes some of the best equipment out there for field use, but it’s also the most expensive with some manufacturers being 1/3 – 1/2 the price for similarly capable units. Other manufacturers are working on creating units designed specifically for EMS and may have similar durability. I suggest asking your manufacturer what height their probes and units are drop tested and guaranteed for to gauge their durability in the rough EMS environment. Accidents happen and the last thing you want to do is to spend all the money you saved replacing broken probes every 6 months.
Why ultrasound, Why now? Ultrasound’s use in the prehospital field is strongly reminiscent of the 12 lead’s emergence in EMS. When 12 lead ECG’s came into EMS, it didn’t happen overnight and there were a lot of questions. Nobody knew how to use the data gathered from them and it took years, even decades, to integrate prehospital ECG’s into beneficial patient workflows. Ultrasound is no different. However it is an extremely valuable tool that has proven its usefulness in many fields of medicine, it is only a matter of time and technology before it becomes a mainstay of EMS. A few hours with one in your hand and you will understand why.
Where do I go to learn more about ultrasound? Well right here of course! As our blog continues we will be posting more and more information about learning ultrasound for EMS professionals. Many of our crew are learning the art themselves and will no doubt be posting their resources on here. We hope to bring together research reviews on the topic, device reviews, and a resource page for your up to date learning, along with the usual topic discussion posts. There are multiple ways to get your hands on ultrasound and we will talk more in-depth about this soon. In the meantime if you have any specific questions or comments, please leave them below or feel free to contact us on twitter. Until then, be safe and go save some lives!