Prehospital Use of Point-of-Care Ultrasound (POCUS)
February 27, 2019
Author: Peter Bonadonna, EMT-P, CIC
Point-of-Care Ultrasound (POCUS) is an exciting and powerful technology that can dramatically improve prehospital assessment and care. It can provide accurate, lifesaving information to guide treatment. Unlike, a formal ultrasound it is designed to help trained health care providers answer specific questions related to patient care needs at the bedside. In place of complicated measurements, POCUS is a binary process1. It provides a “yes” or “no” as you are trying to interpret things like, “Is there fluid around the heart?”
I was introduced to ultrasound by a cardiologist who served as a medical director more than 30 years ago. At that time, the machines were large and expensive, but I recognized that this could be a great technology for the ambulance. Now that POCUS machines are small, affordable and give very clean images2, I believe they will be the most significant addition to EMS since the 12-lead ECG.
Sadly, the use of POCUS is off to a slow and rocky start in the United States. Let me explain some of the impediments and the reasons why I believe we should work to implement this technology in the prehospital environment.
Perhaps the single most important factor slowing EMS adoption is that most American physicians have not readily adopted the idea. In fact, we lag Europe’s experience by 20 years and, unsurprisingly, prehospital use is even more rare and sporadic.
Prehospital ultrasound in the United States is in its infancy. While exact numbers are not available, there are perhaps a few dozen known HEMS and ground-based EMS agencies around the country using the technology. Most are still in the testing and feasibility stage. While there are some physicians and paramedics who are enthusiastically encouraging the use of POCUS, they often run into major road blocks from supervisors or leaders who believe it is invasive, not in the scope of practice and that the benefits do not outweigh the costs.
While these ultrasound machines can be an expensive and somewhat intimidating piece of equipment, the challenges to implement its use are relatively simple and straightforward. The cost has reached a level where many EMS systems can now afford to buy them and, based on my experience, it is easier to teach paramedics to use and read ultrasound images than to use and read the 12-lead ECG.
It is also important to change the mindset of paramedics, paramedic educators and EMS physicians who continue to believe that obtaining vital signs, history, mechanism of injury (MOI) and physical exam always results in accurate, reliable information. Using MOI assessments may not be useful in decision making3 and normal vital signs doesn’t mean that everything is okay. To make matters worse, abnormal vital signs doesn’t always mean there is a serious problem. In the infrequent circumstance where the vital signs are abnormal, they are not specific to the problem and treatment choices are still very difficult. Physical exams of the acutely ill or injured patient often misses pathology even when life-threats are present3. This gives the EMTs and paramedics a false sense that the patient is doing well. For example, paramedics rarely, if ever, identify cardiac effusion in the field with physical exam and so they believe that it is a rare condition. Compounding this problem is the difficulty for ambulance crews to get follow-up information on their patients. This harms the prehospital paramedic profession by asking them to “fly blind.”
Additionally, many paramedic educators do not yet understand all the benefits that ultrasound can offer. Instructors who are not knowledgeable about ultrasound are then unable to teach it to their students. Interestingly, Point-of-Care Ultrasound is included in the January 2009 National Standard for Paramedic curricula; however, very few paramedic programs include it. Most don’t even realize it’s in the standards and are ill prepared to teach it.
Nearly all paramedics have already been educated about the necessary anatomy, body planes, body landmarks and theory to easily learn and use POCUS. The physics and operation theory can be simplified, and six hours of training typically works well.
After the initial training, students can then practice their skills both in a classroom lab session as well as the ED under the guidance of an experienced physician sonographer. Hopefully, this will be able to transition to normal instructors as they become more comfortable teaching the content. A helpful adjunct to this progress is the prevalence of online videos that can teach the student all the concepts they need to know other than probe mechanics and knobology.
Many useful, reliable, exams can be quickly performed at the scene or in a moving ambulance4 with POCUS. Four- to six-hour blocks of training of specific uses should allow ultrasound to be used gradually and, as mastery builds, additional skills can be added. The P-FAST/E-FAST is a reasonable starting point. P-FAST exams are easy to learn and perform, and they may help identify injuries that would have otherwise been missed. (insert video of How fast is the FAST here) This video was filmed in the back of a moving ambulance. This exam took less than two minutes and identified 23 unique and important pieces of information related to the patient’s condition. (see figure of 23 items) Then based on the specific needs of an EMS system, a medical director can add other exams such as:
- IVC Volume assessments
- Cardiac Effusion/Tamponade
- Cardiac arrest assessment
- Verify cardiac capture with external pacing
- IV starts and other procedures
- COPD vs. Pulmonary Edema
- Pregnancy and ruptured ectopic pregnancy
- Obstructive uropathy
- Pleural effusions
- Long bone fractures5
- Identifying non-salvageable arrest patients (to date the most accurate method) 5
Will This Change the Care?
Another common statement that comes up regarding ultrasound is, “So what if the paramedic finds these pathologies, it won’t change the field care.” This was once stated about 12-lead ECG use in ambulances. Today, no one would argue that early detection of cardiac problems significantly improves care at the hospital that is beneficial for patients.
Ultrasound could provide similar patient benefits. For example, if lung sliding was performed in the P-FAST, it would prevent paramedics from needling a chest inappropriately. Blavis et al showed that this was a 1-in-4 occurrence5. Finding a plethoric IVC would caution the paramedic from running in lots of fluid, and a patient with a large bilateral pleural effusion would not be subjected to Albuteral or CPAP treatments which may cause harm. Lung ultrasound can easily and accurately discriminate between heart failure with pulmonary edema and COPD6. This is a constant struggle in the field that is not appreciated in the ED because chest x-ray often solves the dilemma.
Training and Educating Paramedics
Once paramedics discover that physical exam and history do not reliably get them to the correct diagnosis it is easy to convince them to combine physical exam and history with imaging. Many studies show sensitivities and specificities soar from 30-95% or better7. In fact, for the younger paramedic who grew up with video games and a joystick, the eye-hand coordination is easily and quickly mastered. During the last decade of training paramedics at Monroe Community College an ultrasound machine was available in the classroom and was continually used it to teach anatomy, physiology and physical exam.
It’s time for reliable, repeatable methods that have high (or higher) sensitivity and specificity than current techniques. In order to do this, we will have to introduce and educate many people about the benefits and lack of dangers regarding prehospital ultrasound.
- Bowra J, McLaughlin RE, 2010. Emergency Ultrasound Made Easy : p. 2
- Medscape, Expert Rev Clin Immunol ©2013
- Malcolm J. Boyle, Erin C. Smith, Frank Archer: Is mechanism of injury alone a useful predictorof major trauma?
- CJEM. Use of point-of-care ultrasound in long bone fractures: a systematic review and meta-analysis. 2017 Mar;19(2):131-142. doi: 10.1017/cem.2016.397. Epub 2016 Dec 5.
- Noble VE, Nelson BP. 2011 Manual of Emergency and Critical Care Ultrasound. Second.
- Walcher F, Weinlich M, Conrad G, et al. 2006. Prehospital ultrasound imaging improves management of abdominal trauma. Br J Surg 93:238-242
- Heegaard W. Hilderbrandt D, Reardon R, Plummer D, Clinton J, Ho J. 2010 Prehospital ultrasound by paramedics: Results of field trial. Acad Emerg Med 17(6):624-330
- Ma OJ, Mateer JR, Reardon RF, Joing SA, 2008. Ma & Mateer’s Emergency Ultrasound. Third Edition: p. 62
- Snaith B, Hardy M, Walker A, 2011. Emergency ultrasound in the prehospital setting: the impact of environment on examination outcomes. Emerg Med J doi:10.1136/emj.2010096966
- Plumber D, Clinton J, Matthew B, 1998, Emergency Department ultrasound improves the time to diagnosis and survival of abdominal aortic aneurysm. Academic Emergency Medicine 5:417
- Kiev J, Eckhardt A, Kerstein MD. 1997 Reliability and Accuracy of Physical Examination in Detection of Abdominal Aortic Aneurysms page(s): 143-146
- Wagner PR, Hedrick WR, 2015 Point-of-Care Ultrasound Fundamentals, Principles, Devices, and Patient Safety. P. 153-163
- Lichtenstein, DA. 2010 Whole Body Ultrasonography in the Critically Ill. (multiple references in narration) Keep it Simple, no need for heavy science backgrounds p.3-5 , Disinfection p. 21, GI Peristalisis p.43-46, Recognize Patency of a Vein p. 90-93, Lung pathology sen./spec. p.185, Pericardial Tamponade p. 217-219