Let’s say you are working in a busy emergency department. You get a call that a patient is being brought in by ambulance in cardiac arrest. You quickly assemble your team, assign roles, and discuss the plan—just in time for the patient to arrive. A paramedic performs one-arm compressions on an elderly man, pale yellow–his mouth stented open with a laryngeal mask airway. Your swarm of providers descends upon the patient, performing their jobs simultaneously in perfect concert. Airway, ventilations, rhythm checks, epinephrine: everything is running smoothly, but the patient is in pulseless electrical activity. During a rhythm check, someone looks at the heart with ultrasound. You glance at the screen and see a blurry subcostal cardiac view. You can barely make out the pericardium, but you see a weak contraction of the ventricles; there’s still no pulse. Compressions are quickly resumed. You consider all of the information – what are the chances this patient will survive? Should we keep going? Should I place a transesophageal probe? Wait, do I even have one of those?! Is ultrasound enough evidence to determine if further efforts are futile? Amidst your thoughts you hear a loud and eager call out: “I got a pulse!”. The team buzzes again – blood pressure, electrocardiogram, labs, vasopressors, cooling. You wonder, “Why did I even do that ultrasound? Is there any evidence it helps?”.

The difficulty encountered in this scenario is one that occurs countless times across the world’s hospitals each day. Point-of-care ultrasound (POCUS) has exploded off the shelves over the past decade. It has been borrowed from the hands of sonographers and cardiologists and made available to anyone who can afford a machine (training course optional). Overall, this has been a remarkably positive movement. Safer procedures, faster diagnoses, and sometimes a replacement for more potentially harmful imaging modalities. However, it is not without dangers. Those who use it aren’t always looking for the evidence for POCUS, as if it is somehow outside of the requirement for evidence. Others might not use this modality when it is indicated, ignoring the evidence that supports the use of POCUS. Both practices are unsafe. This is a big problem…but it’s one we can fix with the concept of evidence-based sonology.

Practicing based on the best available evidence has been a cornerstone of medicine since its advent; however, only more recently has it seen a visible resurgence. Now that it is in vogue there are physicians who are evidence-based medicine (EBM) specialists, there are EBM blogs and EBM courses. We teach our learners EBM principles and practices. So why has POCUS almost eluded this trend? Why would the evidence for POCUS not be examined with the same perspicacity as resuscitative endovascular balloon occlusion of the aorta (REBOA) in the emergency department, for example? I have some theories. In the early days, POCUS was practiced by a few champions with a dream who understood how POCUS could revolutionize practice. However, ultrasound equipment was not yet widely available. This limited initial studies to case reports and case series on new uses, touting primarily theoretical benefits to patients. As anyone who has used ultrasound knows, this tool holds a powerful allure by allowing its user to magically look into the body and directly visualize physiology and pathology. It is easy to imagine that after a while you build up a confidence; when you see something it must really be there. In a sense, the rapid outbreak of ultrasound use and the ever-expanding list of applications outran the available evidence basis.

A review of a subset of ultrasound-related abstracts showed that there is now increasing research, although most of it would be classified as quasi-experimental, which may not be enough to inform practice.¹ But the times, they are a’ changin’. Now ultrasound is ubiquitous, at least at most academic centers, in emergency departments, ICUs, and other places that care for the acutely ill. Therefore, the body of literature is growing, and now we just have to pay attention to it. Enter evidence-based sonology (EBS).

Your first question is probably – sonology? What’s that? Did he just misspell sonography? No. Sonology is a term that implies an expertise in the entire spectrum of POCUS. Not only the acquisition (the “-graphy”) of the images, but additionally the indications for performing it, the interpretation, and the subsequent appropriate medical decision making.² This is important because the evidence for this modality could fall apart at any one of these levels, so practitioners must be attuned to the hurdles of each step. Your second question probably is, isn’t this just EBM? Of course! But it is something that we could improve, and therefore we need to rebrand this practice to continue teaching it as a concept to anyone that uses POCUS. There are several reasons why this is important. As POCUS becomes more integrated into medical practice, it is important that we are all on the same page. Research helps us understand the benefits and limits of this tool for each application. It helps us to know the best time to use the tool, how accurate it is when we use it, how it affects patients when we use it, and potential harms associated with it.

So where do we go from here? There are 3 main ways you can practice EBS:

1. Know the evidence
2. Model the evidence
3. Make the evidence (AKA perform research)

As far as knowing the evidence, this is nothing new for anyone practicing in a medical field. You know how to get a hold of journals. These days it’s easier than ever. You can even use social media, podcasts, and blogs to further distill the information for you. Just make sure you read the original evidence yourself and develop your own decisions about how it will change your practice. Secondly, you have to actually implement what you learn. Obviously, not all research articles are practice-changing, but many will at least add something to your understanding of POCUS in clinical practice. For example, in the aforementioned case of cardiac arrest, recent literature could have informed many steps of using POCUS. Cardiac activity on ultrasound has an odds ratio of 3.6 for survival to admission.³ Patient’s in PEA with cardiac activity on POCUS might benefit from continuous adrenergics instead of standard ACLS.⁴ Furthermore, an understanding that there is the risk of misdiagnosis of cardiac standstill and the risk of delaying chest compressions, might make you pay closer attention to these details during use of POCUS.^5,6 Practicing with this evidence is not only the safest practice, but for those at teaching institutions, it can help create a newer generation of EBS followers. Lastly, make the evidence. Do the research. If you have a question, go find the answer. Collaboration is easier now that ultrasound is more widespread, as is evidenced by more multi-center trials.^7-9 Talk about research ideas at national meetings and consider research groups for important questions.

There is now a greater evidence basis for POCUS than ever before. No longer are we restricted to a few case reports and our own intuition. We have randomized controlled trials; we have meta-analyses; we have real patient-centered outcomes. Know the evidence, model the evidence, and make the evidence. These are simple practices that we need to support for the sake of our patients. Now it’s up to you. Will you start practicing EBS? Think of creative ways to begin promoting this concept today.

References:

1. Prats MI, Bahner DP, Panchal AR, et al. Documenting the growth of ultrasound research in emergency medicine through a bibliometric analysis of accepted academic conference abstracts. [published online ahead of print April 15, 2018]. J Ultrasound Med. doi.org/10.1002/jum.14634.
2. Bahner DP, Hughes D, Royall NA. I-AIM: a novel model for teaching and performing focused sonography. J Ultrasound Med. 2012; 31:295–300.
3. Gaspari R, Weekes A, Adhikari S, et al. Emergency department point-of-care ultrasound in out-of-hospital and in-ED cardiac arrest. Resuscitation. 2016; 109:33–39.
4. Gaspari R, Weekes A, Adhikari S, et al. A retrospective study of pulseless electrical activity, bedside ultrasound identifies interventions during resuscitation associated with improved survival to hospital admission. A REASON Study. Resuscitation. 2017; 120:103–107.
5. Huis In ‘t Veld MA, Allison MG, Bostick DS, et al. Ultrasound use during cardiopulmonary resuscitation is associated with delays in chest compressions. Resuscitation. 2017; 119:95–98.
6. Hu K, Gupta N, Teran F, Saul T, Nelson BP, Andrus P. Variability in Interpretation of Cardiac Standstill Among Physician Sonographers. Ann Emerg Med. 2018; 71:193–198.
7. Smith-Bindman R, Aubin C, Bailitz J, et al. Ultrasonography versus computed tomography for suspected nephrolithiasis. N Engl J Med. 2014; 371:1100–1110.
8. Atkinson PR, Milne J, Diegelmann L, et al. Does point-of-care ultrasonography improve clinical outcomes in emergency department patients with undifferentiated hypotension? An International Randomized Controlled Trial From the SHoC-ED Investigators. Ann Emerg Med. 2018; 72:478–489.
9. Gaspari R, Weekes A, Adhikari S, et al. Emergency department point-of-care ultrasound in out-of-hospital and in-ED cardiac arrest. Resuscitation. 2016; 109:33–39.

Do you already practice evidence-based sonology? If not, will you start?  Comment below, or, AIUM members, continue the conversation on Connect, the AIUM’s online community. 

Michael Prats, MD, is currently Assistant Ultrasound Director and Director of Ultrasound Research in the Department of Emergency Medicine at the Ohio State University Wexner Medical Center. He is the founder of the Ultrasound G.E.L. Podcast that reviews recent articles in point of care ultrasound. Follow him on Twitter by his handle @PratsEM or visit ultrasoundgel.org.