Hocus POCUS?

Written by: Omar Hilal, MD. Edited by: Jeff Greco, MD

It is well known that ultrasound is an integral part of Emergency Medicine training, the utility of which ranges through organ systems as well as varying levels of patient acuity. POCUS (point-of-care ultrasound) can help to guide providers along the right path when considering the differential diagnosis for critically ill patients. I would like to think that in EM, the utility of ultrasound is well understood and appreciated. However, although ultrasound is ubiquitous in the ER, should some of the techniques/learning be extended to our internal medicine and surgery colleagues upstairs? 

There will always be patients who decompensate, be that in the ER or on the floor. There will always be patient’s who are on the border of ICU level care and regular floor care. For these patient’s, it might be beneficial to have our colleagues receive some training in POCUS to help them make more informed decisions for their patients in the face of acute decompensation when help is not always readily available. 

How efficient and accurate is bedside ultrasound?  To answer this question, let's look at an article from the Clinical Medicine Journal. In their article, “Point of Care Ultrasound: Unnecessary gadgetry or evidence based medicine” [1] Nicholas Smallwood and Martin Dachsel dissect the efficiency and usage of ultrasound, especially for thoracic and abdominal issues as well as for hypotension and cardiac arrest.

In terms of US usage for thoracic complaints, Smallwood and Dachsel discussed the utility of US for pleural procedures and differentiating common causes of respiratory distress. Most procedures involving the thoracic cavity that initially were done blind have either been fully revamped as US guided or have implemented some component of ultrasound assistance to ensure greater procedural accuracy and less complications. For pleurocentesis, the incidence of pneumothorax was found to be drastically reduced in a group of 342 patients from 18% to 3% under US guidance according to a retrospective cohort study  from 1991 done by Raptopoulos V et al. [2] In addition to thoracic procedures, there is significant utility of ultrasound in differentiating the causes of respiratory distress. Even basic knowledge in this type of ultrasound technique can be very useful for our colleagues upstairs. Smallwood and Dachsel referenced a paper by Lichtenstein and Meziere that details the Bedside lung ultrasound in emergency (BLUE) protocol, which illustrated “very good diagnostic accuracy of lung ultrasound for respiratory failure in the most common respiratory conditions” and noted that this could be “achieved with a rapid, protocolised, reproducible approach. 

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Note that a pitfall of this study is that it was in a critical care setting so the data might not be generalizable to all floor and emergency medicine patients due to the higher degree of acuity in this population.

A more generalizable study was done in a single ED in Italy with 2683 patients which illustrated that “POCUS significantly reduced the time to diagnosis (24 +/- 10 min vs 186 +/- 72 min), and performed as well as clinical examination plus chest X-ray (CXR) for diagnosing acute coronary syndrome, pneumonia, pleural effusion, pericardial effusion, pneumothorax and dyspnoea from other causes” [5] Although most patients will have already received a working diagnosis by the time they are admitted and upstairs, they are not excluded from developing new onset dyspnea and shortness of breath and may require quick decision making to help ensure good patient outcomes. 

Although cardiac arrest or rapid response teams exist in many hospitals, there are times that these individuals predisposed and a representative from the team cannot arrive in time to address an acute and time-sensitive situation.  Therefore, knowing basic focused cardiac ultrasound skills would be helpful. Skills are simple as visualizing cardiac activity on ultrasound during a code can help dictate the ensuing care and even reduce time of pulse checks, allowing for more time for compressions. Smallwood and Dachsel suggest that bedside echo during cardiac arrest can “help stratify early a cohort of patients in whom the prognosis was exceptionally poor, which may help influence the decision to continue.” Similarly, if tamponade is found to be the source of the arrest, it is something that is correctable at the bedside and can drastically change the patient’s outcome. 

Smallwood and Dachsel also touch upon the rapid ultrasound in shock and hypotension (RUSH) protocol. In this exam, a provider can assess cardiac, lung, IVC, aortra, and peritoneal windows to help discriminate between obstructive, hypovolemic, cardiogenic, and distributive shock. For patients who decompensate and require IV boluses for resuscitation or even the initiation of pressors, the RUSH protocol, which has been endorsed by societies such as the American Society of Echocardiography as well as the British Society for echocardiography, can aid providers in any setting with important clinical information that will dictate their management to better serve patients. A randomised control trial from 2004 of 184 ED patients with undifferentiated hypotension showed that “immediate, goal-directed ultrasound increased the rate of correct diagnosis of shock aetiology from 50% to 80%” with a NNT of 3.3 and an average scan time of 5.8 min. [7]

If the evidence points towards bedside ultrasound being an invaluable skill in caring for patients, why is its utility still limited? Smallwood and Dachsel suggest that one of the significant barriers to opening US up to other departments is the lack of standardization in a curriculum, and the lack of skilled instructors who can permeate this knowledge. Additionally, the standards that do get published don’t always necessarily include everything that's pertinent. For example in Europe, the Royal College of Radiologists have published training standards for medical and surgical subspecialties, but these standards are lacking in details pertaining to respiratory failure and “lack the binary approach that POCUS encourages.” [9] In order for POCUS to reach our colleagues upstairs in medicine and surgery, more concerted efforts need to be made to develop a more integrated and readily available curriculum for them. They certainly have the capacity and appetite to learn ultrasound skills. More support for them will translate to better care for our patients. 

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 [1] Smallwood, Nicholas, and Martin Dachsel. “Point-of-Care Ultrasound (POCUS): Unnecessary Gadgetry or Evidence-Based Medicine?” RCP Journals, Royal College of Physicians, 1 June 2018, www.rcpjournals.org/content/clinmedicine/18/3/219.

[2]  Raptopoulos V, Davis LM, Lee G, et al. Factors affecting the development of pneumothorax associated with thoracentesis. Am J Roentgenol 1991;156:917–20

[3]  Lichtenstein DA, Mezière GA. Relevance of lung ultrasound in the diagnosis of acute respiratory failure: the BLUE protocol. Chest 2008;134:117–25. 

[4] Smallwood, Nicholas, and Martin Dachsel. “Point-of-Care Ultrasound (POCUS): Unnecessary Gadgetry or Evidence-Based Medicine?” RCP Journals, Royal College of Physicians, 1 June 2018, www.rcpjournals.org/content/clinmedicine/18/3/219.

[5] Zanobetti M, Scorpiniti M, Gigli C, Nazerian P, Vanni S. Point-of-care ultrasonography for evaluation of acute dyspnea in the ED. Chest 2017;151:1295–301.

[6] Goodman A, Perera P, Mailhot T, Mandavia D. The role of bedside ultrasound in the diagnosis of pericardial effusion and cardiac tamponade. J Emerg Trauma Shock 2012;5:72-5

[7] Jones AE, Tayal VS, Sullivan DM, Kline JA. Randomized, controlled trial of immediate versus delayed goal-directed ultrasound to identify the cause of nontraumatic hypotension in emergency department patients. Crit Care Med 2004;32:1703–8

[8] “The RUSH Exam - Rapid Ultrasound for Shock and Hypotension.” EMCrit Project, emcrit.org/rush-exam/.

[9] Royal College of Radiologists. Ultrasound training recommendations for medical and surgical specialties: third edition. London: RCR, 2017