Ultrasound in Emergency Medicine: “To B mode or not to B mode?”

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By Dr Anna Colclough, ST5 EM Trainee.

Ask any of my colleagues, and they would mostly tell you my enthusiasm for Ultrasound in the Emergency Department verges on the pathological.  There have been many a day where they find a picture thrust in front of them with the pride and eagerness that is normally reserved for new parents showing off little Bobby’s first attempt at eating Spaghetti Bolognaise.  Sadly, this was not a picture of a bright eyed 10 month old smothered in Passata but rather a Dilated Left Ventricle with an aneurysmal apex.  My colleagues have learnt that the only way to appease me is to make the desired noises of interest and admiration and I will be on my way.

My interest in the subject goes back years now and stemmed from a horrendous experience of a patient who was diagnosed with sepsis having presented with collapse, but later transpired had a massive PE. This prompted me to invest some considerable time and money into learning some skills in Echocardiography.   One MSc later my fate was sealed, I am an Echo-obsessive sonophile.

THE PAST

Emergency Medicine is a relatively young specialty and Point of Care Ultrasonography (PoCUS) has been finding its feet and role alongside the growth of the specialty. PoCUS is now firmly incorporated into the Emergency Medicine curriculum for UK EM trainees.

The birth of ultrasonography in the emergency department can be traced back to work in the early 1980’s by some German fellas, Tiling et al (1)who published the first works on the use of Ultrasound on patients who had been on the receiving end of blunt abdominal trauma.  In the early 1990’s with machines becoming more compact and more portable this took off further with seminal publications by Kimura et al(2) and Tso et al(3) on rapid ultrasound in blunt abdominal trauma and so the FAST scan (Focussed Assessment with Sonography for trauma) was born.  In 1994 the first curriculum for Emergency Ultrasound was published by Mateer et al. (4)and we were off! A whole world of possibilities lay before us, emergency physicians had a new ‘toy’ that let you see inside people without first discussing it with a Radiologist.  In the U.S. it rapidly gained favour with the Residency Training Programmes and is part of the core curriculum. And here in the UK it has been part of the RCEM curriculum for Higher Training since 2006. (5)

 THE PRESENT

The role of FAST scanning has gone in and out of favour since these early years and with the advent of Major Trauma Centres and improved availability of CT scans it has less of a role in trauma, but is still regularly used e.g. to establish which cavity to cut open first in a haemodynamically unstable person.

Other applications for US have seen a huge expansion, most notably its use in Vascular Access where it is considered best practice for Central Access and it is of huge use in difficult Peripheral Access.

Other applications include (and this list is far from exhaustive); guidance of chest drains in Pleural effusions and Ascitic drains, US guided lumbar punctures, Musculoskeletal US for Achilles tendon rupture, US in shoulder dislocation, Rule in US in Testicular Torsion and Regional Anaesthesia such as femoral nerve blocks.

There are also broad applications for the use of Echocardiography in the ED and inspired by our critical care colleagues who have been using this modality routinely for some years more confident ED physicans are beginning to see the benefits of its use in everyday practice to help differentiate the causes of shortness of breath and chest pain in the ED.

Echocardiography is also used in conjunction with other focussed ultrasound to allow rapid diagnosis with patients with patients with hypotension of unexplained cause.  A number of PoCUS protocols now exist for this.  The most widely adopted is known as the RUSH protocol (Rapid Ultrasound for shock and hypotension)(6).  It consists of focused ECHO (Pump), Abdominal Aorta (Pipes) and search for abdominal free fluid and pleural ultrasound (Tank).

 

 

Echo in patients with undifferentiated shortness of breath is an interesting one a number of studies have been done that show a significant reduction in time to diagnosis and treatment and improved accuracy of diagnosis (7) In America physicians are avidly picking up the US instead of their stethoscopes but in the UK there is a lack of confidence with the use of Echo in the ED which I feel will not be overcome until the curriculum embraces training in more comprehensive Echocardiography.

THE FUTURE

My personal view (and I am quite clearly biased) is that echocardiography has the potential to make the greatest impact in the emergency department as a diagnostic tool by rationalising our differential diagnoses particularly in patients with shock or shortness of breath(8).

Ultrasound remains one of the most operator dependant imaging modalities and there can be great interobserver variability, any persons practicing the art of ultrasound on patients should be aware of it and their limitations.

The buzz word here is clinical governance. Guidelines have been set by the Royal college of emergency medicine and the European association of cardiovascular imaging on the requirements to be an independent practitioner for level 1 ultrasound and for focussed echo by non-cardiologists(9) for the latter it is suggested that it takes of 350 echo’s to have the basic skills to be an independent practitioner, and at least 100 scans a year to maintain competency.  Its use in the ED should be limited to look for gross abnormalities that would alter management and abnormalities should be referred to specialist teams.  As always in the emergency department Ultrasound is a rule in modality not a rule out.

There have been great developments with the quality of the point of care ultrasound machines and these can now produce images that rival those in the Ultrasound Department.  In addition to this the development of pocket sized devices (GE Vscan) and even smartphone devices (mobisante SP1 system) make personal ultrasound systems available to the most enthusiastic physicians, arguably replacing the stethoscope.

 

 

 

Other exciting future applications include US in Scaphoid fractures(10), post reduction US in Colles fractures and paediatric forearm fractures (11)(no radiation involved!).  Eye ultrasound (optic nerve sheath diameter) to assess for signs of raised intracranial pressure (12)(potentially reducing the need for the ophthalmoscope!) Kimberly et al(2008). And its use in the prehospital environment with research showing positive benefits in diagnosis, triage and treatment decisions. (13)

So, Love it or hate PoCUS is here to stay so let’s put the ‘US’ in UltraSound.

 REFERENCES:

  1. Tiling T LF, Kaiser G. Die wertigkeit des ultra-schalls beim stubpfen bauchtrauma. Unfallmedi-zinische Tagungen der Landesverbaende der Gewereblichen Berufsgenossenschaften. 1980;40:103-7.
  2. Kimura A OT. Emergency center ultrasonog-raphy in the evaluation of hemoperitoneum: aprospective study. J Trauma. 1991;31:20-3.
  3. Tso P RA, Cooper C, et al. Sonography inblunt abdominal trauma: a preliminary progress report. J Trauma. 1993;33:39-43.
  4. J M. Model curriculum for physician training in emergency ultrasonography. Ann Emerg Med 1994;23:95-102.
  5. Subcommittee. CoEMU.Emergency medicine ultrasound—level 1 training document2006.
  1. Dina Seif PP, Thomas Mailhot, David Riley and Diku Mandavia. Bedside Ultrasound in Resuscitation and the Rapid Ultrasound Shock Protocol. Critical Care Research and Practice. 2012.
  1. Laursen CB. Focused Cardiac Ultrasound in the Emergency Department for patients admitted with Respiratory Symptoms. Clinical Pulmonary Medicine. 2015:298-304.
  2. A. Colclough PN. Pocket-sized point-of-care cardiac ultrasound devices:Role in the emergency department. herz. 2017;42(3):255-61.
  1. Badano ANNAHPLFGAVBCFAFBAPLGJLZLP. Emergency echocardiography: the European Association of Cardiovascular Imaging recommendations. Eur Heart J Cardiovasc Imaging 2013;14:1-11.
  2. Munk B BL, Kroner K, et al. Ultrasound for the diagnosis of scaphoid fracture. Journal of Hand Surgery. 2000;25B(4):369-71.
  3. Christopher Ern-Yoong Wong AS-YA, Kee-Chong Ng. Ultrasound as an aid for reduction of paediatric forearm fractures. Int J Emerg Med. 2008;1(4):267-71.
  4. Rajajee V VM, Fletcher JJ, Jacobs TL. Optic nerve ultrasound for the detection of raised intracranial pressure. Neurocrit Care 2011;15(3):506-15.
  5. Mazen J. El Sayed EZ. Prehospital Emergency Ultrasound: A Review of Current Clinical Applications, Challenges, and Future Implications. Emerg Med Int 2013.

 

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