On August 20-21, King Chulalongkorn Hospital Memorial Hospital was host to the WINFOCUS course:
Essential Ultrasound Guided Invasive Procedures in Emergency and Critical Settings

Dr. Suthaporn Lumlertgul was the director of this course, held at the hospital’s cutting edge surgical training center. Faculty including Mount Sinai’s Bret Nelson, as well as Luca Neri (past president of WINFOCUS), Yuen Chi Kit, Henry Cheng and Mok Ka Leung.

Left to right: Luca Neri, Bret Nelson, Suthaporn Lumlertgul, Henry Cheng, Mok Ka Leung, Yuen Chi Kit

The course covered ultrasound guidance for procedures such as venous access, pericardiocentesis, thoracentesis, nerve blocks, foreign body localization, and others. Physicians from many countries were in attendance.

Upcoming WINFOCUS training courses around the world are listed here.

A middle-aged male presented to the ED with 2 weeks history of increasing exertional dyspnea. Air entry was reduced clinically. A focused bedside ultrasound demonstrated the above findings. What artifact is missing?

1.The “normal” mirror image of the liver above the diaphragm is missing! It is reassurring when present. The air in normal lung reflects about 99% of the ultrasound beam (i.e. you can’t see past the diaphragm, hiding all normal structures below it). So what’s above the diaphragm is an artifical reflected image of the liver or spleen, thanks to the diaphragm which behaves as a specular reflector (see below). In this case, massive pleural effusion replaces the normal aerated lung, allowing the ultrasound beam to shine through, revealing the vertebral column “C” that was not normally seen. In addition, a tongue of atelectatic lung “E” is found sticking into the pleural fluid, and the superior edge of the diaphragm also well defined

2. Closer look at the vertebral column shows that it is brighter above the diphragm than below. Why? Fluid attenuates ultrasound beam energy less than soft tissue. Therefore, more ultrasound energy passes through fluid than soft tissue for the same distance travelled. So there is actually a stronger ultrasound beam reflected back at “C” compared to “D” , thus making it look brighter. This artificial “brightness” is termed acoustic enhancement. In fact, all clear fluid structures is expected to demonstrate acoustic enhancement.

3. Why did the gerota’s fascia seems to disappear as we trace it from “A” to “B”? Anatomically, it didn’t. That’s an artifact from reflection. Fascia (like the diaphragm) form brightly reflective tissue interface (termed specular reflectors) as opposed to soft tissues (which are diffuse reflectors, having a grey appearance). At “A”, the approaching ultrasound beam hits the specular reflector head on, around 90 degrees. Acting like a mirror, the fascia reflects significantly more ultrasound beam back to the transducer, making it look bright. On the other hand, at “B”, the beam hits it at a much shallower angle. This fasica readily bounces the beam away from the transducer to the left side of the image instead of mostly back towards the transducer, thus making it look dark.

When something unreal is missing, something real may be happening.

Rob has also completed a two-year critical care medicine fellowship in addition to his EM training. Rob sees a particular role for bedside ultrasound in further uniting these two specialties. He brings advanced training in focused transthoracic and transesophageal echocardiography to Sinai.

He has a strong background in ultrasound education internationally and has served as advisor and instructor with ICCU Imaging, Inc.  Among other academic pursuits this year, Rob is excited to examine possible role for transesophageal echocardiography in the ED. Beyond ultrasound, Rob has particular interests in ED-based critical care, sepsis and organ donation after cardiac death.

Rob has brought his family from the North and is grateful for the hospitality shown by his new ED colleagues and support staff at Sinai.

The first and most important step in paracentesis is confirming there is ascites to begin with!

Physical examination findings can be misleading, and inserting a needle blindly into the abdomen can cause complications unnecessarily. Note the black free fluid in the image, with echogenic bowel loops floating within.

Several approaches are commonly used. Each one starts with an assessment for peritoneal fluid, localization of area suitable for paracentesis (no nearby vessels, large enough pocket, etc.). Next, measure the distance from skin to peritoneum to establish a sense of how far the needle lust penetrate before expecting to yield ascites. This is followed by either:

1. Real time (dynamic) ultrasound guidance. Probe held in non-dominant hand (or by assistant); dominant hand guides needle with real-time guidance using short- or long-axis technique
2. Static guidance: Mark the location for paracentesis (use a pen, pressure from a pen cap or fingernail, or even using a nearby mole/skin blemish as a landmark!), and then proceed with the tap using that mark as a guide. It is critical that the mapping is performed immediately before the paracentesis, and the patient remains in the same position. If the patient moves or is re-positioned,  the patient must be scanned again because the pocket of fluid would have shifted due to the highly mobile floating bowel loops.

As the needle is inserted into the abdomen using either technique, it is wise to hold slight negative pressure on the plunger of the syringe. This way, as soon as fluid or blood is encountered, the operator will note both a pressure change and a flash of fluid into the syringe.

The official language for the conference is English, and it will be held in Tuscany!

This is an EFSUMB accredited Euroson school event. For more information please visit here.

1. In this Cochrane review, the authors’ conclusion was that there was insufficient evidence for the use of ultrasound-based clinical pathways in the initial diagnostic workup of patients with blunt abdominal trauma. Ultrasound was not sensitive and lacked diagnostic accuracy. However, the use of ultrasound did reduce the use of CT scans. The take-home message is that ultrasound should not be used as a single rule-out test for significant intra-abdominal injury and the ED resident should be aware of ultrasound’s limitations.

Stengel D, Bauwens K, Sehouli J, Rademacher G, Mutze S, Ekkernkamp A, Porzsolt F. Emergency ultrasound-based algorithms for diagnosing blunt abdominal trauma (Review). The Cochrane Collaboration. February 18th, 2008.

2. Interestingly, this review used the same methodology as the Cochrane review and found that an adequately performed FAST exam can predict the need to send a patient to the operating room, with a high degree of sensitivity (98.9%) and specificity (98.1%).

Melniker LA. The value of focused assessment with sonography in trauma examination for the need for operative intervention in blunt torso trauma: a rebuttal to “emergency ultrasound-based algorithms for diagnosing blunt abdominal trauma (review)”, from the Cochrane Collaboration. Critical Ultrasound Journal. 2009;1:73-84.

3. Thoracic ultrasound has become part of the standard assessment of the trauma patient. Ultrasound has been shown to be much more sensitive than CXR in the detection of pneumothorax when compared to CT as the gold standard. There are many studies proving this point and this is a good example.

Blaivas M, Lyon M, Duggal S. A prospective comparison of supine chest radiography and bedside ultrasound for the diagnosis of traumatic pneumothorax. Acad Emerg Med. Sep 2005;12(9):844-849

Some of the topics discussed are supported by plenty of evidence (ie the use of RSI as an intubation technique), some were simply fun to discuss (holding your breath while intubating) and some remain quite reasonably controversial (the use of etomidate for RSI in sepsis).

I highly recommend visiting Dr. Reuben Strayer’s blog for a brief and enlightening discussion of the use of rocuronium for RSI. Also, Dr. Scott Weingart’s EMCrit blog and podcasts are an excellent source for ED critical care topics. Finally, The Airway Site contains links to key airway management references as well as information on the Difficult Airway Course.

Selected References:

• Farmery AD, Roe PG: A model to describe the rate of oxyhemoglobin desaturation during apnoea. Br J Anaesth 1996; 76:284-91
• Naguib et al. Optimal dose of succinylcholine revisited. Anesthesiology 2003; 99:1045-1049
• Bozeman et al. A comparison of rapid sequence intubation and etomidate-only intubation in the prehospital air medical setting. Prehosp Emerg Care: 2006; 10:8-13
• Sackles et al. Airway management in the emergency department: a one-year study of 610 tracheal intubations. Ann Emerg Med 1998; 31:325-332
• Li J et al. Complications of emergency intubation with and without paralysis. AJEM 1999: 17(2); 141-143
• Mallon WK et al. Rocuronium vs. succinylcholine in the emergency department: A critical appraisal. JEM 37(2); 183-188
• Strayer RJ. Rocuronium vs. succinylcholine revisited. JEM 2010 Apr 22. [Epub ahead of print]
• Cardiopulmonary resuscitation by bystanders with chest compression only (SOS-KANTO): an observational study, Lancet 369 (2007), pp. 920–926.
• Bobrow et al. Passive oxygen insufflation is superior to bag-valve-mask ventilation for witnessed ventricular fibrillation out-of-hospital cardiac arrest. Ann Emerg Med. 2009;54:656-662.
• Brimacombe JR and Berry JM. Cricoid pressure. Can J Anaesth. 1997 Apr;44(4):414-25

FERNE’s seizure and status epilepticus management guide

Key practice guidelines related to seizures:

Special thanks to Professor Andy Jagoda (Department of Emergency Medicine, Mount Sinai, New York)

The gallbladder:

• has a bright (echogenic) wall
• is surrounded by liver
• attaches to the middle hepatic ligament
• is a contained structure
• can be traced to the portal vein

The duodenum:

• has a darker (hypoechoic) wall
• is next to the liver, not in it
• cannot be traced to the middle hepatic ligament
• is a tubular structure
• does not connect to the portal vein

More images and explanation after the break!

Also, because of the presence of air within the duodenum, it often casts a ‘dirty’ shadow rather than a ‘clean, dark’ shadow from the acoustic shadowing of a classic gallstone. Check out the following images and see if you agree with the findings as labeled.

Some may argue that these pictures demonstrate the WES (wall-echo-shadow). There’s the hyperechoic wall, the anechoic bile and the stone is casting the shadow… however, the shadow’s all wrong. The “shadow” is NOT an anechoic area extending to the edge of the screen. Instead, it represents a ring-down artifact.

Therefore, going by all of the above criteria, the images are not that of a gallbladder/stone, but more likely the duodenum.

1. The presence of some artifacts can help us to identify anatomy:  e.g. “an aorta” is  “the aorta” because it’s resting on the spine, which is “the spine” because it casts a shadow (what if the spine does not cast a shadow….?)

2. The absence of artifacts can also reveal pathology:  e.g. in  FAST with right hemothorax, loss of the mirror image of the liver above the diaphragm not only reveals the blood and superior aspect of the diaphragm, it also allows  the vertebral column (above the diaphragm) to show up! The spine above the diaphragm is never seen because the normal aerated lung scatters all of the ultrasound energy above the diaphragm.

3. Both the real image and artifact arise because of certain assumptions that that ultrasound machine makes. When they are all met, you get a real image; when any assumption is not, well, you get an artifact. And thankfully, there are only four such assumptions. Here’s a quick review of them as we begin this series of what’s real and what’s not.

Assumption ONE:

A pulse of ultrasound beam emitted by the transducer travels in a straight line, is reflected at an interface, and travels back to the transducer (exactly along the path it was emitted, only in the reverse direction)

Assumption TWO:

All the returning echoes of the beam are presumed to have arisen only from the center (i.e. axis) of the beam and hence are displayed as such (i.e. along a vertical line on the screen that represents the axis)

Assumption THREE:

The speed of ultrasound beam (emitted and/or reflected) is always and exactly 1540m/s

Assumption FOUR:

The intensity of the displayed echo is dependent on the acoustic properties and size of the interface where it is being reflected

And with that, we’ll make good use of what’s not really there to find out what’s really going on.