Ultrasound
Print
E-mail
Reprint

sound-1

sound-2“Technology has become so disruptive!” your veteran charge nurse exclaims. “Every time I have to answer one of these mass emails to our department, our organization loses money. My time is very valuable!” she bemoans. “How am I supposed to concentrate on patient care when my work email account dings every 2 minutes with an ‘Urgent’ message?” Your colleague overhears the conversation as he walks by and stops tweeting on his smartphone just long enough to text both of you “Get back to work slackers!”

Before you have time to respond, your charge nurse notifies you that you have four GSW’s due to arrive in 5 minutes. You start mobilizing all of your staff and resources (by texting everyone all at once) and delegate roles to every person in the trauma bays. The GSW victims arrive en masse and your ED team and trauma team begin their resuscitations like a well-orchestrated dance recital. 

As you are supervising two of your residents putting in bilateral chest tubes, your eager medical student runs up to the trauma bay with a pair of Google Glass. You are researching ways to incorporate wearable technology like Google Glass into your clinical practice and medical education so you and your medical student have a few pairs of Glass with you at work. You put on Glass and ask your medical student, “What can I help you with?” He informs you that your senior resident wants you to take a look at an ocular ultrasound of a patient he staffed with you a little while ago. He knows you are going to be tied up in the trauma bays for quite some time and wants to know if he can discharge the patient with ophthalmology follow up.

sound-3The patient in question is a 55 year-old male who presents to the ED with a chief complaint of visual changes. He complains of photopsia in his right eye and a small area of painless blurriness in his right temporal visual field. He has had a retinal detachment in his left eye before and he is worried he’s now having one in his right eye. His symptoms started an hour ago and he denies any trauma, instrumentation, or anticoagulation. His visual acuity is 20/30 bilaterally with corrective lenses and there were no abnormalities noted on his fluorescein-aided slit lamp exam. His intraocular pressures were normal and your resident thought he saw a vitreous hemorrhage on fundoscopy. Your plan was to perform a B-mode ocular ultrasound at the bedside and to determine if he requires urgent or emergent ophthalmology evaluation.

You turn on Google Glass and link to your senior resident who is also wearing Google Glass while performing the bedside ocular ultrasound (Image 1). Through Glass you can see the ultrasound screen as he views it. What does the B-mode ocular ultrasound demonstrate? What’s the patient’s diagnosis? (Images 2 & 3)

What do the images show? 

 01 As a part of a trial experiment,Teresa Wu integrates wearable technology (Google Glass) into clinical practice and medical education.
02 B-mode ocular ultrasound image of the patient’s right eye.
03 B-mode ocular ultrasound image of the patient’s right eye with oculokinetic movements.

 

Detached Retina

Through Google Glass you are able to witness the patient’s ocular ultrasound without having to leave the bedside of your most critical patients in the trauma bay. On ultrasound, the patient has obvious hyperechoic vitreous hemorrhage in his posterior/vitreous chamber. With oculokinetic movements, you see the vitreous hemorrhage swirling around like the agitation cycle of a washing machine and then layering inferiorly. You suspect that he has a posterior vitreous detachment with associated vitreous hemorrhage (Image 4).

sound-4

Image 4: Vitreous detachment (arrow) with associated vitreous hemorrhage. AC=anterior chamber. PC=posterior chamber

Through Glass, you tell your senior resident to tilt the probe slightly superiorly and have the patient look up, down, left, and then right. With Google Glass on, your resident can hear your voice via bone conduction and the patient never hears any part of your conversation. While he scans, you catch a glimpse of a very small retinal detachment in the patient’s superior nasal retina (Image 5).

sound-5

Image 5: B-mode ocular ultrasound demonstrating a vitreous hemorrhage (VH) and very small retinal detachment (RD).

Given these findings and the patient’s previous history of retinal detachment, you have your resident call ophthalmology immediately. Ophthalmology comes in to see the patient and opts to perform pneumatic retinopexy at the bedside. As the ophthalmologist finishes up with the patient and congratulates you on picking up the very small detachment on ultrasound, he sees you wearing your Google Glass and exclaims, “Isn’t technology wonderful? How did we used to practice without it?” You thank him for his services, post a blurb on Facebook about how awesome your consultants are, answer two emergent emails on your phone, and text all of your residents to get ready for the three retaliation traumas that are about to roll through your door.

 

sound-6Pearls & pitfalls for Diagnosing Posterior Vitreous Detachment vs. Retinal Detachment via Ultrasound

1. Ocular ultrasound can be used to image the pupil, lens, vitreous chamber, retina, optic nerve, and retrobulbar space. It does not require pupillary dilatation to optimize imaging. Ultrasound is especially useful in a patient whose retina may be obscured by blood, edema, cataracts, or opacification of the cornea, and for evaluation of the vitreous chamber in uncooperative patients who won’t keep their eye open for fundoscopic evaluation.

2. It is often helpful to place a piece of Tegaderm or other thin, transparent semi-occlusive dressing over the patient’s closed eyelid before applying gel. Test to make sure the dressing you have available does not pull off the patient’s eyelashes or eyebrows during removal.

3. Place a high-frequency (10-7 MHz) linear array transducer horizontally over the patient’s closed eyelid. Some ultrasound machines have ocular or ophthalmology presets. If your machine does not have that option, turn up the gain to improve your evaluation of the vitreous chamber, posterior vitreous, and retina.

4. Systematically obtain images of all four retinal quadrants by having the patient look up, down, left, and right during the scan. Make sure you get a clear view of the periphery where many occult findings can be missed. Scan the contra-lateral eye for a comparison view.

5. If you think you visualize something in the posterior chamber of the eye, perform oculokinetic echography. During kinetic echography, have your patient perform voluntary saccadic globe movements while you hold the linear array transducer motionless over the patient’s closed eyelid. With these saccadic movements, you may see swirling or floating particles in the posterior chamber after the patient stops moving their eye.  

6. It is often difficult to distinguish a retinal detachment from a vitreous hemorrhage and a vitreous detachment. Vitreous hemorrhage can often layer in a linear fashion and appear similar to a retinal detachment during oculokinetic scanning. Both posterior vitreous detachments and retinal detachments can appear conical shaped with their apex attached at the optic disc. It is important to remember that the posterior hyaloid base is a lot less dense than the retina, so it will fade if the gain is turned down. Because the vitreous is highly mobile, a vitreous detachment will look like ‘swaying seaweed” during oculokinetic evaluation.

7. Conversely, a detached retina will be clearly visible as a bright white hyperechoic line undulating in the posterior chamber during oculokinetic scanning. Because the retina is a stiffer entity, it will move rather slowly compared to the vitreous detachment. You may also note very distinct attachment points to the posterior globe.

8. Posterior vitreous hemorrhages in and of themselves are not dangerous, and will likely resolve over time as the vitreous degenerates. The problems arise when vitreous fluid gets in between the posterior vitreous and the retina and exacerbates a retinal detachment. Then you have a true ophthalmologic emergency that needs to be addressed.

9. Be systematic when you perform your ocular scans. Don’t prematurely stop your scan just because you find one abnormality. In this patient, he had a posterior vitreous detachment with associated vitreous hemorrhage and a very small retinal detachment. The small retinal detachment could have easily been missed once the diagnosis of a posterior vitreous detachment and vitreous hemorrhage was made.

10. Practice, Practice, Practice: The best way to minimize errors is through experience, so scan lots of normal anatomy. The more scans you do, the better you will be able to differentiate abnormal from normal, even when you may not be sure exactly what the abnormality is. An image library of normal and abnormal scans helps immensely, so check out the Soundings archives on www.EPMonthly.com or go to www.ERPocketBooks.com.

11. Stay up to date on how you can use bedside ultrasound to enhance your clinical practice. Check out the ultrasound app “SonoSupport” available now for smartphones and tablets. If you prefer a physical pocketbook with the quick essentials of EM ultrasound, take a look at the Tarascon Emergency Department Quick Reference Guide

 

Special thanks to Christian Dameff and Jeff Tully for their assistance and expertise with our Google Glass projects and research. Here’s to discovering novel ways to enhance patient care and medical education worldwide.

 

Teresa S. Wu (@TeresaWuMD) is the Associate Residency Director, and Director of Ultrasound and Simulation Programs and Fellowships, for the Maricopa EM Program in Phoenix, Arizona. She is also the creator of SonoSupport, an ultrasound app for smartphones and tablets.

Brady Pregerson (@TheSafetyDoc) manages a free online EM Ultrasound Image Library and is the editor of the Emergency Medicine Pocketbook series. For more info visit EMresource.org.

 

Add comment

Security code
Refresh

Popular Authors

  • Greg Henry
  • Rick Bukata
  • Mark Plaster
  • Kevin Klauer
  • Jesse Pines
  • David Newman
  • Rich Levitan
  • Ghazala Sharieff
  • Nicholas Genes
  • Jeannette Wolfe
  • William Sullivan
  • Michael Silverman

Earn CME Credit