Tag Archives: critical care

CME-Jim-group

2014 Emergency and Critical Care Ultrasound CME Course

The Mount Sinai Department of Emergency Medicine hosted its annual ultrasound CME conference on April 25. Faculty, fellows, nurses and PAs from a number of institutions and specialties took part in our tenth annual course.

The course was directed by Bret Nelson, MD who introduced ultrasound physics and machine controls, followed by lectures on assessment of  airway and breathing (Jim Tsung, MD, MPH), cardiovascular ultrasound (Jennifer Huang, DO), trauma evaluation (Phil Andrus, MD) and procedure guidance (Amy Sanghvi, MD).

After lunch an intensive hands-on session with live models, task simulators and sim cases rounded out the experience.

Faculty group photo

SonoSweden 2014 course

At the end of January, Bret Nelson joined an incredible team of international a faculty for the largest SonoSweden course to date. Course director Christofer Muhr hosted this unique, intensive hands-on conference at the scenic Yasuragi hotel in Stockholm, Sweden. Over thirty faculty and one hundred participants took part in this three-day course.

Among the faculty were lung ultrasound pioneer Vicki Noble, Matt Dawson and Mike Mallin (creators of the Ultrasound Podscast) and others from around the globe.

Registration is not yet open for the 2015 course, but check out the SonoSweden website for a countdown timer- there were over 100 people on the waiting list for this year’s course!

Papilledema and the Crescent Sign

 

What’s abnormal in this image?

 

Screen shot 2012 08 09 at 6.27.44 PM1 230x300 Papilledema and the Crescent Sign

Here’s a hint.  Here is an example of normal.

 

Screen shot 2012 08 09 at 6.18.41 PM1 256x300 Papilledema and the Crescent Sign

When evaluating for possible elevation in intracranial pressure, it has been shown that optic nerve sheath diameter (ONSD) measurements correlate with elevated intracranial pressures.(1,2)  The optic nerve attaches to the globe posteriorly and is wrapped in a sheath that contains cerebral spinal fluid.  The optic nerve sheath is contiguous with the dura mater and has a trabeculated arachnoid space through which cerebrospinal fluid slowly percolates.

Eye Sono 261x300 Papilledema and the Crescent Sign

ONSD Normal Ranges

Normal Adults < 5 mm
Children >1 yr < 4.5 mm
Infants < 1 yr <4 mm

 

The ONSD is measured 3 mm posterior to the globe for both eyes.  A position of 3 mm behind the globe is recommended because the ultrasound contrast is greatest.  It is best to average two measurements of each eye.  An average ONSD greater than 5 mm is considered abnormal and elevated intracranial pressure should be suspected.

 

ONSD large Papilledema and the Crescent Sign

ONSD Measurement

 

Crescent Sign

In severe cases of elevated ICP, one can see an echolucent circle within the optic nerve sheath separating the sheath from the nerve due to increased subarachnoid fluid surrounding the optic nerve.  Ophthalmologists refer to this as the crescent sign.

 crescent 2 Papilledema and the Crescent Sign

 

 The Case

40 yo female patient presents with several months of frontal headache associated with photophobia and blurry vision.  Symptoms have gotten much worse over the last few days and she has had difficulty reading and watching TV because of her visual symptoms.  She denies fevers, chills, nausea, vomiting, or focal weakness.   Pt is hypertensive 170/100.  Her vital signs are otherwise normal.

  • Visual acuity – 20/30 OD, 20/70 OS
  • CT head is normal
  • Bedside point of care ultrasound

papilledema cropped from Sinai EM Ultrasound on Vimeo.

Papilledema 2 cropped from Sinai EM Ultrasound on Vimeo.

This patient had enlarged ONSD (measurements were 6 mm bilaterally) as well as papilledema(arrow).

 

Papilledema arrow Papilledema and the Crescent Sign

Arrow notes papilledema

 

Lumbar puncture was performed.  Opening pressure was 44.  30 cc’s of CSF was drained and the closing pressure was 11.  The patient’s headache and visual symptoms improved .  She was started on acetazolamide and admitted to the neurology service.  MRI brain prior to lumbar puncture showed posterior scleral flattening bilaterally with protrusion of the optic nerve in the the globes bilaterally consistent with increased ICP.

This patient’s papilledema and increased ONSD correlated with a markedly increased opening pressure during lumbar puncture and suggests that ocular ultrasound may play a role in the ED management of patients with suspected pseudotumor cerebri.

Pseudotumor cerebri

Elevated intracranial pressure in the abscence of intracranial mass lesion.  Most common in young, over weight women. If the diagnosis is missed, persistently elevated intracranial pressure can lead to optic atrophy and blindness.

Treatment

  • Lumbar puncture to drain CSF to a normal opening pressure.
  • Medical:  Diomox (acetazolamide), high dose steroids
  • Surgical : Optic nerve sheath fenestration, VP shunt

Summary

The ability to diagnose papilledema using bedside sonography is useful to emergency physicians, as many non-ophthalmologist clinicians do not feel confident in their ability to perform an accurate nondilated fundoscopic examination. (3)  Ultrasound provides a useful alternative means of determining the presence or absence of papilledema in a patient in whom fundoscopy cannot be adequately performed.

 

 

[1] Geeraerts T, Launey Y, Martin L, et al. Ultrasonography of the optic nerve sheath may be useful for detecting raised intracranial pressure after severe brain injury. Intensive Care Med 2007;33(10):1704-11 [electronic publication 2007 Aug 1]. PMID: 17668184

 

[2] Kimberly HH, Shah S, Marill K, Noble V. Correlation of optic nerve sheath diameter with direct measurement of intracranial pressure. Acad Emerg Med 2008;15(2):201-4. PMID: 18275454

 

[3] Wu EH, Fagan MJ, Reinert SE, Diaz JA. Self-confidence in and perceived utility of the physical examination: a comparison of medical students, residents, and faculty internists. J Gen Intern Med 2007;22 (12):1725-30 [electronic publication 2007 Oct 6].  PMID: 17922165

 

Bubble test

bubbles 300x225 Bubble testWe already know it is helpful to use ultrasound to guide placement of central venous catheters.

How can we use ultrasound to help confirm proper placement of an internal jugular catheter?

There are several methods which have been described:

  • Visualize the needle entering the vein (optimally in the long axis)
  • Visualize the guide wire in the vein
  • Visualize the tip of the triple lumen catheter in the right atrium, then pull back 2 cm
  • Bubble test (more on this below)

In addition there are non-ultrasound-related methods to confirm placement (but who cares about those?):

  • Chest x-ray
  • Blood gas drawn through central venous catheter port
  • Pressure transduction (quantitative- manometry)
  • Pressure transduction (qualitative- attach IV tubing and check height of blood column)

So let’s get back to that bubble test. In order to confirm that the catheter has been placed in the superior vena cava, inject 5-10 cc normal saline through the catheter while visualizing the right heart on a subxiphoid 4-chamber view.  When done right should look something like this :

Saline flush right heart from Sinai EM Ultrasound on Vimeo.

So this is a neat trick after the catheter is in, but the horse is out of the barn at that point. Ideally you should confirm proper venous placement prior to dilating the vessel and placing the central line. You could do this while the needle is in the vessel, but that’s a bit unstable. Instead consider using the long angiocatheter found in most central line kits to puncture the internal jugular vein.

After the flash (and ultrasound confirmation of venous puncture) advance the catheter and remove the needle. You then have an angiocatheter in the central venous system, which can be used for manometry, blood gas analysis, or the saline push necessary for the bubble test. Some people have used this angiocatheter during ACLS situations to administer a few doses of code medications in a shorter time than it would take to complete a “full” central line.

Once proper venous placement is confirmed, you can advance the guide wire through the angiocatheter and continue the procedure as normal.

For a great overview of central venous catheterization, check out this post by Haru Okuda and Scott Weingart at EMCrit.org.

Further Reading

Prekker ME, Chang R, Cole JB, Reardon R.  “Rapid confirmation of central venous catheter placement using an ultrasonographic “Bubble Test.” Acad Emerg Med 2010;17(7):e85-6. (PMID: 20653578)

Intubation devices

Many new developments in ultrasound were demonstrated at the ACEP conference in Denver this week. Since airway management rivals ultrasound as my academic interest, I’d like to focus for a moment on an intubating device I saw demonstrated at an ultrasound vendor booth.  I’ve seen lots of organs on my ultrasound screen- hearts, gallbladders, eyeballs, prostates. I’ve even seen airway structures, but not like this:

VividTrac Intubation devices

The VividTrac is a single use, USB video intubation device. It is a channeled blade video laryngoscope similar in concept to the King Vision or the AirTraq Optical Laryngoscope. The channel is designed to pass the endotrachel tube through. This is in contrast to non-channeled video laryngoscopes like the Storz C-MAC or the Verathon Glidescope, where the endotracheal tube is guided with a stylet and not directed through the video device itself.

What is interesting about the Vivid device is it hooks up to a monitor using a standard USB cable. Thus, it can be connected to different types of monitors, PDAs or tablets which accept USB input, or… an ultrasound machine monitor! Theoretically one could use an existing ultrasound machine with a variety of probe types as well as a device like this.

There are many device manufacturers involved in R&D of devices which might lead to a technology convergence. Ultrasound probes, video intubation devices, cardiac monitoring equipment, etc. could all transmit images to a monitor, via wires or wirelessly. Thus, pluripotent monitors could be used with a variety of devices depending on the needs of any given patient. This could increase the amount of information relayed via the monitors, and even what is transmitted to the electronic medical record. Importing vital signs, ultrasound images, EKGs, or other clinical images could all be captured in this way. It will be interesting to see how many other devices can learn to communicate with each other as the technology develops.

Straight Suture Safety

finger bandage 300x271 Straight Suture SafetyHopefully you are using ultrasound to guide your insertion of central venous catheters. Once they are in, you still have to suture them at some point. Straight suture needles are often used to secure arterial and venous catheters to the skin. These types of suture needles have been demonstrated to be more dangerous than curved or blunt suture needles, with up to seven times higher rate of injury for health care workers. By utilizing the plastic needle sheath present in most central venous line kits as a “thimble,” counter pressure and skin puncture may be achieved without bringing the fingers near the sharp end of the suture. Here’s an image from Bret Nelson’s article on the technique.

Straight Sutre Safe 500x213 Straight Suture Safety

Panel A shows counter-pressure being applied with the cap to direct the tip of the needle. Panel B shows the needle tip safely sheathed within the cap.

The video below demonstrates this technique in real time:

 

Safety technique for straight suture needle from Sinai EM Ultrasound on Vimeo.

 

Other authors have illustrated alternative techniques to reduce the risk of self-injury when using straight suture needles.  Steven Bauer uses a 5-mL syringe to ensconce the emerging straight needle. This can provide even more distance, and he also uses it to guide tying an ‘air knot’ when needed!

syringe needle cap Bauer Straight Suture Safety

Haney Mallemat has just posted a video where he demonstrates using the paper envelope the suture is packaged in to distance the needle tip from your fingers.

Keep in mind NONE of these techniques has been studied- there is no evidence that they reduce needlesticks. We DO know that using curved, blunt-tip suture needles used with needle drivers and forceps is safer than using straight sutures. Whichever method you use please be careful!

References

  • Nelson BP. Making straight suture needles a little safer: a technique to keep fingers from harm’s way. J Emerg Med. 2008 Feb; 34(2):195-7. Epub 2007 Oct 1. (PMID: 18282537)
  • Bauer S, Tauferner D, Carlson D. Improving straight needle safety: an alternate method. J Emerg Med. 2011 Jul; 41(1):e19-20. Epub 2009 Sep 17. (PMID: 19765943)
  • Centers for Disease Control and Prevention. Evaluation of blunt suture needles in preventing percutaneous injuries among healthcare workers during gynecologic surgical procedures—New York City, March 1993–June 1994. MMWR Morb Mortal Wkly Rep 1997;46:25–9. (PMID: 9011779)
  • Edlich RF, Wind TC, Hill LG, Thacker JG, McGregor W. Reducing accidental injuries during surgery. J Long Term Eff Med Implants 2003;13:1–10. (PMID: 12825744)

 

Effusion

RUQ fluid 500x363 EffusionUltrasound is quite sensitive in detecting even very small pleural effusions; it has been demonstrated to perform better than chest x-ray and nearly as well as CT scan. In order to assess for pleural fluid, the transducer should be directed through the liver (Right side) or spleen (Left side) and diaphragm. In a normal thorax, a mirror image artifact will generally be seen above the diaphragm. When effusion is present, fluid eradicates this artifact, creating an anechoic appearance in the costophrenic angle.

The image above demonstrates a common pitfall in abdominal and thoracic ultrasound. The liver is visible in the near field, and a dark anechoic structure is evident just deep to the liver. Some see this fluid and may note a positive FAST examination or free intraperitoneal fluid. Others may see this appearance and diagnose pleural effusion or hemothorax. While it is true the anechoic area represents fluid, there is a more correct response.

The inferior vena cava can generally be seen posterior to the liver, towards the patient midline. As it is filled with blood it will appear anechoic. below the diaphragm it will course parallel and to the [patient's] right of the Aorta. Just above the diaphragm it will quickly merge into the Right Atrium.

As with most scanning, fanning through multiple planes will generally sort out the true anatomy. In the clip below we see the IVC as the operator sweeps medially, and the the pleural effusion is more evident in the lateral portions of the sweep. One (of many) giveaways is that the hepatic veins drain into the IVC, and even in this brief sweep through the IVC a hepatic vein is visible anteriorly, draining into the IVC.

Pleural effusion and mimic from Sinai EM Ultrasound on Vimeo.