When you come across peripheral intravascular air, take steps to minimize further entrainment of air and migration of air to the heart and lungs.
Aortic dissections are insidious killers that are often undetectable by history and physical exam alone. Obviously, providers must have a high index of suspicion for these as their presentations are highly variable. CT angiography, and less often, transesophageal echocardiography are classically the diagnostic modalities that providers use to identify this rare, deadly diagnosis. However, getting a patient over to CT can sometimes be delayed whether it is for transportation, or stabilizing the patient before CT scan.
A 73 year old lady with only a past medical history of hypertension that presented to our emergency department with intermittent focal left upper extremity numbness and weakness, and bilateral lower extremity pain. She presented hypotensive and tachycardic. The astute clinician had a high index of suspicion of dissection and while the patient was getting prepared to go to CT scan obtained the following clip of the parasternal long axis of the heart:
It is obvious here that the aortic outflow tract is dilated (usually, it should be the size of the left atrium).
Then the physician obtained a suprasternal view of the aortic arch and obtained the following clip:
Then, given the focal neurologic symptoms, she got the following images of the right carotid, in which you can see an intimal flap and also more distally, a blood clot in the carotid:
To investigate the distal extension of the clot, the following views were obtained of the abdominal aorta with an actual intimal flap:
Finally, at the level of the bifurcation, extension of the dissection into the bilateral iliacs is visualized
CT surgery was notified before the CT scan and the patient was taken directly from the CT scanner (which revealed the image below) to the OR..
Tips on POCUS for aortic dissection:
- A parasternal long axis view can be helpful to visualize a dilated aortic root and/or a pericardial effusion in the setting of a suspected dissection
- Evaluating carotid arteries, the distal aorta, or the iliac arteries can help diagnose an extensive dissection.
- Point of care ultrasound should be used to quickly make a diagnosis, speed further imaging, or get a consultant involved expeditiously. Similar to much of what we do with point of care ultrasound, this tool should be used to rule in a diagnosis, rather than to rule out a diagnosis.
- Point of care ultrasound can be used to make a quick diagnosis at the bedside before more consultative imaging, making it an invaluable tool in identifying this covert killer.
By Dr. Raashee Kedia
Acute vision change
A 51 year old female with a history of diabetes presented to the ED with acute onset of left eye painless blurry vision.Â Vitals were within normal limits.Â Fingerstick was 450.
On exam : Visual acuity was 20/30 in the right eye but could only count fingers in left eye at 1 foot. There were no external signs of trauma, conjunctivitis or proptosis. Pupils were equal and reactive to light.Â Ocular ultrasound of her right and left eyes were performed and shown below:
IN the left eye a bright echogenic linear structure can be seen floating in the posterior aspect of the globe. Â This was concerning for retinal detachment, which is a clear ocular emergency. Ophthalmology evaluated the patient in the emergency department and diagnosed a vitreous hemorrhage. The patient was discharged home.
How do you tell the difference between a vitreous hemorrhage and a retinal detachment?
First, a little anatomy of the eye:
The vitreous is a clear, gelatinous, and avascular substance, filling the space bound by the lens, retina, and optic disc. The retina is composed of multiple layers that form the posterior wall of the globe behind the vitreous. A retinal detachment occurs when these layers separate.
There is an internal membrane that separates the retina from the vitreous. This forms a potential space between the membrane and the vitreous called the subhyaloid space.
A vitreous hemorrhage occurs when blood extravasates into the vitreous or in the subhyaloid space. If bleeding has occurred in the subhyaloid space, it can appear boat-shaped on the surface of the retina, forming a superior straight line in an upright patient but changing with the position of the patient.
Ocular ultrasound is a quick and accessible way to assess ocular pathology. In patients with acute visual change, evaluation for retinal detachment is important to prevent complete and possibly permanent visual loss.
Ocular ultrasound is highly sensitive in the detection of retinal detachment in the ED.
With ocular ultrasound it can be difficult to distinguish between vitreous hemorrhage and retinal detachment. However, it is important to distinguish between these pathologies as they carry two different treatments and a different sense of urgency.
In an intact globe, the retina cannot be differentiated from the other choroidal layers on ultrasound.
Ultrasound of retinal detachment will show a thick hyperechoic membrane floating in the posterior globe. It never detaches from the optic nerve posteriorly.
Vitreous hemorrhage may layer and form a hyperdense linear density that can mimic a retinal detachment.
Decrease the gain to help differentiate between the two.
Vitreous hemorrhage is usually less dense and will fade as the gain is decreased. It usually layers inferiorly with gravity. Ocular movements produce a rapid, staccato motion of the hemorrhage, unlike a retinal detachment that is stiffer and slower in movements.
Schott, M, Pierog, J.,Williams, S. â€œPitfalls in the use of ocular ultrasound for evaluation of acute vision loss.â€ Journal of Emergency Medicine, Vol 44. Nov 2012.
Yanoff M, Duker JS. Opthalmology. 3rd ed. St Louis, MO: Mosby, An Imprint of Elsevier; 2008.
DiBernardo C, Greenberg E. Opthalmic ultrasound: A diagnostic atlas. 2nd ed. New York: Thieme MEidcal Publisers; 2007.
The FAST exam is generally described as a trauma assessment (hence the acronym). But it is often used as a metanym to mean any assessment of the peritoneum for fluid. In fact when I was a resident folks would often say, “let’s FAST that gallbladder,” or “get the FAST machine so we can put that central line in.” And we didn’t have Twitter.
Anyway, here are a few cases where the “FAST” was used in a non-trauma patient to assess the peritoneum:
Cirrhotic with abdominal pain and tenderness:
who was found to have ascites, and spontaneous bacterial peritonitis
Lower abdominal pain in pregnancy:
who was found to have hemoperitoneum from a ruptured ectopic pregnancy
Diffuse abdominal tenderness in a healthy ten-year-old:
who was found to have idiopathic seromas of the peritoneum, pleura, and pericardium!
Shortness of breath and abdominal distension:
which turned out to be massive abdominal abscesses
Diffuse abdominal tenderness and distension after hysteroscopy:
which was complicated by a bowel perforation; hence fecal material throughout the peritoneum
Take home points:
- Assessment of the peritoneum greatly aids medical and surgical diagnoses
- Fluid appears black (anechoic) on ultrasound. Very difficult to tell what TYPE of fluid by appearance alone
- Your clinical assessment must guide the differential diagnosis for your ultrasound findings
The operator correctly noted the presence of a pleural effusion, and a bit of lung tissue can be seen towards the left side of the screen floating in fluid. In addition, there are THREE shadows evident, each from a different source. Can you spot them?
So let’s take these one at a time, with labels:
Is the easiest one. It extends almost from the first pixel at the top of the screen down to the far field. We can’t even see the characteristic echotexture of skin or subcutaneous tissue in the near field. There’s no contact here between the transducer and skin, possibly due to:
- the probe not touching at all
- clothing or an EKG lead getting in the way
- not enough gel (the novice’s answer to everything but sometimes still true)
The most interesting one of the bunch. Probably two major factors at work here. First, this section of diaphragm is a particularly bright reflector so it can create a shadow behind it due to the sheer amount of reflection occurring. Second, the density difference between the diaphragm and pleural effusion is creating a refraction artifact, often referred to as an edge artifact. Beams of sound which were roughly parallel as they struck this interface get bent at different angles based on whether they hit the dense diaphragm or the less dense fluid. The space in between the formerly tightly spaced beams is displayed as blackness, or the absence of returning echoes.
That’s a rib shadow. Did you know that ribs grow back if you remove them?
This young healthy woman presented in her first trimester of pregnancy with lower abdominal pain and vaginal bleeding. She had diffuse abdominal tenderness and was mildly tachycardic with a normal blood pressure. After IV access was established, labs and blood bank sample were sent, and the following ultrasound of the right upper quadrant was obtained:
So there’s a bit of free fluid in Morison’s pouch. Can we make it more evident for the kids in the back row? The next image was taken with the patient in Trendelenberg position:
That made a pretty big difference.
In this sagittal view of the uterus the bladder is visible to the screen right; there is free fluid in the pelvis just to the left of this, and it can be seen to move with probe pressure on the lower abdomen.
Thus a diagnosis of ruptured ectopic pregnancy was strongly suspected, and the patient underwent emergency laparoscopy with the obstetrics service.
This patient presented with diffuse abdominal pain, tachycardia, and peritonitis on physical examination. A FAST exam was performed to assess for free intraperitoneal fluid, and the following view of was obtained transversely in the pelvis.
First, just look at the still image and make your best guess. Then press play:
Did the large anechoic structure in the near field look like the bladder? Or was it the anechoic area in the far field? The operator was thrown off a bit by the complex echoes within the anterior structure. Remember the bladder is going to conform to the shape of the pelvis as it enlarges, so it will take on a characteristic square/trapezoidal shape in transverse orientation. But for the same reasons free fluid will take the same shape. Through the sweep from cranial to caudal you’ll notice two fluid collections; the anterior one seemed to have much more internal echo and debris. Don’t assume that’s the peritoneal fluid- urine can also look that way.
This was the sample obtained when a Foley catheter was inserted into the bladder:
Here is the longitudinal (sagittal) view through the pelvis:
As usual, the sagittal view gives a better overview of the anatomy of the pelvis. When using the transverse view of the pelvis, you can miss small amounts of pelvic fluid more easily, confuse fluid collections for the bladder, and make incorrect assumptions. Just more support for the sonographic dogma of imaging everything in two planes.
CT scan confirmed free intraperitoneal fluid but no free air or other signs of bowel perforation. The hemoglobin was stable through several assessments. The patient had an obvious urinary tract infection and renal failure on laboratory evaluation. Thus the fluid was thought to be new onset of ascites in the setting of urosepsis and mult-organ dysfunction.
- Always image anatomy in at least two planes, and fan through anything that isn’t moving.
- Rethink assumptions when the anatomy doesn’t look as it should. For example, an oddly-shaped or highly echoic bladder may not be bladder at all, or it might just be an abnormal bladder.
- ALWAYS clean the machine and put it back where you found it when you are done.
I had to throw that in there, sorry.