"Level 1 trauma...high speed car crash...GCS 6, was intubated in the field...ETA 5 minutes."
The patient arrives. You start your ABCs. The patient is intubated with BL breath sounds. You start circulation when you notice the pulses on BL lower extremities are absent with no obvious injury below the waist. You trace it up and notice decreased femoral pulses. The patient is getting exposed and you see a significant seatbelt sign on the chest. There’s a high suspicion for aortic injury. Let’s talk about blunt thoracic aortic injuries.
Background: Right off the bat: 80% of these patients do not make it to the hospital. Most of these patients die on the scene, however you may be able to do something for the 20% that make it to your ED. Up to 2 percent of patient who sustain blunt trauma to the thorax sustain a blunt thoracic aortic injury. 70% of patients are male.
Associated with rapid deceleration events, aortic injury occurs with MVC most of the time, followed by pedestrian struck, followed by fall from significant height. Sudden deceleration causes the injury at the aortic isthmus.
Where is the isthmus? Why is the isthmus? Good questions. So I looked it up:
Why do injuries occur at this spot of the aorta? Well there are several theories. 1. The aortic isthmus is a transition zone between the unfixed aortic arch and the fixed descending aorta; sudden deceleration causes the two parts to go in different directions leading to tearing. 2. The tissue surrounding the isthmus is weaker compared to the rest of the aorta. 3. The Osseous Pinch (new band name 2021): the aorta is trapped between the bones of anterior chest and the vertebral column during deceleration force.
An initial tear in the intima then leads to more intimate pathology- that of aortic dissection. A tear in the intima in a high pressure vessel leads to bleeding which can penetrate the adventitia, worsening until the point of pseudoaneurysm and free rupture. This is one of the main reasons you're not out of the woods if they're among the lucky 20% of folks to make it to the hospital.
Diagnosis: Gotta be on your A game. It won't always be apparent from the history and physical that you're dealing with an aortic injury. High speed injury, patient complaining of chest pain, back pain, SOB, trouble swallowing- all good places to start thinking about aortic injury in the setting of trauma. Good luck getting the patient to tell you any of these things, because a GCS <8 is present in up to 41% of patients with blunt thoracic aortic injury.
Physical exam findings that can tip you off include finding seatbelt sign across the chest, steering wheel sign, new murmur on auscultation. On the rarer side of things, you may see subclavicular hematoma or pseudocoarctation leading to increased pulses and hypertension of upper extremities, and decreased pulses and hypotension of the lower extremities.
CXR can show a widened mediastinum. One study by Bruckner et al found that the positive predictive value of a CXR with widened mediastinum is only 5%, but a cxr with the absence of widened mediastinum has a NEGATIVE predictor value of 99%.
Get a CTA of the chest if possible.
Aortagraphy is technically the gold standard for diagnosing blunt aortic injury. I'll be sure to get those right alongside my cardiac biopsies to diagnose myocarditis. Jokes aside, angiography is invasive and comes with its own complications and risks. And our wonderful CT techs and their wonderful machine is just calling to us from down the hall.
An alternative in a more unstable patient who is intubated is TEE. Like CTA, it also has a high sensitivity and specificity for detecting injury.
Grading is based on findings found on CTA. Let's breakdown the classification:
Type 1: Intimal Tear
Type 2: Intramural hematoma
Type 3: Pseudoaneurysm
Type 4: Rupture
Work up and management:
A 👏T👏 L 👏S. This is still a trauma, through and through when this arrives to your ED. Primary survey with ABCDEFast. Two large bore IVs. Fluid and blood. Secondary and tertiary surveys, imaging performed based on patient's clinic status.
For hemodynamically unstable patients, in the setting of trauma, go to the OR.
For the (initially) hemodynamically stable patient
Type 1 injuries may be managed conservatively- this means medical management- treat it like an aortic dissection. Aggressive HR control and BP control. HR below 100 and goal SBP 100. Esmolol is drug of choice, if another drug needed, can use diltiazem, nitroglycerin, nitroprusside.
Grades 2-4 require repair. Options include open repair with thoracotomy vs endovascular repair with aortic stent graft.
Oftentimes there are associated injuries. Injuries strong enough to hurt the aorta via deceleration is usually associated with blunt head, cardiac, lung, and bone injury. In fact, up to 81% of patients have an associated injury. The reason this is important, aside from having more things to treat in the ED, is that these can be distracting injuries to the true big bad laying in hiding.
Note: Thoracic aortic injury is a contraindication for REBOA therapy.
Sources:
https://www.annalsthoracicsurgery.org/article/S0003-4975(10)65322-2/pdf
https://cardiothoracicsurgery.biomedcentral.com/articles/10.1186/s13019-020-01101-6
https://pubmed.ncbi.nlm.nih.gov/16564268/
https://wikem.org/wiki/Traumatic_aortic_transection
https://www.ncbi.nlm.nih.gov/books/NBK555980/