All posts by The Trauma Pro

Head

What You Need To Know About: Frontal Sinus Fractures

April 20, 2021 The Trauma Pro Leave a comment

Fracture of the frontal sinus is less common than other facial injuries, but can be more complex to deal with, both in the shorter and longer terms. These are generally high energy injuries, and facial impact in car crashes is the most common mechanism. Fists generally can’t cause the injury, but blunt objects like baseball bats can.

Here’s the normal anatomy:

$sinus-fracture-treatment$

Source: www.facialtraumamd.com

There are two “tables”, the anterior and the posterior. The anterior is covered with skin and a small amount of subcutaneous tissue. The posterior table is separated from the brain by the meninges.

Here’s an image of an open fracture involving both tables. Note the underlying pneumocephalus.

frontal_sinus1

A third of injuries violate the anterior table, and two thirds violate both. Posterior table fractures are very rare. A third of all patients will develop a CSF leak, typically from their nose.

These fractures may be (rarely) identified on physical exam if deformity and flattening is noted over the forehead. Most of the time, these patients undergo imaging for brain injury and the fracture is found incidentally. Once identified, go back and specifically look for a CSF leak. Clear fluid in the nose is, by definition, CSF. Don’t waste time on a beta-2 transferring (see below).

If a laceration is clearly visible over the fracture, or if a CSF leak was identified, notify your maxillofacial specialist immediately. If more than a little pneumocephalus is present, let your neurosurgeon know. Otherwise, your consults can wait until the next morning.

In general, these patients frequently require surgery for the fracture, either to restore cosmetic contours or to avoid mucocele formation. However, these are seldom needed urgently unless the fracture is an open fracture with contamination or there is a significant CSF leak. If in doubt, though, consult your specialist.

Related posts:

Imaging, New technology

New Technology: Using AI To Interpret Pelvic X-rays

April 16, 2021 The Trauma Pro Leave a comment

Look out, radiologists! The computers are coming for you!

Radiologists use their extensive understanding of human anatomy and combine it with subtle findings they see on x-ray shadow pictures. In doing this, they can identify a wide variety of diseases, anomalies, and injuries. But as we have seen with vision systems and game playing (think chess), computers are getting pretty good at doing this as well.

Is it only a matter of time until computer artificial intelligence (AI) starts reading x-rays? Look at how good they already are at interpreting EKGs. The trauma group at Stanford paired up with the Chang Gung Memorial Hospital in Taiwan to test the use of AI for interpreting images to identify a specific set of common pelvic fractures.

The Stanford group used a deep learning neural network (XCeption) to analyze source x-rays (standard A-P pelvis images) from Chang Gung. These x-rays were divided into training and testing cohorts. The authors also applied different degrees of blurring, brightness, rotation, and contrast adjustment to the training set in order to help the AI overcome these issues when interpreting novel images.

The AI interpreted the test images with a very high degree of sensitivity, specificity, accuracy, and predictive values, with all of them over 0.90. The algorithms generated a “heat map” that showed the areas that were suspicious for fracture. Here are some examples with the original x-ray on the left and the heat map on the right:

The top row shows a femoral neck fracture, the middle row an intertrochanteric fracture, and the bottom row another femoral neck fracture with a contralateral implant. All were handily identified by the AI.

AI applications are usually only as good as their training sets. In general, the bigger the better so they can gain a broader experience for more accurate interpretation. So it is possible that uncommon, subtle fractures could be missed. But remember, artificial intelligence is meant to supplement the radiologist, not replace him or her. You can all breathe more easily now.

This technology has the potential for broader use in radiographic interpretation. In my mind, the best way to use it is to first let the radiologist read the images as they usually do. Once they have done this, then turn on the heat map so they can see any additional anomalies the AI has found. They can then use this information to supplement the initial interpretation.

Expect to see more work like this in the future. I predict that, ultimately, the picture archiving and communications systems (PACS) software providers will build this into their product. As the digital images are moving from the imaging hardware to the digital storage media, the AI can intercept it and begin the augmented interpretation process. The radiologist will then be able to turn on the heat map as soon as the images arrive on their workstation.

Stay tuned! I’m sure there is more like this to come!

Reference: Practical computer vision application to detect hip fractures on pelvic X-rays: a bi-institutional study. Trauma Surgery and Acute Care Open 6(1), http://dx.doi.org/10.1136/tsaco-2021-000705.

Philosophy

Do I Have To Call My Trauma Team For Incoming Transfers?

April 13, 2021 The Trauma Pro Leave a comment

I had a great question sent in by a reader last week:

Some trauma centers receive a number of transfers from referring hospitals. Much of the time, a portion of the workup has already been done by that hospital. If the patient meets one or more of your trauma activation criteria, do you still need to activate your team when they arrive?

And the answer is: sometimes. But probably not that often.

Think about it. The reason you should be activating your team is that you suspect the patient may have an injury that demands rapid diagnosis and treatment. The purpose of any trauma activation is speed. Rapid evaluation. Fast lab results. Quick access to CT scan or OR. If a significant amount of time has already passed (transported to an outside hospital, worked up for an hour or two, then transported to you), then it is less likely that a trauma activation will benefit the patient.

There are four classes of trauma activation criteria. I’ll touch on each one and the need to activate in a delayed fashion if present, in priority order.

Physiologic. If there is a significant disturbance in vital signs while in transit to you (hypotension, tachycardia, respiratory problems, coma), then you must activate. Something else is going on that needs to be corrected as soon as the patient arrives. And remember the two mandatory ACS criteria that fall into this category: respiratory compromise/need for an emergent airway, and patients receiving blood to maintain vital signs. But a patient who needed an airway who is already intubated and no longer compromised does not need to be a trauma activation.
Anatomic. Most simple anatomic criteria (e.g. long bone or pelvic fractures) do not need a trauma activation unless the patient is beginning to show signs of physiologic compromise. However, anatomic criteria that require rapid treatment or access to the OR (proximal amputations, mangled or pulseless extremities, spinal cord injury) should be activated.
Mechanism. Most of the vague mechanistic criteria (falls, pedestrian struck, vehicle intrusion) do not require trauma activation after transfer to you. But once again, if the mechanism suggests a need for further rapid diagnosis or treatment (penetrating injury to abdomen), then activate.
Comorbidities. This includes underlying diseases, extremes of age, and pregnancy. In general, these will not require trauma activation after they arrive.

Bottom line: In many cases, the patient transferred in from another hospital will not need to be a trauma activation, especially if they have been reasonably assessed there. The patient should be rapidly eyeballed by your emergency physicians, and if there is any doubt about their condition, activate then.

However, if little workup was done at the outside hospital (my preference), and the injuries are “fresh” (less than a few hours old), then definitely call your team.

Thorax

Delayed Hemothorax In Older Adults: Real Or Not?

April 6, 2021 The Trauma Pro Leave a comment

I came across an interesting paper in the Journal of Trauma & Acute Care Surgery Open recently. I always read these articles a bit more critically, though, because the peer review process just doesn’t feel quite the same to me as the more traditional journal process. But maybe it’s just me.

In this paper, the authors decided to look at the incidence of delayed hemothorax because “emerging evidence suggests HTX in older adults with rib fractures may experience subtle hemothoraces that progress in a delayed fashion over several days.” They cite two references to back up this rationale.

They retrospectively reviewed records from two busy US Level I trauma centers for adults age 50 or older who were diagnosed with delayed hemothorax (dHTX). Delayed was defined as 48 hours or more after initial chest CT showed either a minimal or trace HTX. The authors went on to analyze the characteristics and demographics of the patients involved.

Here are the factoids:

A total of 14 older adults experienced dHTX after rib fractures, an overall incidence of 1.3% (!)
About half were diagnosed during the initial hospitalization for the fractures
All patients had multiple fractures, with an average of 6 consecutive ones; four had a flail chest
One third progressed from a trace HTX, two thirds had a completely negative initial chest CT
Only one third were taking anticoagulants or anti-platelet agents
Patients with multiple fractures, posteriorly located, and displaced were most likely to develop dHTX

The authors concluded that “delayed progression and delayed development of HTX among older adults with rib fractures require wider recognition.”

Bottom line: Really? First, I looked at the papers cited by the authors as the rationale for doing this study. They each found dHTX in about 10% of patients, but their definition was very broad: any fluid visible on upright chest x-ray. Furthermore, the patients were not really “older” either. Average age was around 50.

So I’m not sure yet whether this is a problem, especially with the low incidence of 1.3%. This study doesn’t come right out and state how many patients they reviewed to find their 14, but it can be calculated to be 14 / 1.3% = 1,177. This incidence is only one tenth of that found in the two studies cited. Seems relatively uncommon, and half were discovered while the patients were still in the hospital. Thus only 0.65% sought readmission for chest discomfort or difficulty breathing.

This study required chest CT for rib fracture diagnosis. Is all that radiation (and possibly contrast) really necessary? And did these patients get another chest CT to delineate the pathology? More radiation?

Overall, this paper was not very helpful to me. Yes, I have seen patients come back days or weeks later with a hemothorax that was not seen during their first visit. It’s just that this study raises many more questions that should have been easily answered in the discussion. But they weren’t.

Given that only about a half of a percent of rib fracture patients develop delayed hemothorax after discharge, it is probably prudent to provide information to the patient recommending they see their practitioner if they develop any symptoms days or weeks later. And a simple chest x-ray should do.

Reference: Complication to consider: delayed traumatic hemothorax in older adults. Trauma Surgery & Acute Care Open 2021;6:e000626. doi: 10.1136/tsaco-2020-000626.

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