All posts by The Trauma Pro

Abstracts, Imaging

Best Of EAST 2023 #8: Use Of AI To Detect Rib Fractures On CT

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Artificial intelligence systems (AI) are increasingly finding their way into medical practice. They have been used to assist pathologists in screening microscope specimens for years. Although still amazingly complicated, one of the most obvious applications for trauma is in reading x-rays. Counting rib fractures may be helpful for care planning, and characterizing fracture patterns may assist our orthopedic colleagues in evaluating and planning rib plating procedures.

The trauma group at Stanford developed a computer vision system to assist in identifying fractures and their percent displacement.  They used a variation on a neural network deep learning system and trained it on a publicly available CT scan dataset.  They used an index of radiographic similarity (DICE score) to test how well their model matched up against the reading of an actual radiologist.

Here are the factoids:

  • The AI network was trained on a dataset of 5,000 images in 660 chest CT scans that had been annotated by radiologists
  • The model achieved a DICE score of 0.88 after training
  • With a little jiggering of the model (reweighting), the receiver operating characteristic curve improved to 0.99, which is nearly perfect

The left side shows a CT scan rotated 90 degrees; the right side shows the processed data after a fracture was detected.

Bottom line: This paper describes what lies ahead for healthcare in general. The increasing sophistication and accuracy of AI applications will assist trauma professionals in doing their jobs better. But rest easy, they will not take our jobs anytime soon. What we do (for the most part) takes very complex processing and decision making. It will be quite some time before these systems can do anything more that augment what we do.

Expect to see these AI products integrated with PACS viewing systems at some point in the not so distant future. The radiologist will interpret images in conjunction with the AI, which will highlight suspicious areas on the images as an assist. The radiologist can then make sure they have reported on all regions that both they and the AI have flagged.

Here are my questions and comments for the presenter/authors:

  • How can you be sure that your model isn’t only good for analyzing your training and test datasets? If neural networks are overtrained, they get very good at the original datasets but are not so good analyzing novel datasets. Have you tried the on your own data yet?
  • Explain what “class reweighting” is and how it improved your model. I presume you used this technique to compensate for the potential issue mentioned above. But be sure to explain this in simple terms to the audience.
  • Don’t lose the audience with the net details. You will need to give a basic description of how deep learning nets are developed and how they work, but not get too fancy.

This is an interesting glimpse into what is coming to a theater near you, so to speak. Expect to see applications appearing in the next few years.

Reference: AUTOMATED RIB FRACTURE DETECTION AND CHARACTERIZATION ON COMPUTED TOMOGRAPHY SCANS USING COMPUTER VISION. EAST 2023 Podium paper #16.

Abstracts, Imaging

Best Of EAST 2023 #7: The CT Autopsy

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Back in the day, autopsy after trauma death was fairly commonplace. Nowadays, it is typically reserved for fatalities that involve a potential crime. And it can be challenging to get the medical examiner to release copies for trauma performance improvement.

One potential remedy for this began to surface in the literature about twenty years ago: the virtual (or CT) autopsy. This entails sending the postmortem patient to the scanner for head, cervical, chest, and pelvic scans. Although it seems like an exciting idea, there are several logistical issues that I will discuss later.

The trauma group at Indiana University performed a retrospective study to determine the common injury patterns in patients who died at or up to one hour after ED arrival. Their goal was to identify injury patterns that might improve the focus and quality of resuscitative efforts in living patients. They reviewed their experience with doing postmortem CT over a nine-year period. The primary goal was to identify sources of hemorrhage, TBI, and cervical spine injury. They also wanted to identify significant pneumothorax and misplaced airway devices.

Here are the factoids:

  • There were 80 decedents in the study, and they were severely injured, with an average ISS of 42
  • About three quarters arrested prior to arrival, and the remainder arrived with a pulse
  • The most common major injuries were severe TBI (41%), long bone fractures (25%), hemoperitoneum (23%), and cervical spine injury (19%)
  • A moderate pneumothorax was present in 19% of cases
  • Misplaced airway was identified in 5%
  • There was no difference in injury or device mishap patterns between pre-hospital and in-hospital arrest patients (although the number of patients was probably too small to detect one)

The authors concluded that the injury patterns between those who died prior to arrival vs. after were the same. They also noted that patients in arrest should automatically have their chest decompressed and the airway position checked.

Bottom line: This is an intriguing study of a concept I’ve been thinking about for years. The quality improvement benefits could be amazing! Imagine getting immediate feedback on the cause of death and how it might influence future resuscitations. The authors pointed out the power of this with their discovery of missed pneumothorax and malpositioned airways.

But, as mentioned above, there are a host of logistical problems to work out first. Here is a partial list:

  • Who accompanies the patient to scan? A nurse? The team?
  • Covered or uncovered? It might be creepy for people in the hallways to see a covered person being wheeled around. That’s why hospitals always have those white, wheeled boxes. But it’s equally creepy to see a person who is not moving or breathing being transported.
  • Be prepared for your radiologists to gripe about doing free reads
  • Where does the report go? It shouldn’t go to the medical record. Or should it?
  • What about liability issues? If the team misses something big and the report goes to the chart, it’s fair game for a lawsuit.
  • And many more!

Here are my questions and comments for the presenter/authors:

  • How did you come to do this study? It appears that your group has been performing CT autopsies for almost a decade. Was there a protocol? Was it done on every eligible patient? If not, could this have skewed your results?
  • Do you have the statistical power to detect any differences between the various groups? A few of your results did approach significance. Perhaps more subjects would have helped.
  • Tell us how you have addressed the logistical problems above.

This is great work; perhaps it will stimulate a move toward embracing this concept!

Reference: CHARACTERIZATION OF FATAL BLUNT INJURIES USING POST-MORTEM COMPUTED TOMOGRAPHY. EAST 2023 Podium paper #14.

 

Abstracts, Resuscitation

Best Of EAST 2023 #6: The Best Place To Intubate Bleeding Patients

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Forty years ago, the presumption was that the best way to intubate a trauma patient was to take them to a fully equipped operating room and have an anesthesiologist perform it. Then, a few years later, we finally figured out it could be done in the emergency department. The key to doing it safely was that the trauma bay needed to look like an OR, with appropriate airway equipment, lights, and drugs. And you had to ensure that your intubator had sufficient skills.

But we are all too familiar with one subset of trauma patients much more sensitive to the intubation process: those who are bleeding and in shock. They are desperately compensating to attempt to maintain their vital signs as much as they can with their sympathetic tone. Unfortunately, the intubation process and the drugs we use can eliminate this reflex and lead to immediate hemodynamic collapse.

The trauma group at Johns Hopkins postulated that intubation in the ED could lead to worse outcomes in this particular group of patients. They analyzed three years of data from the National Trauma Data Bank dataset, isolating patients at Level I and Level II trauma centers who underwent immediate hemorrhage control surgery after arrival. Patients who were dead on arrival, intubated for airway concerns, or underwent resuscitative thoracotomy were excluded.

The authors used a regression model to determine any association between intubation and mortality. They also analyzed the usual secondary outcomes (complications [cardiac arrest, ARDS, AKI, sepsis], transfusions, and time in the ED).

Here are the factoids:

  • Nearly ten thousand patients at 253 trauma centers met inclusion criteria
  • Most patients were men with penetrating injury
  • One in five underwent intubation in the ED before their hemorrhage control operation and suffered a 17% mortality rate vs. 7% in the OR intubation group, which was a significant difference
  • Median dwell time in the ED was 31 minutes vs. 22 minutes in the OR group
  • Transfusion amount was significantly higher in the ED vs. OR group (6 vs. 4 units RBC)
  • Rates of all complications were significantly higher in the ED vs. OR groups (except sepsis)
  • Overall, cardiac arrest with CPR occurred in 10% of ED vs. 4% OR intubations
  • Centers that had low ED intubation rates generally had significantly lower post-intubation cardiac arrest events than those with higher ED intubation rates.

The authors concluded that ED intubation of patients requiring hemorrhage control was associated with multiple adverse events. They recommended that these patients be taken to the OR, where both intubation and rapid bleeding control can be achieved.

Bottom line: This nice, clean abstract addresses a simple question. Although it uses a large database, the authors focused on a limited number of variables, keeping the analysis uncomplicated.

The abstract paints a clear picture that agrees with the subjective observations of many trauma professionals that intubation in these patients can be dangerous. They found significant increases in mortality and complications in patients intubated in the ED.

Does this mean that the procedure is not being done as well there? Absolutely not! I believe the key is in the ED dwell time data, which shows an average of 9 more minutes spent there for intubation. Previous research has shown how even a few minutes count when it comes to hemorrhage control. This abstract provides some hard numbers that show how important it really is to get to the OR.

Here are my questions and comments for the presenter/authors:

  • First, a minor point: how can the “median” GCS be 15? Fifteen is the highest it can go. The median is the number where half the results are higher and half are lower. So if no results can be higher, none can be lower. Does this mean that every one of your 10K patients was wide awake?
  • Please explain the figure a little better. Does it just show the mix of low vs. average vs. high ED intubation rates? Or does it go along with the statement that high intubation rate centers have a higher likelihood of cardiac arrest in these patients?

I really enjoyed this abstract and am looking forward to any additional details provided at the presentation.

Reference: EMERGENCY DEPARTMENT VERSUS OPERATING ROOM INTUBATION OF PATIENTS UNDERGOING IMMEDIATE HEMORRHAGE CONTROL SURGERY, EAST 2023 Podium paper #13.

Abstracts, Guidelines, Imaging

Best Of EAST 2023 #5: Imaging The Elderly

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Several papers have been published over the years regarding underdiagnosis when applying the usual imaging guidelines to elderly trauma patients. Unfortunately, our elders are more fragile than the younger patients those guidelines were based on, leading to injury from lesser mechanisms. They also do not experience pain the same way and may sustain serious injuries that produce no discomfort on physical exam. Yet many trauma professionals continue to apply standard imaging guidelines that may not apply to older patients.

EAST sponsored a multicenter trial on the use of CT scans to minimize missed injuries. Eighteen Level I and Level II trauma centers prospectively enrolled elderly (age 65+) trauma patients in the study over one year. Besides the usual demographic information, data on physical exams, imaging studies, and injuries identified were also collected. The study sought to determine the incidence of delayed injury diagnosis, defined as any identified injury that was not initially imaged with a CT scan.

Here are the factoids:

  • Over 5,000 patients were enrolled, with a median age of 79
  • Falls were common, with 65% of patients presenting after one
  • Nearly 80% of patients actually sustained an injury (!)
  • Head and cervical spine were imaged in about 90% of patients, making them the most common initial studies
  • The most commonly missed injuries involved BCVI (blunt carotid and vertebral injury) or thoracic/lumbar spine fractures
  • 38% of BCVI injuries and 60% of T/L spine fractures were not identified during initial imaging
  • Patients who were transferred in, did not speak English, or suffered from dementia were significantly more likely to experience delayed diagnosis

The authors concluded that about one in ten elderly blunt trauma patients sustained injuries in body regions not imaged initially. They recommended the use of imaging guidelines to minimize this risk.

Bottom line: Finally! It has taken this long to perform a study that promotes standardizing how we perform initial patient imaging after blunt trauma. Granted, this study only applies to older patients, but the concept can also be used for younger ones. The elderly version must mandate certain studies, such as head and the entire spine. Physical exams can  still be incorporated in the guidelines for younger patients but not the elderly.

The overall incidence of BCVI was low, only 0.7%. But its presence was missed in 38% of patients, setting them up for a potential  stroke. Some way to incorporate CT angiography of the neck will need to be developed. The risk / benefit ratio of the contrast load vs. stroke risk will also have to be determined.

Here are my questions and comments for the presenter/authors:

  • Did you capture all of the geriatric patients presenting to the study hospitals? By my calculation, 5468 patients divided by 18 trauma centers divided by 14 months of study equals 22 patients enrolled per center per month. Hmm, my center sees more than that number of elderly injured patients in the ED per day! Why are there so few patients in your study? Were there some selection criteria not mentioned in the abstract?
  • Why should we believe these study numbers if you only included a subset of the total patients that were imaged?

My own reading of the literature leads me to believe that your conclusions are correct. I believe that all centers should develop or revise their elderly imaging guidelines to include certain mandatory scans regardless of how benign the physical exam appears. Our elders don’t manifest symptoms as reliably as the young. But the audience needs a little more information to help them understand some of the study numbers.

Reference: SCANNING THE AGED TO MINIMIZE MISSED INJURY, AN EAST MULTICENTER TRIAL. EAST 2023 podium abstract #12.

Head, Resuscitation

Best Of EAST 2023 #4: Whole Blood In Patients With Shock And TBI

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We know that even a brief shock episode in patients with severe TBI dramatically increases mortality. Therefore, standard practice is to ensure good oxygenation with supplemental O2 and an adequate airway ASAP and to guard against hypotension with crystalloids and blood if needed.

Many papers (and several abstracts in this bunch) have been written about the benefits of whole blood transfusion. The group at the University of Texas in Houston compiled a prospective database of their experience with emergency release blood product usage in patients with hemorrhagic shock.

They massaged this database, analyzing a subset of patients with severe TBI, defined as AIS Head of 3. They specifically looked at mortality and outcome  differences between those who received whole blood and those who received component therapy.

Here are the factoids:

  • A total of 564 patients met the TBI + shock criteria, and 341 (60%) received whole blood
  • Patients receiving whole blood  had higher ISS (34 vs. 29), lower blood pressure (104 vs. 118), and higher lactate (4.3 vs. 3.6), all indicators of more severe injury
  • Initial univariate analysis did not identify any mortality difference, but using a weighted multivariate model teased out decreases in overall mortality, death from the TBI, and blood product usage
  • Neither statistical model demonstrated any difference in discharge disposition of ventilator days

The authors concluded that whole blood transfusion in patients with both hemorrhagic shock and TBI was associated with decreased mortality and blood product utilization.

Bottom line: This is yet another study trying to tease out the benefits of giving whole blood. The results are intriguing and show an association between whole blood use and survival. But remember, this type of study does not establish causality. It’s not possible to rule out other variables that were not available or not considered that could be the cause of the difference.

In this type of study, it’s essential to look at the design. Was it possible to create the study to record a complete set of variables that the researchers thought might contribute to the outcomes? Or is it a retrospective analysis of someone else’s data that contains just a few of them? This study falls into the latter category, so we have fewer data elements to work with and the likelihood that others that are not present could contribute to the outcomes.

The details of the multivariate analysis are also important. The authors stated that weighted multivariate analyses were performed. It’s not possible to provide details in a standard abstract, but these will be important for the audience to understand.

Here are my questions and comments for the presenter/authors:

  • Tell us more about the database you used for the analysis. What was the purpose? How many data elements did you collect, and how are they related to your research questions?
  • How did you decide which variables to include in your multivariate analysis? And how did you determine the weights? These can have a significant effect on your results.
  • This is a preliminary proof of idea study. How should this be followed up to move from association to causation?

This is just one of many exciting studies trying to shed light on the forgotten benefits of whole blood in trauma. I’m looking forward to seeing the final manuscript!

Reference:  PATIENTS WITH BOTH TRAUMATIC BRAIN INJURY AND HEMORRHAGIC SHOCK BENEFIT FROM RESUSCITATION WITH WHOLE BLOOD. EAST 2023 Podium paper #2.