Category Archives: Abstracts

Abstracts, Pharmacy, Solid organ

Best Of EAST 2023 #10: Early VTE Prophylaxis In Adolescents With Solid Organ Injury

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Chemoprophylaxis against venous thromboembolism (VTE) is routine in trauma care. In most cases, it can be initiated shortly after admission in most trauma patients. However, there are a few major exceptions, including eye injuries and brain injuries with intracranial hemorrhage.

Solid organ injury used to be cause for concern when considering prophylaxis, but most trauma centers are now comfortable beginning within 24 to 48 hours after injury. Having said that, those numbers are for adult patients. What about the younger ones?

The University of California Irvine group queried the TQIP database (3 recent years) to examine outcomes for adolescent patients (12-17 years old) given VTE prophylaxis after injury to liver, spleen, and/or kidney. They excluded patients who had TBI, anticoagulation or coagulopathy, immediate laparotomy, transfers in, and patients who died or were discharged within 48 hours. They matched patients for age, comorbidities, grade of injury, overall severity of injury, and hypotension/need for transfusion.

Eligible patients who received chemoprophylaxis early  (within 48 hours) vs. late were reviewed to identify any differences in complications, length of stay, failed non-op management, and mortality.

Here are the factoids:

  • A total of 1,022 cases were isolated from the TQIP database, and 417 adolescent cases were matched to adults
  • VTE rate was statistically the same, 0.6% in the early group vs. 1.7% in the delayed group
  • Failed non-op management was identical at 5.9% vs. 5.6%
  • There was one death in the delayed group and none in the early group (not significant)
  • ICU LOS was the same at 3-4 days
  • One item not mentioned in the body of the abstract: hospital length of stay was significantly longer in the early group: 9 days vs. 6 days

The authors concluded that early VTE prophylaxis in adolescent trauma patients did not increase failure of nonoperative management, nor did it decrease the incidence of VTE.

Bottom line: This is a study that needed to be done. Due to IRB restrictions, it is typically more challenging to perform actual studies on children and adolescents. Retrospective use of databases helps overcome this problem, although it always introduces a few unwanted wrinkles.

We frequently assume that adolescents behave physiologically like adults. Although often true, you can’t always count on it. Those of us who take care of children and young adults know that they tend to do better than adults by most measures. But again, this is an assumption and needed to be studied.

This database study was limited to three years of data and only produced 417 matched cases for study. This is a small number, and I always worry about statistical power. If the results of such a study are negative, one is left wondering if a proper power analysis was done.

One puzzling result left me wondering about the power question. Patients who received early prophylaxis had exactly the same rate of VTE as those who received it late. Adult data indicates that early use should decrease this complication. Is this another indication of a statistical power problem? Would the inclusion of more patients have shown a real difference?

The other result that struck me (and was not commented upon in the body of the abstract) was the statistically significant 50% increase in hospital length of stay for the early prophylaxis group. Is there some unknown variable that was not matched that caused it? This is one of the known pitfalls of these retrospective database studies.

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

  • Broken record question: Did you have enough cases to provide adequate statistical power? This study showed a negative result. Did you have enough matched cases to actually be able to detect a difference if there was one? Why not add a few more years of data and recalculate?
  • How do you explain the failure of early VTE prophylaxis to protect these patients from DVT or PE? Is this also a statistical power problem?
  • Why is the hospital length of stay significantly longer in the early prophylaxis group?

This intriguing paper follows my bias toward treating these patients exactly the same as adults with early chemoprophylaxis. I just need a few of the loose ends tied up.

Reference: SIMILAR RATE OF VENOUS THROMBOEMBOLISM AND FAILURE OF NON-OPERATIVE MANAGEMENT FOR EARLY VERSUS DELAYED VTE CHEMOPROPHYLAXIS IN ADOLESCENT BLUNT SOLID ORGAN INJURIES: A PROPENSITY-MATCHED ANALYSIS. EAST 2023 Podium paper #27.

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Abstracts, Imaging

Best Of EAST 2023 #9: CT Of The Lumbar Spine

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It is becoming clearer and clearer that patients with suspicion for fractures of the thoracic (T) and lumbar (L) spine should be imaged only with CT scan. Conventional imaging just doesn’t have enough sensitivity, even in younger patients with healthy bones. But when we obtain CT of the T&L spines there is a choice: just look at the axial / helical slices, or have the computer reconstruct additional images in the sagittal and coronal planes. The belief is that this multiplanar imaging will assist in finding subtle fractures that might not be seen on axial views.

The group at Rutgers in New Jersey tried to determine if adding the reconstructions amounted to overkill. They performed a retrospective review of patients at their Level I center over a six-year period. They focused on studies performed in patients who had T and/or L fractures who also had both CT of the chest, abdomen, and pelvis (CAP) and thoracic and lumbar reconstructions. Additional data were obtained from a review of the medical record and trauma registry.

Here are the factoids:

  • A total of 494 patients had both CAP and reconstructions
  • There were 1254 fractures seen on CAP, and an additional 129 fractures seen with recons (total of 1394)
  • The majority of additional injuries not detected on CT CAP were transverse process fractures
  • The number of other fracture patterns not seen on CT CAP were statistically “not significant”
  • However, these numerically “not significant” fractures included 51 vertebral body fractures, 6 burst fractures, 3 facet fractures, and 2 pedicle fractures
  • No unstable fractures were missed on CT CAP
  • More MRIs were performed in the patients who had recons, there were more spine consultations, and 11% underwent operative fixation vs. 2% for CTA only (!!)

The authors concluded that CT CAP alone was sufficient to identify clinically significant thoracic and lumbar fractures. They also stated that clinically insignificant injuries identified with reconstructions were more likely to undergo MRI and use excess resources. They urged us to be selective with the use of T&L reformats.

Bottom line: Wow! I have a lot of questions about this abstract! And I really disagree with the findings.

You studied fewer than 500 patients with T or L spine fractures over a six year period. This is only about 80 per year, which seems very low. This suggests that many, many patients were being scanned without recons to start with. How did patients get selected out to get recons? Were there specific criteria? I worry that this could add some bias to your study.

The number of fractures seen only on the recon views besides transverse process fractures were deemed “statistically insignificant.” However, looking at the list of them (see bullet point 5 above) they don’t look clinically insignificant. It’s no wonder that recons resulted in more consults, MRI scans, and spine operations!

I worry that your conclusion is telling us to stop looking for fractures so we won’t use so many additional resources. But their use may be in the best interest of the patients!

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

  • Why did you decide to do this study? I didn’t realize that not doing the recons was a thing in major blunt trauma. Was there some concern that resources were being wasted? Was there an additional cost for the reconstructions?
  • How many patients only received CT CAP? The greater the number of these, the higher the probability that some non-random selection process is going on that might bias your findings.
  • How did you get separate reports for the non-reconstructed images? Did you have new reads by separate radiologists? Typically, the report contains the impression for the entire study. It would be unusual for the radiologist to comment on the non-recon images, then add additional findings from just the reconstructions.
  • Doesn’t the increased numbers of spine consults, MRIs, and operative procedures in the patients with reconstructions imply that these otherwise occult fractures needed clinically important additional attention? 

I worry that readers of this abstract might take away the wrong message. Unless there is some additional compelling data presented, this study is certainly not enough to make me change my practice!

Reference: UTILITY OF CT THORACOLUMBAR SPINAL RECONSTRUCTION IMAGING IN BLUNT TRAUMA. EAST 2023 Podium paper #20.

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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.

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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.

 

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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.

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