Category Archives: Abstracts

Best of AAST #11: The Need For Trauma Intervention Score (NFTI)

The Trauma Measurement Workgroup at Baylor University in Dallas has been working on a new indicator for identifying major trauma. In a paper published in the Society of Trauma Nursing last year, they determined that six trauma registry variables best identified these patients:

  • transfusion of packed cells within 4 hours of arrival
  • discharge from ED to OR within 90 minutes of arrival
  • discharge from ED to interventional radiology
  • discharge from ED to ICU with a stay > 3 days
  • mechanical ventilation within 3 days, not including OR or procedures
  • death within 60 hours of arrival

Traditionally, Injury Severity Score (ISS) has been used to measure anatomic injury, the Revised Trauma Score (RTS) to quantify physiologic derangement, and their combination (TRISS) to estimate survival.  The authors postulate that physiologic reserve is another determinant of survival, and that NFTI might provide a way to quantify this reserve. One of the QuickShot presentations at the AAST meeting demonstrates how the authors applied this metric.

A multi-institutional data collaborative collected information on more than 88,000 across 35 trauma centers. A complicated mathematical and statistical analysis was carried out, testing how well high ISS (>15), low RTS (<4), and NFTI+ (at least one NFTI variable) predicted mortality, complications, full trauma team activation, length of stay, and procedures performed within 3 days of arrival.

The authors found that NFTI was significantly better at predicting all the outcome variables except full trauma activation than ISS or RTS. And it was still pretty good at that one.

Bottom line: So what does all this mean? The design and analysis of all the numbers is sound. The only thing I take issue with is the assumption that NFTI reflects the “reserve” that a patient has available to combat serious injury. The authors postulate that NFTI is not affected by frailty and comorbidities like ISS and RTS are. I have not seen the manuscript, so perhaps the authors explain the rationale there. But it seems like a stretch. 

What happens if we remove that assumption? Then this study becomes a comparison of a new way to predict resource utilization and/or survival vs ISS and RTS. It uses future variables (as does ISS), so it is difficult to apply this information on patient arrival to treat them any differently, until the first NFTI factor is triggered. But it does predict them well. I think there is considerable potential for NFTI, but we just need more work to make it more useful as early as possible.

Reference: The need for trauma intervention (NFTI) defines major trauma more accurately than injury severity score (ISS) and revised trauma score (RTS): data from a collaboration of 35 adult trauma centers. QuickShot presentation #9, AAST 2018.

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Best of AAST #10: Pediatric Contrast Extravasation And Pseudoaneurysms

There is a significant amount of variation in the management of pediatric solid organ injury. This is well documented between adult and pediatric trauma centers in t, but also apparently between centers in different countries. A poster from a Japanese group in Okinawa Japan will be presented this week detailing the relationship between contrast extravasation after spleen or liver injury and pseudoaneurysm formation.

In adults, the general rule is that pseudoaneurysms just about anywhere slowly enlarge and eventually rupture. This group sought to define this relationship in the pediatric age group. They performed a multi-center observational study of retrospectively enrolled children, defined as age 16 and less. Those who had contrast extravasation on initial CT were monitored for later pseudoaneurysm formation.

Here are the factoids:

  • 236 patients were enrolled across 10 participating centers, with about two-thirds having liver injury and the remainder with splenic injury
  • 80% of patients underwent followup CT scan (!!)
  • 33 patients (15%) underwent angiography (!!!!)
  • 17 patients with CT scan (2%) had pseudoaneurysm formation and 4 of them had a delayed rupture
  • Overall, pseudoaneurysms occurred in 29% of those with contrast extravasation and 5% without extravasation
  • The authors concluded that contrast extravasation was significantly associated with pseudoaneurysm formation after adjusting for variables such as ISS, injury grade, and degree of hemoperitoneum

Bottom line: This is an abstract, so a lot is missing. What was the age distribution, especially among those who underwent angiography? Was the data skewed by a predominantly teenage population, whose organs behave more like adults? The abstract answers a question but ignores the clinical significance.

For those trauma professionals who routinely care for pediatric patients, you know that contrast extravasation in children doesn’t act like its adult counterpart. Kids seldom decompensate, and for those who are mistakenly taken for angiography, the extravasation is frequently gone. The authors even admitted in the conclusion that aggressive screening and treatment for pseudoaneurysm was carried out.

The real question is, what is the significance of a solid organ pseudoaneurysm in children? Based on my clinical experience and reading of the US literature, not much. Of course, there is a gray zone as children move into adulthood in the early to mid-teens. But this does not warrant re-scanning and there should be no routine angiography in this age group. Contrast extravasation in pediatric patients warrants close observation for a period of time. But intervention should only be considered in those who behave clinically like they have ongoing bleeding. 

Reference: Association between contrast extravasation on CT scan and pseudoaneurysm in pediatric blunt splenic and hepatic injury: a multi-institutional observational study. Poster 31, AAST 2018.

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Best of AAST #9: Popliteal Atery Injury Repair

Injury of the popliteal artery is potentially devastating. Since this vessel is essentially and end artery, any complication resulting in thrombosis can result in limb loss. Traditionally, significant injuries have been treated with open repair and/or bypass. However, endovascular therapies have been making inroads in this area. Short-term outcomes appear to be equivalent. But what happens in the long term? Is one better than the other?

Scripps Mercy in San Diego (yes, same as yesterday’s abstract!) performed a retrospective review of the same California state discharge database. This time, they focused on patients with popliteal artery injury, and the attendant complications of fasciotomy and amputation. They stratified the patients into open and endovascular groups.

Here are the factoids:

  • 769 patients with popliteal artery injury were identified over an 8-year period
  • 59% were managed with an open operation, 4% using endovascular techniques, 2% combined, and 34% nonoperatively
  • Fasciotomies were performed significantly more often in the open group (41% vs 19%)
  • More amputations were performed in open cases, but this was not significantly different (11% vs 3% [1 patient in the endovascular group])
  • Embolism or thrombosis was significantly more likely during the first admission in endovascular or combined endo/open cases
  • Patients requiring both endo and endo+open procedures  were 5x more likely to undergo a later amputation, and 4x more likely to die after discharge

Bottom line: First, remember the limitations of this study: (very) small numbers, and a large database that precludes teasing out details. It suggests that open repair of popliteal injury is superior to endovascular due to higher thrombosis/embolism and amputation rates. Performing a fasciotomy is somewhat subjective, and may be done by surgeon preference to protect the limb. But amputation is more objective.

Unfortunately, we will not get anything more definitive any time soon. This 8-year analysis of a huge state database yielded only 769 cases, or 96 per year. In a state with 39 million people. That’s three injuries (reported) per million people per year. We will never generate a study that will tell us the full answers. But in the meantime, consider endovascular repair of popliteal artery injury only in patients for whom an open procedure is more challenging or risky (e.g. obesity, associated wounds).

Reference: Outcomes for popliteal artery injury repair after discharge: a large-scale population-based analysis. Session XXII Paper 55, AAST 2018.

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Best of AAST #8: Complications After Trauma Laparotomy

With the introduction of damage control laparotomy (DCL) in the early 1990s, the trauma literature has focused on the nuances of this procedure. A significant amout of research has looked at patient selection, techniques, optimum time to closure, and complications afterwards. Studies on the single-look trauma laparotomy (STL) seem to have fallen behind. When compared to DCL, it seems to have relatively few complications.

But is that really so? A paper from the 1980s showed a nearly 50% complication rate after STL, but this included some trivial things like atelectasis which padded the numbers. A group at Scripps Mercy in San Diego looked at long-term complications after  STL in a state-wide California database. They were able to identify patients who underwent STL who were then readmitted for complications at a later date. They studied this data over an 8-year period.

Here are the factoids:

  • A total of 2,113 patients had a STL during the study period
  • One third (712) were readmitted at least once, with a median time to first readmission of 110 days
  • 30% of these patients had a surgery-related complication:
    • bowel obstruction 18%
    • infection 9%
    • incisional hernia 7%
  • Mechanism of injury was not related to development of complications

Bottom line: More than 10% of patients undergoing single-look trauma laparotomy develop significant complications. This is much higher than the complication rate seen after typical general surgical procedures. The difference between these groups and the reasons are not clear. Additional work must be done to tease out the risk factors, and our patients should be counseled on these potential complications and when to return for evaluation. Finally, the trauma surgeon should always use their best judgment to avoid an unnecessary trauma laparotomy.

Reference: Long-term outcomes after single-look trauma laparotomy: a large population-based study. Session IV Paper 14, AAST 2018.

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EAST 2018 #11: Prehospital Cervical Spine Clearance

More and more often, I am receiving trauma activation patients after blunt trauma with no cervical collar in place. Up until a year ago or so, literally everyone with even a hint of blunt trauma had one in place. Now, it is becoming a rarity. It seems that there has been a shift in the philosophy and practice of prehospital providers and the guidelines they follow. 

The group at SUNY Stony Brook reviewed their experience with prehospital spine clearance (meaning non-placement of a collar by EMS) over a 6 year period. They analyzed trends in prehospital spine immobilization during this period.

Here are the factoids:

  • Over 5,000 patients were analyzed, and the incidence of cervical spine injury remained constant at 9% over the study period
  • Placement of prehospital cervical immobilization decreased from 54% to 35%
  • The incidence of spine injury in patients without immobilization  increased from 4% to 6%
  • Of those without immobilization, 15% had a major spine injury (AIS > 3), and 19% had multisystem injuries
  • Factors significantly associated with “inappropriate” prehospital clearance included fall mechanism, elderly, functional dependence, dementia, and presence of comorbidities

Bottom line: This study is intriguing, but I worry that the study population is a bit too small to draw the best conclusions. I say this because the incidence of cervical injury is significantly higher in this study that in a larger one with 34,000 patients. This may indicate either a small sample size or some type of sample bias. I’m unclear about what data the prehospital agencies used to relax the immobilization criteria, and whether or not the criteria are being applied appropriately. It does appear, however, that the elderly are at higher risk for having an injury and not being immobilized.

Here are some questions for the authors to consider before their presentation:

  • How did you define cervical injury, and why is the incidence in your study so much higher?
  • Do the prehospital agencies delivering patients to your center utilize the same clearance guidelines?
  • Big picture question: What should we do to make sure that cervical immobilization is applied appropriately?

Reference: EAST 2018 Podium abstract #34.

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