Tag Archives: AAST2022

Abstracts, Outcomes

Best Of AAST 2022 #12: Angioembolization For Liver Injuries

Leave a comment

Solid organ injuries are relatively common from both blunt and penetrating mechanism due to the fact that the liver is the largest organ in the torso. Management of minor injury is relatively straightforward, but more complex injuries quickly become complicated. Unlike the spleen, there is no option to just “drop it in the bucket.” And recovery from high-grade hepatic injuries is fraught with issues like bleeding and bile leaks. These patients may take weeks or months to fully recover.

A wide variety of operative techniques for controlling liver bleeding were developed in the 1900s. These became a little less relevant late in the century with the addition of angiography and embolization to our suite of management techniques. Remember, angioembolization does not replace operative management, which is mandatory in unstable patients. But it can certainly help control bleeding and may reduce the need to operate early.

The group at Johns Hopkins hypothesized that angioembolization (AE) improves survival in patients with severe hepatic injuries. They collected data from 29 trauma centers in an AAST multicenter study. It focused on adult patients with Grade III-V injury from either blunt or penetrating mechanism. The data were sliced and diced by mechanism and type of management. There were three management possibilities: nonop management with or without AE, operative management with AE before or after, and operative management alone.

Here are the factoids:

  • A total of 1,697 blunt and 733 penetrating liver injury patients were studied with similar median ISS
  • As expected, higher ISS and blood transfusion > 6u was significantly associated with higher mortality
  • In the blunt injured patients managed nonoperatively, there was no association between mortality and use of AE although the p value was 0.056
  • Similarly, blunt trauma patients who underwent an operation and had AE either before or after had no difference in mortality (p value 0.09)
  • There was a significant survival advantage if AE was added to nonoperative management

The authors concluded that angioembolization does not improve survival in most severe liver injury cases with the exception of high-grade penetrating injury.

Bottom line: This abstract focuses on survival advantage from the use of AE. However, I think most trauma professionals actually use it as an adjunct to make other management (operative or nonoperative) easier. So I’m not surprised that they didn’t find much positive to say except in the case of penetrating injuries.

I also worry that the p values for both groups of blunt patients (operative + AE, nonop + AE) were very close to significance. Any time a study provides a negative conclusion because significance was not reached, I want to be sure it had the statistical power to detect it in the first place. With p values of 0.09 and 0.056, could a few more patients in each group have achieved statistical significance?

I don’t see that this abstract could (or even should) change our practice in the use of AE. I suspect that it does have an impact on complications, and it may help us stay out of the abdomen in severe cases where opening it could result in uncontrollable bleeding.

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

  1. Did you do a power analysis to determine if you could actually show a significant difference in the blunt patients? Although you had 1,697 total blunt patients, we do not know how many were in the operative vs nonop groups and the AE vs no AE subset of the nonop management group.
  2. Were there any differences in the ISS, age, or other demographics in the pre vs post or AE/no AE blunt subsets that might reveal some selection bias for patients undergoing in one subset vs the other? Since this is pooled data from many trauma centers, each surgeon determines if AE is used and when. It becomes very important to try to identify other factors that may explain your results.
  3. Do you recommend any changes in clinical care based on these results? What needs to be done to definitively answer the question?

This is interesting preliminary work, but I believe it needs additional refinement before we learn enough to change our current practice.

Reference: AAST MULTICENTER STUDY: DOES ANGIOEMBOLIZATION IMPROVE SURVIVAL FOR SEVERE HEPATIC INJURIES? AAST plenary paer #51, AAST 2022.

Abstracts, Technology

Best Of AAST 2022 #10: REBOA For Pelvic Fractures

Leave a comment

Papers for Resuscitative Endovascular Balloon Occlusion of the Aorta (REBOA) use in trauma patients have been accumulating for the past decade or so. There are three zones within the aorta, and the REBOA balloon can be inflated in either Zone II for abdominal vascular injuries or Zone III for pelvic bleeding. Here’s a nice diagram for reference:

The original studies focused on Zone II deployments, but over the past five years or so there has been growing focus on using REBOA in Zone III. Pelvic arterial bleeding can be quite problematic, and if the patient is hypotensive in the emergency department, it is not permitted to take them to interventional radiology for management. The only choice is a trip to OR for preperitoneal packing or some less effective procedure.  With the use of Zone III REBOA, it became possible to stabilize vital signs and then allow transport to IR or hybrid OR for angioembolization.

After the initial rush of very positive research, more recent papers are a bit more tempered with results that are not as cut and dried. This abstract from Hartford Hospital attempts to add a bit more information about the use of Zone III REBOA in patients who required a hemorrhage control procedure. The authors performed a retrospective review of four years of TQIP data. They compared outcome data in hypotensive adult patients with pelvic fractures requiring some type hemorrhage control procedure. The authors divided patients into REBOA+ and REBOA- groups, and looked at mortality, blood utilization, lengths of stay, and REBOA complications.

Here are the factoids:

  • Of the 4,453 patients who met inclusion criteria, only 139 patients underwent Zone III REBOA
  • The REBOA+ patients had lower BP and GCS and ISS was higher prompting the use of propensity matching
  • In order to equalize comparisons patients were propensity matched the the variables listed above, yielding 121 pairs for study
  • In-hospital and 24-hour mortality were double in the REBOA+ group (50.5% vs 25% and 31% vs 14.3%, respectively)
  • Blood transfusion was also higher in the REBOA+ group (median 4L vs 1.75L)
  • AKI was higher in the REBOA+ group (16% vs 7%) but the amputation rates were the same (no numbers given)

The authors concluded that Zone III REBOA appears to have worse outcomes and suggest that more prospective studies are indicated.

Bottom line: I have been a REBOA skeptic for some time so I have to be careful not to feed my confirmation bias. Many of the previously published positive papers include authors who have a relationship with one of the major REBOA device manufacturers. Papers from centers without any conflicts of interest are generally less positive.

Despite my own bias I also have some major questions about this abstract. The biggest thing is that I can’t make the statistics work. Granted, the entire analysis is not in the abstract. But the mortality rates given in percentages don’t yield integers when multiplied by the 121 patients in each group.

This makes me worry that we are not seeing all the statistics and we are somehow getting relative risk rather than absolute risk. I’m also confused about why the SBP, ISS, and GCS matched groups would have a difference in AKI rates in addition to the mortality numbers. Are there other significant variables affecting morbidity and mortality that were not identified or controlled?

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

  1. Review the mortality calculations for us. How can you have a hospital mortality rate of 50.5% with 121 patients (= 61.105 people)? Provide the absolute mortality numbers so we can do the math.
  2. Why are the transfusion numbers so much higher in the REBOA+ group? Isn’t this device supposed to reduce bleeding? It seems unlikely that REBOA is making them bleed more. Is there something else going on?
  3. Similarly, why would AKI be higher in REBOA+ patients? The balloon is located below the kidneys and they should benefit from better perfusion.
  4. Could there be other factors not analyzed that contributed to the poorer outcomes in the REBOA+ group? What might they be?

I suspect the snapshot that the TQIP data allows may not be enough to let us see the entire picture here. I am looking forward to additional information during the presentation to help clarify these issues.

Reference: DOES THE USE OF REBOA IMPROVE SURVIVAL IN PATIENTS WITH PELVIC FRACTURES REQUIRING HEMORRHAGE CONTROL INTERVENTION? AAST Plenary paper #46, AAST 2022.

Abstracts, Thorax

Best Of AAST 2022 #9: Management Of Low Grade Blunt Thoracic Aortic Injury

Leave a comment

It has been interesting to watch the evolution of the treatment of blunt thoracic aortic injury (BTAI). In my training, patients with an abnormal mediastinal contour on chest x-ray were whisked away to interventional radiology for a thoracic aortic angiogram. Yes, there was no such thing as a CT scan for anything but the head! Here’s a sample chest x-ray:

I wrote a post 12 years ago describing the various findings of a blunt aortic injury, many of which are present above. You can the post by clicking here.

In the 1-2% where the angio was positive (yes, you read that right; we did a lot of negative angiograms) the patient was then whisked off to the OR for an open aortic graft via thoracotomy. The advent of CT scans of the torso and improving resolutions allowed us to be more selective with angiography. And finally as CT angiography matured, aortic angiography became a thing of the past.

Then came TEVAR about 20 years ago. There were some growing pains as we refined the technology, but now this endovascular procedure is the standard of care for most aortic injuries. While there was also a place for nonoperative management, it was really just maintaining a reasonably low blood pressure to protect the vessel while getting the patient into good enough condition to tolerate anoperation.

Now we are beginning to slice and dice treatment based on grade. Many centers have recognized that an intimal injury (Grade I) is only a very minor disruption to the inside of the vessel and does not make it more susceptible to rupture. Grade II management has been less clear. Here is a diagram of the various grades.

It makes sense that an invasive procedure may be less helpful for injuries that do not disrupt the layer of the vessel that provides its strength. But remember, common sense isn’t always the truth.

The group at Dell Seton Hall reviewed all patients with low grade BTAI (Grades I and II) in the Aortic Trauma Foundation Registry for a six year period. Their hypothesis was that these injuries could be successfully treated with medical management alone. They reviewed the data for mortality, complications, vent days, and lengths of stay.

Here are the factoids:

  • A total of 880 patients were enrolled and 274 had low grade injuries; 5 were then excluded when their lesion progressed and they underwent TEVAR
  • Of the 269 remaining patients, 81% were treated with medical management (81% Grade I, 19% Grade II) and the remainder with TEVAR (20% Grade I, 80% Grade II)
  • Rates of thoracotomy, craniectomy, and sternotomy were the same in both groups, but TEVAR patients were more likely to have a laparotomy (31% vs 15%)
  • Mortality was significantly higher in the TEVAR group (18% vs 8%) but the mortality from the aorta was not quite significant (4% vs 0.5%)
  • Complications (DVT and ARDS) were also significantly higher in the TEVAR group
  • Vent days and lengths of stay were equivalent

The authors concluded that medical management alone is safe and appropriate, with a lower mortality and decreased complications compared to routine TEVAR.

Bottom line: Hmm, color me skeptical. Remember, this is a registry study, so information tends to be limited outside the usual demographics and data points that are very pertinent to the purpose of the registry. The most important concept is that the patients in each group must be identical in every way except for the intervention.

We can try to make them as identical as possible by matching pairs or subgroups of patients. But the biggest problem is that the number of patient characteristics that might be important to match may not be available for analysis in the database.

When the patients were initially treated at contributing centers, there were no specific rules that the individual surgeons had to follow to decide between medical management and TEVAR. They could pick and choose based on their own experience. Could the surgeon have recognized some patients as higher risk and opted for TEVAR to make sure the aorta would not become an issue in conjunction with their other injuries? And unfortunately, perhaps that higher risk issue is what ultimately killed them and not the aorta. It’s basically a form of unhealthy user bias.

This abstract is an interesting tidbit that should push us to question whether medical management is better, at least in some subsets of low grade aortic injury patients. Then someone can perform a more robust study to confirm or refute its safety. Unfortunately, this may never happen due to the low incidence of this injury. It took six years to accumulate only 269 eligible patients in this registry!

Here are my questions for the authors and presenter:

  • What data points are actually in the registry? Specifically, is there fine detail about the other injuries the patient had? Could these have contributed to TEVAR mortality, or the selection of the patient for TEVAR to try to reduce the perceived mortality risk?
  • When you stated that there was “no difference in demographics or mechanism of injury” what were these, exactly?
  • What did patients actually die from in the Grade I and Grade II groups? Be more specific than “aortic-related” or not.
  • Do you have any worries about the five patients whose lesions progressed? When should patients be re-scanned to identify those who might benefit more from TEVAR?

This is a thought provoking abstract, and I am very interesting in hearing what the next steps should be.

Reference: MEDICAL MANAGEMENT IS THE TREATMENT OF CHOICE FOR LOW GRADE BLUNT THORACIC AORTIC INJURIES. Plenary paper #45, AAST 2022.

Abstracts, Trauma Center

Best of AAST 2022 #8: Financial Vulnerability Of Trauma Centers

Leave a comment

Here’s another abstract on trauma center / system finance. Trauma centers are part of the safety net in the healthcare systems of many countries. The way they are funded varies tremendously. In the US, health insurance pays most of the bill for patient care. Unfortunately, not all patients are covered, so there is financial risk to the center based on how many underpaying patients present for care.

The group at Scripps Mercy in San Diego performed a financial health analysis of all ACS-verified trauma centers in the US. They applied a Financial Vulnerability Score metric (FVS), although I could not locate anything on this via an internet search. They analyzed the RAND Hospital Financial Database, which is based on information obtained from the CMS Healthcare Cost Report Information System. Using this data they calculated the FVS for each center. They sub-grouped the hospitals into high, medium, and low vulnerability and compared them.

Here are the factoids:

  • A total of 617 trauma centers were identified and analyzed: 194 Level I, 278 Level II, and 145 Level III
  • Level III trauma centers made up 59% of the high financial risk centers
  • The majority of Level I and II centers were in the middle or low risk categories
  • Characteristics of high risk centers were lower number of beds, negative operating margin, and less cash on hand
  • Low risk centers had greater asset to liability ratios, lower outpatient shares, and 3x less uncompensated care
  • The largest proportion of HFR hospitals were in New England and East North Central regions
  • Non-teaching centers had significantly higher financial risk than teaching hospitals (46% vs 29%)

The authors concluded that about 25% of Level I and II trauma centers are at high financial risk and that factors such as payor mix and outpatient status should be targeted to reduce this risk.

Bottom line: This is a fascinating abstract but leaves a lot to the imagination. The databases used have not been used in previous papers, and the information contained in them is proprietary. The FVS is also new and I have not been able to obtain any details.

Nevertheless, if the data and analysis are sound it may provide some new information to trauma centers and perhaps some insight on what factors to address to lessen their financial vulnerability. This is a lot of ifs. Hopefully the authors will enlighten us during the presentation so we can appreciate the real world value of the analysis.

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

  • Please explain both the dataset used and the new FVS metric. Most readers and listeners are unfamiliar. We need to see how the data and analysis apply to trauma center financials and how the FVS has been validated.
  • How can the vulnerability factors be addressed? Payor mix is based on patient coverage and their socioeconomic status. It would seem to be difficult to manipulate by the trauma center. Outpatient vs inpatient status is also difficult to change and not fall afoul of CMS rules. What were other factors that were identified that could help centers reduce their financial vulnerability?

This could be an interesting abstract, but there was not enough room in the abstract to reveal all the details. Hopefully all will become obvious during the presentation.

Reference: FINANCIAL VULNERABILITY OF TRAUMA CENTERS: A NATIONAL ANALYSIS, Plenary paper #41, AAST 2022.

Abstracts, Trauma Systems

Best Of AAST 2022 #7: Funding State Trauma Systems

Leave a comment

As of about 10 years ago, every state in the US has implemented a state trauma system. The way these systems are funded and their sources vary widely. Most receive their funds via some combination of a line item in the budget, grants, or fees levied on state residents. The total per capita funding amount can be calculated based on the total dollars received divided by the state population.

The per capita funding across the US varies widely. Some provide very little assistance while others are much more generous. I have visited trauma centers in nearly every state and have witnessed the difficulties many state trauma systems face due to funding shortfalls.

Does financial support have an impact on trauma care? A better question is, do state systems have an impact on trauma care? The literature on that last question tells us the answer is a resounding yes. We assume that having some money improves what the system can do. But that’s just an assumption. Until now.

The group at Northwestern University did a deep dive into the financial support of state trauma systems to address this question. Their goal was to measure the impact of it on something easily measurable: mortality. They selected five states to study based upon their broad geographic and demographic variability and the availability of comprehensive data for analysis.

Two states (MA, NY) allocated $0.00 per capita trauma funding, and three provided between $0.09 and $1.80 per capita.  The authors analyzed data from comprehensive patient encounter databases from these states. Their primary goal was to compare mortality differences between the two levels of support. They were also able to link ED and inpatient encounters and analyze triage decisions for appropriateness.

Here are the factoids:

  • Nearly a quarter of a million patients with ISS > 15 were analyzed over a study period of two years
  • Median age was 72 and ISS was 17 (older with significant injuries)
  • Trauma mortality was significantly decreased in the states that provided financial support compared with those that did not (odds ratio 0.75)
  • All triage levels were associated with a similar decrease in mortality (appropriate triage to a Level I or II center, undertriage admitted to a Level III or IV center, and re-triage (emergent transfer from an ED to a Level I or II center))
  • The best improvement in mortality was seen in re-triaged patients in funded states (odds ratio of 0.63)

The authors concluded that state system funding was associated with lower mortality in severely injured patients and that increasing funding may facilitate it.

Bottom line: Several papers have been written showing the benefit of having a trauma system, and all of the US has bought into this concept. However, funding of these systems varies widely by state. The assumption (up to now) has been that just having a system is enough. This abstract goes a step further and suggests that actually paying for it is important, too. 

The authors performed quite of bit of data manipulation and used some sophisticated statistical tools that I am not familiar with. However, the authors are certainly qualified, and I am going to assume that the analysis was sound. 

The one important point to keep in mind is that this paper is one of the first of its kind but can only show association, not causation. Nevertheless, it is an important contribution to the trauma system literature. It will definitely prompt additional research which will hopefully corroborate the results. This line of work should give state systems the ammunition to approach their legislatures to open the pocketbook and improve the outcomes of their residents. Mortality reductions of 25-37% cannot be ignored!

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

  1. Please explain the data sources you used and the analysis (briefly). These are very comprehensive databases and appear to contain a wealth of data. Tell us why you chose them, how you linked them, and explain your analyses.
  2. Why limit your analyses to these five states? Could you have found some with even higher levels of support that would drive your point home even better?
  3. Be sure to provide more detail on your analysis of triage status. There are some important lessons to be learned here regarding state triage criteria vs mortality.
  4. Are you planning any additional similar studies? This is important work that will help state systems obtain a more appropriate level of support.

This is an intriguing abstract that should prompt additional research regarding state trauma system funding. 

Reference: THE IMPACT OF STATE TRAUMA FUNDING ON TRIAGE AND MORTALITY OF TRAUMA PATIENTS. Plenary paper #38, AAST 2022.