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Abstracts, Prevention

Best of AAST 2022 #3: VTE Risk After Spinal Cord Injury

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Venous thromboembolism (VTE) is always a concern in trauma patients. But patients with spine fractures are at much higher risk and those with spinal cord injuries on top of it even more so. The best tool we have right now for prevention is chemoprophylaxis with some type of heparin. Unfortunately, VTE prophylaxis is commonly interrupted or delayed due to concern for causing bleeding. These concerns may relate to concomitant injuries (e.g. solid organ injury) or necessary surgical procedures.

About five years ago, the Army provided a $4.25M grant to fund the Coalition of Leaders in Thromboembolism (CLOTT) study group. It involved contributions from 17 Level I trauma centers attempting to look at the incidence, treatment, and prevention of VTE after trauma. Additional phases are now under way to look at offshoot discoveries from the original research.

A group from the University of California – Sand Diego performed a secondary analysis of a subset of the CLOTT study in patients age 18-40 over a three year period. Patients with a diagnosis of spinal cord injury who were admitted for at least 48 hours were analyzed. The authors focused on timing of the start of VTE prophylaxis, VTE rates, and missed prophylactic dosing. They also reviewed any bleeding complications.

Here are the factoids:

  • From the entire CLOTT study group, 343 met criteria and had sustained a spinal cord injury
  • Most subjects were young (mean 29) and male (77%) and had sustained blunt injury (79%)
  • A total of 44 patients (13%) developed VTE – 30 DVT, 3 pulmonary embolism, and 11 pulmonary thrombus
  • Only one in five patients started chemo-prophylaxis prior to 24 hours, and this increased to about 50% at 48 hours (!)
  • VTE rate overall was 9.6% (?)
  • The rate trended lower in patients who received their prophylaxis within 48 hours (7% vs 13% but not significant)
  • Missed doses of chemo-prophylaxis were common (30%) and were associated with higher VTE rates

The authors concluded that VTE rates are high in these patients and early chemoprophylaxis is critical in limiting thrombotic events.

Bottom line: Hmm. This abstract confuses me a little. Actually, I had expected a higher VTE rate in this patient group. I’ve seen reports 2x to 3x higher than reported here. But yes, I do believe that these patients are at high risk.

And looking at the chart, it appears that there is a trend toward higher rates in patients who missed doses rather than those who did not. But the real questions are:

  1. Is it real? That is, are those differences significant? The only analysis in the abstract compares early vs late administration and that is trending toward significance but didn’t quite make it there. And remember that the graph you are looking at cuts off at 18% which makes the differences look much bigger.
  2. What can we do about it? Many trauma professionals are still uncomfortable giving prophylaxis early because of fear of bleeding. This is probably unwarranted, but we just don’t have enough hard data to say so. Anecdotal data about surgeons operating uneventfully through chemoprophylaxis is growing, though.

My impression of this study is that it shows some interesting trends, but probably doesn’t include enough subjects to know the real answer for sure. 

Here are my questions for the authors / presenter:

  1. Tell us about the statistics. How did you calculate the rates that are cited in the paper? I can’t figure out the math.
  2. What is the difference between a pulmonary embolism and pulmonary thrombus? Is it merely the presence or absence of concomitant clot in the legs or pelvis? Why distinguish between the two if you are lumping them all together as “VTE?”
  3. What are we to do with this data? Obviously, everyone wants to provide VTE prophylaxis in a timely manner. But there are a raft of reasons why clinicians are “not comfortable” doing it. Any suggestions?

Reference: VENOUS THROMBOEMBOLISM RISK AFTER SPINAL CORD INJURY: A SECONDARY ANALYSIS OF THE CLOTT STUDY. Plenary Paper 23, AAST 2022.

 

Abstracts, Trauma Center

Best of AAST 2022 #2: How Much Does It Cost To Be A Trauma Center?

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Becoming and remaining a trauma center is an expensive proposition. Some components can pay for themselves (surgical specialists and operating rooms) but others are required yet generate no revenue. These costs must somehow be offset for a trauma center to remain viable.

How much does it actually cost? There have been two papers that deal with this topic (see references). One was published way back in 2004 and examined readiness costs averaged across 10 Florida trauma centers. They comingled data for these hospitals, which were a mix of adult, pediatric, Level I and Level II centers. They arrived at a median annual cost of readiness of $2.1 million.

A similar study was published in 2017 for Level I and Level II centers in Georgia. They were ultimately able to estimate that the annual average readiness cost for Level I centers was $6.8 million, and for Level II centers was $2.3 million.

That’s a lot of money! These hospitals tend to be larger and have specialty centers that allow them to generate enough revenue to support the non-revenue parts of the trauma program.

But what about Level III and Level IV centers? They are generally much smaller hospitals. In many more rural states they are critical access hospitals with 25 or fewer beds. They don’t have a wealth of other programs that can generate significant excess revenue.

So how much does it cost them?  A group at Mercer University in Atlanta attempted to quantify this issue. They developed a survey tool along the lines of the previous work. They sent this to all 14 Level III and Level IV trauma centers in the state, who based their numbers on 2019 data.

Here are the factoids:

  • For Level III centers, the average annual readiness cost was $1.7 million
  • The most expensive components for Level III centers were for clinical medical staff. This was most likely related to stipends for service / call coverage.
  • For Level IV centers, the cost was only $82 thousand and primarily involved administrative costs (most likely trauma program personnel)
  • Education and outreach programs are mandated for these centers but the centers actually spent only $8,000 annually. The authors believe this represented significant under-resourcing by the hospitals.

The authors concluded that there is a need for additional trauma center funding to enable Level III and IV centers to meet the requirements set forth by the American College of Surgeons.

My comments: This is a very enlightening paper on the cost of being a trauma center. Only two papers have previously explored this, and only for higher level centers. However, the devil is in the details. The nuts and bolts numbers and the assumptions made on how they fit together are key. But it does provide some enlightening information on what it costs to be a trauma center. And the disparity between the two levels is fascinating / frightening.

Here are my questions for the authors / presenters:

  • What assumptions did you have to make to arrive at these numbers? Please explain the details of your model and where you think the weaknesses in it may lie.
  • Why is it so much more expensive to be a Level III center? The abstract places the blame on “clinical medical staff.” Are these on-call stipends or something else?
  • What would you tell wannabe Level III or IV centers looking to become a trauma center? Unfortunately, these numbers might scare some of the off.

Thanks for an intriguing and challenging paper! The discussion will be very interesting!

References: 

  1. ASSESSING TRAUMA READINESS COSTS IN LEVEL III AND LEVEL IV TRAUMA CENTERS. Plenary session paper #10, AAST 2022.
  2. The cost of trauma center readiness. Am J Surg 187(1):7-13, 2004.
  3. What Are the Costs of Trauma Center Readiness? Defining and Standardizing Readiness Costs for Trauma Centers Statewide. Am Surg 83(9):979-990, 2017.

 

Abstracts, Complications

Best of AAST 2022 #1: The Trauma-Specific Frailty Index (TSFI)

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Let’s start with the paper that is kicking off the 81st Annual Meeting for the AAST. Everyone recognizes that many of our elderly patients don’t do well after trauma. Unfortunately, elderly is a very imprecise term. According to the TRISS method for predicting mortality it begins at age 55. But we have all seen many patients younger than that who appear much older physiologically. And a few older ones who are in excellent condition.

How can we determine who is frail and thus more likely to develop complications or even die after injury? The trauma group at the University of Arizona – Tucson published their original paper on a 50-variable frailty index in 2014 in order to address this issue. Unfortunately, 50 variables were found to be very unwieldy, which vastly decreased its usability.

They immediately decided to strip it down to the most significant 15 variables, and named it the Trauma-Specific Frailty Index. This tool simply predicted whether the patient would have a favorable discharge (home), or an unfavorable one (skilled nursing facility or death). The TSFI was very good at this, and was far better than using age alone.

The authors rolled the TFSI out to the AAST multi-institutional study group. A total of 17 Level I and II trauma centers participated in a three-year prospective, observational study. All patients with age > 65 had their TFSI calculated. They were stratified into three groups, including non-frail, pre-frail, and frail. The outcomes studied were expanded and included mortality, complications, discharge status, and 3 month status for readmission, falls, complications, and death.

Here are the factoids:

  • A total of 1,321 patients were enrolled across all centers with a mean age of 77 and median ISS 9
  • A third each were classified as non-frail, pre-frail, and frail
  • The overall study group had a 5% mortality, 14% complication rate, and 42% unfavorable discharge rate
  • Frail patients had a higher complication rate vs the pre- and non-frail groups (21% vs 14% vs10%) which was significant
  • They also had a higher mortality rate (7% vs 3% vs 4%) with p=0.048 although significant on multivariate analysis
  • Overall, 16% were readmitted within 3 months and 2% died. This was not stratified in the abstract by frailty group.

The authors claim that the TFSI is an independent predictor of worse outcomes, and that it is practical and effective and should be used in the management of geriatric trauma patients.

Comments: I find the concept of the abstract very interesting. I think most of us can identify the obviously frail patients when we see them. The TFSI promises more objective identification  using 15 variables. For reference, here they are:

  • Comorbidities
    • Cancer history
    • Coronary heart disease
    • Dementia
  • Daily activities
    • Help with grooming
    • Help with managing money
    • Help doing housework
    • Help toileting
    • Help walking
  • Health attitude
    • Feel less useful
    • Feel sad
    • Feel effort to do everything
    • Falls
    • Feel lonely
  • Sexual function
  • Serum albumin

The authors showed that all of the outcomes were significantly and negatively associated with the patient’s frailty index. The analysis appears reasonable, and the numbers are both statistically and clinically significant. 

But the big question now is, how do we use the results? The 15-variable version is reasonably workable. Is it any better than the trauma professional walking into a room and doing a good eyeball test? The study did not look at that. Either way, what can we do when we identify the truly frail patient? What can we alter in the hospital care that might make a difference? Right now, options are limited. Much of what led to the patient’s frailty is water under the bridge due to possibly decades of lifestyle choice or pre-existing disease.

I think that the next step in this train of thought is to start applying specific interventions in patients identified as frail or better yet, pre-frail. Here are my questions for the authors and presenter:

  1. What’s next? You’ve shown that you have a numerical tool that identifies patients who may have a less than desirable outcome. If we implement this, what can we do to try to reduce those undesirable outcomes?

This was thought provoking work, and I am looking forward to the full presentation!

Reference: PROSPECTIVE VALIDATION AND APPLICATION OF THE TRAUMA SPECIFIC FRAILTY INDEX: RESULTS OF AN AAST MULTI-INSTITUTIONAL OBSERVATIONAL TRIAL. AAST 2022 Plenary Paper 1.

Abstracts

It’s AAST Month, 2022!

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As many of you are aware, the 81st Annual Meeting of the American Association for the Surgery of Trauma is taking place later this month. Keeping to tradition, I will be analyzing select abstracts that caught my interest over the coming weeks.

As in the past, I’ll analyze what’s available in the short abstract format and provide a bit of background about why it might be important. I will then examine the design and methods and review the results.

Finally, I will provide my own analysis, as well as questions for the authors and presenter that they might encounter at the meeting. In addition to sharing all of this with you, my readers, I always send a message to the authors so they can personally check out the post.

I will get started with an analysis of Oral Paper #1, a multi-center trial using the Trauma Specific Frailty Index.

Complications

Fat Embolism Syndrome And Orthopedic Surgery

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Regardless of the exact mechanism for the development of fat embolism syndrome, in trauma it most commonly occurs when the medullary (bone marrow) cavity of a long bone is violated. This occurs first when the bone is fractured, and again when it is instrumented for fixation. The initial shower of emboli cannot be prevented. However, ongoing emboli can be reduced with early fixation. This can be in the form of a good splint, or surgical external or internal fixation.

One type of internal fixation, intramedullary (IM) nailing, has been associated with embolism and FES for some time. This technique was introduced 80 years ago and has been refined significantly since. Here is a picture of a femur with an IM nail.

The nail is inserted proximally near the greater trochanter. The marrow cavity is first reamed to make insertion of the nail easier. This causes a number of changes in the physiology of and pressures within the marrow cavity. Pressure increases during the initial reaming, and hits a peak when the reamer enters the distal fragment. Once complete, there are no further increases as the nail is inserted. However, these pressure changes alter medullary blood flow and allow emboli to enter the venous system.

Reaming is actually beneficial in several ways. It simplifies and shortens the surgical procedure. And in animal models there is evidence that bone debris from the reaming process collects at the fracture site, creating an autograft that may improve healing.

A surgical group in Ireland has been using a novel technique for lavaging the marrow cavity during fixation for several years. Once the bone is entered proximally, a cut piece of suction tubing is inserted into the end of the bone. Suction is then applied for 2-3 minutes. The procedure continues, including reaming, then the suction procedure is repeated. Unfortunately, FES is uncommon, so it is difficult to judge whether their technique really works. The authors believe it is safe, but recommend formal studies to prove efficacy.

Use of an additional venting hole between the trochanters has also been studied in a small randomized trial. This allows for drainage of marrow during the reaming process, reducing any pressure rise. The number of embolic events detected using transesophageal echo was significantly reduced in the vented group (20% vs 85% of patients).

Next, prevention and treatment of fat embolism syndrome.

References:

  1. A Simple and Easy Intramedullary Lavage Method to Prevent Embolism During and After Reamed Long Bone Nailing. Cureus 9(8):e1609, Aug 2017.
  2. Relevance of the drainage along the linea aspera for the reduction of fat embolism during cemented total hip arthroplasty. A prospective, randomized clinical trial. Arch Ortho Trauma Surg 119:146, 1999