Tag Archives: VTE

Pharmacy

Battle of the Heparins: Unfractionated vs Low Molecular Weight

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Most trauma programs tend toward using low molecular weight heparin (LMWH) products for VTE prophylaxis over plain, old-fashioned unfractionated heparin (UH). How did this happen? LMWH is more expensive than UH, and there is precious little high quality research supporting it.

But, LMWH is very convenient, as it only needs to be given only once or twice daily via subq injection, whereas UH is given as a continuous infusion or subq three times a day. And a fair amount of lower quality data suggests that it is effective in decreasing deep venous thrombosis (DVT) and pulmonary embolism (PE).

This abstract comes from Sunnybrook in Toronto. The authors used sophisticated statistical models to compare centers that predominantly use LMWH to prevent VTE vs those that use UH.

Here are the factoids:

  • This was a huge data analysis from the ACS Trauma Quality Improvement Program database (~ 110,000 records from 214 trauma centers)
  • LMWH was most commonly used, 74% of the time
  • Patients who were more likely to need rapid reversal were more often given UH (older patients, severe TBI, early intracranial interventions)
  • Pulmonary embolism was significantly lower with LMWH (1.8% vs 2.4%)
  • This significant effect was present across all subgroups, including patients with shock, blunt multisystem injury, penetrating trunk injury, isolated orthopedic injury, and severe TBI
  • Trauma centers that predominantly used LMWH had significantly lower PE rates compared to UH (1.2% vs 1.8%)

Bottom line: Even given the vagaries of using huge, retrospective database reviews, this is pretty good data. The use of LMWH appears to be superior to UH in reducing the incidence of pulmonary embolism. It does not prevent it completely. But it’s a good start.

What the authors do not say, and I am curious about, is the impact on DVT. That is a much more common problem than PE. Was there any difference? Did they run out of room to comment on it in the abstract? I kind of doubt it. The devil will be in the details. Listen in on the presentation at the meeting!

Reference: Efficacy of low molecular weight heparin vs unfractionated heparin to prevent pulmonary embolism following major trauma: results from the American College of Surgeons Trauma Quality Improvement Program. AAST 2016 Paper #5.

Complications

How To Predict Venous Thromboembolism In Pediatric Trauma

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As with adults a decade ago, the incidence of venous thromboembolism (VTE) in children is now on the rise. Whereas adult VTE occurs in more than 20% of adult trauma patients without appropriate prophylaxis, it is only about 1% in kids, but increasing. There was a big push in the early 2000′s to develop screening criteria and appropriate methods to prevent VTE. But since the incidence in children was so low, there was no impetus to do the same for children.

The group at OHSU in Portland worked with a number of other US trauma centers, and created some logistic regression equations based on a large dataset from the NTDB. The authors developed and tested 5 different models, each more complex than the last. They ultimately selected a model that provided the best fit with the fewest number of variables.

The tool consists of a list of risk factors, each with an assigned point value. The total point value is then identified on a chart of the regression equation, which shows the risk of VTE in percent.

Here are the factors:

Note that the highest risk factors are age >= 13, ICU admission, and major surgery.

And here is the regression chart:

Bottom line: This is a nice tool, and it’s time for some clinical validation. So now all we have to do is figure out how much risk is too much, and determine which prophylactic tools to use at what level. The key to making this clinically usable is to have a readily available “VTE Risk Calculator” available at your fingertips to do the grunt work. Hmm, maybe I’ll chat with the authors and help develop one!

Reference: A Clinical Tool for the Prediction of Venous Thromboembolism in Pediatric Trauma Patients. JAMA Surg 151(1):50-57, 2016.

General

EAST 2016: How Long Does VTE Risk Last In TBI?

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Most trauma patients
are considered to be at some risk for deep venous thrombosis (DVT) and/or
venous thromboembolism (VTE) during their hospital stay. Trauma professionals
go to great lengths to screen for, prophylax against, and treat these problems.
One of the tougher questions is, how long do we need to worry about it? For
fractures, we know that the risk can persist for months. But what about head
injury?

A group at Brigham
and Women’s Hospital did a large database study looking at the VTE risk in adults
who sustained significant head injury, with only minor injuries to other body
regions. They tried to tease out the risk factors using multivariate regression
models.

Here are the
factoids:

  • Patients were only included if their AIS Head
    was >3, and all other AIS were <3
  • Of the over 50,000 patients in the study,
    overall incidence of VTE was 1.3% during the hospital stay, and 2.8% overall
    within 1 year     of injury
  • Risk factors for VTE after discharge included
    age > 64 (3x), discharge to a skilled nursing facility (3x), and prolonged
    hospital length of stay     (2x)
image

Incidence of VTE over time

Bottom line: View this paper as a glimpse of a potential unexpected
issue. The risk of VTE persists for quite some time after head injury (and
probably in most other risky injuries like spine and pelvic fractures. The
three risk factors identified seem to identify a group of more seriously
injured patients who do not return to their baseline soon after injury. We may
need to consider a longer period of screening in select patients, but I believe
further work needs to be done to help figure out exactly who they are.

Reference: How long should we fear? Long-term risk of
venous thromboembolism in patients with traumatic brain injury. EAST 2016 Oral
abstract #28.

General

More On DVT In Children

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Deep venous thrombosis has been a problem in adult trauma patients for some time. Turns out, it’s a problem in injured children as well although much less common (<1%). However, the subset of kids admitted to the ICU for trauma have a much higher rate if not given prophylaxis (approx. 6%). Most trauma centers have protocols for chemical prophylaxis of adult patients, but not many have similar protocols for children.

The Medical College of Wisconsin looked at trends prior to and after implementation of a DVT protocol for patients < 19 years old. They used the following protocol to assess risk in patients admitted to the PICU and to determine what type of prophylaxis was warranted:

image

The need for and type of prophylaxis was balanced against the risk for significant bleeding, and this was accounted for in the protocol. The following significant findings were noted:

  • The overall incidence of DVT decreased significantly (65%) after the protocol was introduced, from 5.2% to 1.8%
  • The 1.8% incidence after protocol use is still higher than most other non-trauma pediatric populations 
  • After the protocol was used, all DVT was detected via screening. Suspicion based on clinical findings (edema, pain) only occurred pre-implementation.
  • Use of the protocol did not increase use of anticoagulation, it standardized management in pediatric patients

Bottom line: DVT does occur in injured children, particularly in severely injured ones who require admission to the ICU. Implementation of a regimented system of monitoring and prophylaxis decreases the overall DVT rate and standardizes care in this group of patients. This is another example of how the use of a well thought out protocol can benefit our patients and provide a more uniform way of managing them.

Related posts:

Reference: Effectiveness of clinical guidelines for deep vein thrombosis prophylaxis in reducing the incidence of venous thromboembolism in critically ill children after trauma. J Trauma 72(5):1292-1297, 2012.

General

DVT In Children: How Old Is Old Enough?

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Adult trauma patients are at risk for venous thromboembolism (VTE). Children seem not to be. The big question is, when do children become adults? Or, at what age do we need to think about screening and providing prophylaxis to kids? As of yet, there are no national guidelines for dealing with DVT in children.

Researchers at Johns Hopkins went to the NTDB to try to answer this question. They looked at the records of over 400,000 trauma patients aged 21 or less who were admitted to the hospital. 

Here are the interesting factoids:

  • Only 1,655 patients (0.4%) had VTE (1,249 DVT, 332 PE, 74 DVT+PE)
  • VTE patients were older, male, and frequently obese
  • VTE patients were more severely injured, with higher ISS and lower GCS
  • Patients with VTE were more likely to be intubated and receive blood transfusions, and had longer hospital and ICU stays

The risk of VTE stratified by age was as follows:

image

Bottom line: Risk of VTE in pediatric trauma patients follows the usual injury severity pattern. But it also demonstrates a predictable age distribution. Risk increases as the teen years begin (13), and rapidly becomes adult-like at age 16. Begin your standard surveillance practices on all 16 year olds, and consider it in 13+ year olds if their injury severity warrants.

Related post:

Reference: Venous thromboembolism after trauma: when do children become adults. JAMA Surgery online first October 31, 2013.