Tag Archives: DVT

Should I Apply Compression Devices To Patients With DVT?

December 26, 2023 The Trauma Pro Leave a comment

Everyone knows that venous thromboembolism (VTE) is a potential problem in hospitalized patients, and especially so in trauma patients. Several groups of them are at higher risk by virtue of the particular injuries they have sustained and the activity restriction caused.

Nearly every trauma program uses some form of screening and prophylaxis in an attempt to reduce the occurrence of this problem, which can result in deep venous thrombosis (DVT) and/or pulmonary embolism (PE). Screening looks at patient factors such as age, obesity, and previous VTE, as well as injury risk factors like spine and pelvic fractures and decreased mobility.

Based on the screening protocol, prophylaxis may be prescribed depending upon the level of VTE risk, which is then balanced with bleeding risk from the brain, solid organ, or other injuries. The choices we have are primarily mechanical vs chemical and consist of compression devices (sequential or not) and various heparins.

But an age-old question continues to resurface: if a patient breaks through their prophylaxis and develops DVT, is it safe to apply compression devices to the extremity?

There has always been the fear that doing things that increase flow in the affected extremity may cause clots to dislodge and ultimately cause a PE. Seems logical, right? But we know that often, our common sense about things is completely wrong. Couldn’t just moving around cause pieces to break off? A meta-analysis of 13 studies published in 2015 showed that early ambulation was not associated with a higher incidence of new PE. Furthermore, patients who suffered from pain in the affected extremity noted significant improvements with early ambulation.

If ambulation makes the pain better, could the veins be recanalizing more quickly? Another study examined a small group of 72 people with DVT receiving anticoagulants, half of whom were prescribed exercise and compression stockings and the other half stockings only. There was a huge amount of variability in the rates of recanalization, but ultimately, there were no significant differences with or without exercise.

So just lying in bed is not good, and exercise/ambulation may actually make people feel better. But interestingly, bedrest alone does not appear to increase the likelihood of PE! It does decrease the risk of developing problems other than the VTE, like pulmonary complications.

But what about compression devices? Common sense would say that you are intermittently increasing pressures in the leg veins, which could dislodge any loose clots and send them flying to the lungs, right?

Unfortunately, I couldn’t find a paper from anyone who had the courage to try this. Or perhaps no institutional review board (IRB) would approve it. But the key fact is that every compression device manufacturer includes existing DVT as a contraindication in their product documentation. They don’t have any literature either, so I assume it’s an attempt to limit litigation, just in case.

Bottom line: Walking provides at least as much muscle compression as compression devices. But the simple truth is that we have no solid research that either supports or condemns the use of active compression devices in patients with known DVT. And we probably won’t, ever.

Compression stockings seem to be safe, but they really don’t do much. They are white, but don’t do much more than contribute to hospital clothing fashion. Since the manufacturers define existing DVT as a contraindication, application of their product would be considered an off-label use. So it looks like we cannot in good faith use these devices in patients with diagnosed DVT.

References:

Bed Rest versus Early Ambulation with Standard Anticoagulation in The Management of Deep Vein Thrombosis: A Meta-Analysis. PLOS One , April 10, 2015, https://doi.org/10.1371/journal.pone.0121388
Bed Rest or Ambulation in the Initial Treatment of Patients With Acute Deep Vein Thrombosis or Pulmonary Embolism: Findings From the RIETE Registry. Chest 127(5):1631-1636, 2005.
Does supervised exercise after deep venous thrombosis improve recanalization of occluded vein segments? A randomized study. J Thrombosis Thrombolysis 23:25-30, 2006.

Complications

Predicting VTE Risk In Children

April 21, 2023 The Trauma Pro Leave a comment

There’s a lot of debate about if and at what age injured children develop significant risk for venous thromboembolism (VTE). In the adult world, it’s a little more clear cut, and nearly every patient gets some type of prophylactic device or drug. Kids, we’re not so certain about at all.

The Children’s Hospital of Wisconsin tried to tease out these factors to develop and implement a practice guideline for pediatric VTE prophylaxis. They prospectively reviewed over 4000 pediatric patients admitted over a 6 year period.

It looks like the guideline was developed using some or all of this data, then tested using regression models to determine which factors were significant. The guideline was then tweaked and a final model was implemented.

Here are the factoids:

588 of the patients (14%) were admitted to the ICU, and 199 of these were identified as high-risk by the guidelines
Median age was 10 (this is always important in these studies)
VTE occurred in 4% of the ICU patients, and 10% of the high-risk ones
Significant risk factors included presence of central venous catheter, use of inotropes, immobilization, and GCS < 9

Bottom line: This abstract confuses me. How were the guidelines developed? What were they, exactly? And the results seem to pertain to the ICU patients only. What about the non-ICU kids? The abstract just can’t convey enough information to do the study justice. Hopefully, the oral presentation will explain all.

I prefer a very nice analysis done at the Oregon Health Science University in Portland. I wrote about this study earlier this year. The authors developed a very useful calculator that includes most of the risk factors in this model, and a few more. Input the specific risks, and out comes a nice score. The only issue is, what is the score threshold to begin prophylaxis and monitoring? Much more practical (and understandable) than this abstract. Check it out at the link below.

References:

Evaluation of guidelines for injured children at high risk for venous thromboembolism: A prospective observational study. J Trauma Acute Care Surg. 2017 May;82(5):836-844.
A Clinical Tool for the Prediction of Venous Thromboembolism in Pediatric Trauma Patients. JAMA Surg 151(1):50-57, 2016.

Pharmacy

How Early Can We Start Chemoprophylaxis In TBI Patients?

April 26, 2022 The Trauma Pro Leave a comment

We’ve learned a couple of things in the last two posts by reviewing recent systematic review / meta-analysis studies. First, low molecular weight heparin provides better prophylaxis against venous thromboembolism (VTE) than unfractionated heparin. And giving prophylaxis within the first 72 hours of admission significantly decreases the incidence of VTE with no increase in existing intracranial bleeds or mortality.

So the only remaining question is, how low can you go? That is, how soon can you safely start chemoprophylaxis? The trauma group at George Washington University in DC put together a study to examine this question.

They, and one other Level I trauma center, performed a retrospective cohort study of adult, blunt TBI patients over a three year period. Patients with penetrating brain injury, and those with any other body region with significant injury (AIS >1) were excluded so this group truly represented isolated brain injury. Other exclusion criteria were progression of blood on CT within 6 hours, and crani or death within 24 hours. Early VTE prophylaxis was defined as occurring within 24 hours, and late was > 24 hours.

All patients had hourly neuro evaluations and a repeat head CT at six hours after admission. All had compression devices applied to their legs, and received either low molecular weight (LMWH) or unfractionated heparin (UH) at a fixed dose regarding of body habitus. Anti-Factor Xa levels were not measured.

Here are the factoids:

Between the two centers, 264 met inclusion criteria
About 40% received early prophylaxis and the remaining ones received their drug after 24 hours
ISS was higher (18 vs 15) and GCS was lower (13 vs 14) in the late therapy group
About 88% of patients in the early prophylaxis group received LMWH vs only 63% in the late group
Average time to prophylaxis start in the early group was 17 hours vs 47 hours in the late group
There were no differences in bleed progression between early and late groups (5.6% vs 7%)
The craniotomy / craniectomy rates were the same in early and late groups (1.9% vs 2.5%)
VTE rate was the same in early vs late groups (0% vs 2.5%)

Bottom line: The authors concluded that there was no additional risk in giving early VTE prophylaxis in TBI patients with a stable CT seven hours after arrival. This was true for patients with subdural, epidural, subarachnoid, and intraparenchymal bleeds.

But there are some limitations to consider. This was a retrospective study, and was a “how we do it” study” as well in terms of the choice of LMWH vs UH. This means there was not protocol for the form of heparin used; that was determined by surgeon preference.

There was also a difference in ISS and GCS between groups. However, the difference may not have been clinically significant, and it could have made the late group look worse if it were. Statistically, it did not.

And finally, the numbers are small and there was no power analysis. So there is the question of whether a significant difference could have even been detected.

What does it all mean? Well, it suggests that early (within 24 hours) chemoprophylaxis does not cause harm compared to later administration. But the study is not definitive enough to change practice yet. It should definitely prompt discussions and practice guideline development for starting prophylaxis after 24 hours of CT scan stability now. And hopefully these authors (or others) are planning a better prospective study to help us start even sooner!

Reference: Early chemoprophylaxis against venous thromboembolism in patients with traumatic brain injury. Am Surgeon 88(2):187-193, 2021.

Pharmacy

Early vs Late Chemoprophylaxis In Patients With Intracranial Hemorrhage

April 22, 2022 The Trauma Pro Leave a comment

In my last post, we looked at our knowledge base regarding the use of unfractionated heparin versus low molecular weight heparin. And the latter won. Today, let’s dig into the question of early versus late prophylaxis in patients with TBI and intracranial hemorrhage.

Neurosurgeons are remarkably cautious when considering anticoagulant thromboprophylaxis in these patients. Obviously, there is always concern for making the bleeding worse. This is very undesirable where there is little extra space and drainage is complicated.

But as we know, dogma about these issues tends to get spread very easily, with little scientific support. Let’s review another systematic review and meta-analysis (see last post) that examines the question.

As is usual, there have been a lot of contributions to this area over the years. Unfortunately, many are not entirely related to the question or have significant bias or design flaws. Of a total of 1,490 papers identified by the authores during PubMed searches only 29 were on topic. And of these only 11 were suitable for analysis. Early prophylaxis was defined as within 72 hours, although the authors were able to slice and dice this into shorter intervals.

Here are the results:

Progression of hemorrhage. There was no significant progression of intracranial bleeds seen at 24, 48 or 72 hours. However, this result is probably somewhat biased by the fact that fewer patients with severe injury are enrolled in studies of VTE prophylaxis. The overall odds ratio for early vs late administration was 0.86 favoring early prophylaxis. However, the confidence interval crossed the midline, so there was no difference noted in progression of bleed or mortality with early VTE prophylaxis.
Occurrence of DVT. Many of the studies indicated a decrease in VTE in the patients given early prophylaxis. This was noted at all three time intervals as well. The overall odds ratio was 0.58, which was statistically significant. This means that patients with early prophylaxis at any point had their risk of VTE reduced almost by half.
All cause mortality. Could their be other issues with early VTE prophylaxis that would increase mortality? This analysis showed that the odds ratio was 0.83 favoring early prophylaxis decreasing it. This is a 17% reduction in mortality, but unfortunately was not statistically significant. Although there is a trend toward lower mortality with early prophylaxis, it is not significant.

Bottom line: Again, this type of analysis is powerful but can suffer from the combined weaknesses of its individual papers. However, the best information we have thus far shows that early prophylaxis prior to 72 hours of admission does not appear to be harmful, does not result in progression of intracranial bleeding or excess mortality, and cuts the risk of VTE almost in half.

In my next post, I’ll explore a recent paper that examines how early we can really go with VTE prophylaxis.

Reference: Clinical outcomes following early versus late pharmacologic thromboprophylaxis in patients with traumatic intracranial hemorrhage: a systematic review and meta-analysis. Neurological review 43:861-872, 2020.

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