Category Archives: Abstracts

Best Of EAST #9: Is TXA Associated With VTE?

January 14, 2020 The Trauma Pro Leave a comment

Most trauma programs can be divided into two types: those that believe in tranexamic acid (TXA) and those that don’t. I won’t get into the details of the CRASH-2 study here. But those centers that don’t believe usually give one of two reasons: they don’t think it works or they think the risk of venous thromboembolism (VTE) is too high.

EAST put together a multi-institutional trial to see if there was an association between TXA administration and subsequent VTE. The results are being reported as one of the paper presentations at the meeting this week. A retrospective study of the experience of 15 trauma centers was organized. A power analysis was preformed in advance, which showed that at least 830 patients were needed to detect a positive result.

Adult patients who received more than 5 units of blood during the first 24 hours were included. There were a lot of exclusionary criteria. They included death within 24 hours, pregnancy, pre-injury use of anticoagulants, interhospital transfer, TXA administration after 3 hours, and asymptomatic patients that had duplex VTE surveillance (huh?). The primary outcome studied was incidence of VTE, and secondary outcomes were MI, stroke, length of stay, and death.

Here are the factoids:

There were 1,333 eligible patients identified, and 887 (67%) received TXA
Females were significantly (over 2x) more likely to receive TXA (46% vs 19%)
80% of patients given TXA received VTE prophylaxis, whereas only 60% of those who did not receive TXA got prophylaxis (also significant)
TXA patients had a statistically significantly higher ISS (27) compared to non-TXA patients (25) but this is not clinically significant
Mortality in the TXA group was significantly lower (17% vs 34%)
The number of units of blood, plasma, and platelets transfused were significantly lower in the TXA group
VTE rate appeared lower in the TXA group, but once multivariate analysis was applied, there was no difference

The group concluded that there was no association between TXA and VTE, but that it was linked to decreased mortality and transfusion need.

My comment: This was a study done the way they are supposed to be! Know your objectives and study outcomes up front. Figure out how many patients are needed to tease out any differences. And use understandable statistics to do so.

But, of course, it’s not perfect. No retrospective study is. Nor is any multi-institutional trial. There are lots of little variations and biases that can creep in. But the larger than required sample size helps with reducing the noise from these issues.

Basically, we have a decent study that shows that the clinical end points that we usually strive for are significantly improved in patients who have TXA administered. We don’t know why, we just know that it’s a pretty good association.

This study shows that the usual reasons given for not using TXA don’t appear to hold true. So hopefully it will convert a few of the TXA non-believers out there. I’m excited to hear more details during the presentation at the meeting.

Reference: Association of TXA with venous thromboembolism in bleeding trauma patients: an EAST multicenter study. EAST Annual Assembly, Paper #13, 2020.

Abstracts, CNS, Complications

Best Of EAST #8: Early vs Late Full Anticoagulation In TBI

January 13, 2020 The Trauma Pro Leave a comment

Trauma professionals are always reluctant to anticoagulate TBI patients with demonstrated blood in their head. In recent years, we’ve become more comfortable providing prophylactic doses of low molecular weight heparin after a suitable period. This is typically 24-48 hours after a stable head CT in patients with select types of intracranial hemorrhage (ICH) who are at increased risk for venous thromboembolism.

But what about therapeutic dose anticoagulation in these patients? Let’s say that you have a patient with ICH who has developed a significant pulmonary embolism (PE)? Is is safe to give full dose anticoagulation? And if so, when?

The group at Shock Trauma in Baltimore attempted to answer this in one of the EAST Quick Shot presentations scheduled for this week. The did a retrospective review of 4.5 years of their own data on these patients. They specifically selected patients who had both ICH and PE and compared those who received full anticoagulation within 7 days of injury vs those who were dosed after 7 days. Outcomes studied included death, interventions for worsening ICH, and pulmonary complications.

Here are the factoids:

A total of 50 patients had both ICH and PE, but only the 46 who received therapeutic anticoagulation were analyzed
19 patients (41%) received early anticoagulation, and 27 received it late (59%)
There were 4 deaths in the early group (2 from the PE, 1 from multi-system organ failure, 1 from the TBI) vs none in the late group, and this was statistically significant
3 patients in the early group (18%) vs 2 in the late group (7%) had an increase in their ICH (p=0.3), and none required intervention

The authors concluded that their study failed to show any instances of clinically significant progression of ICH after anticoagulation, and that it is not associated with worse outcomes, even if started early. Thus they recommend that ICH should not preclude full anticoagulation, even early after injury.

My comment: I always say that you shouldn’t let one paper change your practice. Even a really good one. In order to ensure that you are providing the best care, more work must always be done to confirm (or refute) the findings of any provocative research. And this little Quick Shot, with little opportunity for questions from the audience, should definitely not change it!

The major issues to consider here are common ones:

This was a retrospective study and it does not appear that any guideline was followed to determine who got early vs late anticoagulation. So who knows what kind of selection bias was occurring and how the surgeon decided to prescribe anticoagulation? It’s very possible that patients with a “bad CT” were put into the late group, and the not so bad ones in the early group. This would bias the results toward better outcomes in the early anticoagulation group.
It’s also a very small study that is extremely underpowered. The authors comment on the fact that the outcomes of the early group were not worse than the late group. However, looking at their sample size (46) shows that they would only be able to show differences if they were about 5x worse in the early group. They would realistically need about 350 total patients to truly show that the groups behaved the same. Their small numbers also preclude saying that there were no ICH progressions. There very well could have been if 300 more patients were added to the series.
And isn’t death a significant outcome? The authors indicated that 2 of the 4 deaths were a result of the PE. Yet there was a significant association (p=0.02) of increased death in the early anticoagulation patients that can’t be discounted.

Bottom line: It’s way too early to consider giving early anticoagulation to patients with ICH and pulmonary embolism. It may very well be shown to be acceptable, eventually. But not yet. And a much bigger prospective study will be required to confirm it.

Reference: Therapeutic anticoagulation in patients with traumatic brain injuries and pulmonary emboli. EAST Annual Assembly Quick Shot #7, 2020.

Abstracts, Complications

Best Of EAST #7: Is There A Relationship Between Number Of Transfusions And Infection?

January 10, 2020 The Trauma Pro Leave a comment

It has long been known that blood transfusion decreases immunocompetency for a period of time. This has been taken advantage of in transplant surgery for decades. And blood transfusions are used liberally in major trauma. So could blood transfusion make it more likely for a trauma patient to suffer complications such as pneumonia, sepsis, and surgical site infections?

The group at the Massachusetts General Hospital explored this possibility. The analyzed four years of TQIP data, examining patients who received blood transfusions within four hours of arrival. They excluded transfers in, patients with incomplete transfusion counts, and those who died within 48 hours.

They focused on pneumonia, sepsis, and surgical site infections and statistically controlled for demographics, comorbidities, injury severity, and surgical/procedural interventions.

Here are the factoids:

A million patients (!) were reviewed and about 41,000 met study criteria
The odds ratio of infectious complications increased from 1.23 after 2 units to 4.89 after 40 units
Each additional unit after 40 increased the odds of an infection by another 4.9%

The authors concluded that blood transfusion is associated with a dose dependent risk of infectious complications and that patients should be resuscitated to achieve prompt hemorrhage control (really?).

My comment: Well, this certainly looks fairly straightforward. Of course, it suffers from the usual drawbacks of massaging large databases. And remember, it shows an association, not cause and effect. How can we tease out whether the higher infection risk is due to badly hurt patients who need major surgery and prolonged ICU stays with pneumonia? The authors have tried to reduce this as much as possible using logistic regression. Unfortunately, many of the variables are very interdependent and I don’t believe the methods can fully overcome this. And there may be other factors not available for analysis in the TQIP data.

Here is my only question for the authors and presenter:

- How can you be sure that you have fully controlled for the key variables that might influence your final analysis? Yes, you considered demographics, three listed comorbidities (cirrhosis, diabetes, and steroid use), injury severity, and some interventions. But might there be other factors not listed and maybe not even in the TQIP data? Ideas?

This is one of those papers that makes you say “hmm”. But don’t we always try to stop the bleeding promptly. I’m not sure what alternative we have to giving blood.

Reference: Overtransfusion comes at a significant cost: the dose-dependent relationship between blood transfusions and infections after major trauma. EAST Annual Assembly abstract #26, 2020.

Abstracts, Prevention

Best Of EAST #6: Uber / Lyft vs Drunk Driving

January 9, 2020 The Trauma Pro Leave a comment

Ride share services like Uber and Lyft are now pretty much ubiquitous. It’s so easy to get a ride these days one would think that the incidence of car crashes due to drunk driving should be declining, right?

Well, nobody knows for sure. But the group at Tulane decided to look at their own data for alcohol-related car crashes over a seven year period. They also combed regional traffic databases for more information and compared the data from pre- to post- arrival of ride share services.

Here are the factoids:

There were 1474 patients involved in alcohol-related crashes (ARC)
The proportion of alcohol-related ARCs decreased significantly from 39% to 29%
The overall annual incidence of fatal ARCs seen at Tulane decreased significantly from 11.6 to 5, and also decreased significantly within the region
However, the incidence of ARCs only decreased within the 21-24 year age group(!)

My comment: This is very interesting work! The statistics appear to be sound and the number sufficiently large. It shows that it might be possible to decrease drunk driving injuries using methods other that the usual prevention efforts. It is puzzling, though, that the effect is only seen in a very narrow age group in the population. Practically everyone can use a ride-hailing app these days. Even I do!

Here are my questions for the authors and presenter:

How do you explain the very narrow age-range that appears to be affected? Remember, this study shows an association, not cause and effect. Could it be that something else is reducing alcohol-related crashes in this specific age group, and it has nothing to do with ride share availability? What else could it be?
How can this decrease in 21-24 year olds hold when there was such a significant decrease in overall alcohol-related crashes? Was everyone driving around New Orleans in that age group? Otherwise, how can this be explained?

I am fascinated by this study. But it’s going to be difficult to separate out other confounding variables and causes to be able to point definitively to any benefit from ride share services.

Reference: Do ride sharing services affect the incidence of alcohol-related motor vehicle collisions? EAST Annual Assembly abstract #22, 2020.

Abstracts

Best Of EAST #5: Keeping Blood From Going Bad

January 8, 2020 The Trauma Pro Leave a comment

What goes around comes around. Whole blood was the only transfusion product available until about 60 years ago, when the whole blood banking system switched to fractionating blood products. Now we are discovering the benefits of whole blood again. The military has been using fresh whole blood for some time. As civilians, we’ve had less access to whole blood. But once obtained, it must be used within 21 days. This is half the storage time for the usual bag of packed red cells, and may result in some waste of this valuable product.

The group at the University of Cincinnati wondered if fractionating and preserving an expiring bag of whole blood might extend the life of those red cells. They obtained 21- day old (expiring) whole blood and separated the red cells, preserving them using the usual technique. They then analyzed the cells weekly until expiration at 42 days for viability, storage damage and coagulation status.

Here are the factoids:

The number of units tested was not listed in the abstract
Damage from storage of the extracted red cells appeared to be consistent with normal damage expected from packed red blood cells
When mixed with plasma with a 1:1 ratio, clotting time, clot formation time, and maximum clot formation did not change as the salvaged cells aged

The authors concluded that the salvaged cells aged just like packed RBCs. They suggested that this may provide a method for extending the life of whole blood and allowing transfusion into patient in hemorrhagic shock.

My comment: This is an intriguing paper and suggests a way of extending the life and use of valuable whole blood. It appears to have been well done and analyzes standard markers of red cell dysfunction. However, the authors did not provide the number of units they tested. This is critical, since they are trying to show that the values tested are statistically the same (no difference between packed RBCs and those salvaged from whole blood). Some of their comparison numbers appear very different, but are not statistically significant. I worry that the number of units tested might be too small to show a difference.

Here is my question for the authors and presenter:

Exactly how many units of whole blood did you use in this study? And did you do a power analysis to ensure that you don’t have a Type II error (false negative) with the “not significant” results?

This is a great idea and stands to save money and stretch our supply of blood!

Reference: Save it – don’t waste it! Maximizing utilization of erythrocytes from previously stored whole blood. EAST Annual Assembly abstract #6, 2020.

Home of the Trauma Professional's Blog