Monthly Archives: September 2023

Abstracts, Pharmacy

Best Of AAST #5: Door-To-Prophylaxis Time

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Today’s abstract continues the theme of VTE prophylaxis. The authors introduce another timing parameter in this one: the “door-to-prophylaxis” time. Just as it sounds, this is the time interval between admission to the ED and initiating chemo-prophylaxis. Just like some centers struggle with how long to wait to start it after a solid organ injury (see previous post here), many find it challenging to get it ordered in the first place.

The authors retrospectively reviewed their registry data over four years. They compared adult patients who arrived as a highest-level of activation and received blood during their resuscitation. They were divided into two groups: those with DVT or pulmonary embolism (VTE group) and those without (no VTE group). The door-to-prophylaxis time was defined as the time from hospital arrival to the first dose of medication.

Here are the factoids:

  • Just over 2,000 patients met inclusion criteria, with 106 experiencing VTE and 1,941 without it
  • VTE patients had higher ISS (29 vs. 24), higher lactate levels (4.6 vs. 3.9), and more post-ED blood transfusions (8 vs. 2)
  • There was no difference in the need for dose adjustment or missed doses between the groups
  • Door-to-prophylaxis time was significantly longer in the VTE group (35 vs. 25 hours)
  • When controlling for age, sex, ISS, lactate, and post-ED transfusions, each hour of delay increased the likelihood of VTE by 1.5%

The authors concluded that the door-to-prophylaxis time was significantly associated with increased incidence of VTE. They suggest that the door-to-prophylaxis time should be utilized as a performance improvement metric for this condition.

Bottom line: Unfortunately, we need a lot more information here. There was not enough room for details about the statistical analysis in the abstract, but they will be essential to know. And the authors remind us that this study shows association, not causation. 

Severe injury and blood transfusion are already known to be associated with a higher likelihood of VTE. The fact that the longer door-to-prophylaxis group had more frequent VTE may very well be due to their higher ISS and greater number of transfusions. Those events themselves may have led to the hesitation in starting a heparin.

Early prophylaxis is certainly a desirable goal in any trauma patient. But we need more than a new metric. We need more concrete information on the specific reasons for the delay and to prove that it is safe to give the drug early in patients who have those potential delaying factors.

Reference: “Door-to-prophylaxis” time as a novel quality improvement metric in preventing venous thromboembolism following traumatic injury. AAST 2023, Plenary paper #38.

Abdomen, Abstracts, Pharmacy

Best Of AAST #4: Starting VTE Prophylaxis After Solid Organ Injury

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Venous thromboembolic disease (VTE) continues to be a major issue in trauma patients. Most trauma centers have prophylaxis guidelines to try to reduce this problem. These guidelines typically recognize specific injuries that increase the risk of bleeding if anticoagulants are given. Typical ones include hemorrhagic injuries to the brain, pelvic and spine fractures, and solid organ injuries.

Typically, VTE prophylaxis starts immediately upon admission. But when these high-risk injuries are present, it is usually delayed for a period of time. Unfortunately, that period may be highly variable. Many centers have adopted 2-3 days to delay administration of low molecular weight heparin in patients with solid organ injury.

The AAST initiated a prospective multi-institutional trial comparing early (<48 hours after admission) and late (>48 hours) administration of prophylactic agents. Patients were older than 16 years, had any number of liver, spleen, or kidney injuries, and were initially treated nonoperatively. Patients who were transferred, died in the ED, were pregnant, had a bleeding disorder, or were taking anticoagulants or platelet inhibitors were excluded. A power analysis was performed, and more than the needed number of patients were enrolled.

Here are the factoids:

  • A total of 1173 patients were enrolled, and there were 589 liver injuries, 569 spleen injuries, and 289 kidney injuries
  • About 75% of patients (864) had early prophylaxis
  • Patients were younger (median 34 years), and two-thirds were male, with a median ISS of 22
  • Early VTE prophylaxis patients had significantly lower rates of VTE (3% vs. 7%)
  • There was no significant difference in failure of nonoperative management (5% early vs. 7% late)
  • The early prophylaxis group received fewer units of blood after prophylaxis started (17% vs. 23%)
  • Patients receiving VTE prophylaxis after 48 hours were 2.2x more likely to develop VTE

The authors concluded that early VTE chemoprophylaxis was associated with lower rates of VTE with no increase in complications. They recommended that it should become the standard of care for these patients.

Bottom line: Seeing such a well-designed and nicely executed study is refreshing. If the facts are borne out in the final manuscript review, this should become the standard of care for VTE prophylaxis in patients with solid organ injuries. 

I wish the authors would have stipulated that the chemoprophylaxis was required to be low molecular weight heparin. Unfortunately, there are still more than a few centers using unfractionated heparin. There could be a difference in efficacy and failure rates between the two. This could complicate the statistical analysis. Hopefully, the presenter will address this during the meeting.

I would also like to see a breakdown of when the early VTE prophylaxis actually started. Were they all close to 48 hours? Or were there enough at 24 hours to show this is also safe and effective?

It’s time for everyone to review their VTE prophylaxis guidelines. Get ready to make some major changes in your patients with solid organ injury!

Reference: When is it safe to start VTE prophylaxis after blunt solid organ injury? A prospective AAST multi-institutional trial. AAST 2023, Plenary paper #23.

Abstracts, Thorax

Best Of AAST #3: When To Place A Chest Tube For Hemothorax

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There is an art to deciding when to place a  chest tube for either hemothorax or pneumothorax. For the most part, the trauma professional examines the imaging and then uses some unknown internal metric to declare that it is “too big.” Then it’s time to insert some type of chest drain.

There have been attempts over the years to make this decision more quantitative. One of the better-known ones is the 2-cm rule for pneumothorax. If the distance from the chest wall to the lung on the chest x-ray is >2cm, it is “too big.”

But what about hemothorax? The Medical College of Wisconsin trauma group performed a retrospective review of 391 patient charts to test a new 300cc rule defining when a hemothorax is “too big.” This guideline was implemented in 2018-2019, and patients presenting before implementation were compared to those arriving after.

The 300cc threshold is determined by using Mergo’s formula for calculating the volume of a square prism. Obviously, this requires a CT scan for calculation, so patients who had a tube placed before scanning or did not have one were excluded. They were also excluded from the study if their pneumothorax met the 2-cm rule. The authors studied how many patients could be observed, how many needed tube drainage, observation failure, and later need for a VATS procedure or thoracotomy.

Here are the factoids:

  • About 60% of the study group was admitted after the new criteria were implemented, and both groups were demographically similar
  • After implementation, the number of patients that were just observed increased significantly from 52% to 71%
  • Of course, this means that the number of chest tubes inserted was significantly less (42% vs. 61%)
  • There was no difference in observation failure (delayed placement of a tube), 18% vs. 24%
  • There were also no differences in pulmonary complications, 30-day readmissions, or 30-day mortality
  • The average ICU and hospital length of stays were significantly shorter as well

The authors concluded that implementing their 300cc guidelines correlated with decreased length of stay and no increase in failure or complication rates.

Bottom line: Although this is a relatively small series, the differences between the groups quickly achieved significance. There are three major questions that I have. First, how was the 300cc threshold arrived at? Was this borne of clinical judgment, or did some previous work suggest it?

My next question has to deal with the accuracy of the volume calculation. Mergo’s formula was used to determine the volume of a rectangular solid. As we all know, hemothoraces and pneumothoraces are not cubes. They can be very irregular and influenced by patient position. However, I did find a paper from the University of Florida that found the correlation coefficient between the volume calculated by Mergo’s formula vs. using 3-D software estimation was 0.9, which is excellent. So this approximation appears to be a very good one.

Finally, using the 300cc rule is predicated on getting a CT scan. Does every patient need a chest CT? Part of the resuscitation process for major trauma involves obtaining a chest X-ray. The obviously large hemothorax can justify inserting a chest tube at that point. But the reality is that most of these patients do go on to chest CT, so this is a minor change in practice for most. 

Although I love to see confirmatory studies before practice changes, this one study can lead us to change our practice guidelines now. It is a relatively minor one and will allow us to avoid placement of a few more chest tubes and to shave off a few days of hospital stay. The logical follow-up study for the authors is to extend the post-discharge window for complications to 60 or 90 days to ensure that delayed procedures were not required in the observation group.

References:

  • Implementing the 300-cc rule safely decreases chest tube placement in traumatic hemothorax. AAST 2023 Plenary paper #22.
  • New formula for quantification of pleural effusions from computed tomography. J Thorac Imaging. 1999 Apr;14(2):122-5. 

 

Abstracts, Extremity

Best of AAST 2023 #2: Immediate Postoperative Prosthesis

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Blunt vehicular trauma is the most common cause of severe lower extremity trauma, particularly motorcycle crashes. Occasionally, the injury is so severe that the limb cannot be saved, and amputation is necessary. The conventional treatment is to protect the amputation incision, provide physical therapy, and fit a prosthesis once the stump is mature. This typically takes a month or two.

Unfortunately, losing any limb has a significant psychological impact on our patients’ physical and mental well-being. The concept of immediate postoperative prosthesis (IPOP) has been gaining traction in recent years in an attempt to improve early mobility and mental health among these amputees.

A group from India designed a randomized, controlled trial to compare patients undergoing IPOP after lower extremity amputation to those receiving conventional prosthetic treatment. They randomly enrolled 30 patients in each group and measured differences in quality of life, depression and anxiety, and various mobility scores.

Here are the factoids:

  • Both groups were modestly injured, with 85% having ISS < 15; this indicates that injuries were mostly limited to the extremity
  • Mangle extremity severity score was also low, indicating the incidence of vascular and severe soft tissue injury was also low
  • Quality of life scores for the physical, psychological, social, and environmental domains were significantly higher in the IPOP group
  • The Amputee Mobility Predictor score (AMP) was significantly higher after 12 weeks after IPOP
  • The Trinity Amputee Prosthesis Experiences Scales (TAPES) for psychosocial, activity restriction, and prosthetic satisfaction domains were significantly better in the IPOP group
  • The physical screening tests for directional control and overall stability were also significantly higher in IPOP patients

The authors concluded that IPOP improves quality of life, decreases depression and anxiety, and increases mobility in amputees compared to standard therapy.

Bottom line: It is common sense that allowing early mobility would help our patients, both physically and mentally. This paper makes it clear that IPOP makes a very real difference. This small study bears additional confirmatory work, but given the level of significance found, the concept will likely be proven.

It does take some extra effort to apply a well-fitted early prosthesis. This typically takes place in the OR. The prosthesis must be easy to remove for wound care and protect the stump from injury while weight-bearing.  It is best done by an orthopedic surgeon and skilled prosthetist at the end of the amputation procedure. 

Hopefully, this concept will catch on to help patients with this potentially devastating procedure recover more quickly and retain their mental health.

Reference: RCT to study the effect of immediate post-operative prosthesis vs. conventional prosthesis on balance & QOL in BK amputees following trauma. AAST 2023, Plenary paper #21.

Abstracts, Pharmacy

Best of AAST #1: Aspirin Vs Low Molecular Weight Heparin For VTE Prophylaxis

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The 82nd Annual Meeting of the American Association for the Surgery of Trauma begins next week. As is my custom, I will be reviewing some of the more interesting (to me) oral presentation abstracts until the last day of the meeting.

When reading abstracts, keep in mind that you are seeing just a snippet of a finished manuscript. The authors are given very little print space to fully describe their research idea, their methods, and their results’ significance. Sometimes, what is seen in the abstract varies significantly from what is actually heard at the meeting. But mercifully, this does not happen often. The abstract is usually an intriguing look at some new and exciting work.

Having said all that, an abstract should not be a reason to change your practice! It is usually early work and needs to be fully vetted at peer review. Even then, it needs to be taken in context with past, similar research before trickling down to patient care.

The first abstract is fascinating. Our orthopedic surgery colleagues have been trying to use aspirin for venous thromboembolism (VTE) prophylaxis for decades. Frequently, they are thwarted by the trauma surgeons, who are thoroughly indoctrinated in the low molecular weight heparin (LMWH) camp.

This work comes from the Shock Trauma Center in Baltimore and is a follow on to a paper published in the New England Journal of Medicine earlier this year. The paper demonstrates that aspirin is not inferior to LMWH when used for VTE prophylaxis of patients. There was no difference in death from all causes, VTE occurrence, wound complications, or bleeding events.

The abstract is a follow-on to that manuscript. The authors performed a secondary analysis of the initial data to see if aspirin provided the same apparent level of protection in patients with high risk for VTE as measured by the Caprini score.

Here are the factoids:

  • A total of 12,211 patients were enrolled in this multi-center, and the same outcomes listed above were monitored for 90 days
  • Of the total group, 3052 were judged to be high risk: 46% had a femur fracture, 42% had a pelvic/acetabular fracture, 48% had a thoracic injury, 39% had a spinal injury, and 35% had a head injury
  • There was no difference in death, deep venous thrombosis, pulmonary embolism, or bleeding in the two groups
  • Patient-reported satisfaction was significantly better by 68% in the aspirin group

The authors concluded that outcomes for aspirin vs. LMWH are similar, even in patients at high risk for VTE.

Bottom line: This is an intriguing abstract, pointing me to the original paper published in NEJM. This multi-center study was performed in conjunction with the research coordinating center at Johns Hopkins, which designs some top-notch research. This study was no exception.

I am fascinated with this work because it shows that our orthopedic colleagues were right! They’ve been trying to get us to use aspirin for a long time. It’s very cheap compared to LMWH, by a ratio of about 50,000:1. 

If you’ve followed me for a long time, you would know I have been skeptical of the VTE prophylaxis establishment. Looking historically at its evolution over the last 40+ years, the incidence of DVT and fatal PE have changed very little despite the introduction of heparin, low molecular weight heparin, and anti Factor Xa monitoring. But it’s been established practice, so we’ve had to abide by the rules. Now, a cheaper alternative to all of this is being shown to be just as (in)effective. 

I suspect that if others bear out this work, we will be able to use a cheaper prophylaxis drug that does not require injection. But we still need to work on figuring out the basis for this problem to hopefully reduce it to near zero someday.

References: 

  • Risk-stratified thromboprophylaxis effects of aspirin versus low-molecular-weight heparin in orthopaedic trauma patients. AAST 2023 Plenary Paper 3.
  • Aspirin or Low-Molecular-Weight Heparin for Thromboprophylaxis after a Fracture. N Engl J Med 2023; 388:203-213.