Category Archives: Thorax

Abstracts, Thorax

Best Of AAST 2021: Liposomal Bupivacaine For Rib Fractures

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The mainstays of rib fracture management are pain control and pulmonary toilet. The pain part of the equation can be managed in many ways, using topical, oral, IV, and injectable medications.

Rib blocks have been a mainstay for achieving some degree of local pain control. Classically, xylocaine was injected in the area around the costal nerve at or proximal to the fracture site. Then we found that if we combined the anesthetic agent with epinephrine, we could prolong the effect. New, longer-acting agents came around, and we could achieve a longer duration of action.

Then there is the new kid on the block: liposomal bupivacaine, also known as Exparel in the US.  The manufacturer was able to take molecules of bupivacaine and encapsulate them in a lipid membrane. When injected, these little liposomes slowly release their cargo, with a more prolonged anesthetic effect. Allegedly.

Sounds great! But does it work? The group at University of Cincinnati designed a prospective, double-blinded, randomized placebo control study of liposomal bupivacaine vs saline injection for pain control in up to six rib fractures. Subjects had significant injury as measured by their inability to achieve at least 50% of the desired inspiratory capacity. The authors monitored a number of respiratory parameters, as well as the pain score.

Here are the factoids:

  • Two cohorts of 50 patients were recruited, one received liposomal bupivacaine in up to six rib fractures, and the other received saline injections
  • The bupivacaine group achieved higher incentive spirometry volumes over the first two days, by about 200 cc
  • There was no change in daily pain scores in either group
  • Both groups showed a similar decrease in opioid use over time
  • Hospital and ICU lengths of stay were the same, and there were no complications or adverse events

Bottom line: Hmm. What’s going on here? There is a moderate amount of literature out there that does indicate a positive effect from liposomal bupivacaine in other conditions. But there are also some blinded, randomized studies that fail as well. So there are three possibilities:

  1. Liposomal bupivacaine isn’t a panacea, and works better in some situations than others
  2. This study failed to show a real difference for some reason
  3. A combination of both

This is a relatively small study, and the authors were not able to share their power analysis. They did not state if the spirometry volumes were significantly different, although I’m not sure 200 cc is clinically relevant. Maybe. But pain scores remained similar and opioid use declined as expected in both. 

These kinds of studies can be important. The difference in cost between injecting liposomal bupivacaine ($19 / ml) vs regular bupivacaine (10 cents / ml) vs saline/nothing (free) is striking. The premium price for the liposomal form needs to have a clear benefit or a cheaper product should be used.

Here are my questions for the presenter and authors:

  • Was your study big enough to show a result? Show us your power analysis.
  • How significant was the incentive spirometry result. Was the difference clinically noticeable?
  • What is your takeaway for this study? Your conclusion parrots the results. What will you do differently now, if anything?

Reference: INTERCOSTAL LIPOSOMAL BUPIVACAINE INJECTION FOR
RIB FRACTURES. AAST 2021, Oral abstract #20.

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Head, Thorax

How Common Is BCVI, Really?

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Blunt carotid and vertebral artery injuries (BCVI) are an under-appreciated problem after blunt trauma. Several screening tools have been published over the years, but they tend to be unevenly applied at individual trauma centers. I will discuss them in detail in the next section.

For the longest time, the overall incidence of BCVI was thought to be low, on the order of 1-2%. This is the number I learned years ago, and it has not really changed over time.

But how do we know for sure? Well, the group at Birmingham retrospectively reviewed every CT angiogram (CTA) of the neck they did in a recent two-year period. They did this after adopting a policy of imaging each and every one of their major blunt trauma patients for BCVI. Each patient chart was also evaluated to see if the patient met any of the criteria for the three commonly used screening systems.

During the study period, a total of 6,287 of 6,800 blunt trauma patients underwent BCVI screening with CTA of the neck. They discovered that 480 patients (7.6%) were positive for BCVI!

This is a shocking 8x higher than we expected! Why hasn’t this been obvious until now? Most likely because we were previously only aware of patients who became symptomatic. Luckily, many of these patients dodge the proverbial bullet and never exhibit any symptoms at all.

So why should we be worried? This is one of those clinical entities like blunt thoracic aortic disruption that potentially has terrible consequences if ignored. Although the number of patients who develop sequelae from their BCVI is small, suffering a stroke can be catastrophic.

Should we perform a screening study for all blunt trauma patients? Seems like overkill, or is it? Is there any way we be more selective about it?

In the next post, I’ll review the three current screening tools  used to determine which patients should receive CTA, and how good they are.

Reference: Universal screening for blunt cerebrovascular injury. J Trauma 90(2):224-231, 2021.

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Head, Thorax

It’s BCVI Week!

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This post will kick off a series of posts on BCVI. What is that, you ask? There seems to be some confusion as to what the acronym BCVI actually stands for. Some people believe that it means blunt cerebrovascular injury. This is not correct, because that term refers to injury to just about any vessel inside the skull.

The correct interpretation is blunt carotid and vertebral artery injury. This term refers to any portion and any combination of injury to those two pairs of vessels, from where they arise on the great vessels, all the way up into the base of the skull. Here’s a nice diagram:

Note that we will be excluding the external carotid arteries from this discussion, since injuries to them do not have any impact on the brain. They can cause troublesome bleeding, though.

These arteries are relatively protected from harm during blunt trauma. But given enough energy, bad things can happen. Fortunately, injuries to these structures are not very common, but unfortunately many trauma professionals under-appreciate their frequency and severity.

Over the next four posts, I’m going to provide an update on what we know about BCVI. I will try to tease out the true incidence, review the (multiple) screening systems, and discuss various ways to manage these injuries.

In the next post, we’ll explore the incidence of this injury. Is it truly as uncommon as we think?

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Thorax

Delayed Hemothorax In Older Adults: Real Or Not?

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I came across an interesting paper in the Journal of Trauma & Acute Care Surgery Open recently. I always read these articles a bit more critically, though, because the peer review process just doesn’t feel quite the same to me as the more traditional journal process. But maybe it’s just me.

In this paper, the authors decided to look at the incidence of delayed hemothorax because “emerging evidence suggests HTX in older adults with rib fractures may experience subtle hemothoraces that progress in a delayed fashion over several days.” They cite two references to back up this rationale.

They retrospectively reviewed records from two busy US Level I trauma centers for adults age 50 or older who were diagnosed with delayed hemothorax (dHTX). Delayed was defined as 48 hours or more after initial chest CT showed either a minimal or trace HTX. The authors went on to analyze the characteristics and demographics of the patients involved.

Here are the factoids:

  • A total of 14 older adults experienced dHTX after rib fractures, an overall incidence of 1.3% (!)
  • About half were diagnosed during the initial hospitalization for the fractures
  • All patients had multiple fractures, with an average of 6 consecutive ones; four had a flail chest
  • One third progressed from a trace HTX, two thirds had a completely negative initial chest CT
  • Only one third were taking anticoagulants or anti-platelet agents
  • Patients with multiple fractures, posteriorly located, and displaced were most likely to develop dHTX

The authors concluded that “delayed progression and delayed development of HTX among older adults with rib fractures require wider recognition.”

Bottom line: Really? First, I looked at the papers cited by the authors as the rationale for doing this study. They each found dHTX in about 10% of patients, but their definition was very broad: any fluid visible on upright chest x-ray. Furthermore, the patients were not really “older” either. Average age was around 50. 

So I’m not sure yet whether this is a problem, especially with the low incidence of 1.3%. This study doesn’t come right out and state how many patients they reviewed to find their 14, but it can be calculated to be 14 / 1.3% = 1,177. This incidence is only one tenth of that found in the two studies cited. Seems relatively uncommon, and half were discovered while the patients were still in the hospital. Thus only 0.65% sought readmission for chest discomfort or difficulty breathing.

This study required chest CT for rib fracture diagnosis. Is all that radiation (and possibly contrast) really necessary? And did these patients get another chest CT to delineate the pathology? More radiation?

Overall, this paper was not very helpful to me. Yes, I have seen patients come back days or weeks later with a hemothorax that was not seen during their first visit. It’s just that this study raises many more questions that should have been easily answered in the discussion. But they weren’t.

Given that only about a half of a percent of rib fracture patients develop delayed hemothorax after discharge, it is probably prudent to provide information to the patient recommending they see their practitioner if they develop any symptoms days or weeks later.  And a simple chest x-ray should do.

Reference: Complication to consider: delayed traumatic hemothorax in older adults. Trauma Surgery & Acute Care Open 2021;6:e000626. doi: 10.1136/tsaco-2020-000626.

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Thorax

Detecting Rib Fractures In The Elderly

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It’s well known that our elders do less well than younger folks after injury. The number of complications is higher, there tends to be more loss of independence during recovery, and mortality is increased. This is not only true of high energy trauma like car crashes, but also much lower energy events such as a fall from standing.

Rib fractures are common after falls in the elderly and contribute to significant morbidity if not treated adequately. Traditionally, they are identified through a combination of physical exam and chest x-ray. Unfortunately, only half of rib fractures are visible on x-ray. It falls to the physical exam to detect the rest.

A group at Beth Israel Hospital in Boston explored the utility of using chest CT in an attempt to determine if this would result in more appropriate and cost-efficient care in the elderly. They performed a retrospective study of 3 years of their own data on patients aged 65 or more presenting after a mechanical fall and receiving a rib fracture diagnosis. Imaging was ordered at the discretion of the physician. A total of 330 patients were elderly, fell, and had both chest x-ray and chest CT obtained. This was a very elderly group, with a mean age of 84 years!

Here are the factoids:

  • Rib fractures were seen on chest x-ray in 40 patients (12%) and on CT in an additional 56 ; 234 patients had no fractures on either
  • When fractures were seen on both studies, CT identified a median of 2 more fractures than chest x-ray
  • Patients with fractures not seen on chest x-ray were admitted significantly more often than those without fractures (91% vs 78%)
  • Mortality, admission to ICU, ICU length of stay, and hospital length of stay were not different if fractures were seen only on CT
  • CT scan identified new issues or clarified diagnoses suggested by chest x-ray in 14 cases, including one malignancy
  • Rib detail images were obtained in 13 patients and proved to be better than chest x-ray, but not quite as good as CT scan

Conclusion: use of CT for rib fracture diagnosis resulted in a few more admissions, but no change in hospital resource utilization, complications, or mortality.

Bottom line: Hmm…, read the paper closely. The authors conclude that more patients with CT-only identified rib fractures are admitted. But compared to what? Unfortunately, patients without rib fractures on CT. What about comparing to patients who had fractures seen on chest x-ray too? If that number is the same, then of what additional use is CT? Identifying a few incidentalomas?

Given that there is no change in the usual outcome measures listed here, it doesn’t seem like there is any additional benefit to adding CT. And I can see a lot of downsides: cost, radiation, and possible exposure to IV contrast. In my mind, there is still nothing that beats a good physical exam and a chest x-ray. Skip the CT scan. And don’t even think about ordering rib detail images! That’s so 1990s. And even if no rib fractures are seen on imaging, physical exam is the prime determinant for admitting your patient for aggressive pain management and pulmonary toilet.

Reference: Chest CT imaging utility for radiographically occult rib fractures in elderly fall-injured patients. J Trauma 86(5):838-843, 2019.

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