Category Archives: Complications

Abstracts, Complications

Best Of AAST #8: Duplex Screening For DVT

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To screen on not to screen, that is the question. If you do more testing, you will find more cases. But does it make a difference clinically? Sounds like some of the questions coming up in our current discussion of the Coronavirus. But that’s what we really need to know.

The group at Intermountain Medical Center in Salt Lake City performed a 2 ½ year randomized, prospective study of screening duplex ultrasound of the lower extremities vs no screening study. They used the Risk Assessment Profile (RAP) developed by Greenfield, first published in 2000. Any patient at moderate or higher risk for DVT (RAP score >5) was enrolled in the study. They were randomized into two groups: a screening group who received duplex scans on days 1, 3, 7, and then weekly, and a “no routine screening” group. All patients received chemoprophylaxis per the trauma service’s existing protocol.

The RAP score is a 17 factor scale that assigns a specific number of points based on underlying medical conditions, iatrogenic factors like central lines or transfusions, injury-related factors, and age.

Here are the factoids:

  • A total of 3,236 trauma patients were identified, and the 1,989 who were at moderate or higher risk for DVT were evenly randomized to screening vs no screening
  • There were no differences in age, sex, BMI, mechanism, ISS, or length of stay between the two groups
  • The incidence of DVT was 15% in the screened group vs 1.7% in the no screening group

The authors concluded that screening diagnoses more DVT, most of which is below the knee. And they also noted that screening identified DVT more often than clinical exam alone, but does not result in fewer PE or deaths. They suggest that more work needs to be done to identify exactly who benefits from duplex screening the most.

Here are my comments:

Finally, an easy to follow and well-designed study! But I think some of the results may be missing from the abstract. That section cuts off in the middle of some of the statistics, and there is no mention of the clot location or PE/mortality rates mentioned in the conclusion.

I also worry that a thousand patients in each group may not be enough. We are working with low incidence end points like PE and death, and this is an association study with many potential confounders/factors that may not have been recorded. I generally like to see the ability to detect a minimum of a 2x effect. So if the incidence of PE is 1.5%, I like to see the ability to detect a difference if the other group is 3%.

And speaking of study size. The RAP score was first described in 1997 and was a pilot study. They drew their conclusions from only 53 patients, and the only risk factor that they could show that was a statistically significant predictor of DVT was age. They concluded that surveillance of patients with RAP > 5 was warranted. This abstract builds upon this work, but is trying to say that maybe we don’t need to do duplex scans.

Here are my questions for the presenter and authors:

  • Is there some text missing from the end of the results section of the abstract? It seems to end unexpectedly, and some things are mentioned in the conclusions that are not in the results.
  • Why did you choose the RAP score? There are other risk assessment tools available out there. What is so special about RAP?
  • Is your sample size large enough to detect differences in incidence of PE or death? My back of the envelope calculations suggest at least 1,500 patients would be needed in each group.
  • How long did you follow patients to determine if they had PE or death? Until they were discharged? Later than that?  This makes a big difference in the eventual incidence of these outcomes.
  • Based on what you found, is there any value to treating asymptomatic proximal DVT? It sounds like you are saying that screening is not needed at all because PE and death are the same. Isn’t there value in treating proximal DVT if you find it?

This abstract certainly got me thinking! I am looking forward to the presentation and discussion of this abstract!

Reference: Head in the sand? The value of routine duplex ultrasound screening for venous thromboembolism in the trauma patient: a randomized Vanguard trial. AAST 2020, Oral Abstract #16.

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Complications

Early Antibiotic Administration In Open Fractures

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Recommendations for open fracture management has evolved over the past 20 years. The old-timey rule used to be: all open fractures need to be treated within 8 hours. This treatment could be washout and ORIF, washout and external fixation, or just washout alone. The washout was the constant across all types of management.

Then the orthopedics literature began to suggest that “lesser” fractures (Gustilo I – II) could go a bit longer. Some centers extended their required time to washout up to 12 or even 16 hours. Subsequently, the value of early IV antibiotics was recognized, and the time to washout started to change again.

Now, we have recommendations for early IV antibiotics competing with the old recommendations for prompt washout. Who is winning?

There are two recent papers that seem to provide conflicting recommendations regarding antibiotics. The first is in process for publication by the ortho group at San Francisco General Hospital. They studied 230 open fracture patients at their Level I Trauma center over a five-year period. They monitored for surgical site infection that occurred during the first 90 days after injury.

Here are the factoids:

  • It took 450 consecutive patients to find the 230 study patients due to these exclusion criteria: missing documentation of antibiotic administration, delayed presentation, and loss to followup
  • There were 169 Gustilo Type I or II fractures and 61 Type III fractures
  • They noted a trend (p = 0.053) toward infection in patients who had antibiotic administration an average of 83 minutes after arrival vs those who received them within one hour
  • Patients who received their antibiotics 2 hours after arrival had a 2.4x increase in likelihood for infection within 90 days

But there was another paper published in the same journal this year that shows the opposite result. This one is from the University of Bristol in the UK. This one reviewed only Gustilo Type III fractures and observed changes in the deep infection rate, before and after the National Health Service guidance on antibiotic administration changed from within three hours to one hour post-injury.

Some more factoids for you:

  • A total of 176 patients were identified at a single center, and only 152 were left after the usual exclusions
  • Average time to antibiotic administration decreased from 180 minutes to 160 minutes after the new guidance was issued (60 minutes(!))
  • Only 12 patients developed deep infections with a median followup of 26 months
  • On regression analysis, no obvious factors  for increased risk were identified

Bottom line: So what gives? Two different answers: antibiotics given after 2 hours is associated with an increased risk of infection, vs no difference?

No, not really. Talk about apples to bananas. The first study looks at all open fractures, not just the most severe. It does not really define “surgical site infection,” so can we assume it was any infection? We don’t know. The second study looked only at deep infections.

The sample sizes are marginal in both studies, although the first was able to show a significant result despite this. And, of course, these are association studies, so other factors could be at play to manifest an infection or not. Both groups showed an 8-11% infection rate of some kind in their Gustilo Grade III fractures. 

But the biggest issue with the second study is that, despite guidance that antibiotics should be given within an hour, the average time decreased from 3 hours to only 2:40. This is still beyond the two hour threshold to higher infection rates suggested in the first paper.

So what do I make of all of this? The UK paper is lacking the power and enough of a treatment change to be taken seriously. The San Francisco paper shows borderline results with a 2.4x increase in all infections if antibiotics are given after 2 hours. 

So until we have better data and larger series, 1 hour antibiotic administration seems like a painless way to decrease the likelihood of an infection. But whether that can safely delay the time to washout remains to be seen.

References:

  • Delay of Antibiotic Administration Greater than 2 Hours Predicts Surgical Site Infection in Open Fractures. Injury, in press, May 29, 2020.
  • Time to intravenous antibiotic administration (TIbiA) in severe open tibial fractures: Impact of change to national guidance. Injury 51:1086-1090, 2020.
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Complications

More On Lead Poisoning And Retained Bullets

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Trauma professionals frequently have to leave bullets in patients. It is often more disruptive to go digging the projectiles out than to just leave them in place. But patients always want to know why and what the consequences might be.

In my last post, I discussed a very old paper on what we know about lead levels and retained bullets. Very recently, a meta-analysis was published that provides a better picture of this topic. They somehow managed to find over 2000 articles dealing with lead toxicity and bullets out there. But after someone had the pleasure of reviewing each of them, they found only 12 that had any meaningful or actionable information.

Here are the factoids:

  • All studies were observational (duh! It would be difficult to get your IRB to approve a study where patients were shot on purpose)
  • There were five cross-sectional studies, four case-control studies, and three prospective cohort studies
  • The studies were small, with a median of only 26 patients (range 15-120)
  • Eleven of the twelve studies showed an association with retained bullets and elevated blood lead levels
  • Three studies showed elevated blood levels if a fracture was present
  • The higher the number of retained fragments, the more likely lead levels were to be high
  • Higher lead levels were associated with retained fragments near a bone or joint
  • There were no good correlations with number of fragments and location vs actual lead toxicity

Bottom line: Even using meta-analysis, it is difficult to tease out meaningful answers to this question. That speaks to the low numbers of papers and their quality. However, this study does provide a little bit of guidance.

Retained bullet fragments are probably not a big worry in most patients. The bothersome cases are those where the fragments are in or near a bone or joint. And even though few patients actually developed lead toxicity, lead levels approaching 5 micrograms/dL can have physiologically significant negative effects. 

Recommendation: If your patient has a retained bullet fragment near a bone or joint, or they have “multiple” retained fragments (no good definition of this), they should have blood lead levels measured every three months for a year. If the level is rising, and certainly if it reaches the 5μ/dL level, attempts should be made to remove the fragments.

Reference: Lead toxicity from retained bullet fragments: A systematic review and meta-analysis. J Trauma 87(3):707-716, 2019.

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Complications

Can Lead Poisoning Occur After A Gunshot?

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This is a fairly common question from victims of gunshots and their families. As you know, bullets are routinely left in place unless they are superficial. It may cause more damage to try to extract one, especially if it has come to rest in a deep location. But is there danger in leaving the bullet alone?

One of the classic papers on this topic was published in 1982 by Erwin Thal at Parkland Hospital in Dallas. The paper recounted a series of 16 patients who had developed signs and symptoms of lead poisoning (plumbism) after a gunshot or shotgun injury. The common thread in these cases was that the injury involved a joint or bursa near a joint. In some cases the missile passed through the joint/bursa but came to rest nearby, and a synovial pseudocyst formed which included the piece of lead. The joint fluid bathing the projectile caused lead to leach into the circulation.

The patients in the Parkland paper developed symptoms anywhere from 3 days to 40 years after injury. As is the case with plumbism, symptoms were variable and nonspecific. Patients presented with abdominal pain, anemia, cognitive problems, renal dysfunction and seizures to name a few.

Bottom line: Any patient with a bullet or lead shot that is located in or near a joint or bursa should have the missile(s) promptly and surgically removed. Any lead that has come to rest within the GI tract (particularly the stomach) must be removed as well. If a patient presents with odd symptoms and has a history of a retained bullet, obtain a toxicology consult and begin a workup for lead poisoning. If levels are elevated, the missile must be extracted. Chelation therapy should be started preop because manipulation of the site may further increase lead levels. The missile and any stained tissues or pseudocyst must be removed in their entirety.

Granted, this is a very old paper. Over the years, a few papers on the topic have popped up from time to time. In my next post, I’ll review a meta-analysis on this topic that was published just last year.

Reference: Lead poisoning from retained bullets. Ann Surg 195(3):305-313, 1982.

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Complications

What Does A Retained Surgical Sponge Look Like?

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Surgeons and surgical residents rarely see these. And because it’s so uncommon, they frequently don’t recognize the telltale findings on radiographic studies. The TSA runs into the same problem in screening passengers for weapons and other hazards at airports. But it’s the bane of any surgeon’s existence. And it’s a major reason why OR personnel take such great pains to account for everything in the room. It is a catastrophe, and always a preventable one, when some piece of equipment goes missing and ends up left inside a patient.

A number of methods have been developed to try to eliminate this problem. They include careful counts, having someone record anytime anything is placed inside, x-rays, and most recently, RFID tags.

After counting, x-ray is the most common way to try to find missing objects. One would think that these foreign bodies would be easy to see. Metallic instruments are rather easy to spot. But many trauma professionals, even those who work in the OR, have never seen what a positive image of a sponge actually looks like. So here they are. You should never miss one on an xray now.

Surgeons typically use two types of sponges in the OR: Ray-Tec sponges and standard lap pads. Ray-Tecs look like a 4×8 piece of gauze with a mysterious blue string woven throughout it. The string is the only part that shows up on x-ray, and it is very thin and somewhat hard to see. Here are some Ray-Tec sponges outside the body:

And here’s one that was left inside. Note the little squiggle in the left lower quadrant and how easy it is to overlook.

On the other hand, a laparotomy pad is a 4×4 folded cloth pad that unfolds into a larger pad. It has a blue radiopaque tag sewn in the corner, extending along one edge of the pad. Here’s what they look like outside the body:

And here’s one inside a patient. Note the irregular object in the right upper quadrant. Many times the tag is scrunched up and doesn’t look like one.

Bottom line: It’s important for anyone who works in the OR on any body part to be familiar with the appearance of these tags on x-rays. Since it’s generally impossible to get accurate counts before or after a trauma procedure, always image the involved body cavity looking for these telltale signs before closing the patient.

Note: These images  were taken from the internet. Patients were not treated at Regions Hospital.

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