What Is: Lunchothorax?

Here’s an operative tip for trauma professionals who find themselves in the OR. Heard of “lunchothorax?” I’m sure most of you haven’t. The term originated in a 1993 paper on the history of thoracoscopic surgery. It really hasn’t been written about in the context of trauma surgery, though.

Lunchothorax is an empyema caused by pleural contamination in patients with concomitant diaphragm and hollow viscus injury. This most commonly occurs with penetrating injuries to the left upper quadrant and/or left lower back. The two penetrations tend to be in close proximity (diaphragm + stomach), but may occasionally be further away (diaphragm + colon).

One of the earlier papers describing the correlation of gastric injury and empyema was written by one of my mentors, John Weigelt. Although gastric repair is usually simple and heals well, his group did note a few severe complications. Of 243 patients with this injury, 15 developed ones that were considered severe, and 10 of those were empyema! What gives?

It turns out that the combination of gastric contents and pleural space is not a good one. It’s not really clear why this is. Is it bacterial? The acid? Undigested food? I’ve seen cases with what I would consider minimal contamination go on to develop a nasty empyema. This is also borne out in a National Trauma Databank review from 2009. It looked at complications in patients with a diaphragm injury and found that a gastric injury increased the probability of empyema by 3x. Interestingly, there was no increased risk of empyema with a concomitant colon injury.

Bottom line: Lunchothorax, or empyema after even minimal contamination from a hollow viscus, is a dreaded complication of thoraco-abdominal penetrating injury. Any time the stomach and diaphragm are violated, I recommend thoroughly irrigating the chest. It’s probably a good idea for concomitant colon injury as well, but there’s less literature support.

This can be done through the diaphragm injury if it is large enough, or through a chest tube inserted separately. Most of the time, you’ll be placing the chest tube anyway because the pleural space has been violated via the abdomen. In either case, copious lavage with saline is recommended to clear all particulate material, with a few extra liters just for good measure. There’s no data on use of antibiotics, but standard perioperative coverage for the abdominal injuries should be sufficient if the lavage was properly performed.

References:

  • The history of thoracoscopic surgery. Ann Thoracic Surg 56(3):610-614, 1993.
  • Penetrating injuries to the stomach. SGO 172(4):298-302, 1991.
  • Risk factors for empyema after diaphragmatic injury: results of a National Trauma Databank analysis. J Trauma 66(6):1672-1676, 2009. 

Closing Velocity And Injury Severity

Trauma professionals, both prehospital and in trauma centers, make a big deal about “closing velocity” when describing motor vehicle crashes.  How important is this?

So let me give you a little quiz to illustrate the concept:

Two cars, of the same make and model, are both traveling on a two lane highway at 60 mph in opposite directions. Car A crosses the midline and strikes Car B head-on. This is the same as:

  1. Car A striking a wall at 120 mph
  2. Car B striking a wall at 60 mph
  3. Car A striking a wall at 30 mph

2010-saab-9-5-head-on-crash-test_100313384_m1

The closing velocity is calculated by adding the head-on components of both vehicles. Since the cars struck each other exactly head-on, this would be 60+60 = 120 mph. If the impact is angled there is a little trigonometry involved, which I will avoid in this example. And if there is a large difference in mass between the vehicles, there are some other calculation nuances as well.

So a closing velocity of 120 mph means that the injuries are worse than what you would expect from a car traveling at 60 mph, right?

Wrong!

In this example, since the masses are the same, each vehicle would come to a stop on impact because the masses are equal. This is equivalent to each vehicle striking a solid wall and decelerating from 60 mph to zero immediately. Hence, answer #2 is correct. If you remember your physics, momentum must be conserved, so both of these cars can’t have struck each other at the equivalent of 120 mph. The injuries sustained by any passengers will be those expected in a 60 mph crash.

If you change the scenario a little so that a car and a freight train are traveling toward each other at 60 mph each, the closing velocity is still 120 mph. However, due the the fact that the car’s mass is negligible compared to the train, it will strike the train, decelerate to 0, then accelerate to -60 mph in mere moments. The train will not slow down a bit. For occupants of the car, this would be equivalent to striking an immovable wall at 120 mph. The injuries will probably be immediately fatal for all.

Bottom line: Closing velocity has little relationship to the injuries sustained for most passenger vehicle crashes. The sum of the decelerations of the two vehicles will always equal the closing velocity. Those injuries will be consistent with the change in speed of the vehicle the occupants were riding, and not the sum of the velocities of the vehicles. 

Artificial Platelets Under Development!

Uncontrolled bleeding is the bane of trauma professionals everywhere. Early in a resuscitation, we focus on identifying potential sources. We’ve developed numerous techniques for plugging them up. And we have processes in place to replace the blood that’s been lost.

Unfortunately, blood products are a perishable item. Packed red blood cells have a typical shelf-life of 42 days. Whole blood lasts only 21-35 days. Plasma is only suitable for up to five days once thawed. However, it can be frozen and used only when needed.

Platelets are another short-lifespan product, typically lasting only five days. This is a major reason for the relative lack of availability, especially at smaller hospitals. Unfortunately, freezing them or attempting cold storage renders them less active. For this reason, the platelet shortage persists.

As you know, platelets are fragments of cells produced by the bone marrow that have a major function in hemostasis. They bind to injured surfaces of disrupted blood vessels. Seconds later, they become activated and begin to clump with other platelets. They also release factors that result in fibrin deposition, creating a clot that helps stop bleeding.

Researchers have been trying to develop artificial blood substitutes for decades. I remember reading about rat experiments using these products in the 1980s. Unfortunately, they remain experimental to this day.

I found a recent article describing recent work on artificial platelets that piqued my interest. It was published by the biomedical engineering groups at North Carolina State University and UNC Chapel Hill. They used nanoparticles made of an ultrasoft microgel that were similar in size and shape to natural platelets. Fibrin-binding antibody fragments were embedded on the surface. These were selected to target only activated fibrin and not circulating fibrinogen.

Source: Science Translational Medicine

The groups devised a rat and pig trauma model by creating a liver laceration and then infusing varying doses of the artificial platelets (AP). Postmortem analysis of the wounds showed:

  • The APs did home in on the injured sites and were found in the injured areas
  • There was increased fibrin deposition at the wound site when compared to saline controls
  • Less bleeding was seen in the animals that received the APs vs saline
  • No significant deposition of APs was found in other tissues
  • The APs were excreted in the urine of the animals

Bottom line: This is very exciting, if preliminary, work. These artificial platelets are relatively easy to produce and can be frozen or stored at room temperature for extended periods. They appear harmless to the animals and decrease bleeding from the liver injury.

I am still somewhat cautious in my assessment. This same excitement was present 40 years ago in the early years of artificial hemoglobin solutions. And look where we are now. But, fingers crossed, there may be a solution to our chronic platelet shortage at some point in the future.

Reference: Ultrasoft platelet-like particles stop bleeding in rodent and porcine models of trauma. Sci Transl Med. 2024 Apr 10;16(742):eadi4490. doi: 10.1126/scitranslmed.adi4490. Epub 2024 Apr 10. PMID: 38598613.

The “Backward Finochietto” Problem

Resuscitative thoracotomy is a (sometimes) life-saving procedure reserved for trauma patients in extremis. Thankfully, most trauma centers do very few of these a year. However, that makes it one of those “high severity – low frequency” procedures that generate many, many quality improvement problems. Many of these issues are due to operator unfamiliarity or equipment availability.

Today, I’ll highlight a problem that crops up occasionally at various trauma centers across the US: the “backward Finochietto.” One of the most essential components of the resuscitative thoracotomy is rapid access to the chest. A large skin incision is typically made, the thoracic wall and intercostal musculature are divided, and the pleural space is entered.

It’s not easy to insinuate your arm between the ribs in an average person. But, of course, there’s a retractor for that! Von Mikulicz presented the first rib spreader at a German surgical society meeting in 1904.  Various versions of this instrument were devised over the next three decades to make it easier and faster to use.

The Finochietto retractor was introduced in 1936 and boasted several enhancements. It used a rack and pinion system to make it easier for the surgeon to spread the chest wall and made it unlikely to close on its own. The turning lever was hinged so it could flattened and placed out of the surgical field. The blades contained fenestrations so chest wall tissue could protrude into them and keep it from slipping when opened. It remains a workhorse instrument for us today and is found in most instrument packs for resuscitative thoracotomy.

But there is a potential problem. Some Finochietto retractors consist of only two pieces: a blade with the linear gear teeth (the rack) and another blade that fits onto it with the turning handle (the pinion). See the image below:

Looks great, right? However, there is one downside. The retractor parts that hook into the soft tissue are of a fixed depth. What if your patient has a more generous body habitus? Placing multiple sets of this retractor into the thoracotomy pack is not practical.

The solution is to allow detachable blades of various sizes. Here’s a modern-day example:

The good news is that the retractor tips are interchangeable. The bad news is that they are sometimes interchangeable with the wrong arm of the retractor! Hence the “backward Finochietto” problem. It’s impossible to use the retractors with the blades on the wrong side, and it takes time the trauma professional does not have to figure out how to snap them off and switch them around.

So what’s the solution? This is clearly an instrument reprocessing quality issue. These instruments are expensive, so your hospital may not be excited about purchasing new ones just for the trauma bay. It all boils down to foolproofing it in as many ways as possible.  Here are some tips:

  • Provide an educational session for all of the reprocessing techs. Unfortunately, this effect will wear off as staff turnover occurs.
  • Post a photograph of a properly assembled retractor for the techs to use when processing the tray.
  • Use colored instrument marking tape on each piece of the instrument. For example, a green tape strip should be placed on both the rack arm of the retractor and the left blade. Use red tape for the pinion arm and the right blade. All the tech needs to do now is match the colors as they assemble the retractor.

Bottom line: This problem is more common than you may think. Ask one of your old-timer trauma surgeons and I’ll bet they can tell you some stories. But it is easily avoided with a little creativity and some tape! Be sure to do it now so it doesn’t pop up in the heat of a resuscitative thoracotomy .

NFTI And STAT: Can They Replace The Cribari Grid?

In my last post, I reviewed using the Cribari grid to evaluate over- and under-triage at your trauma center.  This technique has been a mainstay for nearly two decades but has shortcomings. The most important one is that it relies only on the Injury Severity Score (ISS) to judge whether some type of mistriage occurred.  The ISS is usually calculated after discharge, so it can only be applied after the fact. And its correlation with outcomes varies.

What is NFTI, Exactly?

Five years ago, the Baylor University in Dallas group sought to develop an alternate method of determining who needed a full trauma team activation. They chose resource utilization as their surrogate to select these cases. They reviewed 2.5 years of their registry data (Level I center).  After several iterations, they settled on six “need for trauma intervention” (NFTI) criteria:

  • blood transfusion within 4 hours of arrival
  • discharge from ED to OR within 90 minutes of arrival
  • discharge from ED to interventional radiology (IR)
  • discharge from ED to ICU AND ICU length of stay at least three days
  • require mechanical ventilation during the first three days, excluding anesthesia
  • death within 60 hours of arrival

Patients who had at least one NFTI criterion were considered candidates for full trauma activation, and if an activation did not occur, the encounter would be regarded as undertriage. On the flip side, if no NFTI criteria were present and an activation did occur, it would be overtriage.

The First NFTI Paper

In their first published paper, the Baylor group analyzed nearly 5,000 trauma activations, split roughly in half for full versus partial trauma activations. Two-thirds of the full activations met at least one NFTI criterion. This means that about a third might be considered overtriage since they did not require one of the critical resources or die within 60 hours of arrival. And looking at the partial activations, fully 75% did not meet any NFTI criteria. There were 561 deaths in the overall group (12%). Of those, only 13 did not meet any NFTI criteria, but every one had a DNR order in place.

Now let’s translate all this into under- and overtriage numbers:

  • Undertriage: 22% (partial activations that were NFTI +)
  • Overtriage: 58% (any level of activation in a NFTI – patient)

The authors concluded that NFTI assesses anatomy and physiology using only measures of early resource utilization. They believe that it self-adjusts for age, frailty, and comorbidities and is a simple and effective tool for identifying major trauma patients.

But is it better for evaluating over- and undertriage than the Cribari grid? I’ve had several people tell me that it is. But if you look at the numbers above, overtriage is in the usual range, and undertriage is higher than the usual raw Cribari numbers. Even the authors suggest that it might be used to determine if the patient needed a trauma activation. Up to this point, NFTI is interesting, but not better than Cribari on its own.

The following year, these authors published a paper that further refined their concept. They rolled NFTI into something called the Standardized Triage Assessment Tool (STAT). Basically, the Cribari matrix is applied to the trauma activation data as usual. The fallouts (over- and undertriage groups) are then tested against the NFTI criteria. Cribari undertriage patients who were NFTI negative were now considered appropriate triage, as were Cribari overtriage who were NFTI positive. NFTI was basically used to do another level of screening on the outliers before resorting to individual chart review.

Once again, let’s look at over- and undertriage experience in the paper:

  • Undertriage: 9.1% undertriage (Cribari) reduced to 3.3% by adding STAT
  • Overtriage: 50% overtriage (Cribari) reduced to 31% by adding STAT

The authors concluded that adding STAT to the review process tightens up the numbers, reducing the number of charts that need to be reviewed individually. It also standardizes comparisons between hospitals that use STAT. This may be helpful for future triage-related research.

What Does It All Mean?

The Cribari grid has been around a long time, and people are both comfortable and facile using it. But it does tend to overestimate undertriage. In my experience, the raw Cribari undertriage rate is usually 12-22%. Individual chart analysis reduces this by about 10%. Overtriage rates are anywhere from 40% to 90%, and most centers do not review those charts because they don’t care much about reducing it.

Applying NFTI criteria to the over- and undertriage fallouts from Cribari makes sense. It appears to appropriately reduce both rates significantly. Undertriage remains the most significant factor to monitor. If you choose to adopt the use of the STAT technique, consider manually reviewing the undertriage charts that are being reclassified as appropriate for a few cycles. This should help confirm that STAT is really working for you.

One last thing. Using Cribari or NFTI or STAT does not absolve you of having good triage criteria for trauma activations. It is not possible to know a patient’s ISS or NFTI status as they are rolling through the door. The quality of your activation criteria are the first screen to try to ensure appropriate triage. If you keep finding undertriage events occurring, first look at your criteria. If those seem to be fine, then it’s time to scrutinize the people applying them!

Helpful Tools

The authors of the STAT paper provided some Excel spreadsheets to help add the Cribari matrix, NFTI, or STAT to your registry. Note that this only works for TraumaBase! If you use a different registry, contact your vendor for assistance.

The spreadsheets consist of three tabs/pages. On the first, enter the specific field names from your TraumaBase implementation. This fills in the code on the second tab which will be added to TraumaBase. The third tab gives explicit directions on how to add the feature to your registry.

Here are the downloadable file links provided by the authors:

References:

  1. Asking a Better Question: Development and Evaluation of the Need For Trauma Intervention (NFTI) Metric as a Novel Indicator of Major Trauma. J Trauma Nursing 24(3):150-157, 2017.
  2. Avoiding Cribari gridlock: The standardized triage assessment tool improves the accuracy of the Cribari matrix method in identifying potential overtriage and undertriage. J Trauma Acute Care Surg. 2018 May;84(5):718-726.

Home of the Trauma Professional's Blog

Do you want to get a daily email every time there’s a new post? See what I’m up to.

Click here to get details and subscribe!

[accua-form fid=”1″]

[mc4wp_form id=”2023″]