Category Archives: Thorax

How To Evaluate A Stab To The Diaphragm – Part 2

February 26, 2018 The Trauma Pro Leave a comment

Yesterday I gave a little perspective on the use of CT in assessing the diaphragm after penetrating injury. Today, I’ll break it down into some practical steps you can follow the next time you see one.

Step 1. Stable or unstable? If your patient arrives with unstable vital signs, and there is no other source but the abdomen, the answer is simple. Go to the OR for a laparotomy. Period. They are exsanguinating and the hemorrhage needs to be stopped.

Step 2. Mark the sites of penetration and take a chest x-ray. This will let you evaluate the potential trajectory of the object, and will give you your first glimpse of the diaphragm.

Step 3. Examine the abdomen. Actually, you should be doing this at the same time you are setting up for Step 2. If your patient has peritoneal signs, no further evaluation is needed. Just go to the OR for laparotomy. Look at the chest x-ray once you get there.

Step 4. Right side? If your appreciation of the path of penetration involves just the liver, take the patient to CT for evaluation of chest, abdomen, and pelvis. You need to see all three of these areas to assess for blood and fluid in both body cavities. After the study, if you still think the injury is limited to the liver, admit the patient for observation.

Step 5. Left side? Look at that chest x-ray again. If there are any irregularities at all, strongly consider going to the OR and starting with diagnostic laparoscopy. These irregularities can be glaring, like in the x-ray above. But they can be subtle, like some haziness above the diaphragm or small hemothorax. Obviously, if the injury is as clear as on the x-ray above, just open the abdomen. But if in doubt, start small. And remember my advice on “lunchothorax.”

Step 6. Admit and observe. Check the abdomen periodically, and repeat the chest x-ray daily. If anything changes, consider diagnostic laparoscopy. As a general rule, I don’t keep patients NPO “just in case.” Most will pass this test, and I don’t see a reason to starve my patients for the low likelihood they need to go to the OR.

Step 7. Make sure your patient gets a follow up evaluation. See them in your outpatient clinic, get a final chest x-ray and abdominal exam before you completely clear them.

Abdomen, Thorax

How To Evaluate A Stab To The Diaphragm – Part 1

February 23, 2018 The Trauma Pro Leave a comment

Penetrating injury to the diaphragm, and specifically stab wounds, have been notoriously hard to diagnose since just about forever. Way back in the day (before CT), we tried all kinds of interesting things to help figure out if the patient had a real injury. Of course, we could just go to the OR and lap the patient (laparoscopy did not exist then). But the negative lap rate was significant, so we tried a host of less invasive techniques.

Remember diagnostic peritoneal lavage? Yeah, we tried that. The problem was that the threshold for red cells per cubic mm was not well defined. Some would supplement this technique with a chest tube to see if lavage fluid would drain out. And one paper described instilling nuclear medicine tracer into the abdomen and sitting the patient under a gamma camera for a few hours to see if any ended up in the chest. Groan!

We thought that CT would save us. Unfortunately, resolution was terrible in the early years. If you could actually see the injury on CT, it was probably because a large piece of stomach or colon had already fallen through it. But as detectors multiplied and resolution improved, we could begin to see some smaller defects. But we still missed a few. And the problem is that left-sided diaphragmatic holes slowly enlarge over time (years), until the stomach or colon falls through it. (See below)

A group of radiologists and surgeons in a Turkish trauma hospital recently published a modest series of patients with left-sided diaphragm injuries evaluated by CT. They looked at about 5 years of their experience in a group of patient who were at risk for the injury due to a thoraco-abdominal stab wound. Unstable patients were immediately taken to OR. All of the remaining patients underwent an initial CT scan, followed by diagnostic laparoscopy after 48 hours if they remained symptom free.

Here are the factoids:

A total of 43 stable patients with a left thoraco-abdominal stab were evaluated
30 patients had a normal CT, and 13 had the appearance of an injury
Of those who were CT positive, only 9 of 13 (69%) actually had the injury at operation
Two of the 30 (7%) who were CT negative were found to have a diaphragm injury during followup laparoscopy
So in the author’s hands, there was 82% sensitivity, 88% specificity, a positive predictive value of only 69%, and a negative predictive value of 93%

Bottom line: The authors somehow looked at the numbers and concluded that CT is valuable for detecting left diaphragm injury. Huh? They missed 7% of injuries, only finding them later at laparoscopy. And they had a 31% negative laparotomy rate.

Now, it could be that the authors were using crappy equipment. Nowhere in their paper do they state how many detectors, or what technique was used. Since it took place over a 5 year period, it is quite possible that the earlier years of the study used equipment now considered to be out of date, or that there was no standardized technique.

CT may not yet be ready for prime time. But it can be a valuable tool. Tune in tomorrow for some tips on how and when to look for this insidious injury.

Reference: Evaluation of diaphragm in penetrating left thoracoabdominal
stab injuries: The role of multislice computed tomography. Injury 46:1734-1737, 2015.

Thorax

Practical Tip: Making Sure The Last Chest Tube Hole Is In The Chest

June 26, 2017 The Trauma Pro Leave a comment

I recently wrote about how the completion chest x-ray can lie after insertion of a chest tube. The chest x-ray image is a 2-D representation of the patient, but you really can’t tell where the tube lies in the third dimension (front to back). That’s how a trauma professional can get suckered into thinking they just put a perfect chest tube in, when in reality they have not.

How can you be sure of the position as you are putting it in? It’s a nuisance to have to reposition it after you’ve taken down your sterile field. Here are a few suggestions, but pay particular attention to the last one. I think it’s the best.

Make the incision large enough so that you can visually confirm that the last hole is inside the thoracic cavity. This option is somewhat okay for thinner patients. But it leads to a larger than necessary incision, especially in patients who are obese. Not a great idea.
Estimate proper depth before insertion. Hold the tube over the patient’s chest, and note the distance mark printed on the tube when the tip is placed halfway across the hemithorax (just medial to the nipple). This does take into account the amount of soft tissue on the lateral chest, but is not terribly accurate and you may accidentally contaminate the tube. The usual depth for a patient with normal body habitus is 12-14 cm at the skin. A better choice.
Use the “bamboo flute” technique. Once you have entered the pleural space and placed the end of the tube into it, locate and place your finger firmly over the last hole, like you were playing a flute. Keep it there as you slide the tube in until your finger contacts the ribs around the insertion point. It should be at a right angle to the chest wall. Then push it in another 2-4 cm. As long as you have performed a nice dissection down to the chest wall, this technique is close to foolproof. And double-check by making sure that the tube is at least 12-14 cm at the skin. IMHO, this is the best technique.

This is not a chest tube!

Related posts:

Thorax

What’s The Best Chest Seal For Sucking Chest Wounds?

June 22, 2017 The Trauma Pro 1 Comment

The treatment of a “sucking chest wound” in the field has typically been with application of some type of occlusive dressing. Many times, a generic adhesive dressing is applied, typically the same kind used to cover IV sites. This is quick, easy, cheap, and readily available in the ambulance. But there is a danger that this could result in development of tension pneumothorax, because the dressing not only keeps air from getting in but also keeps any buildup of pneumothorax from getting out.

To avoid this, a number of vented products have been developed and approved by the US Food and Drug Administration (FDA). These devices have some sort of system to allow drainage of accumulating air or blood, typically a one-way valve or drainage channels. They also need to stick well to a chest wall, which may have blood or other fluids that might disrupt the seal completely.

The US Army has a strong interest in making sure the products they use for this purpose work exactly as promised. The US Army Institute of Surgical Research examined 5 currently FDA-approved products to determine their ability to adhere to bleeding chest wounds, and to drain accumulating air and/or blood from the pleural space. They developed an open chest wound with active bleeding in a swine model.

An open hemopneumothorax was created by infusing air and blood, the animal was stabilized, then additional aliquots of air and blood were infused to simulate ongoing bleeding and air buildup. The image below shows the 5 products used and the animal setup:

Here are the factoids:

Creation of the open hemopneumothorax caused the intrapleural pressure to move toward atmospheric pressure as expected, resulting in labored breathing and reduced O2 saturation
Sealing the wound with any of the chest seal products corrected all of the problems just noted
Chest seals with one way valves did not evacuate blood efficiently (Bolin and SAM). The dressings either detached due to pooled blood, or the vent system clogged from blood clot.
Seals with laminar channels for drainage (see the pig picture above) allowed easy escape of blood and air
Success rates were 100% for Sentinel and Russell, 67% for HyFin, 25% for SAM, and 0% for Bolin

Bottom line: Prehospital providers need to be familiar with the products they use to cover open chest wounds. Totally occlusive dressings can result in development of a tension pneumothorax if there is an ongoing air leak from the lung. Vented chest seals are preferable for these injuries. Just be aware that vented seals with drainage channels perform much better than those that rely on a one-way valve.

Reference: Do vented chest seals differ in efficacy? An experimental
evaluation using a swine hemopneumothorax model. J Trauma 83(1):182-189, 2017.

Procedures, Thorax

Long-Term Experience With Endovascular Aortic Repair For Trauma

May 5, 2017 The Trauma Pro Leave a comment

For decades, the treatment of blunt injury to the thoracic aorta was open repair. The big debate at the time was use of cardiac bypass vs fast clamp and sew. But starting in 1997 with the introduction of thoracic endovascular aortic repair (TEVAR) of this injury, we have rapidly moved to the point where most traumatic aortic injuries are repaired using this technique.

A report that was written nearly a decade ago indicated a relatively high complication rate for the procedure. Graft complications were reported in 18% of patients, with 14% showing endoleaks. Stroke and left arm ischemia were also reported.

The diagram above shows insertion for management of an aneurysm, but the technique is similar for trauma. Blunt aortic injury occurs closer to the left subclavian artery and care must be taken to place the endograft closer to but not covering its orifice.

As the insertion systems and stents improved, short term events have been on the decline. Unfortunately, long term followup data has been hard to come by.

Until now. An article that is not yet in print reports 11 years of experience and followup with patient undergoing TEVAR at the ShockTrauma center in Baltimore.

Here are the factoids:

88 patients underwent TEVAR during the study period, all from blunt trauma
Average ISS was 38, showing these patients were severely injured
Overall mortality was 7%, but none was due to the TEVAR procedure
TEVAR-related complication rate was 9% Endoleaks at the ends of the graft occurred in 4 patients, and all required repair. There were 4 other minor leaks that resolved on their own.
26 had all or part of the left subclavian orifice covered at initial operation. None developed ischemia, although 2 had a prophylactic carotid-subclavian bypass before TEVAR.
The longest followup imaging occurred 8 years after the procedure. No long-term complications were noted.

Bottom line: TEVAR has essentially replaced open repair of the aorta, except in special cases. We continue to learn from our experience, and the complication rate is still falling. Other than endoleaks recognized in the postop period, most other complications rarely occur. Long term followup is poor, but in the patients who do return, there were no complications. But remember, this is an expected sampling bias. If the patient had major problems and/or died, they would just be lost to followup. We would never know.

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