The basics of thoracic trauma: It’s all about airflow and pressure

Jun 08, 2023

The Ambulance Driver's Perspective

Assessment and treatment pearls to simplify three common chest trauma presentations

This article originally appeared in the EMS1 Digital Edition "Prehospital trauma: Today's tenets for triage, treatment and transport". Download your copy and find additional resources here.

There’s a classic movie called “The Dirty Dozen,” starring Lee Marvin, Telly Savalas, Donald Sutherland, Charles Bronson and several other big Hollywood names, in which a dozen of the Army’s worst prisoners are recruited and trained as commandos to conduct a near-suicide mission to eliminate a number of high-ranking German officers just before D-Day. It’s a great movie, ranking on several best movies of the last 100 years leaderboards – and if you don’t recognize any of those famous actors I mentioned, get off my lawn.

Well, trauma surgeons also have a dirty dozen, which is what they call the most common presentations of thoracic trauma.

While covering all 12 of these in depth is beyond the scope of this article, there is still a bunch of myth and dogma that can be dispelled about assessing and management common thoracic injuries.

First, let’s not make it more complex than it is: managing thoracic trauma is all about airflow and pressure. The patient needs adequate airflow to the alveoli, and anything that compromises that needs to be managed. Also, the patient must be able to generate negative intrathoracic pressure to breathe effectively. If aiding in generating negative pressure isn’t possible, at the very least, we must ensure that positive pressure within the chest does not accumulate.

Thoracic trauma is the second-leading cause of trauma mortality, comprising 25% of all trauma deaths. Despite that, only 15% of thoracic injuries require surgical intervention, and simple procedures like chest tubes are among that 15%.The vast majority of thoracic injuries are managed medically. Let’s examine assessment and treatment considerations for three of the most common.

We all know the definition of flail chest from our EMT textbooks: three or more ribs broken in two or more places. Yet, many of the findings that we are taught to look for in flail chest aren’t all that common.

For example, paradoxical motion – the movement of that floating flail segment in the opposite direction of the chest – isn’t a common finding. When you do see it, it usually requires a big floating segment and it only sets in after the intercostal muscles have become fatigued. Like any fracture, the muscles surrounding that fracture often spasm, serving to partially splint the broken bones in place.

What you are most likely to find is crepitus and severe pain, and likely self-splinting with the arm on the injured side. I once mistook a flail chest in an injured motorcyclist as a left shoulder injury because he screamed whenever I moved his left arm to take a BP or insert an IV. He was also impaired and answered “yes” when I asked if his left shoulder hurt. As it turned out, he had a whopping flail chest on the left side.

That also demonstrates where you will find the injury – on the patient’s side. The vast majority of rib fractures occur at the post-lateral bend of the ribs, so it is essential that you roll your patients over and inspect the back.

External stabilization of flail chest simply doesn’t work. Don’t bother with the tape and bulky dressings – or the IV bags or sandbags you may have been taught – and instead use analgesia and positive pressure ventilation. Many of these patients hypoventilate themselves right into a problem simply because it hurts too much to breathe at an adequate depth. CPAP is beneficial, but be vigilant for the signs of tension pneumothorax and treat it if it develops.

Penetrating chest wounds are common; wounds big enough to entrain air are not. Open pneumothorax, the classic “sucking chest wound,” is not often seen outside the battlefield environment. In general terms, the hole in the chest has to be 2/3 the diameter of the trachea or larger to entrain air, and pistol caliber gunshot wounds generally do not make that large a hole. Rifle rounds, spears, butcher knives and the like often do.

I once encountered a sucking chest wound in an 85-year-old woman in medical cardiac arrest. The family had been doing chest compressions where they thought the heart should be, but one of the broken ribs they created poked a hole in her chest. We managed to resuscitate her successfully, but explaining why the little old lady with the medical arrest was wearing a chest seal was an experience I’ll not soon forget.

The ability to entrain air directly into the chest interferes with the generation of negative intrathoracic pressure, and results in decreased ventilatory volume and decreased cardiac output. Remember that most of the blood returning to our right atrium is a function of negative intrathoracic pressure. Using an occlusive dressing will allow the patient to return to somewhat normal breathing mechanics.

One thing to remember, however, is that flutter valves often don’t flutter, and vented chest seals often don’t vent.

Vigilance and constant reassessment are better strategies than relying on your equipment to prevent pressure buildup in the chest and tension pneumothorax. If you’re still fashioning occlusive dressings out of Vaseline gauze – the sterile packaging, not the gauze itself – please stop doing so as close to 20 years ago as possible. Instead, use a commercial chest seal, but be aware that the vents on most commercial chest seals often will not activate until four times the normal lung volume builds in the chest. That’s quite a big tension pneumo before your chest seal vents. Watch your patient carefully and burp the chest seal when necessary.

Tension pneumothorax occurs when air from an injured lung escapes into the pleural space and positive pressure builds up, eventually collapsing the injured lung and causing a mediastinal shift of the heart and great vessels. The vena cava kinks, greatly reducing blood return to the heart, and cardiovascular collapse occurs.

That’s what causes the problem. Recognizing the problem is a bit more nuanced.

First of all, ignore that old dogma about tracheal shift. Most of the mediastinal shift occurs below the suprasternal notch and will only be visible on an X-ray. Its presence on physical exam will be subtle, if it’s even there at all. Likewise for hyperresonance to percussion – you have to percuss a lot of normal chests to appreciate what abnormal is, and most prehospital providers simply don’t perform enough percussion to be proficient.

Jugular venous distention is also a red herring. First, any supine patient with sufficient circulatory volume will have some amount of JVD; it’s normal for the jugular veins to engorge when we lie on our backs. The question is, how much is too much? JVD, like beauty, is often in the eye of the beholder. Also, consider the likelihood that your patient simply doesn’t have enough circulatory volume for the jugular veins to engorge. If the patient left a big puddle of blood on the ground back at the scene, or they’re bleeding internally, JVD is not likely.

Subcutaneous emphysema – the “Rice Krispies” sensation when you palpate – may be present, but it’s not likely to be found anywhere but the soft tissues. Check the neck and axillae thoroughly.

A simpler way of looking at this is: if your patient has a pneumothorax and unexplained shock, it’s a tension pneumothorax until proven otherwise. Remember, a simple pneumo is an oxygenation problem, but a tension pneumo is a circulatory problem.

Treating a tension pneumothorax is simple: decompress the chest. It’s a procedure with a stress factor of 10 and a skill factor of 2, but a recent study demonstrates that even a skill factor of 2 may be beyond the capabilities of many paramedics. Many paramedics struggle at finding the correct site for needle thoracentesis [1].

To find the correct site for a needle thoracentesis, first find the Angle of Louis. Palpate the top of the sternum, beginning at the suprasternal notch. A couple of inches down, you’ll feel the sternum markedly flatten where the manubrium fuses to the body of the sternum. This dividing line is called the Angle of Louis and is level with the second intercostal space. Palpate along the top of the rib you find there until you reach the mid-clavicular line. That’s it, that’s your sweet spot.

When you do find the correct site, a simple 14-gauge IV catheter is too short to enter the pleural space [2-5]. Use a needle of at least 2.5 inches, and go in directly over the superior border of the ribs. The inferior border of the ribs covers a nerve bundle and a costal artery, and you’ll hopefully avoid these if you stick to the superior border. Listen for a hiss of air, or even better, use a thoracentesis system with a color-coded window to indicate entry into the pleural space as your chest decompression device.

If you don’t have a thoracentesis system, plug a 10 mL syringe with about 2-3 mL saline in it to the flash chamber on your decompression needle. Draw the plunger all the way to the top, and look for bubbles in the fluid to indicate that you’ve entered the pleural space. There is no need to fashion a flutter valve for your decompression needle – remember, a hole in the chest has to be big to entrain air.

Try these simple assessment and treatment pearls, and you’ll find that your next thoracic trauma patient will be significantly less challenging.

Kelly Grayson, NRP, CCP, is a critical care paramedic in Louisiana. He has spent the past 24 years as a field paramedic, critical care transport paramedic, field supervisor and educator. He is president of the Louisiana Society of EMS Educators and a board member of the LA Association of Nationally Registered EMTs.

He has an Associate of General Studies degree from Louisiana State University at Eunice, Nunez Community College. Kelly has been recognized as the 2016 Louisiana Paramedic of the Year, 2002 Louisiana EMS Instructor of the Year and 2002 Louisiana AHA Regional Faculty of the Year, and with the 2012 Maggie Award for Best Regularly Featured Web Column/Trade and the 2014 Folio Eddie Award for Best Online Column.He is a frequent EMS conference speaker and contributor to various EMS training texts, and is the author of the popular blog A Day In the Life of an Ambulance Driver, "En Route: A Paramedic's Stories of Life, Death and Everything In Between," and "On Scene: More Stories of Life, Death and Everything In Between." You can follow him on Twitter (@AmboDriver), Facebook, LinkedIn, or email him at [email protected]. Kelly is a member of the EMS1 Editorial Advisory Board.