Category Archives: General

General

Does Chest Tube Size Matter? Part 2

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In my last post, I reviewed a large prospective series comparing smaller (28-32 Fr) to larger (36-40 Fr) chest tubes for management of pneumothorax. The authors did not detect any significant difference because the study was underpowered given the incidence of the adverse events examined.

Today, I’ve chosen a more recent paper that attempts to do the same thing. Interestingly, it cites the previous paper as a good example showing no differences! This one is from an emergency medicine group in Fukui, Japan. It is a retrospective review of seven years worth of patients who had a chest tube inserted for hemothorax only.

Here are the factoids:

  • Small bore tubes were 20-22 French, and large bore tubes were 28 French (huh?)
  • The tube selection was made (once again) at the discretion of the attending physician
  • Demographics and injury data from the two groups were equal
  • A total of 124 tubes were placed in 116 patients, 68 small bore and 56 large bore
  • Empyema occurred in 1% in each group
  • Retained hemothorax occurred in 2% of small tube patients and 3% of large tube patients
  • An additional tube was placed in 2% of small tube patients and 7% of large tube patients (p = 0.41)
  • Pain was not evaluated

The authors concluded that “emergent insertion of the small-bore tubes had no difference in efficacy of drainage, complications or need for additional invasive procedures.”

Bottom line: Huh? Once again we have an inferior design (retrospective review) and huge potential for selection bias (no criteria or randomization for tube size). But in this case, the tube sizes are very similar! The difference in diameter between a 20 Fr tube and a 28 Fr one is only 2.5mm! Reason #1 for no apparent differences.

For reason #2, look at the sample size. First of all, this hospital placed only 124 tubes in 7 years. That’s a one tube every three weeks. Is there that little chest trauma, or is a chunk of data missing? This sample size is less than half of that in the previous post, so the statistical power is far weaker. Look at the stats above for additional tube placement. A 3.5x change was not even close to being statistically significant. In fact, this sample size would not show a significant difference for retained hemothorax until one group had nearly 8x the number! No wonder the authors assumed there was no difference. The study was not designed in such a way that it could ever show one!

So throw this study in the trash bin, too. I’ll continue my search for a more convincing “size matters” paper in my next post.

And if you think you’ve got one, send it my way so I can have a look!

Reference: Small tube thoracostomy (20-22 Fr) in emergent management of chest trauma. Injury 48(9):1884-1887, 2017.

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General, Imaging

What Are: These Spondylo… Words

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Spondylosis. Spondylolisthesis. Spondylitis. These words are tossed about blithely by our orthopedic and neurosurgical spine colleagues. But many trauma professionals are confused by the terms. What do they mean? What do they look like?

Let’s start with the root of the word, spondylo… This part is derived from the Greek word spondylos, meaning spine. Now let’s combine it with some of the usual suffixes.

The first one is -osis, so this creates the word spondylosis. Although -osis can denote the “condition of being a …”, in medicine it frequently means a disease or pathological process. Think diverticulosis of the colon. Spondylosis usually denotes a degenerative process of the spine. This is typically due to arthritis and results in bone spurs and disc narrowing. Here is an image of a spine with significant spondylosis:

Now let’s add -listhesis. This is another Greek word that means “slipping or falling.” So in this case, the full word means one vertebra slipping over another. Here’s an image of an anterior spondylolisthesis:

Finally, let’s add -itis. This is the Greek suffix for inflammation. So spondylitis is an inflammatory process of the spine. This can be due to infectious or autoimmune causes. One of the more common types is ankylosis spondylitis, which is an autoimmune variant of rheumatoid arthritis. This causes inflammation of the facet joints and the stabilizing ligaments, leading to fused vertebra and a characteristic patient posture. Here’s a rather extreme case:

I hope this little vocabulary lesson has been helpful. Now go impress your spine specialty colleagues!

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General

Deer Hunting and Tree Stand Injuries

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Deer hunting season is upon us again in Minnesota and Wisconsin, so it’s time to plan to do it safely. Although many people think that hunting injuries are mostly accidental gunshot wounds, that is not the case. The most common hunting injury in deer season is a fall from a tree stand.

Tree stands typically allow a hunter to perch 10 to 30 feet above the ground and wait for game to wander by. They are more frequently used in the South and Midwest, usually for deer hunting. A  study by the Ohio State University Medical Center looked at hunting related injury patterns at two trauma centers.

Half of the patients with hunting-related injuries fell, and 92% of these were tree stand falls. Only 29% were gunshots. And unfortunately, alcohol increases the fall risk, so drink responsibly!

Most newer commercial tree stands are equipped with a safety harness. The problem is that many hunters do not use it. And don’t look for comparative statistics anytime soon. There are no national reporting standards. No matter how experienced you are, always clip in to avoid a nasty fall!

The image on top is a commercial tree stand. The image below is a do-it-yourself tree stand (not recommended). Remember: gravity always wins!

Reference: Tree stands, not guns, are the midwestern hunter’s most dangerous  weapon. Am Surg 76(9):1006-1010, 2010.

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General

Trauma In Pregnancy 5: C-Section – When?

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The perimortem C-section (PMCS) is a heroic procedure designed to salvage a viable fetus from a moribund mother. Interestingly, in some mothers, delivery of the fetus results in return of spontaneous circulation.

The traditional teaching is that PMCS should be started within 4-5 minutes of the mother’s circulatory arrest. The longer it is delayed, the (much) lower the likelihood that the fetus will survive.

The reality is that it takes several minutes to prepare for this procedure because it is done so infrequently in most trauma centers. Recent literature suggests the following management for pregnant patients in blunt traumatic arrest (BTA):

  • Cover the usual BTA bases, including securing the airway, obtaining access and rapidly infusing crystalloid, decompressing both sides of the chest, and assessing for an unstable pelvis
  • Assess for fetal viability. The fundus must measure at least 23 cm.
  • Assess for a shockable vs non-shockable rhythm. If shockable, do two cycles of CPR before beginning the PMCS. If non-shockable, move straight to this procedure.

Bottom line: Any time you receive a pregnant patient in blunt arrest, have someone open the C-section pack while you assess and try to improve the mother’s viability. As soon as you complete the three tasks above, start the procedure! You don’t need to wait 4 minutes!

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General

Trauma In Pregnancy 4: Imaging

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Everyone worries about imaging pregnant patients. As with most medical tests, it always boils down to risks vs benefits. What are the chances of causing mutations or cancers or a spontaneous abortion, and what is the risk of missing a critical injury? In general, reasonable studies involving a fetus at just about any point in gestation won’t cause major problems. At least as far as we know. What is not clear are the longer term, hard to measure effects. So the general philosophy should be to order just what you absolutely need, and shield the fetus during any studies other than of the abdomen/pelvis.

Now, to put these numbers into perspective, have a look at this list of delivered doses from common studies. The table above is listed in milliGrays, and this one is in milliSieverts. These are roughly comparable, except that the former is a measure of radiation dose absorbed, and the latter measures radiation delivered.

Bottom line: Think hard about the imaging you really need. If you generally do this for all patients, you probably won’t change your practice in pregnant women. Don’t worry about chest and pelvic x-rays. Shield the fetus for anything not involving the abdomen/pelvis. For major torso trauma, you probably will need CT of the chest/abdomen/pelvis. If so, do it right. Order with contrast so you don’t get substandard images that need to be repeated.

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