Category Archives: Thorax

Does Chest Tube Size Matter? Part 1

November 27, 2019 The Trauma Pro Leave a comment

Over the next few days I will be reviewing a number of papers that try to determine whether the dogma that bigger chest tube size is better is actually true.

Here are the questions that need to be answered when reading each one to determine if it’s worth its weight:

How good is the study design? Obviously, prospective is better than retro. How did the authors decide to put in a small vs a large tube? Were there enough subjects to achieve any meaningful statistical significance?
Were the tubes used actually different? If the small bore tubes are 30 – 32 French and the large tubes are 36 – 40 French, would that make a difference?
What were the outcomes studied? Mortality and complications like pneumonia and empyema are too crude and uncommon to detect a difference. But what about incidence of retained hemothorax, accidental removal, subjective pain, or clotting?
Did the authors identify and acknowledge any limitations in their study?
Do the conclusions match up with the actual results?

Let’s kick off the chest tube size debate with an oldie but goodie. The first paper I’ll review was published back in 2012 by a busy LA trauma center. They performed a prospective, observational study of their experience with two tube size ranges inserted for hemo- and pneumo-thorax over a three year period. The size ranges were 28-32 for small and 36-40 for large. The size selected was based on the discretion of the attending physician.

A total of 353 chest tubes were placed during the study period. This analysis will only dissect the 275 that were inserted for hemothorax.

Here are the factoids:

Pertinent demographics were identical for the large and small bore tube patients
Pneumonia occurred in about 5% of both groups, and empyema in about 5% of both
Retained hemothorax occurred in 12% of small tubes and 11% of large tubes
Duration of tube placement was about 6 days in each
Additional procedures such as thrombolysis, additional chest tubes, VATS, or thoracotomy were 3-6% in both groups and were not statistically different
Pain scores could only be performed on about 45% of patients, and were not different between the two groups

The authors concluded that there were no differences in complications, tube reinsertion, or need for invasive procedures based on tube size. They also concluded that choice of tube size did not impact outcomes.

Bottom line: The authors seem to be saying that the choice of tube size is not important. And if you only read the abstract or conclusions of this study, you might actually believe it. But wait, the authors end the paper with this telltale sentence:

“Further evaluation of percutaneously placed drainage systems is warranted”

This is code for: “this paper isn’t very good and shouldn’t change your practice; it needs further verification.”

So what are the issues?

There is huge potential for selection bias since the choice of tube size was based on personal preference. For example, the attending could look at the chest x-ray, see a lot of blood, and decide to use a big tube in that patient. No guidelines or randomization were used.
The authors did not acknowledge any limitations of the study in their discussion.
The only outcomes that really counted in this study were incidence of retained hemothorax (which was not very well defined) and additional procedures required. However, if you take the incidence of retained hemothorax in the large bore tube patients and do an analysis of the statistical power of the study, you run into a major problem. Given the number of patients in each of the two groups, this study would only be able to show statistical significance if the number of retained hemothoraces in the small chest tube group doubled! Anything short of 25% retained hemothorax in the small tube group would not be significant. Thus, the authors’ findings that there was no difference between the groups was entirely expected based on sample size.

So this paper does not really say that there is no difference in using a small vs a large chest tube. It says that it was not sufficiently powered to detect anything but a massive difference. Many more patients (thousands) were needed to answer the question.

So the question remains, does (chest tube) size matter? More in the next post.

Reference: Does size matter? A prospective analysis of 28-32 versus 36-40 French chest tube size in trauma. J Trauma 72(2):422-427, 2012.

Thorax

Chest Tube Insertion: Does Size Matter?

November 25, 2019 The Trauma Pro Leave a comment

I’m old school. I cut my teeth during the days when there were only two sizes of chest tubes for trauma: big and bigger. That meant 36 French or 40 French. Period. I even went as far as adding a chest tube insertion video to my collection of YouTube posts:

But recently, someone posted a comment on that video to the effect that we are moving away from large chest tubes for trauma.

But are we? Really? Am I missing something? I’ve written a few posts in the last two years, examining some of the newer research on this topic. One paper was so-so, one was terrible.

So I’ve decided to really hit this topic hard this week. I want to know what the literature really says on this topic. So I’ve located the best papers I could and I’m going to do a teardown over the next few days. That way I can make sure that my video is up to date, and that my (and your) practice is as well.

Tomorrow, I’ll start with work that compares large and smaller bore tubes. Through the week, I’ll work my way down in size to papers suggesting that pigtail catheters are as good as a chest tube.

Hope you enjoy! We’ll all learn something!

Thorax

Flash Pulmonary Edema After Chest Tube Insertion

October 30, 2019 The Trauma Pro Leave a comment

You are seeing a young man in the emergency department who gives a history of falling two days ago. He experienced chest pain at the time which has persisted, but he did not immediately seek medical care. He has noticed that he now gets winded when walking quickly or climbing stairs, and describes pleuritic chest pain.

He presents to your emergency room and on exam has a bruise over his left lateral chest wall. Subcutaneous emphysema is present, and breath sounds are absent. Chest x-ray shows a complete pneumothorax on the left.

You carefully prepare and insert a chest tube in the usual position. A significant rush of air occurs, which tapers off over 15 seconds. Here is the followup image:

About 10 minutes later you are called to his room because he is complaining of dyspnea and his oxygen saturation has decreased to 86%. Breath sounds are somewhat decreased and the tube appears to be functioning properly. You immediately obtain another chest x-ray:

What just happened? This is a classic case of unilateral “flash” pulmonary edema after draining the chest cavity. This phenomenon was first described in 1853 in a patient who had just undergone thoracentesis. It is very uncommon, but seems to occur after rapid drainage of air or fluid from the chest cavity.

Here are some interesting factoids from case reports:

It occurs more often in young men
It is most common when draining large hemo- or pneumothoraces
Rapid drainage seems to increase the incidence
It is likely due to increased pulmonary capillary permeability from inflammatory mediators or changes in surfactant
Symptoms typically develop within an hour after drainage

What should you do? First, if you are draining a large collection of air or blood, do it slowly. Clamp the back end of the chest tube prior to insertion (you should always do this if you value your shoes) and use it to meter the amount of fluid or air released. I typically let out about 300cc of fluid, then wait a minute and repeat until all the blood has been drained. For air, vent it for 10 seconds, then wait a minute and repeat.

In patients at high risk for this condition, apply pulse oximetry and follow for about an hour. If they still look and feel great, nothing more need be done.

References:

Fulminant Unilateral Pulmonary Edema After Insertion of a Chest Tube. Dtsch Arztebl Int 105(50):878-881, 2008.
Reexpansion pulmonary edema after chest drainage for pneumothorax: A case report and literature overview. Respir Med Case Rep 14:10-12, 2015.
Re-expansion pulmonary edema following thoracentesis, Can Med Assn J 182(18):2000-2002, 2010.

Abstracts, Thorax

AAST 2019 #8: Timing Of Thoracic Aortic Injury Repair

September 17, 2019 The Trauma Pro Leave a comment

Over the past two decades, there has been a massive swing from open repair of blunt thoracic aortic injury to thoracic endovascular aortic repair (TEVAR). Although technically a bit more complex, it has decreased both morbidity and mortality significantly. The usual push in fresh trauma patients is to take care of all the life-threatening injuries as soon as possible. And from the days of the open thoracic procedure, this was generally warranted.

However, the optimal timing of repair during the age of TEVAR is not as clear. Is it really necessary to go crashing into the angio or hybrid suite to get this taken care of? Or should it wait until the patient is not as physiologically damaged? The group at University of Texas at San Antonio looked at experience in the National Trauma Databank for some guidance. They reviewed four years of data from 2012 to 2015. Patients who arrested in or prior to arrival in the ED were excluded. Mortality was the primary outcome of interest, but complications and hospital length of stay (LOS) was also noted.

Here are the factoids:

Nearly 6,000 patients with blunt thoracic aortic injury were identifed, and 1,930 (33%) underwent TEVAR, 2% were opened, and 65% were managed nonoperatively
Looking only at TEVAR patients, 69% underwent the procedure within 24 hours, 24% after 24 hours, and the remainder were not recorded (!)
Mortality was significantly higher in the early TEVAR group (6.4% vs 2.1%)
Hospital LOS was significantly shorter in the early TEVAR group (18 vs 22 days)
Logistic regression controlling for hypotension, severe TBI, ISS and older age confirmed the significantly lower mortality in the delayed group

The authors concluded that delayed (>24 hrs) TEVAR was associated with decreased mortality but longer length of stay.

This is a nice, clean abstract to read. The hypothesis and results are easy to understand and make sense. And it’s exactly the kind of poster that makes you think a bit.

The only real downside is that it is an NTDB study, so there is very limited ability to go back and tease out why these results should be true. These results should push the authors to set up a more prospective study so they can figure out why this should be true. We can certainly speculate that it helps to temporize with good blood pressure control while cleaning up other major injuries and correcting deranged physiology. But one never knows until the right study is actually done.

Here are my questions for the presenter and authors:

Were you able to glean any insights into the associations you identified from the other data in the NTDB records you used? This could help design a really good study to see if your impressions are true.
The fact that a quarter of patients had TEVAR at an unknown time throws a big monkey wrench in your results. Can you use any statistical tricks to see if assuming they were either early or late would influence your results. Is it possible that this unknown group could completely neutralized your study?

I’m very excited by this one, and I don’t normally get too excited by posters. Great work!

Reference: Timing of repair of blunt traumatic thoracic aortic injury: results from the National Trauma Databank. AAST 2019, Poster #5.

Complications, Thorax

Trocar Chest Tubes Or Blunt Technique? Part 2

September 3, 2019 The Trauma Pro Leave a comment

In my last post on chest tube insertion technique, I reviewed a paper that compared chest tube insertion complications using two different trocar tips, blunt plastic and sharp metal. The sharp tip tubes caused more complications, although the study was weakened by the fact that the physicians inserting the tubes were complete newbies.

Today, I’ll discuss what the authors call a “best evidence topic” that reviewed the safety of the trocar technique. It is similar to a meta-analysis of available literature that attempts to reach a conclusion regarding this type of tube insertion. A literature search from 1946 to 2013 was conducted seeking to pull all papers on trocar chest tube insertion techniqes. A total of 258 papers were identified, but on closer inspection only 7 were identified that “provided the best evidence to answer the question.”

Here are the factoids from some of these papers:

Tube malposition occurred significantly more often in a series of 106 trocar tubes inserted into 75 ICU patients
In trocar tubes inserted for trauma, CT showed malplacement in 29% vs 19% with non-trocar tubes [This latter number seems very high to me!]
A retrospective study of 1249 patients resulted in the trocar technique being abandoned due to severe lung and stomach injuries
Use of trocar technique was associated with a significantly higher incidence of re-expansion pulmonary edema in 92 patients with spontaneous pneumothorax
A poorly controlled prospective study showed 23 complications with trocar technique and none with blunt dissection. The denominator could not be determined.

Bottom line: Overall, the literature is just not good enough to answer this question. But it does provide some suggestions.

Trocar insertion can be done well in experienced hands. Cardiac surgeons use these all the time, although sometimes they have the benefit of already being in the chest so they can visualize the point of entry and control the tip.
Any chest tube insertion can go awry. It’s very important to learn proper technique, and take care to apply it faithfully, even in emergency situations.
If you really like trocars and want to improve insertion safety, start with the blunt dissection technique first, sweep a finger inside the chest to ensure there are no adhesions, then insert the trocar tube to guide it into position. Please note that I do not believe that we can control the tube once the instrument (trocar or clamp) are removed from the chest. And the tube will work fine just about anywhere it ends up (unless that’s the spleen).
Newbies should be supervised carefully and learn blunt insertion technique first. Be mindful that it is still possible to pass the insertion clamp into the same structures as a trocar if you are not careful. My practice is to place my fingers about 2 cm from the tip of the clamp as I push it through the pleura. If the pleura gives way more easily than anticipated, by fingers will keep the clamp from going too far into the chest.
Always mark your insertion spot before prepping. This will generally be lateral to the nipple in men, so always prep the nipple into your field as a landmark.
Always be careful!

Reference: Is the trocar technique for tube thoracostomy safe in the current era? Interactive CV and thoracic surg 19:125-128, 2014.

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