Category Archives: General

What Percent Pneumothorax Is It?

What percent pneumothorax?

Frequently, radiologists and trauma professionals are coerced into describing the size of a pneumothorax seen on chest xray in percentage terms. They may say something like “the patient has a 30% pneumothorax.”

The truth is that one cannot estimate a 3D volume based on a 2D study like a conventional chest xray. Everyone has seen the patient who has no or a minimal pneumothorax on a supine chest xray, only to discover one of significant size with CT scan.

Very few centers have or use the software that can determine the percentage of chest volume taken up with air. There are only two percentages that can be determined by viewing a regular chest xray: 0% and 100%. Obviously, 0% means no visible pneumothorax, and 100% means complete collapse. Even 100% doesn’t really look like 100% because the completely collapsed lung takes up some space. See the xray at the top for a 100% pneumothorax.

If you line up 10 trauma professionals and show them a chest xray with a pneumothorax, you will get 10 different estimates of their size. And there aren’t any guidelines as to what size demands chest tube insertion and what size can be watched.

Bottom line: The solution is to be as quantitative as possible. Describe the pneumothorax in terms of the maximum distance the edge of the lung is from the inside of the chest wall, and which intercostal space the pneumothorax extends to. So instead of saying “the patient has a 25% pneumo,” say “the pneumothorax is 1 cm wide and extends from the apex to the fifth intercostal space on an upright film.”

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Repeat Imaging: What Good Is It?

I’ve written previously about how often imaging gets repeated once a trauma patient gets transferred to a trauma center (click here). There are many reasons, including clinical indications, need for advanced imaging (reconstructions), or lack of contrast. But at least 20% have to be repeated because the media is incompatible or not sent with the patient. Sounds like a problem, but is it a significant one?

A recent retrospective analysis of about 2,000 transfers to a Level I center looked at the reasons for repeat imaging and changes in outcome due to it. The paper found several interesting things:

  • Repeat imaging was more likely in more severely injured patients
  • Hospitals that transferred more patients to the trauma center tended to do more scans before transfer
  • Patients who had repeat imaging stayed in the ED longer waiting for definitive disposition
  • Repeat images did not improve outcomes (LOS, DC home, mortality)
  • A rough estimate of $354 more in charges was attributed to repeat imaging

Bottom line: Repeat imaging is wasteful, expensive and increases time in the ED. And don’t forget about the radiation exposure. With all the emphasis on pushing hospitals to use an electronic medical record, there needs to be a similar push to standardize methods for transferring radiographic images between hospitals to address the problem of repeat imaging.

Related posts:

Reference: Repeat imaging in trauma transfers: A retrospective analysis of computed tomography scans repeated upon arrival to a Level I trauma center. J Trauma 72(5):1255-1262, 2012.

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Is Applying Or Removing That Cervical Collar Dangerous?

Cervical collars are applied to blunt trauma patients all the time. And most of the time, the neck is fine. It’s just those few patients that have fracture or ligamentous injury that really need it. 

I’ve previously written about how good some of the various types of immobilization are at limiting movement (click here). But what happens when you are actually putting them on or taking them off? Could there be dangerous amounts of movement then?

Several orthopaedics departments studied this issue using an electromagnetic motion detector on “fresh, lightly embalmed cadavers” (!) to determine how much movement occurred when applying and removing 1- and 2-piece collars. Specifically, they used an Aspen 2-piece collar, and an Ambu 1-piece. They were able to measure flexion/extension, rotation and lateral bending.

There were no significant differences in rotation (2 degrees) and lateral bending (3 degrees) when applying either collar type or removing them (both about 1 degree). There was a significant difference (of 0.8 degrees) in flexion/extension between the two types (2-piece flexed more). Movement was similarly small and not significantly different in either collar when removing them.

Bottom line: Movement in any plane is less than 3-4 degrees with either a 1-piece or 2-piece collar. This is probably not clinically significant at all. Just look at my related post below, which showed that once your patient is in the rigid collar, they can still flex (8 degrees), rotate (2 degrees) and move laterally (18 degrees) quite a bit! So be careful when using any collar, but don’t worry about doing damage if you use it correctly.

Related post:

Reference: Motion generated in the unstable cervical spine during the application and removal of cervical immobilization collars. J Trauma 72(6):1609-1613, 2012.

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Extubating Trauma Patients In The ED

Many patients are intubated in the emergency department who need brief control of their airway or behavior. In some cases, the condition requiring intubation resolves while they are still in the department. Most of the time these patients are admitted, typically to an ICU bed, for extubation. This is expensive and uses valuable resources. Is it possible to safely extubate these patients and possibly send them home?

Maryland Shock Trauma and Mount Sinai Medical Center looked at their experience in extubating selected patients in the ED. They looked at a series of 50 patients who were intubated for combativeness, sedation, or seizures. A specific protocol was followed to gauge whether or not extubation should be attempted.

None of the patients who were extubated per protocol required unplanned reintubation. One patient underwent planned reintubation when taken to the OR for an orthopedic procedure. 16% of patients were able to be discharged home from the ED.

Bottom line: A subset of patients who are intubated in the emergency department can be extubated once the inciting factor has resolved. These factors include sedation for painful procedures and combativeness. Following this protocol can reduce admission rates and reduce the use of scarce intensive care unit resources.

Click here to download a copy of the ED extubation protocol.

Related post: Trauma 20 years ago: ED intubation for head injury

Reference: Trauma patients can be safely extubated in the emergency department. J Emerg Med 40(2):235-239, 2011.

NOTE: The EMCrit blog, written by Scott Weingart, covered this topic in November 2010. He is the first author on the paper and has created a nice podcast on the topic. You can find his blog here, and you can download the podcast here.

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The 30:60 Rule For Interventional Radiology

Interventional radiology (IR) can be a very helpful adjunct to the evaluation and management of trauma patients. I’m going to talk specifically about using it for blunt trauma today because the use in penetrating trauma can be a little more nuanced.

For blunt trauma, IR is used primarily to stop bleeding. In a smaller subset of patients, this tool is used to evaluate pulse deficits. There are two basic principles that apply in either case, and I’ve wrapped them up into a single concept: the 30:60 rule for interventional radiology. 

Of course, the second law of trauma still applies: hypotensive patients cannot leave the ED to go anywhere but the OR. Once you make sure you are not violating that one, you can start the process of going to IR.

The two portions of the rule are times: the time for the IR team to arrive to start the evaluation, and the maximum time allowed for them to succeed, hence the 30:60 numbers.

The maximum acceptable time for the patient to wait until the IR team is ready for them is typically 30 minutes. US trauma center verification requires a reasonable arrival time frame, and the vast majority of hospitals have a 30 minute expectation if the team is not already in place. This response time needs to be monitored by the trauma performance improvement program (PI) and addressed if it ever exceeds the limit.

The second number is the maximum time the radiologist is given to be successful. Like other physicians, radiologists like to do a good job and finish the work they start. If they find a particularly tortuous splenic artery to navigate, they will persist at trying to get through it in order to do a selective embolization and kill the smallest piece of spleen possible. Unfortunately, this takes time and radiation (lots). And a bleeding patient is running out of time.

The good thing is that there are surgical alternatives to most of the tasks the radiologist is working on. True, some are much more difficult surgically, like managing a shattered liver or dealing with a bleeding pelvis. In those cases, I may let the interventionalist work a little longer while I keep up with blood transfusions and monitor patient status.

Bottom line:

  • Expect a 30 minute response time from the IR team
  • Let the radiologist know they have about 60 minutes to succeed. If it looks like they can’t make that, have them go to plan B (e.g. main splenic artery embolization instead of selective)
  • Make sure an experienced trauma physician is watching the patient for decompensation and is managing fluids and blood products (no pressors!)
  • If the patient decompensates at any point, they are done in IR and must proceed to OR
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