Coming This Week: Chest Tube Week

I’m dedicating the coming fortnight (that’s two weeks to you non-Brits) to the lowly chest tube. It’s taken for granted, but there is a lot a variability on how we insert, manage, and pull out these devices. Here’s what’s coming, starting tomorrow:

  • Videos on how to insert a chest tube and pigtail catheter
  • A video on how to pull a chest tube properly
  • Chest tube tips and tricks
  • A practice guideline for chest tube management
  • Troubleshooting chest tubes
  • Collection systems gone bad
  • Lateral chest x-ray for pneumothorax: waste of time?
  • When to remove a chest tube
  • Autotransfusing blood from the collection system

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Diagnostic Tip: Nail Discoloration After Severe TBI

Occasionally, patients who have had a severe brain injury but recovered relatively quickly may present with complaints of odd nail discoloration. This may involve fingernails and/or toenails. What gives?

This is actually a byproduct of repeated exams to determine the Glasgow Coma Scale score. A common way to determine the motor component is to squeeze the fingertip or toetip. I’ve seen some neurosurgeons use a pen to apply a great deal of force to the nail.

The discoloration is a resolving subungual hematoma. You may see different colors under different nails, depending on the age of the hematoma. Amaze your colleagues with your knowledge on this one!

New Technology: Blood Type In 30 Seconds!

This one is really exciting! Blood banks typically keep a significant number of units of O- “universal donor” blood available. These units can be given immediately when a trauma patient in need arrives, since it contains no antigens to the common blood types. It takes anywhere from 5-15 minutes for the blood bank to determine the blood type from the patient’s blood. Then and only then can they begin delivering “type specific” blood that matches the patient’s blood type.

Researchers at the Third Military Medical University in China have developed a paper-based test to determine the ABO type as well as the Rh type (D). Indicators for A, B, and D antigens turn a blue color when they are present, allowing the clinician or blood bank to accurately determine the blood type in 30 seconds. 

Why is this important? O- is an uncommon blood type, with only about 6% of the US population carrying it. Yet blood banks have to keep an inordinate amount in stock “just in case.” Using a blood type test like this could significantly cut down on unnecessary use of this rare O- blood. Unfortunately, it will be 1-2 years before the test is commercially available. I’m sure our nation’s blood bankers can’t wait!

Here’s a brief video that demonstrates how it works.

Reference: A dye-assisted paper-based point-of-care assay for fast and reliable blood grouping. Science Translational Medicine 15 Mar 2017:
Vol. 9, Issue 381, eaaf9209.

How To: Retrograde Urethrogram

I’ve gotten a number of recent requests to repost this easy, DIY guide to the retrograde urethrogram. Enjoy!

One of the hallmarks of urethral injury is blood and the meatus in males. The standard answer to the question “how do you evaluate for it?” is “retrograde urethrogram.” Unfortunately, too few people know how to perform this test, and not all radiologists are familiar. Many times it falls to the urologist, who may not be immediately available.

The technique is simple. This is my variation on the standard technique. The following items are needed:

  • A urine specimen cup
  • A tube of KY jelly (not the little unit dose packs)
  • A bottle of renografin or ultravist contrast
  • A 50-60 cc Toomey syringe (slip-tip)
  • A fluoroscopy suite

Pour 25cc of contrast and 25cc of KY jelly in the specimen cup, cap it and shake well. Draw the contrast jelly up into the syringe. Under fluoro, insert the tip of the syringe into the penis and pull the penis toward yourself, pinching the meatus around the tip of the syringe. Slowly inject all the contrast, watching the contrast column on the fluoro screen. Once there is easy flow into the bladder, you can stop the study. If you see extravasation into the soft tissues, stop the study and call Urology.

The advantages to using this technique are:

  • The contrast/jelly mix creates a contrast gel that is less likely to leak from the meatus when injected
  • The jelly makes it easy to insert the catheter if no urethral injury is detected

Normal urethrogram:

Normal urethrogram

Abnormal urethrogram:

Abnormal urethrogram

Prevnar 13 And Spleen Trauma

Recently, I’ve noticed television commercials for Prevnar-13, a 13-valent pneumococcal vaccine for immunocompromised or asplenic adults. And interestingly, I noticed that the CDC has now added a recommendation such that these patients receive this vaccination, and then the good old 23-valent vaccine (Pneumovax) 8 weeks later.

WTF? Patients with splenectomy (or significant angio-embolization) for trauma are considered functionally asplenic. And although the data for immunization in this group is weak, giving triple vaccinations with pneumcoccal, H. flu, and meningococcal vaccines has become a standard of care.

This was difficult enough already because there was debate around the best time to administer: during the hospital stay or several weeks later after the immune system depression from trauma had resolved. The unfortunate truth is that many trauma patients never come back for followup, and so don’t get any vaccines if they are not given during the hospital stay.

And then came the recommendation a few years ago to give a 5-year booster for the pneumococcal vaccine. I have a hard time remembering when my last tetanus vaccine was to schedule my own booster. How can I expect my trauma patients to remember and come back for their pneumococcal vaccine booster?

So what do we do with the CDC Prevnar-13 recommendation? If we add it, it means that we give Prevnar while the patient is in the hospital, and then hope they come back 8 weeks later for their Pneumovax. And then 5 years later for the booster dose. Huh?

Looking at the package insert, I read that Pneumovax protects against 23 serotypes of S. Pneumo, which represent 85% of most commonly encountered strains out there. So it’s not perfect. Prevnar-13 protects against 13 serotypes, and there is no indication as to what percent of strains encountered are protected against.

So I decided to dig deeper and look at the serotypes included in each vaccine. Here they are:

  • Pneumovax: 1, 2, 3, 4, 5, 6B, 7F, 8, 9N, 9V, 10A, 11A, 12F, 14, 15B, 17F, 18C, 19F, 19A, 20, 22F, 23F, and 33F
  • Prevnar: 1, 3, 4, 5, 6A, 6B, 7F, 9V, 14, 18C, 19A, 19F, and 23F

I bolded the serotypes in Prevnar-13 not found in the Pneumovax vaccine. There was only one, serotype 6A. Unfortunately, it’s nearly impossible to find the prevalence by serotype, and it varies geographically and over time.

Bottom line: I’m not an epidemiologist. But making a set of vaccination rules more complicated for a complex population, and for indications that are a bit weak in the first place, seems unwise. Especially since the added vaccine offers protection for only one more serotype of Pneumococcus.

So please help me out here. Show me something I’m missing. Otherwise, I’ll stick to the original three vaccines, and try to remind my patients to get that booster five years down the road.

Related posts:

Reference: Use of 13-Valent Pneumococcal Conjugate Vaccine and 23-Valent Pneumococcal Polysaccharide Vaccine for Adults with Immunocompromising Conditions: Recommendations of the Advisory Committee on Immunization Practices (ACIP). MMWR 61(40):816-819, October 12, 2012.