All posts by TheTraumaPro

What Is A Wide Mediastinum Anyway?

Trauma professionals are always on the lookout for injuries that can kill you. Thoracic aortic injury from blunt trauma is one of those injuries. Thankfully, it is uncommon, but it can certainly be deadly.

One of the screening tests used to detect aortic injury is the old-fashioned chest xray. This test is said to be about 50% sensitive, with a negative predictive value of about 80%. However, the sensitivity is probably decreasing and the negative predictive value increasing due to the rapidly increasing number of obese patients that we see.

A wide mediastinum is defined as being > 8cm in width. In this day and age of digital imaging, you will need to use the measurement tool on your workstation to figure this out.

Unfortunately, it seems like most chest xrays show wide mediastinum these days. What are the most common causes for this?

  • Technique. The standard xray technique used to reduce magnification of the anterior mediastinum (where the aortic arch lives) is a tube distance of 72 inches from the patient, shot back to front. We can’t do this for trauma patients because we can’t stand them up and are reluctant to prone them. The standard trauma room technique is 36 inches from the patient shot front to back. This serves to magnify the mediastinal image and make it look wide.
  • Obesity. The more fat in the mediastinum, the wider it looks. The more fat on the back, the further the mediastinum is from the xray plate and the greater the magnification.
  • Other mediastinal blood. Major blunt trauma to the chest can cause bleeding from small veins in the mediastinum, making it look wide.
  • Thymus. Only in kids, though.
  • Aortic injury. Last but not least. Only a few percent of people with wide mediastinum will actually have the injury.

If you encounter a wide mediastinum on chest xray in a patient with a significant mechanism for aortic injury, then they should be screened using helical CT.

Related post:

What The Heck? Final Answer!

This case involved a young male who had undergone a splenectomy for blunt trauma. He had an unremarkable postop course and was discharged after 5 days. He presented 2 weeks later with abdominal pain out of proportion to his exam. 

The first CT scan hint showed pneumatosis of the cecum, which is decidedly unusual in a young person:

The next CT scan hint showed thrombosis in the superior mesenteric vein:

This case illustrates an uncommon yet dangerous complication of splenectomy: portal and mesenteric veinous thrombosis. It is generally believed to be caused by thrombocytosis resulting from the splenectomy. The pneumatosis is most likely due to problems resulting from venous congestion.

In this particular case, the patient’s abdominal exam was not consistent with a catastrophic problem (yet). He was taken quickly to the interventional radiography department, where a catheter was inserted and lytic therapy was begun. HIs pain resolved, and repeat CT showed recanalization of much of his portal and mesenteric venous system, as well as resolution of the pneumatosis. He was discharged on warfarin therapy.

Bottom line: Uncommon and dangerous: a bad combination. This often results in delayed diagnosis and severe abdominal complications, including loss of much of the intestine. Monitor the platelet count closely postop until it plateaus, and if it still rising on discharge from the hospital, arrange for monitoring as an outpatient. Dogma tells us to treat with aspirin or similar drugs as the count approaches 1 million/cubic mm, but good studies are lacking. Development of this particular complication requires anticoagulation, and possibly lytics or surgical resection depending on patient condition.


Hat tip to StillChucklesandNP for getting the answer with limited information, and whom I had the pleasure of meeting on a recent visit to her hospital!

What The Heck? Some Hints!

Yesterday, I presented the case of a young man with abdominal pain a few weeks after a splenectomy for trauma. One slice of the CT scan was presented, which showed pneumatosis in the wall of the cecum.

There have been some great comments from readers with some interesting reasoning, especially from StillChucklesandNP. Here’s another piece of the puzzle, yet another slice from the CT scan:

  • What’s this?
  • Any other important information?
  • What’s the diagnosis and why?
  • How do you treat it?

Looking forward to more tweets and comments! Answers tomorrow.

What The Heck?

Here’s an interesting one for you to solve!

A 20ish year old male was involved in a motor vehicle crash, sustaining a Grade IV spleen injury. He fails nonoperative management early in his hospital course, undergoing a splenectomy 6 hours later.

He has an uneventful recovery and is ready for discharge after 5 days. His platelet count has plateaued at 600K. He presents to your ED 2 weeks later complaining of abdominal pain. On exam, he is diffusely but mildly tender. His subjective complaints appear to be a bit out of proportion to his exam.

Here is one slice from his CT scan. I’ve put a nice fat arrow on it to help out. But it won’t.

image

  • What does the scan show?
  • Why is it there?
  • What other key piece of information do you want to know?
  • Any other studies?
  • Then what?

Some hints tomorrow! Tweet your answers or leave comments below! Let’s see if anyone can figure this one out!

The Medical Orthopaedic Trauma Service

Our population is aging, and falls continue to be a leading cause of injury and morbidity in the elderly. Unfortunately, many elders have significant medical conditions that make them more likely to suffer unfortunate complications from their injuries and the procedures that repair them.

A few hospitals around the world are applying a more multidisciplinary approach than the traditional model. One example is the Medical Orthopaedic Trauma Service (MOTS) at New York-Presbyterian Hospital/Weill Cornell Medical Center. Any elderly patient who has suffered a fracture is seen in the ED by both an emergency physician and a hospitalist from the MOTS team. Once in the hospital, the hospitalist and orthopaedic surgeon try to determine the reason for the fall, assess for risk factors such as osteoporosis, provide comprehensive medical management, provide pain control, and of course, fix the fracture. 

This medical center  published a paper looking at their success with this model. They retrospectively reviewed 306 patients with femur fractures involving the greater trochanter. They looked at complications, length of stay, readmission rate and post-discharge mortality. No change in length of stay was noted, but there were significantly fewer complications, specifically catheter associated urinary tract infections and arrhythmias. The readmission rate was somewhat shorter in the MOTS group, but did not quite achieve significance with regression analysis.

Bottom line: This type of multidisciplinary approach to these fragile patients makes sense. Hospitalists, especially those with geriatric experience, can have a significant impact on the safety and outcomes of these patients. But even beyond this, all trauma professionals need to look for and correct the reasons for the fall, not just fix the bones and send our elders home. This responsibility starts in the field with prehospital providers, and continues with hospital through the entire inpatient stay.

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Reference: The medical orthopaedic service (MOTS): an innovative multidisciplinary team model that decreases in-hospital complications in patients with hip fractures. J Orthopaedic Trauma, ePub ahead of print, doi: 10.1097/BOT.0b013e3182242678, Aug 27, 2011.