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October Trauma MedEd Newsletter Released

The October newsletter is now available! Click the image below or the link at the bottom to download. This month’s topic is “Inside Stuff”.

In this issue you’ll find articles on:

  • Retained foreign objects after penetrating injury
  • A cool way to remove embedded foreign objects
  • Can lead poisoning occur after a gunshot?
  • Orthopedic hardware and TSA metal detectors
  • Technology: the Vein Viewer
  • Using a 3D printer to plan orthopedic surgery

Subscribers received the newsletter first last weekend. If you want to subscribe (and download back issues), click here.

Click here to download the current issue.

Flying And Pneumothorax: Part 2

Some time ago, I wrote about the effect of flying on pneumothorax (PTX). It was more of a hypothetical treatise, discussing Boyle’s law and such. I also cited a practice guideline and another empiric guideline from the Aerospace Medical Association. But there was little, if any, real data to base recommendations on.

A recent study has tried to rectify this. They performed a prospective, observational study of 20 patients with traumatic pneumothorax. All were treated with either a chest tube (70%) or high flow oxygen therapy (30%) (they must not have read my many posts on the futility of this; see the links below). If a chest tube had been inserted, it had to have been removed for 4 to 48 hours before enrollment in this study, and the PTX had to be resolved to the satisfaction of the surgeon. This did not necessarily mean complete resolution.

Here are the factoids:

  • A hyperbaric chamber was used to simulated the cabin altitudes of commercial jetliners
  • 10 patients were taken up to 8400 feet, the typical cabin altitude when a jet flies at 40000 feet
  • 10 patients were taken up to 12650 feet to compensate for the fact that the altitude of the medical center conducting the study was already 4500 feet (Murray, UT). This simulated an 8400 foot altitude increase for ground dwellers in Murray.
  • Results were measured using portable chest x-ray (!??)
  • PTX etiology was 90% blunt, 10% penetrating
  • At 8400 feet, average PTX size doubled from 4.5mm to 10mm
  • At 12650 feet, average PTX size nearly tripled from 3.2 to 8.7mm. Three of 4 patients without a baseline PTX developed one at this altitude. 
  • Some patients in each group required supplemental O2 to maintain normal oxygen saturation readings

Based on these results, the authors believe that patients who had a PTX might be able to fly sooner than 2 weeks. But there are many problems with this study. First, using a chest x-ray to monitor increases in size (or judge pre-flight size) is notoriously inaccurate. Next, the statistical methods and sample size are just not adequate. And finally, the fact that PTX size increases predicted by Boyle’s law and O2 sat changes occurred is very worrisome.

Bottom line: This study was a nice try, but not robust enough to change anything. Yes, there is little data to support the 2 week no-fly rule after pneumothorax. But the size increases of the PTX in this study were worrisome, particularly because they used a diagnostic test that notoriously underestimates their size. I recommend sticking with the current recommendations and constructing a much better study.

Related posts:

Reference: Cleared for takeoff: The effects of hypobaric conditions on traumatic pneumothoraces. J Trauma 77(5):729-733, 2014.

Up In The Air: Tree Stand Injuries

Deer hunting season is upon us again, so it’s time for emergency departments to start seeing an increase in hunting injuries. Although you would think this would mean 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 recent descriptive 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. 29% were gunshots. The authors found only 3% were related to alcohol, although this seem very low compared to our experience in Minnesota.

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.

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

Commercial tree stand Do-it-yourself tree stand

October Newsletter Released To Subscribers Wednesday!

The October Trauma MedEd Newsletter will be released to subscribers over this Wednesday. I’ll be covering Inside Stuff. Articles include:

  • Managing foreign bodies
  • Orthopedic implants and the TSA
  • Gunshots and lead poisoning
  • And more!

Anyone on the subscriber list as of 8PM Tuesday (CST) will receive it on Wednesday, November 5. I’ll release it to everyone on Friday via the blog. So sign up for early delivery now by clicking here!

Pick up back issues here!

Ever Wonder Where The Golden Hour Came From?

Everywhere you turn in the trauma and EMS world, you run into the concept of the “golden hour.” Basically, it refers to the idea that it’s important to get an injured patient to definitive care promptly, or mortality begins to rise. It has been used to justify a lot of what we do in trauma care and trauma systems. But where did this come from? And is it true?

The BTLS course attributes the term to R Adams Cowley from the ShockTrauma Center in Baltimore. Unfortunately, no references are given. A biography of Cowley entitled Shock-Trauma names him the author of the term, basing it on dog research. No references were given.

A review of Cowley’s research reveals a few tidbits. A case series of patients implies that speed is good, but does not analyze time to definitive care. It does reference older work by other authors, but once again, no relationship between timing and outcome is evaluated.

A textbook edited by Cowley contains a reference to an article about “Cowley’s golden hour.” This article contains a statement that “patients are assumed to be dying and much of the golden hour has passed.” It goes on to state that the first 60 minutes after injury determines the patient’s mortality. It, in turn, refers to another of his earlier articles. This one states that “the first hour after injury will largely determine a critically injured person’s chance for survival." No data or reference is given.

Bottom line: The concept of the "golden hour” has taken on a life of its own. Yes, it’s a good idea. And yes, there is some actual data to support it, although the quality is somewhat lacking. But this does point out the need to question everything, even some of our most deeply held beliefs. They are not always what they seem to be.

Reference: The Golden Hour: scientific fact or medical urban legend? Acad Emerg Med 8(7):758-760, 2001.