Category Archives: General

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.

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The Rectal Exam In Trauma Continues to “Pass”?

This topic continues to come up from time to time. I still see trauma programs that perform the good, old-fashioned digital rectal exam on nearly every trauma patient. But is it really necessary?

In the not so distant past, it was standard operating procedure to perform a digital rectal exam in all major trauma patients. The belief had always been that valuable information about blood in the GI tract, the status of the urethra, and the neuro exam (rectal tone) could be gleaned from this exam.

Unfortunately, a finger in the bum also serves to antagonize or even further traumatize some patients, especially those who may be intoxicated to some degree. On a number of occasions I have seen calm patients become so agitated by the rectal exam that they required intubation for control.

So is it really necessary? A study in 2001 conducted over a 6 month period (1) showed that the rectal exam influenced management in only 1.2% of cases. The authors felt that there was some utility in 3 special cases:

  • Spinal cord injury – looking for sacral sparing
  • Pelvic fracture – looking for bone shards protruding into the rectum
  • Penetrating abdominal trauma – looking for gross blood

A more recent 2005 study (2) was also critical of the rectal exam and found that using “other clinical indicators” (physical exam and other diagnostic study information) was at least equivalent, changing management only 4% of the time. They concurred with the first two indications above as well.

Bottom line: For most major trauma patients, the rectal exam is not worth the patient aggravation it causes. I still recommend it for the 3 special cases listed above, however, as there are no equivalent exams for these potentially serious patient problems. And remember, DON’T do it while the patient is in the logroll position. No patient likes a rectal exam, so they’ll do their best to defeat your puny attempt at spine precautions if you have them on their side. Supine, frog-leg only.

1. Porter, Urcic. Am Surg. 2001 May;67(5):438-41.
2. Esposito et al. J Trauma. 2005 Dec;59(6):1314-9.

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Orthopedic Hardware And TSA Metal Detectors

Many trauma patients require implantable hardware for treatment of their orthopedic injuries. One of the concerns they frequently raise is whether this will cause a problem at TSA airport screening checkpoints (Transportation Safety Administration).

The answer is probably “yes.” About half of implants will trigger the metal detectors, and these days that usually means a pat down search. And letters from the doctor don’t help. It turns out that overall, 38% are detected when the scanner is set to low sensitivity and 52% at high sensitivity.

Here is a more detailed breakdown:

  • Lower extremity hardware is detected 10 times more often than upper extremity or spine implants
  • 90% of total knee and total hip replacements are detected
  • Upper extremity implants such as shoulder, wrist and radial head replacements are rarely detected
  • Plates, screws, IM nails, and wires usually escape detection
  • Cobalt-chromium and titanium implants trigger alarms more often than stainless steel

If your patient knows that their implant triggers the detectors, they have two options: request a patdown search, or volunteer to go through the full body millimeter wave scanner. This device looks at everything from the skin outwards, and will not “see” the implant and is probably the preferred choice. If they choose to go through the metal detector and trigger it, they are required to have a patdown. Choosing to go through the body scanner after setting off the detector is no longer an allowed option.

Reference: Detection of orthopaedic implants in vivo by enhanced-sensitivity, walk-through metal detectors. J Bone Joint Surg Am. 2007 Apr;89(4):742-6.

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Liquid Plasma vs FFP: Impact On Your Massive Transfusion Protocol

In my last post, I discussed the growing number of choices for plasma replacement. Today I’ll look at some work that was done that tried to determine if any one of them is better than the others when used for the massive transfusion protocol (MTP).

As noted last time, fresh frozen plasma (frozen within 8 hours, FFP) and frozen plasma (frozen within 24 hours, FP) have a shelf life of 5 days once thawed. Liquid plasma (never frozen, LQP) is good for the 21 days after the original unit was donated, plus the same 5 days, for a total of 26 days.

LQP is not used at most US trauma centers. It is more commonly used in Europe, and a study there suggested that the use of thawed plasma increased short term mortality when compared to liquid plasma. To look at this phenomenon more closely, a group from UTHSC Houston and LSU measured hemostatic profiles on both types of plasma at varying times during their useful life.

All products were analyzed with thromboelastography (TEG) and thrombogram, and platelet count and microparticles, clotting factors, and natural coagulation inhibitors were measured. They chose 10 units of thawed FFP and 10 units of LQP, and assayed them every 5 days during their useful shelf life.

Here are the factoids:

  • Platelet counts were much higher in day 0 LQP (75K) vs day 0 thawed plasma (7.5K). Even at end of shelf life, the LQP was 1.5x higher than thawed (15K vs 10K).
  • Thrombogram showed that LQP had higher endogenous thrombin production until end of shelf life
  • TEG demonstrated that LQP had a higher capacity to clot that gradually declined over time. It became similar to thawed plasma at the end of its shelf life.
                         (TEG MA for liquid (LQP) and thawed (TP) plasma
  • Most clotting factors remained stable in LQP, with the exception of Factors V and VIII, which slowly declined

Bottom line: Liquid plasma sounds like good stuff, right? Although there are a few flaws in the collection aspect of this study, it gives good evidence that never frozen plasma has better coagulation properties when compared to thawed plasma. Will this translate into better survival when used in the MTP for trauma? One would think so, but you never really know until you try it. Our hospital blood bank infrastructure isn’t prepared to handle this product yet, for the most part. What we really need is a study that shows the survival advantage when using liquid plasma compared to thawed. But don’t hold your breath. It will take a large number of patients and some fancy statistical analysis to demonstrate this. I think we’ll have to look to our military colleagues to pull this one off!

Reference: Better hemostatic profiles of never-frozen liquid plasma compared with thawed fresh frozen plasma. J Trauma 74(1):84-91, 2013.

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Liquid Plasma vs FFP: Definitions

I’ll spend the next few days discussing plasma. This is an important component of any trauma center’s massive transfusion protocol (MTP). Coagulopathy is the enemy of any seriously injured patient, and this product is used to attempt to fix that problem.

And now there are two flavors available: liquid plasma and fresh frozen plasma. But there is often confusion when discussing these products, especially when there are really three flavors! Let’s review what they are exactly, how they are similar, and how they differ.

Fresh frozen plasma (FFP)
This is plasma that is separated from donated whole blood. It is generally frozen within 8 hours, and is called FFP. However, in some cases it may not be frozen for a few more hours (not to exceed 24 hours total) and in that case, is called FP24 or FP. It is functionally identical to FFP. But note that the first “F” is missing. Since it has gone beyond the 8 hour mark, it is no longer considered “fresh.” To be useful in your MTP, it must be thawed, and this takes 20-40 minutes, depending on technique.

Thawed plasma
Take a frozen unit of FFP or FP, thaw, and keep it in the refrigerator. Readily available, right? However, the clock begins ticking until this unit expires after 5 days. Many hospital blood banks keep this product available for the massive transfusion protocol, especially if other hospital services are busy enough to use it if it is getting close to expiration. Waste is bad, and expensive!

Liquid plasma (never frozen)
This is prepared by taking the plasma that was separated from the donated blood and putting it in the refrigerator, not the freezer. It’s shelf life is that of the unit of whole blood it was taken from (21 days), plus another 5, for a total of 26 days. This product used to be a rarity, but is becoming more common because of its longer shelf life compared to thawed plasma.

Finally, a word on plasma compatibility. ABO compatibility is still a concern, but Rh is not. There are no red cells in the plasma to carry any of the antigens. However, plasma is loaded with A and/or B antibodies based on the donor’s blood type. So the compatibility chart is reversed compared to what you are accustomed to when giving red cells.

Remember, you are delivering antibodies with plasma and not antigens. So a Type A donor will have only Type B antibodies floating around in their plasma. This makes it incompatible with people with blood types B or AB.

Type O red cells are the universal donor type because the cells have no antigens on the surface. Since Type AB donors have both antigens on their red cells, they have no antibodies in their plasma. This makes AB plasma is the universal donor type. Weird, huh? Here’s a compatibility chart for plasma.

Next time, I’ll discuss the virtues of the various types of plasma when used for massive transfusion in trauma.

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