What’s The Difference? Liquid Plasma vs FFP

April 18, 2023 The Trauma Pro Leave a comment

Plasma 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.

Head

What Is The Zumkeller Index in TBI?

April 11, 2023 The Trauma Pro Leave a comment

Here’s something you may not have heard of before: the Zumkeller index. Most trauma professionals who take care of serious head trauma have already recognized the importance of quantifying extra-axial hematoma thickness (HT) and midline shift (MLS) of the brain. Here’s a picture to illustrate the concept:

Source: Trauma Surgery Acute Care Open

Zumkeller and colleagues first described the use of the mathematical difference between these two values in prognosticating outcomes in severe TBI in 1996.

Zumkeller Index (ZI) = Midline shift (MDI) – Hematoma thickness (HT)

Intuitively, we’ve been using this all along. At some point, we recognized that if the degree of midline shift exceeds the hematoma thickness, it’s a bad sign. The easiest way to explain this is that there is injury to the brain that is causing swelling so the shift is greater than the size of the hematoma.

The authors of a recent paper from Brazil decided to quantify the prognostic value of the ZI by doing a post-hoc analysis of a previously completed prospective study. They limited their study to adult patients with an acute traumatic subdural hematoma confirmed by CT scan. It used data from the 4-year period from 2012-2015.

They compared demographics and outcomes in three cohorts of ZI:

Zero or negative ZI, meaning that the midline shift was less than the size of the hematoma
ZI from 0.1 mm to 3.0 mm
ZI > 3.0 mm

And here are the factoids:’

A total of 114 patients were studied, and the mechanism of injury was about 50:50 from motor vehicle crashes vs falls
About two thirds were classified as severe and the others were mild to moderate, based on GCS
Median initial GCS decreased from 6 in the low ZI group to 3 in the highest ZI group, implying that injuries were worse in the highest ZI group
Mortality (14-day) was 91% in the highest ZI group and only in the low 30% range in the others
Regression analysis showed that patients with ZI > 3 had an 8x chance of dying within 14 days compared to the others

Source: Trauma Surgery Acute Care Open

Bottom line: This study confirms and quantifies something that many of us have been unconsciously using all along. Of course there are some possible confounding factors that were not quantified in this study. Patients with the more severe injuries tended to also have subarachnoid hemorrhage and/or intra-ventricular blood. Both are predictors of worse prognosis. But this is a nice study that quantifies our subjective impressions.

The Zumkeller Index is an easily applied tool using the measuring tool of your PACS application. It can be used to determine how aggressively to treat your patient, and may help the neurosurgeons decide who should receive a decompressive craniectomy and how soon.

So now go out and amaze your friends! You’ll be the life of the party!

Reference: Mismatch between midline shift and hematoma thickness as a prognostic factor of mortality in patients sustaining acute subdural hematomaTrauma Surgery & Acute Care Open 2021;6:e000707. doi: 10.1136/tsaco-2021-000707

Trauma Center

Trauma Transfers Discharged From The ED

April 7, 2023 The Trauma Pro Leave a comment

Aren’t these embarrassing? A referring center sends you a patient with the idea that they will be evaluated and admitted to your hospital. But it doesn’t work out that way. The patient is seen, possibly by a surgical specialist, bandaged up, and then sent home. Probably to one that is quite a few miles away. Not only is this a nuisance for the patient and an embarrassment for the sending center, it may use resources at the trauma center that are already tight.

Transfer patients who are seen and discharged are another form of “ultimate overtriage.” In this case, the incorrect triage takes place at the outside hospital. The trauma group in Oklahoma City reviewed their experience with these patients over a two year period. They looked exclusively at patients who were transferred in to a Level I center and then discharged.

Here are the factoids:

A total of 2,350 patients were transferred in, and 27% were transferred home directly from the trauma bay (!)
The three most common culprits by injury pattern were face (51%), hand (31%), isolated ortho injury (9%)
A third of these patients required a bedside procedure, including laceration repair (53%), eye exam (24%), splinting (18%), and joint reduction (5%)
Ten facilities accounted for 40% of the transfers

The authors concluded that the typical injuries prompting transfer are predictable. It may be possible to reduce the number of transfers by deploying telemedicine systems to push evaluations out to the referring hospitals.

Bottom line: This is quite interesting. Anyone who works in a Level I or II center is aware of this phenomenon. This abstract went a step further and quantified the specific issues involved. This center ended up discharging over 300 patients per year after transfer in. This is a tremendous drain on resources by patients who did not truly have the need for them.

The authors speculate that telemedicine evaluation may help reduce some of those transfers. This seems like an easy solution. However, it also poses a lot of issues in terms of who will actually staff the calls and how will they be compensated for their time.

There are a number of important take-aways from this abstract:

Know your referring hospitals. In this study, there were 10 hospitals that generated an oversize number of referrals. Those are the targets / low hanging fruit. Identify them!
Understand what their needs are. Are they frequently having issues with simple ortho injuries? Eye exams? This is what they need!
Provide education and training to make them more comfortable. This allows you to target those hospitals with exactly the material they need and hopefully make them more self-sufficient.

This allows the higher level centers to reserve phone and/or telemedicine consultation for only the most ambiguous cases. It’s a better use of telehealth resources that may be needed, typically at night and on weekends.

Reference: Trauma transfers discharged from the emergency department-Is there a role for telemedicine? J Trauma Acute Care Surg. 2022 Apr 1;92(4):656-663.

General

What’s The Best Chest Seal For Sucking Chest Wounds?

April 4, 2023 The Trauma Pro Leave a comment

The treatment of a “sucking chest wound” in the field has typically been with application of some type of occlusive dressing. Many times, a generic adhesive dressing is applied, typically the same kind used to cover IV sites. This is quick, easy, cheap, and readily available in the ambulance. But there is a danger that this could result in development of tension pneumothorax, because the dressing not only keeps air from getting in but also keeps any buildup of pneumothorax from getting out.

To avoid this, a number of vented products have been developed and approved by the US Food and Drug Administration (FDA). These devices have some sort of system to allow drainage of accumulating air or blood, typically a one-way valve or drainage channels. They also need to stick well to a chest wall, which may have blood or other fluids that might disrupt the seal completely.

The US Army has a strong interest in making sure the products they use for this purpose work exactly as promised. The US Army Institute of Surgical Research examined 5 currently FDA-approved products to determine their ability to adhere to bleeding chest wounds, and to drain accumulating air and/or blood from the pleural space. They developed an open chest wound with active bleeding in a swine model.

An open hemopneumothorax was created by infusing air and blood, the animal was stabilized, then additional aliquots of air and blood were infused to simulate ongoing bleeding and air buildup. The image below shows the 5 products used and the animal setup:

Here are the factoids:

Creation of the open hemopneumothorax caused the intrapleural pressure to move toward atmospheric pressure as expected, resulting in labored breathing and reduced O2 saturation
Sealing the wound with any of the chest seal products corrected all of the problems just noted
Chest seals with one way valves did not evacuate blood efficiently (Bolin and SAM). The dressings either detached due to pooled blood, or the vent system clogged from blood clot.
Seals with laminar channels for drainage (see the pig picture above) allowed easy escape of blood and air
Success rates were 100% for Sentinel and Russell, 67% for HyFin, 25% for SAM, and 0% for Bolin

Bottom line: Prehospital providers need to be familiar with the products they use to cover open chest wounds. Totally occlusive dressings can result in development of a tension pneumothorax if there is an ongoing air leak from the lung. Vented chest seals are preferable for these injuries. Just be aware that vented seals with drainage channels perform much better than those that rely on a one-way valve.

Reference: Do vented chest seals differ in efficacy? An experimental
evaluation using a swine hemopneumothorax model. J Trauma 83(1):182-189, 2017.

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