All posts by The Trauma Pro

Why Do We Use Fractionated Blood Components?

May 7, 2019 The Trauma Pro Leave a comment

Tomorrow, I’ll be writing about the use of the newest and greatest blood product: whole blood. Wait, isn’t that what we started out a hundred years ago? How is it that we are even debating the use of blood component therapy vs whole blood? Most living trauma professionals only remember a time when blood components have been infused based on which specific ones were needed.

Prior to about 1900, blood transfusion was a very iffy thing. Transfusions from animals did not go well at all. And even from human to human, it seemed to work well at times but failed massively at others. In 1900, Landsteiner published a paper outlining the role of blood groups (types) which explained the reasons for these successes and failures. With the advent of blood storage solutions that prevented clotting, whole blood transfusion became the standard treatment for hemorrhage in World War I.

When the US entered World War II, it switched to freeze-dried plasma because of the ease of transport. However, it quickly became clear that plasma-only resuscitation resulted in much poorer outcomes. This led to the return to whole blood resuscitation. At the end of WWII, 2000 units of whole blood were being transfused per day.

In 1965, fractionation of whole blood into individual components was introduced. This allowed for guided therapy for specific conditions unrelated to trauma. It became very popular, even though there were essentially no studies of efficacy or hemostatic potential for patients suffering hemorrhage. The use of whole blood quickly faded away in both civilian and military hospitals.

The use of fresh whole blood returned for logistical reasons in the conflicts in Iraq and Afghanistan. A number of military studies were carried out that suggested improved outcomes when using whole blood in place of blood that has been reconstituted from components. That leads us to where we are today, rediscovering the advantages of whole blood.

And that’s what I’ll review tomorrow!

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Massive Transfusion And Tranexamic Acid (TXA)

May 3, 2019 The Trauma Pro Leave a comment

Tranexamic acid has been in use for decades, just not for trauma. The CRASH-2 trial was a massive multi-country study showed that there was a slight mortality reduction from 16% to 14.5% in trauma patients who had or were at risk for “significant hemorrhage.” Moreover, there was no difference in vascular occlusive events, blood product transfusions, or need for surgery. Sounds great, right?

The MATTERs trial was initiated by the US military and tried to address some of the perceived shortcomings of CRASH-2 and found an absolute mortality reduction of 6.7%. But it also showed DVT rates that were 12x higher and PE rates 9x higher when this drug was given.

Since those two studies, a significant number of critiques have been published, as well as some additional research. Unfortunately, this has only served to cloud the picture. TXA is very inexpensive and readily available, so there has been a significant move to adopt both in the trauma center, as well as during prehospital care prior to arrival.

The trauma group at Denver Heath published a study of 232 patients with a 20% mortality rate from their injuries. They identified three subsets of patients based on their fibrinolytic response upon presentation to the hospital: physiologic fibrinolysis (49% of patients), hyperfibrinolysis (28%), and fibrinolytic shutdown (23%).

They found that mortality significantly increased in those receiving TXA who were physiologic or hyperfibrinolytic, but unchanged in those in shutdown. They cautioned that giving this drug before the patient’s fibrinolytic status was known could contribute to mortality.

Bottom line: So confusing! And many centers already include TXA in their massive transfusion protocol. Most have not seen unexpected mortality after giving the drug, so the jury is not in yet. Each trauma center should weigh the currently known pros and cons, and decide whether they are “believers” or not. Carefully review all mortalities and thrombotic complications after administration to see if there was any relation to the use of TXA.

References:

Massive transfusion protocols and the use of tranexamic acid. Current Opinion Hematol 25(6):482-485, 2018.
Tranexamic Acid is Associated with Increased Mortality in Patients with Physiologic Fibrinolysis. J Surg Res 220:438-443, 2017.
CRASH-2 Study of Tranexamic Acid to Treat Bleeding in Trauma Patients: A Controversy Fueled by Science and Social Media. J Blood Transfus Article 874920, 2015.

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TEG And Your Massive Transfusion Protocol

May 2, 2019 The Trauma Pro Leave a comment

Thromboelastography (TEG) and its fraternal twin rotational thromboelastometry (ROTEM) are relatively new toys in the trauma community. They allow for (somewhat) rapid assessment of clotting function, and allow the trauma professional to surmise what products might push abnormal clotting characteristics back toward normal.

Many trauma centers already own this technology due to its use by non-trauma services. But there have been a growing number of research presentations on the topic over the last five years, and many centers are clamoring to buy these units for use in their MTP.

But remember, new technology is usually expensive, and isn’t always all it’s cracked up to be. TEG and ROTEM require a (often-times) new machine and a never-ending supply of disposable cartridges for use, like your ink jet printer. Some hospitals are reluctant to provide the funds unless there is a compelling clinical need.

Surgeons at the University of Cincinnati compared the use of TEG with good, old-fashioned point-of-care (POC) INR testing in a series of major trauma patients seen at their Level I center.

Here are the factoids:

This was a retrospective review of 628 major trauma patients who received both TEG and POC INR testing using an iSTAT device over a 1.5 year period
Median ISS was 13, and there were many sick patients (20% in shock, 21% received blood, 11% died)
INR correlated with all TEG values, with better correlation in patients in shock
Both INR and TEG correlated well with treatment with blood, plasma, and cryoprecipitate
Processing time was 2 minutes for POC INR vs about 30 minutes for TEG
Charges for POC INR were $22,000 vs $397,000 for TEG(!!)

Bottom line: Point of care INR testing and TEG both correlated well with the need for blood products in major trauma patients. But POC INR is much cheaper and faster. Granted, the TEG gurus will say that you can tailor the products administered to meet the exact needs of the patient. But in all my travels, I’ve see very few centers that have fully, effectively, and contemporaneously incorporated TEG or ROTEM into their massive transfusion protocol from start to finish.

The area where TEG and ROTEM are most helpful are in the “mop up” phase at the tail end of the MTP. These tools allow trauma professionals to determine exactly which products are needed to normalize parameters, and they frequently diverge from the 1:1:1 to 1:1:2 ratios at that point to achieve this.

If you don’t have one of these toys yet, make sure that you have a very good clinical reason to do so. If you do, think very carefully about how you can meaningfully incorporate it in the massive transfusion process and write it into your protocol.

Reference: All the bang without the bucks: defining essential point-of-care testing for traumatic coagulopathy. J Trauma 79(1):117-124, 2015.

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What Is The Ideal Blood Product Ratio?

May 1, 2019 The Trauma Pro Leave a comment

Back in the day when I was a resident when a massively bleeding patient came in, we gave crystalloid. And frequently, a lot of it. The books in those days said slam in two liters of saline or lactated Ringer’s solution. It was believed that there was little downside to crystalloid. Consequently, quite a bit of it was given before we ever thought about blood products.

And there were no systems in place to standardize how blood was requested, what was sent, or how much was used. We generally started off with a bunch of packed red cells. Yes, every now and then we might remember to ask for some plasma, and even less commonly some platelets or cryoprecipitate. Ratios? We didn’t really pay attention. In reality, there were probably four red cell packs to one unit of plasma, on average. And the ratio to platelets was so low it was hard to even measure!

By now, we have plenty of data showing that this crystalloid-heavy resuscitation contributed to coagulopathy and poor outcomes. We’ve adopted a more balanced concept of resuscitation, which of course we call “balanced resuscitation.” What does this term mean? Basically, it’s a combination of restricted crystalloid use, more optimized ratios of blood products, and some degree of permissive hypotension in select patients.

Before we dive more deeply into ratios, let’s agree on the nomenclature. You may hear people talking about a 1:1 ratio, or 2:1:1, or even 1:1:2. Which product is which? Always read the paper or text carefully, as there is no real standard here. Typically, if only two numbers are specified, RBCs are first and plasma second. But when three are given, you must determine whether the red cells are first or last. Here are the most common configurations:

RBC : plasma : platelets
Plasma : platelets: RBC

Many papers have been written examining the ratio puzzle. Mortality, complications, renal or lung injury, deep venous thrombosis and pulmonary embolism, lengths of stay, transfusion reactions (of all types), and much more have all been investigated.

The most helpful literature covering transfusion ratios are systematic reviews. The main focus seems to be finding the magic ratio of red cells to everything else. The old-time higher ratios (1:?:4) were generally considered to be inferior, so most research has focused on comparing 1:1:1 to 1:1:2. Here are the main factoids, and all keep to the plasma:platelets:RBC format:

There was no discernible difference in 24-hour or 30-day mortality between groups with ratios of 1:1:1 or 1:1:2
Patients with a 1:1:1 ratio received significantly more platelets and plasma that the 1:1:2 patients
Giving cryoprecipitate or fibrinogen concentrate early had no effect on mortality

Although systematic reviews try to make up for shortcomings of individual studies, they introduce their own problems. However, they overall seem to indicate that the “magic” ratio lies between 1:1:1 and 1:1:2. Most centers strive for the former, but due to many reasons (e.g. no thawed plasma, delivery issues) more realistically try to stay under the latter.

Bottom line: Think about the logistics in your own trauma center, and design your massive transfusion protocol so that you can maintain a ratio somewhere between 1:1:1 and 1:1:2. Every MTP activation should be analyzed by your trauma performance improvement process and must review your final ratios. One thing I’m sure of is that we will continue to refine this over the coming years, so stay tuned!

Reference: Optimal Dose, Timing and Ratio of Blood Products in Massive Transfusion: Results from a Systematic Review. Transfus Med Rev 32(1):6-15, 2018.

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