Tag Archives: MTP

Massive Transfusion: What’s The Right Ratio?

In my last post, I analyzed a survey that studied the massive transfusion protocol (MTP) practices of academic Level I trauma centers in the US. What centers do is one thing. But what does the literature actually support? A group from Monash University in Melbourne, Australia and the National Health Service in the UK teamed up to review the literature available through 2016 regarding optimal dose, timing, and ratio of products given during MTP.

One would think that this was easy. However, the search for high quality ran into the usual roadblock: the fact that there is not very much of it. The authors scanned MEDLINE for randomized, controlled studies on this topic, and found very few of them. Out of 131 articles that were eligible, only 16 were found to be suitable for inclusion, and 10 of them were still in progress. And only three specifically dealt with the ratio question. Even they  were difficult to compare in a strict apples to apples fashion.

Here are the factoids that could be gleaned from them:

  • There was no difference in 24-hour or 30-day mortality between a ratio of 1:1:1 (FFP:platelets:RBC) vs 1:1:2
  • However, a significantly higher number of patients  achieved hemostasis in the 1:1:1 group (86% vs 78%)
  • There was no difference in morbidity or transfusion reactions in the two groups
  • One study compared 1:1 component therapy with whole blood transfusion and found no difference in short-term or long-term mortality or morbidity

Bottom line: As usual, the quality of available data is poor if one limits the field to randomized, controlled studies. Ratios of 1:1:1 and 1:1:2 appear to be equally effective given the limited information available. A number of papers not included in this review (because of their less rigorous design) do seem to indicate that higher ratios of RBC (1:3-4) appear to be detrimental. And as time passes, more and hopefully better studies will be published.

What does this all mean for your MTP? Basically, we still don’t know the best ratio. However, it is recommended that your final ratios of FFP:RBC end up somewhere between 1:1 and 1:2. The only way to ensure this is to set up your MTP coolers so the the ratio of product they contain is better than 1:2. This means more plasma than 1 unit per 2 units of red cells. 

If you set it at the outside limit of 1:2, then that is the best ratio you can ever get assuming everything goes perfectly. However, if you have to thaw frozen plasma, use too much emergency release PRBC before activating MTP, or someone cherry-picks the coolers to transfuse what they think the patient needs, the ratios will quickly exceed this boundary.

So be sure to load your coolers with ratios that are closer to 1:1 to ensure that your final ratios once MTP is complete are what you want them to be. And monitor the final numbers of every one of your MTP activations through your trauma performance improvement program so you know what your patients are really receiving.

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

Massive Transfusion: What Ratios Are People Using?

This is the first of a two-part series on massive transfusion protocol (MTP) ratios. Today, I’ll write about what ratios trauma centers around the country are using. Tomorrow I’ll review the literature we have to date on what the correct ratio should be. Are we all doing the right thing or not?

Back in the old days (which I remember fondly), we didn’t pay too much attention to the ratio of blood to plasma. We gave a bunch of bags of red cells, then at some point we remembered that we should give some plasma. And platelets? We were lucky to give any! And to top it all off, we gave LOTS of crystalloid. Turns out this was not exactly the best practice.

But things have changed. Some good research has shown us that a nice mix of blood component products is good and too much crystalloid is bad. But what exactly is the ideal mix of blood products? And what is everybody else doing? I’ll try to answer these questions in this series.

So first, what are all the other trauma centers doing? An interesting medley of anesthesia and pathology groups from the University of Chicago, a Dallas-based anesthesia group, and a blood center in my home base of St. Paul, conducted a survey of academic medical centers in 2016. They wanted to find out how many actually had a MTP and to scrutinize the details.

They constructed a SurveyMonkey survey and sent it to hospitals with accredited pathology residencies across the US. There were 32 questions in the survey, which asked for a lot of detail. As you can probably personally attest, the longer and more complicated the survey, the less likely you are to respond. That certainly happened here. Of 107 surveys sent out, it took a lot of nagging (initial email plus two nags) to get a total of 56 back.

Here are the factoids:

  • Most were larger hospitals, with 74% having 500 or more beds
  • All had massive transfusion protocols
  • Trauma center level: Level I (77%), Level II (4%), Level III (4%), Level IV (2%), no level (14%)
  • Nearly all (98%) used a fixed ratio MTP; very few used any lab-directed (e.g. TEG/ROTEM) resuscitation
  • Target RBC:plasma ratio: 1:1 (70%), 1.5:1 (9%), 2:1 (9%), other (9%)
  • Only 58% had the same RBC:plasma ratio in each MTP cooler
  • More than 86% had thawed plasma available (remember, these were generally large academic centers)
  • Half stored uncrossmatched type O PRBCs outside the blood bank, usually in the ED; only 1 stored thawed plasma in the ED
  • A total of 41% had more than one MTP (trauma, OB, GI, etc.)
  • 84% had some type of formal review process once the MTP was complete
  • About 68% had modified their MTP since the original implementation. Some increased or decreased ratios, expanded MTP to non-trauma services, decreased the number of units in each pack, changed to group A plasma from AB, or switched from ratio to TEG/ROTEM or back.

Bottom line: This is an intriguing snapshot of MTP practices around the country that is about four years old. Also remember, this is a somewhat skewed dataset. The survey was directed toward hospitals with academic pathology programs, not trauma centers. However, there is enough overlap that the results are probably generalizable. 

Most centers are (were) using MTP packs containing six units of PRBCs, and were attempting to achieve a fixed 1:1 ratio. Half of hospitals had the same number of units in each cooler, half varied them by cooler number. Nearly half had multiple flavors of MTP for different specialties. Very few used TEG/ROTEM during the initial phased of MTP. Most modified their MTP over time.

I’ve written quite a lot on most of these issues. See the links to my “MTP Week” series from earlier this year, below.

Tomorrow, I’ll review what we know and don’t know about the proper ratios to use in your MTP.

Reference: Massive Transfusion Protocols: A Survey of Academic
Medical Centers in the United States. Anesth & Analg 124(1):277-281, 2017.

MTP week series:

What’s The Best Trigger For Your Massive Transfusion Protocol?

Every trauma center verified by the American College of Surgeons Committee on Trauma (ACS-COT) must have a massive transfusion protocol (MTP). The details and logistics of the protocol are up to the individual center. The difficult question is: how is a trauma professional to know that the MTP should be activated?

Sometimes it’s extremely obvious. The patient is very hypotensive. Blood is spurting all over the room. But sometimes it’s more subtle and the need just seems to creep up on you. And frequently, this delays activation and the actual arrival of the blood that is so desperately needed.

I’ve previously written about common triggers for the MTP, including psychic powers, shock index, and ABC index. See the links below to read my MTP week posts. But is one better than the other? The group at Vancouver General Hospital in British Columbia, Canada performed a systematic review of the literature to try to answer this question.

A total of 45 pertinent articles were identified in the literature up to 2017. Fifteen different scoring systems were evaluated involving combinations of clinical assessment, laboratory tests, and ultrasound evaluation.

Here are the factoids:

  • The best validated score using clinical assessment plus ultrasound was the Assessment of Blood Consumption score (click here for my post). This was the easiest to score compared to other systems using ultrasound.
  • Shock index (SI) was the only validated system using just the clinical exam
  • Some other studies were promising, with excellent areas under the receiver operating characteristic curve (AUROC), but had not been validated. The best of the bunch was one from Mina et al, but it is complicated enough to require a smartphone tool for calculation.
  • Other promising studies required laboratory evaluations which preclude their use at the time of patient arrival
  • Scoring systems that used more variables generally showed better correlation with actual need for MTP, but were more less likely to provide suficiently early predictions
  • Most validation studies involved single centers
  • No studies were designed to or able to show improved outcomes

Bottom line: There are many, many systems out there for predicting need for activation of the MTP (at least 15 to date)! This review concludes that the system used should be tailored to the center implementing it.

Simpler is better. I still recommend either Shock Index (SI) or ABC. Shock index is quickly calculated based on physical exam as heart rate divided by systolic blood pressure. The normal range is 0.5 to 0.7. The likelihood of MTP escalates 2x with SI > 0.9, 4x if SI > 1.1, and 7x with SI > 1.3. The ratio can easily be calculated based on numbers available from EMS providers prior to arrival. Basically, pick your threshold.

The Assessment of Blood Consumption (ABC) uses four parameters, three of which could be reported prior to patient arrival:

  • Heart rate > 120
  • Systolic blood pressure < 90
  • FAST positive
  • Penetrating mechanism

If two or more criteria are met, the patient has a 41% likelihood of needing MTP.

So basically, use a system that works for you. From my experience, centers that use a system tend to use ABC. But definitely pick a system, don’t leave it up to chance with the trauma surgeon. And use your trauma PI program to assess utilization to see if it’s the best tool for your center.

Related posts:

Reference: Systematic Reviews of Scores and Predictors to Trigger Activation of Massive Transfusion Protocols. Accepted ahead of print, J Trauma, 2019.

Massive Transfusion And Tranexamic Acid (TXA)

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:

  1. Massive transfusion protocols and the use of tranexamic acid. Current Opinion Hematol 25(6):482-485, 2018.
  2. Tranexamic Acid is Associated with Increased Mortality in Patients with Physiologic Fibrinolysis. J Surg Res 220:438-443, 2017.
  3. 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.

TEG And Your Massive Transfusion Protocol

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.