Tag Archives: transfusion

Complications

EAST 2017 #11: Use of Incompatible (Type A) Plasma For Massive Transfusion

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Type AB plasma is considered “universal donor” plasma, as it contains no antibodies to red cells with either A or B antigens on their surface. Unfortunately, only about 4% of the US population have this blood type and can provide the product. Due to this shortage, some trauma centers have decided to use Type A plasma initially for massive transfusion, and switch to type specific plasma once patient blood has been typed and screened.

This works, since only about 13% of the population have red cells with B antigens on the surface. But are there any adverse effects in those patients who receive potentially incompatible plasma? The EAST Multicenter Study group performed a retrospective study using trauma registry and blood bank data from 5 trauma centers. They looked at adult patients who received plasma as part of the massive transfusion protocol (MTP) over a 4+ year period. Incompatible type A plasma transfusion was defined to occur if a patient had either Type B or AB blood.

Here are the factoids:

  • There were a total of 1212 patients in the study; 93% were compatible and 7% were incompatible type A initial transfusions
  • The usual trauma demographics were seen (young, male) and the average ISS was 25 (they triggered an MTP, remember?)
  • By chance, the incompatible group had a slightly higher ISS (29) and penetrating injury rate (45% vs 33%)
  • The incompatible group received significantly more plasma during the first 4 hours and during the first day
  • There was no difference in mortality sepsis, ARDS, thromboembolic events, or renal failure
  • Regression analysis showed that incompatible plasma was not a predictor of mortality or morbidity
  • There was one hemolytic reaction and one occurrence of TRALI, both in the compatible group

Bottom line: This is the largest study around on the topic, and it does not show any significant problems (at least the ones that were studied) with giving incompatible plasma in acute trauma. How can this be, you ask? Remember, only the first one or two units (the first MTP pack) is potentially incompatible. Hopefully, by the time the second pack is delivered, the blood has been typed. And these patients are potentially receiving multiple units of typed plasma after the initial transfusion which dilutes the incompatible, and multiple transfusions overall which may blunt their immune response. 

This is an important paper that all centers should consider as they update their massive transfusion protocols!

Questions and comments for the authors/presenters:

  1. The abstract states that 5 centers participated, but the tables only list 4. Please explain this.
  2. It is not stated explicitly whether all centers used type A plasma initially. Is this the case?
  3. This is important work! Have any other centers converted to initial use of type A plasma?

Click here to go the the EAST 2017 page to see comments on other abstracts.

Related posts:

Reference: Use of incompatible type A plasma transfusion in patients requiring massive transfusion protocol: outcomes of an EAST multicenter study. Paper #16, EAST 2017.

Abstracts, Critical care

EAST 2017 #4: A More Restrictive Transfusion Trigger?

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For many years, patients were automatically given not one, but two units of blood anytime they got “anemic” while in the hospital. And anemia was defined as a hemoglobin (Hgb) value < 10. Wow! Then we recognized that blood was a dangerous drug, with many potential complications.

We’ve come a long way, with our transfusion trigger slowly dropping and giving just one unit of blood at a time when needed. Many trauma centers use a transfusion trigger Hgb of 7 in younger, healthier patients. The question is, how low can you (safely) go?

The trauma program at Wake Forest University analyzed their data, and found that there was no “physiologic advantage” to transfusions in patients with Hgb of 6.5 to 7. Therefore, they lowered their transfusion trigger from 7 to 6.5 and retrospectively studied the results for the six months before and six months after the switch. Patients with hemorrhage, anticipated surgical procedures, or unreconstructed coronary artery disease were excluded.

Here are the factoids:

  • Of 852 patients admitted to the ICU, 131 met criteria and had a Hgb < 7
  • 72 patients were transfused with a trigger of 7, and 59 with a trigger of 6.5
  • There was no difference in ventilator, ICU, or hospital days, or mortality
  • The transfusion rate dropped by 27%, saving 72 units of blood

Bottom line: We continue to determine how low we can go with this. In healthy patients, the magic number is probably even lower. But we are increasingly seeing older, less healthy trauma patients. The next step is to start looking at subsets to determine what is safe for each group.

Questions and comments for the authors/presenter

  • Tell us the nature of the “preliminary work” that led to this paper. Was it animal data, or some kind of analysis of your patient data?
  • Since coronary artery disease was an exclusion criterion, how did you know a patient had it? By history alone?
  • Please show an age histogram of all units given at each threshold. This will let us see if there is any age bias present.
  • How low did the Hgb actually get in both groups? A histogram would be nice on this one, too.
  • Do you have any recommendations regarding selection based on age, frailty, or other parameters? What is your practice now?
  • Your outcome measures are somewhat crude, meaning that one would not really expect much of a change in those variables due to an extra unit or two of blood. What about adverse reactions that necessitated a fever workup or other intervention? Any differences between the groups there?

Click here to go the the EAST 2017 page to see comments on other abstracts.

Related posts:

Reference:   Effects of a more restrictive transfusion trigger in trauma patients. Poster #38, EAST 2017.

General

EAST 2016: (F)utility Of Transfusion In Flight

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Air transport of trauma patients has resulted in the creating a mobile intensive care unit in the passenger compartment of the aircraft. Since trauma patients frequently need blood, it was logical to begin stocking blood products on board. Once again, though, it sounds like a good idea. But does it make a difference?

Vanderbilt University carried out a retrospective review of aeromedical transports to its Level I trauma center. The authors chose overall mortality and 24-hour mortality as their endpoints.

Here are the factoids:

  • 5581 patients were entered into the study. This represented all trauma scene transports to this trauma center over 7 years.
  • Only 4% of these patients (231) received blood in the aircraft.
  • Multivariate regression analyses were performed with and without propensity score matching. (Sorry, just had to throw that in there to make your head spin!)
  • There was no significant improvement in 24-hour or overall mortality when blood was given. This was true using all of their statistical methods.

Bottom line: This abstract seems to corroborate a few other studies that show no benefit to prehospital blood administration. So why do we still do it? Because we don’t know the full answer yet. Using mortality alone is a very crude outcome measure. What about early complications, ventilator times, time in the ICU, and other soft measures? More work is needed to slice and dice this appropriately enough to answer the question.

Reference: Blood transfusion: in the air tonight? EAST 2016 Oral abstract #5, resident research competition.

General

ABC: A Quick & Dirty Way to Predict Massive Transfusion

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It’s nice to have blood available early when major trauma patients need it. Unfortunately, it’s not very practical to have several units of O neg pulled for every trauma activation, let alone activate a full-blown massive transfusion protocol (MTP). Is there any way to predict which trauma patient might be in need of enough blood to trigger your MTP?

The Mayo Clinic presented a paper at the EAST Annual Meeting a few years ago that looked at several prediction systems and how they fared in predicting the need for massive transfusion. Two of the three systems (TASH – Trauma Associated Severe Hemorrhage, McLaughlin score) are too complicated for practical use. The Assessment of Blood Consumption tool is simple, and it turns out to be quite predictive.

Here’s how it works. Assess 1 point for each of the following:

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

A score >=2 is predictive of massive transfusion. In this small series, the sensitivity of ABC was 89% and the specificity was 85%. The overtriage rate was only 13%.

The investigators were satisfied enough with this tool that it is now being used to activate the massive transfusion protocol at the Mayo Clinic. Although the abstract is no longer available online, it appears to be remarkably similar to a paper published in 2009 from Vanderbilt that looks at the exact same scoring systems. Perhaps this is why it never saw print? But the results were the same with a sensitivity of 75% and a specificity of 86%.

Here’s a summary of the number of parameters vs the likelihood the MTP would be activated:

ABC Score         % requiring massive transfusion
0                                1%
1                               10%
2                               41%
3                               48%
4                             100%

Bottom line: ABC is a simple, easy to use and accurate system for activating your massive transfusion protocol, with a low under- and over-triage rate. It doesn’t need any laboratory tests or fancy equations to calculate it. If two or more of the parameters are positive, be prepared to activate your MTP, or at least call for blood!

Related post:

References: 

  • Comparison of massive blood transfusion predictive models: ABC, easy as 1,2,3. Presented at the EAST 24th Annual Scientific Assembly, January 26, 2011, Session I Paper 4. (No longer available online)

  • Early prediction of massive transfusion in trauma: simple as ABC (assessment of blood consumption)? J Trauma 66(2):346-52, 2009.

General

Blood Transfusion With Component Therapy vs Whole Blood

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About 40 years ago, blood banks started moving away from keeping whole blood and began separating it into components (packed cells, platelets, plasma, etc.) for more targeted use. For most uses, this is just fine. But what about trauma?

Trauma patients bleed whole blood. Doesn’t it make sense to give whole blood back? Much of our experience with massive transfusion is derived from our colleagues in the military. Two decades ago, the norm was to give 4 units of packed red cells or so, then give two units of plasma, and every once in a while slip in a bag of platelets. Our military experience seems to indicate that this 4:2:1 ratio is not optimal, and that something like 1:1:1 is better.

If you think about it, whole blood is already 1:1:1. Splitting it into components and then giving each one of them back separately seems to be a lot of extra work (and expense) to accomplish the same thing as just giving a unit of whole blood. And if you look at the purple table above, rebuilding a unit of whole blood from components isn’t nearly as good as whole blood. Plus it triples the exposure to infectious agents and antigens, since the components will usually come from (at least) three separate donors. Note that the data in the table above is true for fresh whole blood (not practical in civilian life); banked whole blood will still lose some coagulation activity. 

Is it time to think about supplying whole blood to trauma centers? And actually looking at whether the outcomes are better or not?