Tag Archives: transfusion

EAST 2019 #5: Safety Of Whole Blood

What goes around comes around. Fifty years ago, blood banks began fractionating whole blood into separate products so that specific component therapy could be administered. Over a relatively brief period of time, the switch to components became nearly complete, and whole blood was not available for civilian use. For decades, trauma professionals have had to treat our trauma patients losing whole blood, but having only components available to replace it. Unfortunately, taking blood apart and putting it back together just isn’t the same, as you can see below:

In recent years, there has been a significant movement to reintroduce whole blood. Many trauma centers are experimenting with it, and it seems we are having to relearn how to use it again. At last year’s EAST meeting, the US Army Institute of Surgical Research presented a paper that demonstrated improved survival in select severely injured patients. This year, an abstract from the University of Texas in Houston is being presented that explores the safety of giving whole blood.

This was a single-hospital study where cold-stored low titer type O whole blood (WB) was stocked in the center’s helicopters and emergency department. Components were also available. The center reviewed their 7 month experience with trauma patients who received either type of product. Their outcome variables were safety profile and transfusion reaction rates.

  • 161 patients received component therapy and 95 received WB during the study period
  • ISS was statistically similar, but the abbreviated injury score for chest was higher in the whole blood group (see first two bullet points below)
  • Whole blood patients were more markedly impaired in the prehospital setting (higher pulse and lactate, lower blood pressure)
  • Whole blood patients received fewer units of products after leaving the ED, which is an 80% reduction when matched for the usual variables (0 vs 3)
  • Mortality was the same in the two groups (26% WB vs 22% component)
  • There was only one transfusion reaction, and it occurred in the component group

The authors concluded that whole blood appeared to be a safe alternative to 1:1 component therapy, and was associated with a reduced need for post-ED transfusion.

  • How were patients selected to receive components vs whole blood? Or were they? This could potentially influence many of the variables you analyzed (vital signs, lab values). Be sure to explain how selection bias may have influenced your results.
  • Some of your variables are statistically similar (i.e. ISS) but clinically different, or vice versa (24 hour bilirubin, chest AIS). Be prepared to explain why these results are or are not meaningful.
  • What do the terms safety profile and impact mean in your objectives section. You mention transfusion reaction rate separately, so what other safety and impact factors were you measuring?
  • Once again, statistical power is a question. Did you do a power analysis? I worry that a difference of 1 transfusion reaction in 250 patients was used to call whole blood safe.
  • How do you know the decrease in post-ED transfusions was due to use of whole blood? Please make sure to summarize the resuscitation given to the two groups while they were in the ED. Did the component group receive fewer units in the ED, thus requiring more afterwards? And vice versa for the whole blood group. Did they get more enroute to the hospital and in the ED?

This was a very interesting abstract. I’m looking forward to hearing many more details when you present.

Reference: Safety profile and impact of low-titer group O blood for emergency use in trauma. EAST 2019 Paper #16.

Jehovah’s Witnesses And Blood Transfusion Demystified

Injury can be a bloody business, and trauma professionals take replacement of blood products for granted. Some patients object to this practice on religious grounds, and their health care providers often have a hard time understanding this. So why would someone refuse blood when the trauma team is convinced that it is the only thing that may save their life?

Jehovah’s Witnesses are the most common group encountered in the US that refuse transfusion. There are more than 20 million Witnesses worldwide, with over 7 million actively preaching. It is a Christian denomination that originated in Pennsylvania during the 1870s.

Witnesses believe that the bible prohibits taking any blood products, including red cells, white cells, platelets or plasma. It also includes the use of any dialysis or pump equipment that must be primed with blood. This is based on the belief that life is a gift from God and that it should not be sustained by receiving blood products. The status of certain prepared fractions such as albumin, factor concentrates, blood substitutes derived from hemoglobin, and albumin is not clear, and the majority of Witnesses will accept these products. Cell saver techniques may be acceptable if the shed blood is not stored but is immediately reinfused.

Why are Witnesses so adamant about refusing blood products? If a transfusion is accepted, that person has abandoned the basic doctrines of the religion, and essentially separates themselves from it. They may then be shunned by other believers.

So what can trauma professionals do to provide best care while abiding by our patient’s religious belief? In trauma care it gets tricky, because time is not on our side and non-blood products are not necessarily effective or available. Here are some tips:

  • Your first duty is to your patient. Provide the best, state of the art care you can until it is absolutely confirmed that they do not wish to receive blood products. In they are comatose, you must use blood if indicated until the patient has been definitively identified by a relative who can confirm their wishes with regard to blood. Mistaken identity does occur on occasion when there are multiple casualties, and withholding blood by mistake is a catastrophe.
  • Talk with the patient or their family. Find out exactly what they believe and what they will allow. And stick to it.
  • Aggressively reduce blood loss in the ED. We are not always as fastidious as we should be because of the universal availability of blood products. Use direct pressure or direct suture ligation for external bleeding. Splint to reduce fracture bleeding.
  • Aggressively use damage control surgery. Don’t go for a definitive laparotomy which may take hours. Pack well, close and re-establish normal physiology before doing all the final repairs.
  • Always watch the temperature. Pull out all the stops in terms of warming equipment. Keep the OR hot. Cover every bit of the patient possible with warming blankets. All fluids should be hot. Even the ventilator gases can be heated.
  • Think about inorganic and recombinant products such as Factor VIIa, tranexamic acid and Vitamin K. These are generally acceptable.
  • Consider angiography if appropriate, and call them early so their are no delays between ED and angio suite or OR and angio suite.

Bottom line: Do what is right for your patient. Once you are aware of their beliefs, avoid the use of any prohibited products. Speak with them and their family to clarify exactly what you can and cannot do. This is essentially an informed consent discussion, so make sure they understand the consequences. Follow their wishes to the letter, and don’t let your own beliefs interfere with what they want.

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.

EAST 2018 #10: Fresh Whole Blood And Survival

Decades ago, our blood bank system began disassembling units of donated blood, ushering in the era of component therapy. Now, it seems, we are seeing the light and starting to re-look at the concept of using fresh whole blood. To see the difference between fresh whole blood and “rebuilt” whole blood from components, read this post.

The military has a keen interest in studying the practice of using whole blood, since combat locations have a considerable number of “walking blood banks” (i.e. soldiers) . An abstract being presented tomorrow at EAST was submitted by the US Army Institute of Surgical Research. They performed a straightforward study looking at mortality in combat casualties, comparing troops who received fresh whole blood (FWB) to those who received component therapy (kind of). They used regression analysis to try to identify and control for other variables, and also analyzed a subgroup who required massive transfusion.

Here are the factoids:

  • A total of 215 soldiers received FWB, and 896 did not. Of note, the non-FWB patients did not necessarily receive platelets.
  • Overall, survival was similar in both groups at about 94%
  • After controlling for physiologic injury severity and blood product/crystalloid volumes, the risk of death was twice as high in the group that did not receive FWB
  • Survival was higher in FWB patients who underwent massive transfusion (89% vs 80%), although this was only marginally significant

Bottom line: I see this an an interesting but preliminary study, with many unanswered questions. It’s not really a comparison of patients receiving fresh whole blood vs component therapy, because not all of the latter patients received platelets. It also did not take into account the specific anatomic injury areas, particularly critical ones such as brain injury. But this study should certainly stimulate some better designed projects for followup.

Here are some questions for the authors to consider before their presentation:

  • Did you do a power analysis to estimate how many patients would need to be enrolled to discover a real difference? If so, how many?
  • Have you performed a subanalysis on patients in the non-FWB group who received platelets? This would then be a comparison of FWB vs component therapy.
  • Any idea of the age of the components given vs the day 0 FWB?
  • Be sure to show and interpret your significance testing in the presentation

Reference: EAST 2018 Podium paper #15.

EAST 2018 #2: Blood Product Age And Mortality

Ever since the start of the modern transfusion age (which was really only about 75 years ago), we’ve been trying to extend the life of banked blood products. Currently, we get about 6 weeks of useful life from packed red blood cells, and varying amounts from other frozen or non-frozen products.

What happens at day 42 for red cells? Or day 5 for platelets or thawed plasma? It’s not like a switch gets flipped and it suddenly goes bad. Each of these products slowly degrades over time, and the myriad components that make them up (proteins, clotting factors, etc) do so at varying rates. It has been recognized for years that some of these products “don’t work so well” when they age, and this has been termed the “storage lesion” of blood.

The next EAST paper I’ll review looks for associations between use of older blood products which probably have a storage lesion, and mortality in trauma patients. It re-analyzed the prospectively collected data on the 680 patients enrolled in the PROPPR trial, which was originally designed to examine the mortality difference between patients with specific FFP:platelet:PRBC ratios given during massive transfusion. In this re-analysis, the authors looked at the mortality after 6 hrs, 24 hrs, and 30 days in patients undergoing massive transfusion, and examined the impact of using “older” blood products. “Old” was defined using the median age of the product; RBCs were old after 20/42 days, plasma after 2/5 days, and platelets after 4/5 days.

Here are the factoids:

  • Plasma age decreased with increasing transfusion. There was no similar change in average platelet or RBC age, though.
  • Patients receiving older RBC and younger plasma had higher mortality
  • Receiving older PRBC was associated with mortality at 6 and 24 hrs, but not 30 days

Bottom line: First, this is an association study, not a causation one. Don’t read anything more into it than you see. And what do you think when you see random mortality numbers like this? For me, either mortality is too crude of a variable to use, or the association is just too weak. If you look at the data table for the study, the confidence intervals of the computed “hazard ratios” barely clear the 1.0 line. To me, this looks like an interesting mathematical exercise, but I can’t tease any clinical significance out of it at all. And I don’t think that re-analyzing this dataset will provide any further clarity.

Here are some questions for the authors to consider before their presentation:

  • Did you try to calculate the statistical power of your dataset? As mentioned above, the associations look weak at best.
  • Did you look at other potential factors like injury severity score or massive transfusion volumes? These would seem to have a much more significant impact on the three survival cohorts?
  • Big picture questions: Where can you go from here? What kind of study could you do to see if this is a real effect vs just a statistical anomaly?

Reference: EAST 2018 Podium paper #3.