Tag Archives: transfusion

EAST 2017 #4: A More Restrictive Transfusion Trigger?

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.

EAST 2016: (F)utility Of Transfusion In Flight

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.

ABC: A Quick & Dirty Way to Predict Massive Transfusion

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.

Blood Transfusion With Component Therapy vs Whole Blood

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?

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.