Category Archives: Laboratory

Laboratory, Resuscitation

MTP Week Part I: How To Build Your Massive Transfusion Protocol

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It’s Massive Transfusion Protocol (MTP) week! I’m releasing the next Trauma MedEd newsletter to subscribers at the end of the week, which deals with advanced MTP topics. So leading up to that, I’ll be reviewing the basics for the next several days. I’ll start today with tips on how to build a solid MTP at your center.

Your massive transfusion protocol is a complex set of processes that touch many, many areas within your hospital. There are five basic components (and a few sub-components) to any MTP, so let’s dig into them one by one. They are:

  • Universality
  • Activation
  • Logistics
    • Components
    • Runners
    • Documentation
    • Coolers
  • Deactivation
  • Analysis

Let’s scrutinize each one, starting with the first two today.

Universality. This means that there should be one, and only one MTP in your hospital. I’ve seen some hospitals that have one MTP for trauma, one for cardiothoracic surgery, one for OB, one for GI, and on and on. Yes, each of those services deals with patients who are suffering from blood loss. But it’s the same blood that your trauma patients lose! There’s no need to create a protocol for each, with different ratios, extra drugs, etc. This can and will create confusion in the blood bank which may lead to serious errors.

Activation. This consists of two parts: how do we decide to activate, and then how does everyone involved find out that the MTP is actually being activated? I’ll discuss activation criteria on Thursday. But what about the notification process? Phone call? Order in the electronic medical record (EMR)? Smoke signals?

The most reliable method is a good, old-fashioned phone call. Do not use your EMR except for documentation purposes. Unless there is a very reliable system in the blood bank that translates an EMR order into an annoying alarm or flashing lights, don’t rely on this at all.

Then decide upon the minimum amount of information that the blood bank needs to begin preparing blood products. This usually consists of a name or temporary patient identifier, sex, and location of activation. Ensure that an ID or transfusion band is affixed to the patient so that wrong blood products are not given in multiple patient events.

Tomorrow, I’ll continue with the logistics of the MTP.

And don’t forget to subscribe to TraumaMed if you want to get a full newsletter discussing advanced MTP topics this Friday. Otherwise, you’ll be reading a post on CT scans and rib fractures in the elderly! Subscribe and download back issues by clicking here.

Links: (note – future links will not be live until 9am the day they are published)

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Laboratory

How Much Plasma Does It Take To Reverse Warfarin?

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For decades, plasma (with vitamin K) was the mainstay for reversing warfarin. Over the past several years, prothrombin complex concentrates (PCC) have made inroads in the management of this problem because of its sheer speed of action.

There are two problems with plasma. First, most hospitals still have only fresh frozen plasma (FFP), and it takes 20-30 minutes to thaw. This adds some up-front time to administration. Then, it takes time to infuse the 250cc or so of volume in each unit. This may be 1 or 2 hours, depending on policy and patient tolerance of a bolus of colloid.

If it always just took one unit of plasma to correct the INR to a desirable range (typically 1.5-1.6), then the whole PCC conversation might be moot. You could potentially have the INR corrected in 30-60 minutes depending on your patient’s cardiovascular system.

But how many does it really take? A group at Eastern Virginia Medical School in Norfolk, VA looked at this problem and tried to come up with a mathematical formula. They examined a year of warfarin reversal data at their hospital. Patients with severe clotting disturbances (advanced cirrhosis, DIC) and those who received additional products (PCC or activated Factor VII) were excluded.

Using data from nearly 1,000 patients, the following formula was derived and validated:

∆ INR = (0.57 ∙ preINR) – 0.72

So a patient with an INR of 3.0 would be expected to show a decrease of 0.99 to about 2.0 after one unit. This formula can be used iteratively to figure out how many units will drop the INR to the goal range.

I don’t know about you, but I hate doing math in the middle of a trauma resuscitation. I need something quick and dirty. A physician from NYU Langone in NYC commented on the article, and derived a nice little table to simplify the process. He calculated the number of plasma units based on some common INR ranges, assuming that the goal was to get it down under 1.5. Here is the table:

Bottom line: This is a nice little piece of information to tuck into your pocket or phone. For patients inside the usual therapeutic values, it will take 2-3 units of plasma to reverse. For your average older human with average comorbidities, expect this to take 4-6 hours, not counting ordering, thawing, and delivery. If my definitions of “life-threatening bleeding” are met (see below), your patient may have significant adverse events during this time frame. So think very seriously about using PCC instead.

Related posts:

Reference: Fresh Frozen Plasma Dosing for Warfarin Reversal: A Practical Formula. Mayo Clin Proc 88(3):244-250, 2013.

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Laboratory, Solid organ

Platelet Count After Spleen Injury

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In most trauma textbooks, the most commonly injured solid organ is the spleen. There is a lot of work available that tells trauma professionals how to detect and manage spleen injuries. However, the treatment of the sequelae is less clear cut. We know that the platelet count generally rises after spleen injury, and especially if it is removed. We think we know that we should be on alert if the platelet count goes over 1 M per microliter (ul) to avoid thrombisis.

What happens during the usual hospital course? Is venous thrombosis actually a problem? A group at St. Michael’s Hospital in Toronto performed a 5 year retrospective review of their patients with splenic injury to try to answer these questions. Children and patients with known pre-existing coagulopathy or that were taking anticoagulants were excluded. All were managed with prophylactic low molecular heparin, although the specific product or protocol were not described.

Here are the factoids:

  • A total of 156 patients were enrolled over 5 years. – This is a relatively low number (31/year). In contrast, here in bustling metropolitan St. Paul we see 80-100 per year.
  • Nonoperative management was performed in 84% of cases, with angio-embolization added in another 8%. The other 8% were taken to OR, where most underwent splenectomy. – This is spot on with national data. However, looking at their injury grade breakdown, it seems like they take out a higher than usual number of low grade spleens.
  • Platelet count rose steadily after admission, peaking at day 16-17.
  • Splenectomy patients had a mean peak platelet count of 890K/ul.
  • Nonop management patients had a mean peak of 604K/ul.
  • Extreme thrombocytosis (counts > 1M/ul) occurred in 25 patients (16%). It occurred in 41% of splenectomy patients, but only 6% of nonop patients.
  • Although DVT and PE occurred in these patients (8%, which seems a bit high), there was no association with thrombocytosis, extreme thrombocytosis, or aspirin use. – This is most likely due to the small size of the study. 

Bottom line: This small study provides some interesting and important information regarding the platelet count trend after splenic injury. Although there was not enough power to look at the association with DVT, PE, and the value of aspirin treatment for extreme thrombocytosis, the platelet count trend info was very interesting. It looks like we should be checking a platelet count about 2-3 weeks after injury to make sure it’s not reaching extreme levels. This can be scheduled during their postop or post-discharge visit. A reminder should also be sent to the primary care physician to be on the lookout for extreme thrombocytosis for the first three weeks post-injury.

Reference: Thrombocytosis in splenic trauma: In-hospital course and association with venous thromboembolism. Injury, in press, 2016.

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