hemoglobin detrmination after transfusion

[Dr. Pepper]

Does anyone have any hard data on how soon after transfusion an accurate hemoglobin/hematocrit may be performed? Thanks - Phil

[GilTphoto]

I would also like to know. My hospital is having a big problem with overtransfusion. About 15 patients per month are transfused to greater than 12 Hgb.

We are considering a policy that H+H's must be done between units, unless rapidly bleeding, to avoid overtransfusion.

Many were having more than a 2 gram increase per unit. We reviewed the patient's weight to see if they were small, but most occurred after Lasix was given, but a few were due to a diluted sample drawn by ER staff for the pre-transfusion H+H. If an H+H had been done between units, most of the overtransfusion would be eliminated.

We are using 2 hours, but no hard reference. Most doctors are ordering: Transfuse 2 units and CBC in AM, which is causing the problem. A very high percentage are also receiving Lasix. WE must have a high number of CHF patients!

[tbostock]

I have never seen any hard data either, but have always recommended the 2 hours if time allows.

And we are also starting to recommend single units, but not much success yet. Seems like the docs LOVE even numbers ("transfuse 2 units of RBC", "transfuse 4 units of FFP").

[Dr. Pepper]

I use the 2 hour rule of thumb as well, I was just wondering if there was a scientific base to that or another time frame.

Terri, you are right about the even numbers, no one ever gets 1 or 3 units of FFP unless they die before getting the last one. Odd that in photography, art and food presentation odd numbers of things in the picture are considered more pleasing to the human eye.

Before automated blood pressure machines, BPs were magically, somehow always in multiples of 5.

[Deny Morlino]

Seems like the docs LOVE even numbers ("transfuse 2 units of RBC", "transfuse 4 units of FFP").

That is because they trained many years ago that "If you are only ordering one unit, you don't need to transfuse." I have had more than one physician explain this to me when asked why 2 or 4 units but not 1 or 3. We have been working on the single unit issue for about 3 years now with our pathologist leading the way by conferring individually with physicians to educate them. Hang in there as we are making progress.

[GilTphoto]

Seems like the docs LOVE even numbers ("transfuse 2 units of RBC", "transfuse 4 units of FFP").

I wish I could get the doctors to order 4 FFP. In my hospital 90% of FFP orders are only for 2 units. And they wonder why the PT, PTT didn't get better. That is if they bother to check them again. About 30% never reorder the PT, PTT.

We want to make it a policy that post transfusion testing of the trigger indicator is done for all products.

Has anyone done that? and cares to share the policy?

oopps. I moved off subject! sorry!

[Mabel Adams]

Years ago I read (Lab Medicine Q&A, I think) that a post-transfusion h&h will be not be accurate until 24 hours after the transfusion due to the patient's blood volume needing time to adjust. I don't know for sure that they had solid science for that idea either but I know that is what they tell you when you donate. Since 24 hrs is highly impractical in acute care you have to check it at a shorter time and realize you are getting a ballpark answer. You also have to try to factor in the CHF, other fluids, lasix etc. etc. that can also alter blood volume. That's why people with no training can't do our jobs.

As for diluted specimens causing overtransfusion, the LEAN approach would be to solve the underlying problem and get better samples collected in the first place--do it right the first time.

[dotdoc]

Does anyone have any hard data on how soon after transfusion an accurate hemoglobin/hematocrit may be performed? Thanks - Phil

Spencer DH, et al. Clinical Chemistry 2011. 57:344-6. The authors in this study measured A1c 28 or more days before and 14-21 days after transfusion. They found that transfusion of one or more units reduced A1c by 0.83% in all subjects. When they looked at subjects with an A1c of 7% or greater prior to transfusion, the decrease in A1c was almost 2%. The mechanism was presumably dilution of the subjects' more glycated blood with less glycated donor blood.

I don't know when A1c is accurate after Xfusion. It's more than 3 weeks.

Our hospital is pushing for a CPOE rule that would prevent ordering A1c within 60 days of a transfusion. The rationale for waiting seems reasonable; I suspect the suggested "60 day" interval is based on the expected avg. in vivo lifespan of donor RBCs.

[aafrin]

That is because they trained many years ago that "If you are only ordering one unit, you don't need to transfuse." I have had more than one physician explain this to me when asked why 2 or 4 units but not 1 or 3. We have been working on the single unit issue for about 3 years now with our pathologist leading the way by conferring individually with physicians to educate them. Hang in there as we are making progress.

I agree the old timers were trained to think "one unit transfusion is no transfusion and should be avoided cause the risks of such a transfusion outweigh the benefits". In those days BBs were told to find out which doctors are giving only one unit transfusion, so that the pathologist could talk to them to avoid such transfusions. During seminars & conferences also such slides were presented. With changing times, available technology, proper scientific understanding & risk mitigation, today complete opposite view is presented.

As to checking H+H, doctors usually check after 2-4 units are transfused for cost-effectiveness, as they presume that one unit will increase hb by 1gm/dl - that is also if they do check. At our hospital also we are talking to doctors, but with a very little headway.

[Jane]

I read recently that H&H equilibrates within 15 minutes after a unit transfusion. I found it in "A Compendium of Transfusion Practice Guidelines" published by ARC in 2010. The same reference says to measure the platelet count 10-60 minutes after transfusion. It doesn't state an amount of time for PT/PTT following plasma.

Hope this helps!

Jane

[SMILLER]

A few random observations:

I think that the current consensus is to transfuse less rather than more. The old "if you only need one unit..." dogma resulted in doctors ordering 2 units instead of one, when the point was that they should be ordering none in situations where only one is ordered. Nowadays, triggers re lower, and we are seeing alot more single unit orders (as opposed to 2 unit) but I think this is a step in the right direction.

Patients apparently do indeed do very well with lower transfusion triggers. There have been studies that show that in many cases, they can do better or as well as patients who have been transfused. Then there are the risks associated with any transfusion: TACO, TRALI, not to mention those annoying febrile reactions.

For patients that need to be transfused regardless of the above: I believe most physicians give blood empirically. By that I mean, if the trigger is reached, you give enough blood or whatever to correct the problem. Only in patients with an ongoing "acute" hematological issue (like a GI bleed, DIC, coumadin reversal, whatever) would you need to check the "effect" of the transfusion.

Having said all that I, too, have heard that hemodynamically, things don't even out for about 24 hours after a transfusion. As noted by others above, a patient's therapy and condition (lasix, other perfusions, active bleeds, etc. etc.) is going to make even that iffy as to being able to predict the precise effect of the transfused product.

Scott

[AMcCord]

We try to wait 30 minutes post red cell transfusion to check the H&H. It seems to correlate pretty well with the H&H we see for the In AM CBC draw the next day on non-bleeding patients, though I have not collected data to prove that. The ARC guideline that Jane mentions made me more comfortable with the 30 minute timing.

[AMcCord]

On the subject 'transfuse 1 or 2'...we are about to launch into a full scale blood management program. Should be a fun time for everyone! but our CMO is very determined to make it work. It will also be wrapped into physician credentialing, so it will have some teeth.