An enlightened Orthopaedic Surgeon, oh happy days!

In an average 70kg person one could expect a 10g/L rise in Hb per unit of blood transfused.  Ideally one unit is transfused at a time the patient reassessed and then another decision made as to the need for further blood.  However if the patient had a post-op Hb of 65g/L and was getting angina it would be reasonable to transfuse 2 units to achieve a Hb >80g/L and then reassess. 

The prescription of an automatic "2 unit top up" is no longer accepted as good transfusion behaviour in "enlightened" circles.

May be not all orthopaedic surgeons are as aware as they should be

Speaking as an enlightened orthopod (our department achieved best practice commendation in NSW last year), I will tolerate Hb down to the low 70's without symptoms in people with no cardiovascular risk. I will act if there is persistent dizziness before then.

My question is then, in the average sized adult, when I wait this for those thresholds, would a single unit be enough? I tend to give two. Should I titrate unit by unit?

Complemets on this concept

i am a rural specialist and i am constatnly frustrated to find my patients transfused 1-2 units post op when their HB is >90!

I even had a patient transferred from A&E with a measured Hb of 140 and 2 units ordeded to be transfused - ordered by a FACEM.

we need better education to the Orthopaedic surgeons and FACEMs regarding rational Blood transfusion practice.

On another note I have recently come back from Afghanistan where we had a frozen Blood bank (RBC, Platelets and FFP) and it was a fantastic asset for serious trauma.

We need the same thing here especially for rural centres

Our old system is more typical of blood bank off site hospitals - probably most private hospitals.

A decision is made pre-op to either group and screen or cross match.  If G&S then this occurs as above.  Now if blood is ordered for the patient a physical cross-match has to take place - the pre-op G&S sample with donor blood.  This takes about 40 minutes for a full cross-match, labeling/issuing, then transport time on top. 

If cross match was ordered pre-op then a physical cross match is performed pre op, the blood is labeled/issued to the patient and transported to the hospital's blood fridge where it stays until required or if not returned to the blood bank.  For this patient the blood is readily available in the local fridge.  The time will mainly depend on the transport time and checking correct blood is taken from the fridge.

When our blood bank moved on site we abandoned our blood fridge in theatre and moved to electronic cross matching.  This now means

- in reality no decision as to G&S or X-match needs to be made pre-op - no need for a Maximum Blood Ordering Schedule (MBOS) - most doctors are unaware of this

- the blood supplier can carry a smaller stock as blood is not pre-allocated to patients and then stuck in distant blood fridges for up to 72 hours, during which time it is not avaialble to be issued to another patient

- previously about 50-60% of blood cross matched and issued to individual patients was transfused, the rest was returned to the blood bank 72 hours later and 72 hours older.  Now 96-7% of blood issued is transfused

- blood can be ordered by phone and delivered rapidly (under 10 minutes).  If antibodies are detected when the blood is grouped and screened pre-operatively then our blood supplier does physically cross match the blood which is labeled/issued for the individual patient, clinicians are informed.

Dr O'Mara does your timing estimates for cross match apply in the private sector as well?

We found in our recent audits that women were more often over transfused than men. Almost half of all women are overtransfused because two units is often too much for the smaller vascular volume that women have.  we are recommending one unit transfusion 'top ups' and reassess the patient.

I note Amandas comment. I found out that most non haematolgists think it takes two hours to crossmatch. They did not realise that it is done by a computer in less than 10 minutes. The exception is iff the patient has antibodies or does not have a valid group and antibody screen.

I think that another reason for the 2 (+) units request related to our blood transfusion laboratory techniques. The older techniques were time consuming and it was more efficient to crossmatch 2 (+) units in case further units were needed. (I think that often if crossmatched blood is available for a patient then it frequently  gets used just because it is there.)

Fortunately with computers and streamlined techniques laboratories can now provide blood for most patients within 10 or so minutes (if a current group and screen sample is available). Therefore, now if the clinical decision has been made that a transfusion is needed then request for a single unit is fine. A number of laboratories actually have introduced a policy of only crossmatching a single unit unless it is a situation of critical bleeding. 

Thanks Bruce and Richard, your comments should be broadcast from the medical hilltops, where ever they may be. Perhaps Google may do the job and they will rise to the top of page one!

The use of 2 units is an old practice that dies hard. Each unit of blood is precious and if one unit is enough to restore adequate oxygen carrying content then that is what a patient should get. This out dated practice does result from the 1960's when people first started to think about oxygen carrying capacity and calculate oxygen content byt the equation. As such it was clear that if you were dealing with a 70kg person to give just one unit would only add about 5-7% of increased Hgb and the thought was thtat it simply was not a big enough boost. Since we rarely know why we are transfusing to begin with (in the 1-2 unit dosages) then having an old rule of thumb like this only sentences patients to twice the risk and creates twice the shortage. The whole goal of re-focussing on transfusion today is to say do we really know what we are doing? And further, in this particular patient do we really have a solid idea of risk and benfit. I put it to the readership that most 1-2 unit transfusions are treating a physician anxiety ( I need to do soemthing, or well maybe a transfusion would help), rather than a real physiologic oxygen delivery analysis or a thoughful risk benefit ratio discussion.

Bruce Spiess, MD

The appropriate amount of blood may be none, one or multiple units of blood depending on the patient and the clinical situation.  Best practice is each transfusion decision should be a conscious one based on a number of variables, maybe many times for one patient, and not just the reflex - give 2 units.  My philosophy is "Why give 2 when 1 will do?"  

A crude analogy would be playing Russian roulette - do you put 1 or 2 bullets in the chamber?  The answer - its a no brainer!!

There are a number of factors which have resulted in modern transfusion practice

The evidence that more is not better when it come to blood and may even be harmful

The evidence that blood can produce adverse effects

The increasing scarcity of blood

The increasing cost of blood

I have been told that the 2 unit transfusion adage is based on a paper from the 1940s but can not remember the details - perhaps someone else can?  Single unit transfusuions were (are?) frowned upon by Blood Banks as poor practice in the 60's.  The 2 unit "top up" transfusion has been taught in Medical Schools ever since and has become deeply entrenched in medical culture.  This was reinforced to me the other day when I stumbled on WHO's South-East Asia's website which currently states single unit transfusions are poor practice!  Education is the name of the game.

I agree and would add.

Dosage of blood component therapy is not different that other medical therapies.

After one unit of red cells the indication for the first unit may no longer be present.

In relationship to transfusion per se being a risk factor for adverse outcomes, there is a dosage effect

I was told the same thing when I was an Intern by my Registrars. It is only now that I realise that it was a load of rubbish. Nothing has changed, we were simply doing the wrong thing without any evidence.  It is interesting how the whole culture of transfusion evolved. We lack evidence for most of our Transfusion culture. It simply happened and we our now just finding out that it may be harmful.

In recent times we used be audited if we only gave a single unit transfusion to post op patients and that it was a 'flag' for an inappropriate transfusion. What has changed to make us think that a single unit is now best practice?