The functional components of a red blood cell concentrate are the red blood cells, the erythrocytes. They are responsible for transporting oxygen in the body. A lack of erythrocytes is called anaemia and, depending on the severity, manifests itself with pallor, tachycardia, reduced resilience and shortness of breath. The exact value at which a patient must be substituted with erythrocytes cannot be defined uniformly. A slowly developing anaemia, e.g. due to occult gastrointestinal bleeding or in the context of leukaemia, cause fewer to no complaints. Acute haemorrhage, on the other hand, is a life-threatening condition that must be treated immediately, with the emphasis here on volume replacement. Additional diseases such as CHD and the patient's age must also be considered.

Most guidelines recommend the transfusion trigger of 7-9g/dl Hb. However, the clinical condition of the patient - the physiological transfusion trigger - is always decisive. The indication for the administration of red blood cell concentrates should always be very strict.

A regular red cell concentrate has a volume of about 300ml, the haematocrit is 50-70%, and the cells are suspended in an additive solution (SAG-M), which reduces the plasma content to a minimum. In Austria, only leucocyte-depleted red cell concentrates are approved.  This measure minimises the occurrence of GvHD and the transmission of cell-bound viruses (CMV).

Indications for additionally pretreated red cell concentrates:

Centrifuging and resuspending the red cells 1-2 times in an isotonic solution removes most plasma proteins and residual platelets. Substances such as potassium, which escape from the cells during storage and accumulate in the additive solution, can also be removed. The main indications for such treatment of red cells are intrauterine transfusion or in patients who have had an allergic reaction to plasma proteins.

Red cells treated this way must be transfused within 12 hours.

Especially for intrauterine transfusion, the washed red cell concentrate is additionally irradiated. The irradiation also inactivates the remaining leukocytes. This prevents an immunosuppressed or immunoincompetent patient from developing GvHD (Graft versus Host Disease). Which patients fall under these definitions depends on the hospital. In 2020, the indications for irradiated ECs were reduced significantly. Leukaemia patients before and after stem cell therapy, children up to about six months of age and patients with primary immunodeficiencies should receive irradiated red cell concentrates in any case. A summary of the indications from the Austrian Haemotherapy Guidelines can be found here. 

And those who would like to know precisely when and why irradiated red cells are indicated should read the British guidelines from 2020:

Foukaneli T, Kerr P, Bolton-Maggs PHB et al. Guidelines on the use of irradiated blood components. British Journal of Haematology 2020; 191: 704.

If you are unsure, you should never forget: radiation does not harm anyone - not even the cells - TA-GvHD (Transfusion-Associated Graft versus Host Disease) almost always kills the patient. However, supplying the patient with blood comes first. Even with a "hard" indication, radiation should be waived if the patient needs blood in an emergency. 

It is also good to know that there have been no reports of TA-GvHD after transfusion of blood older than 14 days. The leukocytes do not survive that long in the blood unit.

In Innsbruck, according to Austrian guidelines, irradiated erythrocyte concentrates can be kept for 14 days. Other institutions sometimes have different shelf-life criteria, which vary between 24 hours and 14 days.

Patients who have developed irregular antibodies - after previous transfusions or through pregnancy - must receive red cell concentrates that do not have the antigen against which the antibody is directed. For most antigens, this is not a big problem. However, suppose it is a very common antigen (i.e., only a few donors do not have the antigen) or a mixture of antibodies. In that case, the blood supply of such patients can be complex and often requires the cooperation of several institutes.

Baby bags are prepared from a regular red cell concentrate which must not be older than five days. One red cell concentrate is divided into four baby bags.

European countries emphasise the short storage time of baby units - a maximum of 5 days. On the other hand, other countries have a different approach to this - because many such units are given to premature babies, a very fresh unit of blood is taken there and assigned to one child. Whenever the child now needs blood transfusions, it is taken from the same unit until it has expired. In this way, you reduce donor exposure in the children. 

The guidelines for treating patients with blood products (haemotherapy) were issued almost 15 years ago by the KAV (Hospital Association) in Vienna. They would have been the basis for using blood products, at least in regional hospitals in Vienna. I doubt that it has been implemented... Since transfusion specialists do everything but give transfusions, we are more or less dependent on the attitude of the individual doctor. Not many years ago, I heard the classic saying "one is none" in a Viennese hospital. Single red cell concentrates were practically not given at all - there were always at least two.

The German guidelines were published, and PBM (Patient Blood Management) began finding its way into surgeons' heads. In the meantime, there has been a considerable decrease in the use of blood units, but... there is still plenty to do.

Blood products are emergency meds and should be used as such. If my aunt needs an artificial joint and the surgery is planned four months in advance, and the aunt is anaemic, then blood products should not be considered. Instead, the main question should be why the aunt is anaemic. And then, the cause of the anaemia is treated.

Austrian haemotherapy guidelines were issued by the ÖGBT in June 2019.