We filter the water we drink, but why not the blood we transfuse is the common refrain one hears from practitioners in India, as they continuously endeavour to improve the safety of the blood components transfused says, Chetan Makam, Vice President and General Manager, Haemonetics
What is Leucoreduction?
The terms leucoreduction and leucodepletion as used interchangeably, depending on the standard followed is a US or EU standard of permissible amounts of WBCs in the final blood component. US Standard < 5×106 WBCs/unit; EU Standard < 1×106 WBCs/unit.
A common misconception is that when the whole blood is spun down into its components and some of the WBCs are segregated into the buffy coat, that this is a leuco depleted product. In reality, this process provided a 1-log reduction in the WBCs, whereas the standards call for a 5-log reduction.
Why should we Leucoreduce?
Leukocytes are unnecessary contaminants in unfiltered blood products and have been reported to be responsible for a variety of adverse reactions, including alloimmunization, febrile non-hemolytic transfusion reactions, immuno suppression and transmission or reactivation of intracellular virus, i.e., cytomegalovirus. Leukocyte reduction has been demonstrated to be clinically effective in reducing the incidence of these transfusion-related complications which can significantly decrease the cost of medical care producing considerable cost reduction for hospitals.
What patient groups are indicated for providing Leucoreduced blood components?
Leucocyte reduced blood components are often provided for specific patient groups, however, a growing number of hospitals are now providing all blood components leucoreduced.
The reasons for this are – growing evidence supporting the benefits of leucocyte reduction for surgery and ICU patients, recommendations of governing bodies, and adoption of Universal Leucoredution in many countries.
Are there countries with 100 per cent Leucoreduction?
In India, only about six percent of the approximately 8.5 million units of blood collected is leucoreduced, compared to 100 percent in many countries such as UK, France, Germany, Switzerland, Austria, Scandinavia, Spain, Portugal, Netherlands, Belgium, many other countries are targeting 100 percent leucoreduction or Universal Leucoreduction (ULR). In US around 80-90 percent of the blood is leucoreduced.
Transplant patients, cardiac surgery patients in the ICU, patients in NICU, oncology patients and thalassemia patients who require multiple transfusion as the primary recipients of leuco reduced blood in India today. While some progressive centers and hospitals that cater to a sizable medical tourism population have adopted near 100 percent leucoreduction, most centers either leuco reduce blood on the clinicians demand or not all.
Filtration of blood can happen at different points along the blood supply chain namely, at the patient bedside, just prior to transfusion, in the lab on demand or as a practice of keeping a small inventory for the patients in critical care or at the time of processing the blood into components, usually at centers that have adopted 100 percent leucoreduction (ULR). Decisions about when and where to leukoreduce are based on cost considerations, convenience and patient benefits.
The timing of when to filter the blood components is also important.
Laboratory and bedside filtration both have advantages. Laboratory filtration at the time of collection prevents the accumulation of bioreactive substances released by stored leukocytes that have been associated with patient reactions. An advantage of bedside filtration is that specific leukocyte reduction filters consistently will reduce the level of the anaphylatoxin C3a, which is associated with proinflammatory and immunomodulatory effects.
Filtering red blood cells
When RBC units are leukocytereduced prior to storage, a decrease occurs in the concentration of substances (e.g., serotonin, histamine, acid phosphatase and elastase) that are released by leukocytes and platelets during storage.