Producing Blood Components from donated Whole blood, or The art of the Impossible? Ian Symonds, Manufacturing Manager NHSBT Colindale

Transcription

1 Producing Blood Components from donated Whole blood, or The art of the Impossible? Ian Symonds, Manufacturing Manager NHSBT Colindale

2 Where does the blood come from & where does it go? Nationally we have a number of static collection sites (principally for Apheresis Platelet collection), and a large number of mobile teams who visit local venues to set up collection sessions. This blood is collected into one of two different pack types, the implications of which we will consider in a minute. These donations are then transported back to a decreasing number of Manufacturing sites, either directly or via our Hospital Services sites (S.H.U. s), for processing into the various blood components which are then distributed back to the S.H.U. s.

3 XXXXX XXXXX XXXXX XXXXX Two different collection packs, What does this mean? Whole blood filter pack (TAT) BAT packs are processed into final components and then leucodepleted. These packs provide the start material for Platelet pools. TAT packs are leucodepleted prior to further processing, and are used for most blood donors. Some products, e.g. Exchange Transfusion and IUT units can only be made from donations collected into this pack. Bottom and Top (BAT) pack

4 So How do the Teams know which Donor to bleed into which pack? Two days in advance of the session a stock algorithm runs to look at projected stocks, site by sits capacity and the number of expected donations. It then instructs the team how many of each pack type to take, and how many of each donor by group and sex to bleed into each pack type. Donors who have particular group characteristics, or who have been previously found suitable for Exchange transfusions for example, are identified from their DHC, and this will also influence the pack choice used. ALL such packs are tagged at session for ease of identification at the Manufacturing site.

5 That was simple, What could go wrong? There may not be sufficient collection activity planned for the demand on a given day, sessions are planned months in advance, demand can vary much more quickly. There may not be the right number of special donors, required Male/Female split or correct blood group mix attend the session (despite the correct donors being called). There may be a donation problem with the one suitable Exchange donor attending the session, e.g. failed venepuncture, Under weight collection, overweight collection etc. There may be a problem with the venue, leading to part or all of the session being cancelled. ALL of the above can impact on the units we receive, and so the components we can produce.

6 What Other considerations are there? If blood is in transit (from time of venepuncture to time of unpacking at SHU / Manufacturing site) for over 7.5 hrs then we can t make frozen products, if it s over 8 hrs then we can t make buffy coats either. If the blood takes more than 12hrs hours from venepuncture to 4oC storage, then it can t be used for Exchange, IUT or LVT production either. Due to the TRALI risk we don t make plasma products from female donors, which obviously reduces the pool of potential donations to work with. The demand for units may not be equal across the country, and the donor location may not match that of the patient. This is especially true for the Ro donor and patient populations. The labs and equipment (Rapid plasma freezers for example) have limited capacity and timeframes to work in so if the total number of units delivered into a Manufacturing site is too high or too low then we can not make a full range of products.

7 How do the packs get streamed at the Manufacturing Site? Using the information (donor sex, group, CMV-ve status, venepuncture time) written on the blood pack, and any information on tags attached to the unit, staff in Manufacturing undertaking session receipt manually sort packs into process streams. They also have to consider daily production targets for frozen products and Exchange units, equipment availability and timelines. Once streamed the packs are then logged onto the IT system to confirm which products we intend to make from each donation. Only once this has taken place can the units be transferred to the filtration or production pods for processing into their different components.

8 Secondary manufacture, re-engineering the past Packs destined for Exchange transfusion are adjusted to the correct heamatocrit on Day 1, and distributed to the SHU s. If not required for this use they are transported back to the Manufacturing site on Day 6 to be remanufactured into a SAG-M suspended red cell. This is suitable for conversion into a Neonatal top-up unit if Hospitals are prepared to take units over 7 days old! Packs for Top-up transfusion have to meet the same testing criteria, but do not need to have been refrigerated as quickly as exchange or LVT units. They are produced from the suitable donations not already processed into Exchange or LVT products, and have the same shelf life as an adult unit.

9 Secondary manufacture, re-engineering the past Other blood components manufactured from finished products include; CD platelets re-suspended in 100% PAS. Neonatal split CD platelets Washed red cells, These can only be produced at a Manufacturing site, and only with the units that are physically there. If the unit required is HLA matched, or phenotyped, there is a chance it will not be at the Manufacturing site this means that it will need transporting from an SHU to the Manufacturing site for processing. Equally, even if the unit is at the manufacturing site, it will still require manufacture before it can be issued, and may then need to be sent to the SHU. All of this takes time, particularly the processing part; with a cell washer taking one hour per unit, while the preparation of a PAS suspended platelet can take nearly two hours.

10 Donations in the right place at the right time and the complications of serology As I have already mentioned, the pressure on some donors and groups is significant. Ro group donors are likely to also have rare phenotypes, O neg donations are used to support multiple patient groups, and so these units are moved to be at the most likely SHU for issue. If rare units require re-manufacture prior to issue, for example conversion to washed units, then they first have to be transported to the nearest Manufacturing site for secondary processing before being issued to the Hospital, either directly, or following internal transport to the issuing SHU.

11 Rejected products Icteric, Lipaemic, clots and red cell contamination. ALL plasma and platelet products are visually assessed for all three of these criteria, against a set of standard photographs and colour charts, and a number of products are discarded as a result of this assessment, however; The acceptable level of red cell contamination is 4x10*6 rbc/ml. Those of you familiar with red cell dilutions for serology will understand how red this is. We reject products below this level, however this does lead to a ratchet up of expectation! Plasma products ALWAYS look worse after thawing than they did pre-freezing, due to haemolysis of any residual red cells and precipitation of dietary fats in the donor circulation. Any donation where blood clots are formed due to poor mixing of the donated blood with the pack anti-coagulant are discarded as they will not filter correctly. The other main cause of incomplete filtration is blood from donors expressing sickle cells.

12 Bank Holidays and timelines Donors tend to like to take time off on Bank Holidays. Equally we have staff off, and Venues can be less available at these times too. In order to get sufficient packs in through the week before and week after the Bank Holiday, we pile the collection into fewer days increasing the difference between the high and low days. Short dated products, e.g. Exchange units, LVT, Ro, Platelets and Neonatal red cells if required less than 5 days old have to be sourced from a quieter than normal Friday, a quiet Saturday and Sunday and a very quiet Monday, so stocks at the start of the Bank Holiday week are always lower than at the start of a normal week.

13 Thank you for your Patients Any Questions?