Hello everyone, how are you all? i hope you all are doing well and i am too. We learned blood bags, blood collection and how the platelet rich plasma is prepared till now. Now we are going to learn about how random donor platelets are prepared. Here also we are going to learn about it through a scenario.

Scenario

Lets consider a patient came to the hospital with the complaints of fever, body pains, petechiae over the body from last 5 days. Then the patient was advised for complete blood count and the platelets counts is about 8000 and remaining all parameters are normal. On peripheral smear manual platelet count is about 9000 which is very low and its called thrombocytopenia. So blood transfusion is advised if platelet counts are less than 10000 and for that we can transfuse either random donor (RDP)and single donor platelets (SDP). So we will see how RDPs are prepared in this post. This is similar like to platelet rich plasma(PRP) but few different things are there. we will see now the procedure and you will get to know the difference.
Step 1 - Whole blood collection
First we will select quadruple bag and the Whole blood is collected about 350ml or 450ml in CPDA or CPD containing blood bag
Step 2 - Processing by centrifugation
The collected whole blood CPDA/CPD bags are need to be subjected to centrifugation. Before centrifugation we have to transfer SAGM from SAGM transfer bag to 100ml buffy coat bag which is smaller bag among all.
1st centrifugation -
1st spin is called soft spin and it has to run at 1650 RPM at 22 degree celsius for 10 mins. The pure red blood cells are settled down and plasma with platelets will be top. Then we have to take out from centrifugation machine and transfer the plasma with platelets into transfer bag. Here we should not discard the pure red blood cells which got settled at the bottom. We have to transfer SAGM from small bag into pure red blood cells bag by keeping it is in hanging position for sometime and after SAGM got transferred into pure red blood cells we have to store it at 2-6 degree celsius and it will be stored for 42 days and it should be used before that thats why date of collection is mentioned on the bag and if it go beyond 42 days we have to discard the bag. Now we have to go for another centrifugation with remaining two bags. You can watch below video for that

2nd centrifugation -
2nd spin is called hard spin and it has 3600 RPM at 22 degree celsius for 10 mins.after centrifugation we will get platelets been settled bottom and top of it will be plasma. Now the plasma is transferred into another empty bag which is attached to it. We have to remove plasma until the platelets with plasma in the bag reaching upto 40-70 ml. This is another difference from PRP where we will remove more plasma there. The we have to rub on the blood to mix the platelets thoroughly. This bag is called random donor platelets (RDPs).
The bag which we transferred the plasma at last and it will be stored at ideally -40 or lower than it. This is called fresh frozen plasma. we will discuss about this fresh frozen plasma in next post.
You can watch the below video for understanding.

This is how random donor platelets are prepared and important thing is here no blood components are discarded like platelet rich plasma procedure. Here we have started with quadruple bag with whole blood collection and at end of the procedure we finally got three bags - 1)Pure red blood cells(PRBC),2)Random donor platelets and 3)Fresh frozen plasma so we are preparing three different components here. But, While preparing Platelet rich plasma we only prepared it and discarding other components.

Hope you understand how random donor platelets are prepared. Now this single donor platelet which is about 40-70 ml when transfused will increase platelet counts about 5000. Thats why 4-6 random donor platelets bags are transfused to raise the platelet counts about 20000 to 30000. As we are preparing from donors who are specifically selected or matched for the recipient. The random donor platelets(RDPs) are stored at 22-24 degree celsius with continuous agitation and stored upto 5-7 days. we have learned so much till now and we will some more in next posts.

References

• Kawthalkar SM. Essentials of Clinical Pathology. 2nd edition 2018.
• TRANSFUSION MEDICINE TECHNICAL MANUAL Third Edition 2023
  Thanks for reading,
  with regards,