HOW I DO – Transfusion of Blood Products PART-3

HOW I DO – Transfusion of Blood Products PART-3

(All the articles published in past are available at www.shyamhemoncclinic.com/blog/)

Question: In last part, we covered most common points related to platelet transfusion. I was very surprised to know that SDP AND RDPARE EQUAL IN TERMS OF RESPONSE, We also learned 1. For an average adult, 4-6 units of RDP are required in most cases. Lower number is not sufficient. 2. Platelets should be transfused as free flow ic. 6 units in about 30. minutes. Much slower will lead to clumping. 3. Highest risk of bacterial infection among all blood products, as they are stored at room temperature. 4. Blood group does not matter for platelet transfusion in adults. Hence patient can receive platelet from any donor. 5. One SDP is equal to about 6 RDPs. 6. No absolute contraindications for platelet transfusion. 7. Side effects of platelet transfusion, hence use only when necessary. Most patients with only petechiae or few ecchymoses do not need platelet transfusion. 8. Antiplatelet agents do NOT reduce platelet number, only reduce their function.

One question raised by our reader is what is the cut off for platelet transfusion?

Answer: Very good question. There is no specific cutoff number when patients must be transfused. But following points will help:

1. In most cases, patients who are actively bleeding should be transfused regardless of the platelet count, until the diagnosis is clear. Since they may have additional coagulopathy, a mechanical reason for bleeding, may have platelet dysfunction due to very active antiplatelet agents (e.g. ticagrelor).
2. For non bleeding patients, it depends on clinical situation. For example, a stable outpatient with no bleeding and a known diagnosis of IIP (immune thrombocytopenic purpura) can be observed without transfusion at practically any platelet count. We have patients with platelet count of less than 5000 (yes five thousand only) for years. Similarly for aplastic anemia, stable, can be observed without transfusion at below 10,000 as well. Same is true for many chronic conditions with low platelets.
3. For admitted patients with no bleeding, no other risk factors for bleeding, we frequently wait till 10,000. With risk factors, target level is higher depending on risk ie. target could be 20,000 or even 50,000.

Que: Thank you. In the same line, what is the cut off for red cell transfusion and what is the ideal product? Packed

red celli.e. PCV or Whole blood or Fresh whole blood?

Ans: Once again very good questions. Briefly, PCV is the standard of care. Whole blood has no advantage whatsoever and no role in modern medicine today. Same true for fresh blood. In regions where blood bank is not available to make components, it is ok to transfuse whole blood. Whole blood has plasma, platelets etc which are of no use to a patient who needs only red cells. This is additional volume and also morerisk of allergic reactions.

Within time frame of expiry of blood products, results are equal. This has been studied and published multiple times.

Hence no advantage of fresh blood, whole or PCV.

Regarding cut off for Hb level, wide variation depending on clinical scenario.

1. Stable outpatient with long standing anemia, especially young patients with no cardiorespiratory compromise, can tolemte very low levels. Such as about 3-4 g as well. To allow for diagnostic work up first. Most clinicians would have seen young ladies especially, with irondeficiency and Hb of 3-4 g doing household work and nearly asymptomatic. In fact, transfusion for such patients may lead to cardiac overload. They have compensated.

cardiac overactivity, and hence they cannot take additional burden easily. Giving them high volume of fluids or

blood can precipitate cardiac failure. Nutritional anemia patients frequently have such compensated anemia,

as it develops very slowly, Including iron or b12 or folic acid deficiency mostly.

2. Patients with other blood disorders like MDS, PRCA, etc also tolerate lower Hb well due to chronicity of disease. Individual patients here may need different cut off for transfusion. For example, some may feel very tired at 8 g and some may be very functional at 6 g. Thalassemia, sickle cell disease etc hemoglobinopathies have different cut offs depending on various criteria.

Cardiac patients may need a higher cut off like 8.

3. Chronic liver disease, renal disease ete patients al so tolerate Hb of about 6-8 frequently.
4. Patients admitted with active bleeding need cut off of about 8-9 g (not too high however) regardless of their

cardiac status, young age, stable vital signs etc. As bleeding rate can change quickly, safety margin is important. Moreover, Gl bleed, retroperitoneal bleed, fracture in thigh, pleural bleed ete can bleed a lot before it is clinically apparent.

5. For other admitted patients, including in ICU, several studies have shown that Hb cut off of about 7 is sufficient. And that maintaining higher Hb of 9 or more did not improve oxygenation, overall outcomes, discharge rate ete. Significant overuse of transfusions happens in admitted patients, much more so in ICU. This

can lead to more side effects, leading to poorer outcomes, and of course cost.

6. Even for cardiac surgery, Hb cut off of 7-8 isappropriate as per multiple trials and guidelines.

August 11th, 2024 ,  Dr Chirag A. Shah; M.D. Oncology/Hematology (USA), 9998084001. Diplomate American Board of Oncology and Hematology. Ahmedabad, drchiragashah@gmail.com , www.shyamhemoncclinic.com