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HCFI Round Table Expert Zoom Meeting on “Blood Transfusion and safety”

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Dr Veena Aggarwal, Consultant Womens’ Health, CMD and Editor-in-Chief, IJCP Group & Medtalks Trustee, Dr KK’s Heart Care Foundation of India    25 October 2021

16th October, 2021, 11am-12noon

Speakers: Dr Jayashree Sharma & Dr DP Lokwani

Key points of HCFI Expert Round Table

#1. Strategies to improve blood safety

Dr Jayashree Sharma, Professor and Head, Dept of Transfusion Medicine, Seth GS Medical College & KEM Hospital, Mumbai

  • Safe blood, when transfused, is expected to benefit a patient without causing any adverse effects. It should be free of any infectious agents such as HIV, hepatitis viruses etc.
  • Blood safety is a concern because donors often fail to report risk factors during pre-donation interviews. 
  • Screening has limitations. A window period exists in current testing technologies and mandatory testing is done only for HIV, HBV, HCV, syphilis and malarial parasite. 
  • There is a risk of bacterial contamination, for which there is no mandatory screening except for monthly quality checks. Patient knowledge and consumer litigation are other issues.
  • Safe blood transfusion is a process and not just a product.
  • Most patients who are given transfusions are immunocompromised. 
  • There is a risk of new and emerging pathogens, which the current safety measures cannot eliminate.
  • Residual cells and cytokines from leukocytes can cause harmful post-transfusion reactions.
  • A repeat donor will be one who follows safe lifestyle behaviors and will be regularly tested for infections (HIV, hepatitis B and C, syphilis and malaria). However, there are many other infectious agents besides these.
  • Voluntary blood donors are the cornerstone of a safe and adequate supply of blood and blood products. It is best for blood banks to switch to 100% voluntary blood donations. But, family and/or replacement donors provide 45% of the blood collected in India.
  • The whole blood is separated into components within 6 hours of collection by differential centrifugation and transferring the components to satellite bags.
  • Packed RBCs can be stored at 4-6oC for 35 days; platelets can be stored for 4-5 days at 22oC and plasma can be stored at -30oC for one year (fresh frozen plasma).
  • The use of diversion pouch in blood bags along with current skin disinfection protocol can significantly reduce the risk of bacterial contamination.
  • The donor blood is screened for antigens and antibodies with ELISA; there is however still a risk of transfusion transmitted infections (TTI).
  • Nucleic acid techniques (NAT) are not dependent on antibodies, unlike rapid/ELISA tests. They directly detect the presence of viral RNA/DNA. NAT can shorten this window phase. 
  • The most important factor concerned with components is leukocytes. The clinical effects of contaminating leukocytes are HLA alloimmunisation, viral transmission (CMV, EBV, HTLV 1 and 2) and immune suppression.
  • Leukodepleted components are transfused to reduce febrile non hemolytic transfusion reactions and CMV transmission, prevent/delay leukocyte alloimmunisation and platelet refractoriness.
  • The different methods of leukoreduction include filtration, RBC washing, centrifugation and removal of buffy coat, freezing and deglyceralisation and apheresis.
  • There is a pathogen reduction technology where the blood is subjected to photosensitizer (UV rays), which damages the nucleic acid of pathogens and white cells. The rationale of targeting nucleic acids is that both pathogens and WBCs require nucleic acid to function.
  • Type and screen refers to the elimination of crossmatch in which blood is set aside with only the ABO-Rh type having been determined and antibody screening done for the presence of the most commonly found unexpected antibodies.
  • Type and screen is more efficient than simple crossmatch without antibody screen. Antibody screening can be done at the time of patient admission before the need for blood arises. It has a predictable turnaround time. The screen cells are characterised to provide appropriate antigens.
  • The advantage of type and screen for patients is that they receive safe and compatible blood; it reduces unnecessary sampling for doing crossmatch; prevents transfusion of serologically incompatible blood; the short turnaround time benefits patients who require a massive blood transfusion.
  • Because of type and screen, clinicians can receive the compatible blood within short turnaround time; it avoids need for repeated crossmatch; reduces unnecessary reservation of crossmatched blood for every patient and prior information about antibody screening helps in scheduling the surgery. 
  • A blood bank which adopts type and screen, gains the confidence of clinicians by issuing safe blood within short turnaround time. It allows optimal use of blood and blood components and reduces unnecessary wastage of blood because of unused and reserved/issued blood.
  • Autologous blood improves blood safety by minimizing risks associated with allogenic transfusion such as transfusion transmitted infections, immune mediated transfusion reactions. It obviates the need for crossmatching and conserves allogenic blood components for patients who are not eligible for autologous donations.
  • Hemovigilance is a set of surveillance procedures, from collection of blood and its components to the follow up of recipients to collect and assess information on unexpected or undesirable effects resulting from the therapeutic use of labile blood products and to prevent their occurrence and recurrence. It is an important tool for improving safe blood transfusion practices in a country.
  • The objective of the hemovigilance program is to collect, collate and analyse data related to transfusion reactions, to create awareness amongst healthcare professionals in the country for participation in the program and to generate evidence-based recommendations and send them to regulatory authorities.

#2. Newer parameters in CBC

Prof Dr DP Lokwani

Founder Vice Chancellor MP Medical Sciences University, Consultant Pathologist Jabalpur hospital & Research Center, Ex Prof and Head, NSCB Medical College Jabalpur, MP

  • Histogram has changed the face of hematology. It is a graphic representation of blood cells and is produced from thousands or millions of signals generated by cells passing through the detector where they are differentiated by their size and frequency of occurrence in the population. Histograms carry a lot of information about anemia if they are interpreted correctly.
  • Early we used to rely only on MCV and MCH, but now if MCV is normal, we say that it is normochromic and normocytic anemia. But this is not so, probably we are dealing with a combined nutritional deficiency anemia. This can be decided by a simple histogram or RDW.
  • RDW is a numerical expression of anisocytosis (change in the size of the cell); if there are many populations of cell size, then RDW will increase e.g., in nutritional deficiency. It will change if it is because of hemolysis due to various causes, both extrinsic and intrinsic.
  • Histogram together with RDW and MCV decides the type of anemia that one is dealing with.
  • Newer parameters give an insight that probably marrow is functioning.
  • Our requirement of blood transfusions is more than 300 million. Correct interpretation of CBC will reduce the blood transfusion load considerably.
  • Every transfusion carries a risk. We should therefore be more rational regarding blood transfusion, which is decided on the basis of the interpretation of anemia or thrombocytopenia in dengue cases.
  • In early iron deficiency, anemia is not yet apparent. MCV is still in the normal range and peripheral smear shows mild anisocytosis but RDW is increased (earliest indicator). Histogram is unimodal but is wider. 
  • Increased RDW combined with normal RBC values (MCV, Hb, Hct) differentiates iron deficiency from normal subjects.
  • If hemoglobin is normal but the graph shows a shift to the left, this means that there are already few microcytic cells, which will present with frank iron deficiency few months later if not detected in time. 
  • RDW shows heterogeneity of cells (normal/microcytic/macrocytic).
  • If the graph shifts to the right, even if hemoglobin is normal, it indicates B12 deficiency and megaloblastosis. 
  • During recovery from iron deficiency, the RBC is increasing, MCV is not yet normal and pre-existing microcytes and newly formed normocytes are seen. These cell populations are easily distinguished on the red cell histogram but not so easily on the peripheral smear.
  • Sophisticated cell counters with 7-part differentials now also generate cytograms. 
  • New platelet indices are plateletcrit (PCT), platelet volume distribution width (PDW), immature platelet fraction (IPF), Platelet larger cell ratio (P-LCR), platelet component distribution width (PCDW), mean platelet mass (MPM), mean platelet component (MPC) and mean platelet volume (MPV).
  • MPV is the ratio of plateletcrit (PCT) to platelet count. It measures thrombocyte volume in femtoliters (fL). It is inversely proportional to the degree of platelet maturity. Increased MPV is indicative of compensated bone marrow under challenge of peripheral platelet destruction/sequestration. Normal to decreased MPV is seen in thrombocytopenia of hypoproliferative bone marrow.
  • PDW measures the variability in size of platelets and reflects the heterogeneity in platelet morphology and size. A high PDW suggests a large range of platelet size due to swelling, destruction and immaturity. In sepsis, PDW increases due to activation and destruction of platelets.
  • P-LCR is a surrogate marker for platelet volume. The normal percentage range is 15-35%. It is an indicator of circulating larger platelets (>12fL), which is presented as percentage. An increase in PLCR usually signifies that there is an increase in new platelets, which are larger in size. It is also used to monitor platelet activity.
  • IPF is the percentage of immature platelets in the total platelet count. The reference range is 1.1 to 6.1%. The IPF percentage increases as production of platelets increases, and low values indicate suppressed thrombopoiesis. It is a sensitive marker for assessing regenerating bone marrow post-chemotherapy or transplant. It better defines pathogenesis of thrombocytopenia than MPV and is a useful marker to predict recovery of platelet counts in dengue. IPF increases in the early phase of sepsis due to platelet destruction. It has resulted in rational use of platelets. 
  • MPC, MPM and platelet component distribution width (PCDW) are new platelet activation parameters. Their clinical significance, reference values and usefulness of some of these parameters is still under investigation. These are more research parameters.
  • RBC related new parameters include nucleated RBCs, fragmented RBCs (schistocytes), spherocytes, immature reticulocyte fraction, reticulocyte hemoglobulin equivalent and the microcytic-to- hypochromic ratio.
  • WBC related new parameters include immature granulocytes, neutrophil volume, neutrophil granularity index, WBC positional parameter, neutrophil reactivity intensity (NEUT-RI), neutrophil granularity intensity (NEUT-GI), reactive lymphocytes (RE-LYMP), antibody-synthesizing lymphocytes (AS-LYMP).
  • Rational use of blood has tremendous clinical indication. It avoids lot of antigenicity as well as morbidity, including late-stage morbidity and mortality.
  • Every component of the blood should be rationally used.

Participants

Dr Arun Jamkar

Dr Ashok Gupta

Dr Jayashree Sharma 

Dr DP Lokwani

Dr Suneela Garg

Dr Rai

Prof Bejon Misra

Dr KK Kalra

Dr Anil Kumar

Mr Saurabh Aggarwal

Dr S Sharma

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