chapter 49. quiz 1 History of Blood Transfusion and infectious diseases

Transfusion Medicine

• The concept of reconstituted "whole blood" was introduced in the 1990s, led by trauma hospitals and the military.
• FFP and platelets were transfused along with PRBCs, resulting in a transfusion ratio similar to that of whole blood.

Patient Blood Management (PBM)

• The term PBM was introduced in the 2010s, focusing on a patient-centered, multi-pronged approach to transfusion medicine.
• PBM aims to maintain hemoglobin concentration, optimize hemostasis, and minimize blood loss to improve patient outcomes.
• Implementation of PBM has reduced the reliance on allogenic blood product transfusions and improved clinical outcomes.

Transfusion History

• In the 1960s, most blood given was in the form of whole blood.
• In the 1970s-1980s, transfusion therapy focused on giving patients only the component of blood that was needed.
• In the 1990s-2000s, the focus shifted to balancing the risks of anemia and transfusion, with improved screening techniques and reduced infectious disease transmission.

Blood Donation and Procurement

• In the United States, donors must be at least 16 years old and weigh at least 110 pounds to be eligible for screening.
• Blood is collected either as whole blood or by apheresis, with specific components separated and returned to the donor.
• Global disparities exist in access to safe blood, with low- and middle-income countries collecting 53% of all blood donations but representing 81% of the world's population.

Transfusion-Transmissible Infections

• Donor screening aims to reduce the risk of transfusion-transmissible diseases, including HIV, hepatitis, and West Nile virus.
• Infectious risks are now rare due to improved screening methods and testing.
• The FDA requires blood products to be tested for various infectious diseases, including hepatitis B and C, HIV, and Zika virus.

Cytomegalovirus (CMV)

• CMV is a common infection that can be transmitted through blood transfusions.
• The primary concern is recipients who are at risk due to pregnancy, immaturity, or immunosuppression.
• Use of leukocyte-reduced blood, frozen deglycerolized RBCs, and screening for CMV antibody-negative donors can help prevent infection.

Zika Virus

• Zika virus is transmitted by mosquitoes and can cause Guillain-Barré syndrome and microcephaly in newborns.
• The FDA requires all blood donations to be tested for Zika virus using NAT.

Other Transfusion-Associated Infectious Diseases

• Other infectious diseases that can be transmitted through blood transfusions include Yersinia enterocolitica, syphilis, malaria, Chagas disease, and variant Creutzfeldt-Jakob disease.

Posttransfusion Hepatitis

• Viral hepatitis was a major complication of blood transfusions, with an incidence of 3-10% before 1985.
• Hepatitis C virus is the primary cause of posttransfusion hepatitis, with chronic active hepatitis and hepatocellular carcinoma possible complications.

Blood Transfusion Indications

• Blood transfusions are given to increase O2-carrying capacity, not to augment intravascular volume.

• A sole Hb value should not be the only basis for a transfusion decision; the overall patient status should be considered.

• The current PBM emphasis is on fewer or even avoidance of blood transfusions, with a focus on restrictive versus liberal transfusion strategies.### Determining Need for Subsequent Blood Transfusions

• Reassess patient's overall condition and clinical situation to determine need for additional blood transfusions

• Key factors to consider include: measurement and trend of vital signs, measurement of blood loss and anticipated blood loss, quantitation of intravenous fluids given, determination of Hb concentration, and surgical concerns

Measurement of Blood Loss

• Measuring blood loss is crucial in assessing need for initial and subsequent blood transfusions
• Standard approach combines visualization and gravimetric measurements based on weight differences between dry and blood-soaked gauze pads
• Anesthesiologists tend to overestimate blood loss by as much as 40%, while optical scanners tend to underestimate blood loss
• No "gold standard" for blood loss quantification exists

Evolution of Blood Transfusion Therapy

• 1960s: most blood given was in the form of whole blood, with fresh frozen plasma (FFP) available for coagulopathies
• 1970s-1980s: transfusion therapy focused on giving only the component of blood needed, with caution regarding administration due to concern about infectivity of blood (e.g., hepatitis and HIV)
• 1990s-2000s: improved screening techniques for HIV and other blood-borne pathogens led to a 10,000-fold decrease in blood transfusion–related infectious disease transmission
• Focus shifted to noninfectious serious hazards of transfusion, such as hemolytic transfusion reactions, TRALI, and TACO

SpHb Monitoring

• SpHb correlates within 1.0-1.5 g/dL with laboratory Hb measurements, but accuracy is not consistent
• Accuracy is affected by Hb levels, resuscitation, finger blood flow, and temperature
• Perfusion index (PI) can be helpful in assessing accuracy of SpHb value
• A PI greater than 4% to 5% can improve accuracy of SpHb
• Bupivacaine digital nerve block and warming the finger can increase PI and accuracy of SpHb