Blood Donor Selection and Blood Collection
The journey truly begins at blood drives and at blood collection centers. Throughout the day, and often, well into the night or early morning hours, teams of blood collection staff move mobile donor coaches into place at blood drives and work fixed-site donation centers. There, volunteer donors are first examined to determine their suitability as donors. Not everyone can give and those who cannot donate include people with certain medical conditions, people who have traveled to places where infection can occur, and those who have engaged in behaviors that might expose them to infection. Potential donors who pass this initial screening can then donate a pint of blood, a unit of platelets, or a unit of plasma, or sometimes a combination of the three. The precious donated blood components, as well as, samples and the paperwork from each donation are carefully sealed and packed for transport to blood processing centers such as TBC’s in Greenville. The journey of donated blood units, associated paperwork and samples diverges at the Biologics Processing Center. In stage 1, the record of donation is entered into the blood center’s central computer. In stage 2, the blood unit undergoes technical processing steps. In stage 3, the blood samples move to the laboratory for testing.
Stage 1: Keeping An Accurate Record of the Donation
Blood centers are required by federal regulations to record, track, and trace every aspect of blood donation; blood processing and testing; and blood component storage and distribution. To do so, bar coded labels are employed to tie together blood donor paperwork and each blood component derived from each donation. Blood centers use highly sophisticated and specially designed “enterprise” software to capture and store the necessary data. The chief regulator of blood establishments, the U. S. Food and Drug Administration, considers blood banking computer hardware and software to be a medical device. Therefore, TBC’s computer systems and the records kept within it are important linchpins that are protected by layers of access control, both physical and electronic; state of the art information technology power and support systems; regular and frequent backup routines; and redundant offsite data servers. Data entry personnel are busiest late in the afternoon and in the evening when bloodmobiles return with their trove of whole blood units.
Stage 2: Blood Component Preparation (Biologics Manufacturing)
Since blood is made up of several components, splitting a blood donation into components means one single donation can offer treatment for more than one patient. Rarely will a person need all of the components within whole blood. Therefore, it is usually separated so that it can be transfused into multiple patients, each with different needs. Biologics manufacturing areas are also busiest in the afternoons and in the evening, but must be ready 24/7. The key blood components are:
- Red Blood Cells: Circular-shaped cells. Because of the hemoglobin and iron they contain, they impart the red color to blood. They carry oxygen to the tissues in the body and are commonly used in the treatment of anemia resulting from kidney failure, gastrointestinal bleeding, or blood loss during trauma or surgery. Red cells must be transfused within 42 days of collection, unless frozen for prolonged storage
- Platelets: Like red blood cells, platelets have no cell nucleus and are disc shaped but are even smaller. They measure 1.5-3.0 m in diameter. The body has a very limited reserve of platelets, so they can be rapidly depleted. They contain pockets (granules) of concentrated clotting proteins and enzymes, the contents of which are released upon activation of the platelet. Platelets promote blood clotting and seal wounds.
- Plasma: Is the watery, liquid portion of the blood where the blood cells and platelets are suspended. Plasma carries the many cellular parts of blood through the bloodstream. Plasma helps maintain blood pressure, provides proteins for blood clotting and balances the levels of salt in the blood. About 55% of blood’s volume is made up of plasma.
- Cryoprecipitate: Is a concentrated extraction of clotting factors from plasma that help control bleeding. Although it consists of several clotting proteins, it is rich in a substance called Factor VIII, often needed by patients with classic hemophilia.
How is blood separated?
A biologics technician separates plasma from the red blood cells by rapidly spinning a unit of blood in a centrifuge for several minutes. Because of centrifugal forces, the plasma will appear at the top of the blood unit’s plastic bag and the red blood cells will be forced to settle at the bottom. In between is a thin, almost imperceptible layer of white blood cells and platelets. The red blood cells and plasma are separated using a machine that squeezes the plasma into an awaiting empty, sterile plastic bag. The machine also squeezes additional preservative chemicals into the red blood cell bag. The red cell bag and the plasma bag are finally physically sealed and separated.
The red blood cell units are stored in refrigerators at a temperature between 34 and 43 degrees Fahrenheit [1-6 C]. These will last for up to 42 days, then red blood cell units undergo a filtration step whereby a special filter known as a leukocyte reduction filter captures and sequesters most of the white blood cells and some of the platelets from the original whole blood donation. Plasma is frozen solid within 24 hours of collection and shortly after separation from the red cells. It is stored in freezers that maintain temperatures below 0 degrees Fahrenheit [below -18C]. The frozen plasma can be stored for up to one year from the time of donation. Plasma can be further processed to yield cryoprecipitate [cryo, meaning cold]. In this manufacturing process, bags of plasma are slowly thawed at about 40 degrees Fahrenheit [1-6C]. While the plasma thaws, proteins “precipitate” to form microscopic granular aggregates. The biologics technician then uses a centrifuge to pack those aggregates to the bottom of the bag and extracts all but about a half fluid ounce [15 ml] of the plasma. The protein aggregates are re-mixed into the small amount of plasma, and the concentrated, cold precipitated clotting proteins are re-frozen at temperatures below 0 degrees Fahrenheit [below -18C]. Cryoprecipitate can be stored for up to one year from the time of donation. If desired, platelets can also be separated from the original whole blood, but many blood centers such as TBC forgo that preparation method in favor of a more direct platelet collection technique.
TBC uses automated blood collection for a process called apheresis to collect specific blood components directly from the donor rather than collecting whole blood. TBC uses apheresis to collect all three of the main blood components, red blood cells, platelets, and plasma, but focuses its efforts primarily toward platelet production. Platelets are stored at room temperature; approximately 68-75 degrees Fahrenheit [20-24C]. Platelets expire 5 days from donation. Once prepared, blood components are moved to temporary “in process” storage environments. State-of-the-art sensors and wireless transmission technology monitors temperatures and critical refrigerator, freezer, and incubator functions to safeguard blood products and valuable information about them. There they await clearance from TBC’s laboratory that all safety checks are in order and the blood components can be labeled and be made available for distribution. Brian Madden is The Blood Connection’s Chief Operating Officer. Madden describes the Blood Connection as the steward of the community blood supply. He says TBC’s heritage of service has been made possible by loyal blood donors, and a dedicated staff of employees and volunteers.
“The Blood Connection is a public entity interacting with generous donors, yet it is the protector of the safety of the blood supply,” said Madden. “At the same time it is a highly regulated biologics manufacturer, and that’s why we have rigid control over every process we perform.”
A single pint of blood is processed according to what hospitals need. Our key products are red blood cells, apheresis platelets, 24-hour frozen plasma, and cryoprecipitate, but we have the ability to produce a wide range of blood products based on the needs of patients. We are fortunate that our donors are very generous, so we usually have an ample supply. Hospitals have to stock enough of eight different ABO blood group and Rh blood types. There are special size packages of blood components — smaller units for children, for example. Also, some patients need blood components that have undergone special treatments such as exposure to radiation which eliminates a harmful immune reaction in those patients.
Stage 3: Testing the Samples
Stage 3a: Examining Characteristics
Cutting edge technology is employed by TBC’s Biologics Testing Laboratory to determine blood type characteristics of the donated blood and to screen it for evidence of infectious disease. Much of this testing occurs overnight and into the early morning hours. The lab aims to have testing completed well before noon each day. The sample tubes collected at donation are centrifuged and logged into a computer system that captures and collates all test results. Testing not only protects the recipient from contracting viruses, parasites, or bacteria, it is helpful to the donor when medical conditions are identified. One tube goes to a robotic instrument for syphilis testing. The same instrument is used to screen blood units for antibodies to a virus called cytomegalovirus. An additional instrument, the Galileo, is used for antibody screening [Blood group O, cytomegalovirus negative units are used for transfusion to infants]. The antibody screen tests for any unexpected antibodies that might cause a transfusion reaction in some patients.
Accurate blood group and type characterization is critical when selecting compatible blood for a patient who needs a transfusion. One tube undergoes viral marker testing, where highly-trained technicians use FDA-approved screening assays to look for evidence of harmful viruses like HIV, Hepatitis B, Hepatitis C, HTLV, and West Nile. More than one method is used for Hepatitis and HIV. One method tests for antibodies formed in response to infection. Another instruments tests for the Hepatitis B and C virus and is a sensitive nucleic acid test (NAT) that looks for DNA or RNA at the core of the viral agent itself.
According to Tracy Bridges, Chief Technical Officer, “TBC and our community are fortunate to have leadership at the board and executive management levels and the resources to provide sophisticated testing instruments and laboratory facilities. We are really on the cutting edge of blood testing technology, and that helps ensure blood safety.”
Additionally, each donor is tested (in their donating lifetime) for evidence of infection from a parasite known as Trypanosoma cruzi which causes Chagas Disease. This is a disease found in Latin American countries but not often in the United States. The infection is often “occult” meaning the infected person is unaware of the infection. Also, the parasite can reside in a number of animal hosts such as dogs, cats, opossums, and raccoons. Latino emigration, missionary travels, and potential veterinary exposure make it prudent to screen for this infectious agent. Because platelets are stored at room temperature there is a risk of bacterial growth in the platelet bag. Therefore, every platelet unit undergoes a bacterial culturing test where laboratory technicians inoculate a bottle of culture broth and incubate the bottles in a warm incubator for five days. Fortunately, because rigorous antiseptic washes and blood collection techniques are used at the donor bedside, bacterial growth is a rare event.
Stage 3b: Segregation and Quarantine of Suspect Units
This is a critical step. If any infectious disease test indicates the blood unit is unsuitable, [what is referred to as “initially reactive”] then lab technicians go to the “in process” refrigerator, freezer, or incubator and pull each and every blood component prepared from that donated unit. Those suspect components are placed in a quarantine environment in a locked room.
Stage 3c: Retesting
The next day, the laboratory retests the suspect sample in duplicate. If one or both of the retests confirm the initial finding, the sample is said to be “repeat reactive.” For some tests, a third confirmation test is required by the FDA.
Stage 3d: Blood Component Discard
If the evidence of infectious disease is confirmed, then a biologics technician disposes of each and every blood component that had been in quarantine. Disposal is via a licensed biomedical waste transporter and incinerator.
Stage 3e: Donor Notification
When evidence for infectious disease is confirmed, TBC notifies the donor and provides counsel as to the significance of the findings.
Stage 4: Labeling and Storage
When tests are complete, blood components are labeled with their blood group and Rh type. By electronically reading the barcode on the bag, the computer prompts the biologics technician that the lab test results are acceptable or not acceptable. According to Mr. Madden, “This is a second check on segregating and quarantining suspect units. We don’t expect to encounter them at this step, but our technicians are watchful to assure that no unsuitable unit gets labeled.” The computer also has the blood group and Rh type of the component and prints a label of that blood group and type. The technician applies the label to the component and re-scans it to confirm the correct label has been applied. Madden said, “The computerized process helps us diminish human error and enables us to efficiently track each unit of blood.” Because the lab finished testing before noon each day, labeling typically occurs in the late morning or early afternoon. After labeling, each unit of blood is kept in a final product storage environment at the appropriate temperature until it is needed by a hospital or by another blood center.
Stage 5: Distribution
Many of TBC’s hospital customers receive routine shipments of blood on a set schedule, and some shipments are distributed to meet emergency needs. A patient could receive a processed blood component as early as 24 hours after it was donated. When orders for blood components arrive, a biologics technician enters the final product storage areas and selects blood components that match the needs of the hospital or blood center. Then, the technician scans the serial numbers and product codes of the components into the central computer and packs the shipping container. Because correct temperatures must be maintained during transport, the technician also packs in an appropriate cooling material (regular ice for red blood cells, special coolant packs for platelets, and dry ice for frozen plasma). A shipping manifest and appropriate labels are also added. TBC uses its own staff and a fleet of courier cars for delivering blood to its regular hospital customers. For shipments destined for more distant locales TBC generally utilizes a national or international express service. TBC is in frequent contact with the AABB’s National Blood Exchange. Every day, somewhere in the United States, there is a shortage of blood. TBC is pleased to be able to meet needs beyond our local horizon. Every two seconds, someone in this country needs blood. Most of us only have to look as far as our circle of friends and neighbors to find someone whose life was touched by the generous gift of a volunteer blood donor. This important testing process ensures that blood donations are safe and available to patients in need. It means one blood donation can safely come to the end of its journey to save the lives of three different people.