Clinical Hematology and Blood Bank: The Blood Cycle and Donation Guidelines

Concepts and Ethics of Blood Donation

Clinical Hematology and Blood Bank, as presented by Professor Graziela Batista at UNICSUL for the Biomedicine program, defines the blood cycle beginning with the capture of donors. The fundamental ethical pillars of blood donation in the Brazilian system are that it must be a voluntary, anonymous, altruistic, and non-remunerated act. A donor should never be compensated or benefit directly or indirectly from their donation. The recruitment process faces the constant challenge of maintaining blood stocks to meet both routine and specific emergency needs. Consequently, there is a continuous effort to sensitize, raise awareness, and educate the population toward becoming responsible and habitual voluntary donors, for both whole blood and bone marrow.

Classifications and Types of Blood Donation

Donations are categorized based on proximity to the recipient and the motivation of the donor. A spontaneous donation occurs when persons are motivated to maintain hemocomponent stocks anonymously and out of altruism. In contrast, replacement donation occurs when individuals are moved by a specific service, family members, or friends of a recipient to meet the needs of a particular patient, thereby replenishing the service's stocks. When considering the recipient, an autologous donation is one made for the donor's own future use, while an allogenic donation is intended for another person. Furthermore, donors are classified by their frequency: a first-time donor is one donating at that service for the first time; a repeat donor has donated two or more times within a $12$-month period; and a sporadic donor returns for a donation after an interval exceeding $12$ months.

Basic Requirements and Pre-Screening for Donors

The fundamental requirements for blood donation involve being in good health and meeting several physiological and administrative criteria. Candidates must be between the ages of $16$ and $69$ years old, with the caveat that the first donation must have occurred by age $60$. The minimum weight requirement is $50\,kg$. Preparation for the procedure involves being well-rested, meaning at least $6\,hours$ of sleep in the preceding $24\,hours$, and being properly fed, specifically avoiding fatty foods in the $4\,hours$ prior to the donation. Identification is strictly required via original documents with recent photos, such as the Identity Card (RG), Professional Identity Cards, Labor and Social Security Card, National Driver's License (CNH) in physical or digital form, National Registry of Foreigners (RNE), Digital Voter Title (with photo), or a Brazilian Passport with parentage information.

Physical and Hematological Screening

Before the collection, a clinical screening process determines the suitability of the candidate based on vital signs and hematological markers. The hematological screening involves determining the concentration of hemoglobin ($Hb$) or hematocrit ($Ht$) through digital puncture or venipuncture. For women, the minimum values are $Hb = 12.5\,g/dL$ or $Ht = 38\%$. For men, the minimum values are $Hb = 13.0\,g/dL$ or $Ht = 39\%$. Physical assessment includes measuring blood pressure; the systolic pressure must not exceed $180\,mmHg$ and the diastolic pressure must not exceed $100\,mmHg$. Pulse measurement must show normal, regular characteristics with a frequency between $50$ and $100\,bpm$. Additionally, the corporal temperature of the donor must not be higher than $37^{\circ}C$.

Donor Donation Intervals and Clinical Interview

There are mandatory waiting periods between donations to ensure donor recovery. Men may donate every $60\,days$, with a maximum of $04$ donations in any given $12$-month period. Women must wait $90\,days$ between procedures, with a maximum of $03$ donations in a $12$-month period. The clinical screening involves a confidential interview to evaluate if the donation poses risks to either the donor or the recipient. This interview assesses diseases, surgeries, invasive procedures, current medications, and vaccinations. During this phase, a donor may also engage in the self-exclusion vote, which is a confidential option to signal whether they have participated in high-risk situations for sexually transmitted infections. If a donor answers "Yes," the blood is still collected and tested, but the bag is discarded regardless of the laboratory results.

Temporary Ineligibility and Vaccination Intervals

Ineligibility for donation can be temporary or definitive. Temporary ineligibility is often linked to recent vaccinations, particularly against Covid-19. Candidates who received the Coronavac (Sinovac/Butantan) or Covaxin (Bharat Biotech) vaccines must wait $48\,hours$ after each dose. Those vaccinated with Oxford/AstraZeneca/Fiocruz, Pfizer/BioNtec/Fosun Pharma, Janssen-Cilag, Sputnik V, or Moderna must wait $7\,days$ after each dose. Other temporary causes include a delay in the menstrual cycle for women of fertile age (until pregnancy is ruled out), allergies (wait $3\,days$ after treatment), or bacterial infections like sinusitis or urinary tract infections (wait $2\,weeks$ after treatment). More severe temporary conditions include Dengue ($4\,weeks$ after cure), Hemorrhagic Dengue ($6\,months$), or piercings and tattoos ($6$ to $12\,months$ depending on the safety conditions of the procedure). If a piercing is in the oral cavity or genital region, the wait is $12\,months$ after its removal due to permanent infection risk.

Permanent Ineligibility and Chronic Conditions

Definitive ineligibility occurs for conditions that permanently compromise blood safety. This includes hepatitis after the age of $11$ (with the exception of confirmed acute Hepatitis A with $IgM$ reactivity at the time of diagnosis). Chronic clinical or laboratory evidence of infectious diseases such as Hepatitis B and C, AIDS ($HIV$), viruses HTLV I and II, and Chagas disease results in permanent rejection. Other causes include illegal injectable drug use, Malaria, and Parkinson's disease. The provided documentation also lists chronic alcoholism, history of stroke ($AVC$), severe cardiovascular diseases (such as coronary disease or heart failure), Type I Diabetes, or Type II Diabetes requiring insulin as permanent barriers. Interestingly, while most cancers cause permanent ineligibility, history of carcinoma in situ of the uterine cervix and basal cell carcinoma of the skin do not necessarily prevent blood donation.

Bone Marrow Donation and REDOME

Bone marrow donation registration is managed by REDOME (National Registry of Bone Marrow Donors). Candidates must be between $18$ and $35\,years$ of age. The process involves collecting a blood sample to identify genetic compatibility data through $HLA$ (Human Leukocyte Antigen) genes. This registration is not an immediate donation but a database entry. Eligibility for bone marrow registration differs slightly from blood donation. For instance, those cured of Hepatitis A can register, and those with Hepatitis B and negative viral load can be evaluated. However, Hepatitis C is an absolute contraindication. Most cancers prevent registration except for treated skin carcinoma or cervical cancer. Autoimmune diseases like Rheumatoid Arthritis, Lupus, and Multiple Sclerosis are permanent blockers, but successfully treated Hashimoto's Thyroiditis or stable Vitiligo are permitted. For mental health, depression is allowed, but Schizophrenia is not.

Blood Collection Procedures and Technical Parameters

Whole blood collection and apheresis are the two primary methods of obtaining blood components. For whole blood, the maximum volume collected is $8\,mL/kg$ for women and $9\,mL/kg$ for men. The standard volume for a donation is $450\,mL \pm 45\,mL$. The collection time should ideally be under $12\,minutes$ and must not exceed $15\,minutes$. Blood bags contain anticoagulants to preserve the product. Common solutions include $CPDA-1$ (citric acid, sodium citrate, sodium phosphate, dextrose, and adenine), which provides a shelf life of $35\,days$. Other variants like $CP2D$ (citrate, phosphate, and dextrose-dextrose) allow for $21\,days$ of storage. The typical amount of anticoagulant in a bag is $60$ to $65\,mL$. For extended storage, additive solutions like $SAG-M$ (saline, adenine, glucose, and mannitol) can preserve red blood cells for up to $42\,days$ at $4 \pm 2^{\circ}C$.

Apheresis and Specialized Component Collection

Apheresis is a specialized process that uses a machine to obtain specific blood components from a single donor and return the remaining components to the donor's circulation. To be an apheresis donor, one must have good venous access, a platelet count above $150 \times 10^{3}\text{/L}$, and a weight over $60\,kg$. The procedure can take approximately $90\,minutes$. Regulations state an interval of $48\,hours$ between plasmapheresis sessions, limited to $4$ times in $2\,months$ and $12$ times per year. For plateletpheresis, the limit is $4$ times per month and $24$ times per year. The maximum extracorporeal volume must not exceed $15\%$ of the donor's total blood volume. Advantages of apheresis include reduced transfusion risk for patients (fewer donor exposures), lower bacterial contamination risk, and standardized components. One unit of plateletpheresis is equivalent to $6$ to $7$ units of platelets derived from whole blood. Disadvantages include higher costs, longer collection times, and the need for more specific infrastructure and trained personnel.

Legislative Framework in Brazil

The "Blood Cycle" and hemotherapy procedures in Brazil are governed by specific regulatory standards. Resolution RDC No 34, dated June 11, 2014, establishes Good Practices for the Blood Cycle. Portaria No 158, dated February 4, 2016, redefines the technical regulations for hemotherapy procedures. Furthermore, Portaria de Consolidação No 5, dated September 28, 2017, consolidates norms regarding health actions and services within the Unified Health System ($SUS$). These documents provide the legal and technical backbone for ensuring safety for both donors and recipients within the national hemotherapy network.