Transfusion Reaction

Blood component therapy encompasses inherent risks, necessitating meticulous surveillance. Complications undergo classification based on temporal onset and underlying mechanism, dividing into acute and delayed, or infectious and non-infectious categories.

Classification of transfusion reactions

Acute transfusion reactions

Reactions manifesting during or within 24 hours of blood product administration.

Acute hemolytic transfusion reaction

• Pathophysiology involves transfusion of incompatible red blood cells, frequently due to mismatch of major blood groups.
• Triggered by preformed immunoglobulin M isohemagglutinins (anti-A or anti-B) destroying donor erythrocytes via complement activation.
• Primary etiology relates to misidentification of patient or blood sample.
• Clinical presentation features fever, chills, flank pain, hemoglobinuria, bleeding, and profound hypotension.
• Neonatal manifestations include increased pallor, hemoglobinemia, hyperkalemia, and acidosis.
• Management demands immediate cessation of transfusion, intravenous fluid resuscitation, and rigorous hemodynamic support.

Febrile non-hemolytic transfusion reaction

• Represents diagnosis of exclusion.
• Pathophysiology involves donor pro-inflammatory cytokines accumulated during storage or recipient antibodies reacting against donor leukocytes.
• Presentation includes temperature elevation exceeding 1°C from baseline, chills, emesis, and headache.
• Management utilizes antipyretic administration and close observation.
• Prevention mandates pre-storage leukoreduction of cellular blood products.

Allergic and anaphylactic reactions

• Pathophysiology involves immunoglobulin E-mediated type I hypersensitivity directed at donor plasma proteins.
• Anaphylaxis specifically threatens individuals with congenital immunoglobulin A deficiency possessing preformed anti-immunoglobulin A antibodies.
• Clinical spectrum ranges from mild urticaria (hives, pruritus) to life-threatening anaphylaxis (bronchospasm, dyspnea, angioedema, hypotension).
• Management incorporates antihistamines for mild reactions; severe reactions require transfusion cessation, epinephrine, corticosteroids, and respiratory support.
• Prevention of recurrent severe anaphylaxis necessitates washing cellular blood components to remove residual plasma.

Pulmonary transfusion reactions

Syndromes of acute respiratory distress emerging within 6 hours of blood product administration.

Septic transfusion reactions

• Pathophysiology stems from bacterial contamination of blood components.
• Higher incidence occurs with platelet transfusions due to obligatory room-temperature storage.
• Frequently involves Gram-negative organisms.
• Presentation features high fever, rigors, emesis, and profound hypotension.
• Management dictates immediate transfusion cessation, culturing patient and residual blood product, and initiating empiric broad-spectrum antimicrobial therapy.

Metabolic complications

• Hypocalcemia results from citrate toxicity (anticoagulant in stored blood) binding ionized calcium during large-volume transfusions.
• Hyperkalemia arises from potassium leakage in stored red blood cells; requires fresh red blood cells (under 5 days old) or washed red blood cells for vulnerable populations like neonates.
• Additional derangements include hypomagnesemia and glycemic fluctuations (hypoglycemia or hyperglycemia).

Delayed transfusion reactions

Complications manifesting days, months, or years following blood product administration.

Delayed hemolytic transfusion reaction

• Pathophysiology features anamnestic humoral response where recipient antibodies target minor donor red blood cell antigens (e.g., Kell, Duffy, Kidd).
• Onset spans 24 hours to 10 days post-transfusion.
• Presentation includes progressive pallor, fatigue, jaundice, and hemoglobinuria.
• High risk noted in sickle cell disease; delayed hemolysis frequently mimics vaso-occlusive pain crisis, obscuring underlying antibody-mediated destruction.
• Prevention demands comprehensive transfusion history review and extended antigen matching.

Alloimmunization

• Pathophysiology features immune system recognition of foreign red blood cell, human leukocyte, or human platelet antigens, generating specific alloantibodies.
• Incidence reaches 17.6% in chronically transfused sickle cell disease patients.
• Frequently targeted red blood cell antigens include Kell, Rhesus E, and Rhesus C.
• Complications include refractoriness to future platelet transfusions and extreme difficulty securing compatible red blood cell units for subsequent needs.
• Prevention utilizes leukoreduction and prophylactic extended phenotypic matching.

Transfusion-associated graft-versus-host disease

• Pathophysiology involves viable donor T-lymphocytes engrafting and launching immunological attack against recipient tissues.
• Highly fatal complication presenting 2 days to 6 weeks post-transfusion.
• High-risk populations include fetuses receiving intrauterine transfusions, neonates undergoing exchange transfusion, individuals with congenital cellular immunodeficiencies, and recipients of directed donations from haploidentical blood relatives.
• Prevention exclusively relies on gamma irradiation of cellular blood products to inactivate lymphocytes or application of pathogen-reduction technology.
• Leukoreduction fails to prevent this complication.

Transfusion-transmitted infections

Stringent donor screening and nucleic acid amplification testing markedly reduce transmission rates, though residual risks remain.

Transfusional iron overload (hemosiderosis)

• Pathophysiology involves cumulative iron toxicity since human physiology lacks active iron excretion mechanisms.
• Each milliliter of packed red blood cells delivers approximately 1 mg of elemental iron.
• Condition uniquely affects chronically transfused patients (thalassemia major, sickle cell disease, bone marrow failure syndromes).
• Organ toxicity targets:
  • Cardiac: Myocardial iron deposition causes cardiomyopathy, arrhythmias, and intractable heart failure; leading cause of mortality.
  • Hepatic: Portal fibrosis, regenerative nodules, cirrhosis, eventual liver failure.
  • Endocrine: Pituitary iron deposition causes growth retardation, delayed puberty, hypogonadotropic hypogonadism, insulin-dependent diabetes mellitus, hypothyroidism, hypoparathyroidism, and adrenal insufficiency.
• Management necessitates rigorous monitoring via serial serum ferritin trends and magnetic resonance imaging T2* to quantify hepatic and cardiac iron burden.
• Pharmacologic intervention utilizes iron chelators (deferoxamine, deferasirox, deferiprone).

Neonatal-specific transfusion complications

Unique physiological vulnerabilities predispose premature neonates to specific transfusion-associated morbidities.

Transfusion-associated necrotizing enterocolitis

• Denotes spectrum of severe gastrointestinal reactions temporally linked to recent blood product administration.
• Pathophysiology remains multifactorial.
• Proposed mechanisms implicate inflammatory substances within packed red blood cell units, oxidative stress, gut immaturity, pre-transfusion small bowel hypoxia, and disturbances in mesenteric blood flow post-transfusion.

Retinopathy of prematurity and bronchopulmonary dysplasia

• Red blood cell transfusion serves as independent risk factor for retinopathy of prematurity.
• Pathophysiology relates to transfusion of adult hemoglobin possessing lower oxygen affinity compared to fetal hemoglobin, causing excessive oxygen release.
• Resultant severe oxidative stress damages developing retinal vessels.
• Pro-inflammatory and anti-inflammatory mediators accumulating in stored red blood cells contribute significantly to bronchopulmonary dysplasia pathogenesis.

General management approach to suspected transfusion reaction

Immediate algorithmic steps required upon suspicion of any acute transfusion reaction,,,,: