Chapter 17: Hematologic and Immune Disorders

Red blood cells transport oxygen through hemoglobin, with production regulated by erythropoietin in response to tissue hypoxia. Platelets initiate hemostasis by forming platelet plugs, while white blood cells—categorized as granulocytes and agranulocytes—serve as primary pathogen defenders through both nonspecific mechanisms like inflammation and phagocytosis, as well as specific adaptive responses including humoral immunity mediated by B cells and cellular immunity orchestrated by T cells. The coagulation cascade, involving intrinsic and extrinsic pathways, produces stable fibrin clots that are subsequently broken down through fibrinolysis to restore normal blood flow. Assessment strategies for critically ill patients include physical examination for signs of altered oxygenation, bleeding manifestations, and infection, supplemented by laboratory evaluation using complete blood count differentials and coagulation profiles. Major pathologic conditions covered include anemia from reduced circulating red blood cells causing tissue hypoxia, neutropenia with absolute counts below safe thresholds increasing infection risk, hematologic malignancies involving dysfunctional white blood cell proliferation, human immunodeficiency virus infection that destroys CD4 helper T cells leading to opportunistic infections, disseminated intravascular coagulation characterized by simultaneous microvascular thrombosis and hemorrhage from consumption of clotting factors, and heparin-induced thrombocytopenia where immune responses to anticoagulation paradoxically produce hypercoagulability. Nursing management emphasizes strict infection control protocols for immunocompromised populations, bleeding precautions with appropriate blood product administration, and targeted treatment addressing underlying etiologies in consumption coagulopathy.