Chapter 13 Alterations in Oxygen Transport PDF

Chapter Alterations in 13 Oxygen Transport Dr. Tashea S. Hilliard, Associate Professor Elsevier items and derived items © 2010, 2005 by Saunders, an imprint of Elsevier Inc.  Learning Objectives 1) Identify the laboratory tests used...

Chapter Alterations in 13 Oxygen Transport Dr. Tashea S. Hilliard, Associate Professor Elsevier items and derived items © 2010, 2005 by Saunders, an imprint of Elsevier Inc.  Learning Objectives 1) Identify the laboratory tests used to detect anemia and polycythemia. 2) Describe the general effects of anemia on body systems. 3) Explain how history, clinical manifestations, and laboratory studies used to differentiate the various forms of anemia. 4) Explain how history, clinical manifestations, and laboratory studies used to differentiate the various forms of polycythemia. 5) Describe the appropriate treatment measures for each of the common types of anemia and polycythemia. Elsevier items and derived items © 2010, 2005 by Saunders, an imprint of Elsevier Inc. Anemia Anemia is a deficit of red cells Low oxygen-carrying capacity leads to hypoxia Polycythemia is an excess of red cells Increased blood viscosity and volume Relative anemia—normal total red cell mass with disturbances in regulation of plasma volume Absolute anemia—actual decrease in numbers of red cells Elsevier items and derived items © 2010, 2005 by Saunders, an imprint of Elsevier Inc. General Effects of Anemia Reduction in oxygen-carrying capacity Tissue hypoxia Compensatory mechanism to restore tissue oxygenation Increased heart rate, cardiac output, circulatory rate, and flow to vital organs Increase in 2,3-DPG in erythrocytes and decreased oxygen affinity of hemoglobin in tissues Elsevier items and derived items © 2010, 2005 by Saunders, an imprint of Elsevier Inc. Manifestations of Anemia Mild anemia (hemoglobin above 8g/dl Minimal symptoms Elderly with CV, pulmonary disease may have symptoms Elsevier items and derived items © 2010, 2005 by Saunders, an imprint of Elsevier Inc. Manifestations of Anemia (Cont.) Moderate/severe anemia (hemoglobin below 8g/dl Orthostatic hypotension/nonorthostatic Pallor Tachypnea HA/lightheaded, fainting Angina, heart failure Nighttime leg cramps Tinnitus or roaring in ears Fatigue, weakness Elsevier items and derived items © 2010, 2005 by Saunders, an imprint of Elsevier Inc. Anemia Related to Decreased Red Cell Production Aplastic Anemia Stem cell disorder characterized by reduction of hematopoietic tissue in the bone marrow, fatty marrow replacement and pancytopenia Caused by toxic, radiant, or immunologic injury to the bone marrow stem cells Elsevier items and derived items © 2010, 2005 by Saunders, an imprint of Elsevier Inc. Anemia Related to Decreased Red Cell Production (Cont.) Aplastic Anemia Insidious onset of symptoms Late symptoms include weakness, fatigue, lethargy, pallor, dyspnea, palpitations, transient murmurs and tachycardia Pancytopenia and granulocytopenia Elsevier items and derived items © 2010, 2005 by Saunders, an imprint of Elsevier Inc.  Anemia Related to Decreased Red Cell Production (Cont.) Aplastic Anemia Treatment Identify and avoid of further toxic exposure Type human leukocyte antigen (HLA) and ABO to identify serologically defined loci and potential donors Maintain minimally essential levels of hemoglobin and platelets Prevent and manage infection Determine efficacy of bone marrow transplantation Administer immunosuppressive therapy or stimulate hematopoiesis and bone marrow regeneration Elsevier items and derived items © 2010, 2005 by Saunders, an imprint of Elsevier Inc. Anemia Related to Decreased Red Cell Production (Cont.) Anemia of Chronic Renal Failure Failure of the renal endocrine function impairs erythropoietin production and bone marrow compensation Decreased RBC count with low HCT and HGB level Treatment consists of dialysis and administration of erythropoietin Elsevier items and derived items © 2010, 2005 by Saunders, an imprint of Elsevier Inc. Anemia Related to Decreased Red Cell Production (Cont.) Anemia Related to Vitamin B12 (Cobalamin) or Folate Deficiency Disruption in DNA synthesis of blast cells in bone marrow produces megaloblasts Pernicious anemia due to lack of intrinsic factor leading to vitamin B12 deficiency Low RBC, WBC, and platelet counts with increased MCV; megaloblastic dysplasia Treatment: replacing nutritional deficiencies Elsevier items and derived items © 2010, 2005 by Saunders, an imprint of Elsevier Inc. Anemia Related to Decreased Red Cell Production (Cont.) Iron Deficiency Anemia Most common nutritional deficiency in the world Insufficient iron for hemoglobin synthesis Hypochromic, microcytic RBCs; low MCV, MCH, and MCHC Treatment: oral administration of ferrous sulfate or intravenous ferric gluconate Elsevier items and derived items © 2010, 2005 by Saunders, an imprint of Elsevier Inc. Anemia Related to Inherited Disorders of the Red Cell Thalassemia Increased RBC destruction (hemolysis) resulting in decreased RBC survival rates Group of disorders associated with the presence of mutant genes that suppress the rate of synthesis of globin chains Classified by the polypeptide chain(s) with deficient synthesis Elsevier items and derived items © 2010, 2005 by Saunders, an imprint of Elsevier Inc. Beta-Thalassemia Elsevier items and derived items © 2010, 2005 by Saunders, an imprint of Elsevier Inc. Anemia Related to Inherited Disorders of the Red Cell Thalassemia Hypochromic, microcytic RBCs, MCV, MCH, and MCHC are low, erythroblastic hyperplasia Treatment Blood transfusions Splenectomy Chelation therapy Bone marrow transplantation Elsevier items and derived items © 2010, 2005 by Saunders, an imprint of Elsevier Inc. Anemia Related to Inherited Disorders of the Red Cell (Cont.) Sickle Cell Anemia Genetically determined defect of hemoglobin synthesis resulting in hemoglobin instability and insolubility Sickled cells cause vascular occlusion Severe anemia, RBCs of different shapes and sizes Treatment of choice is stem cell transplant Elsevier items and derived items © 2010, 2005 by Saunders, an imprint of Elsevier Inc. Sickle Cell Anemia Elsevier items and derived items © 2010, 2005 by Saunders, an imprint of Elsevier Inc. Anemia Related to Inherited Disorders of the Red Cell Hereditary Spherocytosis Defective red cell membrane skeleton, altered membrane properties, and altered cell metabolism Autosomal dominant trait RBCs are fragile microspherocytes, with increased destruction of spherocytes Treatment consists of splenectomy Elsevier items and derived items © 2010, 2005 by Saunders, an imprint of Elsevier Inc. Anemia Related to Inherited Disorders of the Red Cell (Cont.) Glucose-6-Phosphate Dehydrogenase Deficiency Genetic disorder resulting in RBC membrane destruction Do not have hemolytic anemia unless challenged by drugs Treatment is preventive by avoidance of drugs that trigger hemolytic episodes and aggressive infection management Elsevier items and derived items © 2010, 2005 by Saunders, an imprint of Elsevier Inc. Anemia Related to Extrinsic Red Cell Destruction or Loss Hemolytic Disease of the Newborn Fetal RBCs cross placenta, stimulate production of maternal antibodies against antigen on fetal RBC not inherited by mother Maternal antibodies cross into the fetal circulation causing destruction of fetal cells ABO incompatibility most common Rh incompatibility more clinically relevant Elsevier items and derived items © 2010, 2005 by Saunders, an imprint of Elsevier Inc. Anemia Related to Extrinsic Red Cell Destruction or Loss (Cont.) Hemolytic Disease of the Newborn Anemia, reticulocytosis, and nucleated RBCs in blood of infant Standard dose of anti-Rh immune globulin (RhoGAM) is given to the mother before or after delivery In severe cases, in utero blood transfusion and early delivery Elsevier items and derived items © 2010, 2005 by Saunders, an imprint of Elsevier Inc. Anemia Related to Extrinsic Red Cell Destruction or Loss (Cont.) Antibody-Mediated Drug Reactions Exposure to a drug causes destruction and lysis of the sensitized person’s own RBCs Mechanisms include: Hapten mechanisms Neoantigen formation Membrane modification Autoantibody Induction Recognize and discontinue offending medications Elsevier items and derived items © 2010, 2005 by Saunders, an imprint of Elsevier Inc. Anemia Related to Extrinsic Red Cell Destruction or Loss (Cont.) Acute Blood Loss May be from trauma or secondary to a disease process Symptoms develop with activity at 20% loss of blood volume (tachycardia and postural drop in BP), and increase in severity with continued blood loss Blood volume replacement therapy with crystalloids, colloids, and fresh whole blood Elsevier items and derived items © 2010, 2005 by Saunders, an imprint of Elsevier Inc. Anemia Related to Extrinsic Red Cell Destruction or Loss (Cont.) Other Extrinsic Abnormalities Mechanical heart valves and cardiopulmonary bypass machines can result in hemolysis Drugs and chemicals, physical agents, and infectious diseases can cause anemia Venom from insects and snakes can cause hemolytic anemia Hypersplenism and splenomegaly can result in anemia, leukopenia, or thrombocytopenia Elsevier items and derived items © 2010, 2005 by Saunders, an imprint of Elsevier Inc. Transfusion Therapy Medical indications include: Restoration or maintenance of oxygen-carrying capacity, blood volume, hemostasis and leukocyte function Donor testing to ensure safety of blood products Specific pretransfusion testing to ensure blood component will not harm recipient Elsevier items and derived items © 2010, 2005 by Saunders, an imprint of Elsevier Inc. Polycythemia Excess RBCs resulting in increased blood viscosity, leading to clinical symptoms such as hypertension Types of polycythemia are categorized by cause Elsevier items and derived items © 2010, 2005 by Saunders, an imprint of Elsevier Inc. Polycythemia (Cont.) Polycythemia Vera Neoplastic transformation of bone marrow stem cells Absolute increase in RBC mass and leukocytosis, and thrombocytopenia; increased uric acid due to excess proliferation Treatment directed at reducing increased blood volume, viscosity, RBC mass and platelet count with phlebotomy, radioactive phosphorus, and chemotherapeutic agents Elsevier items and derived items © 2010, 2005 by Saunders, an imprint of Elsevier Inc. Polycythemia (Cont.) Secondary Polycythemia Due to chronic hypoxemia with resultant increase in erythropoietin production Increased RBC production without increase in WBCs or platelets Identifying and managing underlying cause of hypoxemia; phlebotomy may be used to decrease cardiovascular workload Elsevier items and derived items © 2010, 2005 by Saunders, an imprint of Elsevier Inc. Polycythemia (Cont.) Relative Polycythemia Due to dehydration with spurious increase in RBC production Elevated hematocrit, hemoglobin, and RBC count Recognize and manage underlying cause; fluid administration is used with management of long-term conditions Elsevier items and derived items © 2010, 2005 by Saunders, an imprint of Elsevier Inc.