Hematology

1
Hematology
Chapter 35
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Hematologic System

• The blood and blood-forming organs comprise the
  hematologic system
• Dysfunction can profoundly affect other body
  systems, resulting in diffuse clinical
  manifestations that characterize blood disorders

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Blood and Blood Components

• Blood consists of cells and formed elements,
  surrounded by plasma
• Formed elements
• Red blood cells (erythrocytes)
• White blood cells (leukocytes)
• Cell fragments (platelets)

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Blood and Blood Components

• Blood settles into three distinct, proportional
  layers when treated with salt

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Blood and Blood Components

• Chief functions
• Delivery of substances needed for cellular
  metabolism in the tissues
• Defense against invading microorganisms and
  injury
• Acid-base balance

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Blood and Blood Components

• All types of blood cells are formed within the
  red bone marrow (present in all tissues at birth)
• In the adult, the red bone marrow is primarily
  found in membranous bone
• Vertebrae
• Pelvis
• Sternum
• Ribs
• Yellow marrow produces some white cells, but is
  composed mainly of connective tissue and fat

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Other Blood-forming Organs

• Lymph nodes
• Produce lymphocytes and antibodies
• Spleen
• Produces lymphocytes, plasma cells, and
  antibodies (and stores large quantities of blood)
• Liver
• A blood-forming organ only during intrauterine
  life
• Plays an important role in the coagulation process

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Plasma

• Clear portion of blood
• About 92 water
• Contains three important proteins
• Albumin
• Most plentiful protein
• Similar to egg white and gives blood its gummy
  texture
• Keeps the water concentration of blood low so
  that water diffuses readily from tissues into the
  blood
• Globulins(alpha, beta, and gamma) transport
  other proteins and provide immunity to disease
• Fibrinogenresponsible for blood clotting

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Plasma

• Functions of plasma proteins
• Maintaining blood pH (acting as either an acid or
  a base)
• Transporting fat-soluble vitamins, hormones, and
  carbohydrates
• Allowing the body to digest them temporarily for
  food
• Plasma also contains salts, metals, and inorganic
  compounds

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Red Blood Cells (RBCs)

• Most abundant cells in the body
• Primarily are responsible for tissue oxygenation
• Comprised of mainly water and the red protein
  hemoglobin

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Red Blood Cells (RBCs)

• Red blood cells have a life span of about 120
  days
• As the cells age
• Their internal chemical machinery weakens
• They lose elasticity
• They become trapped in small blood vessels in the
  bone marrow, liver, and spleen
• They are then destroyed by specialized white
  blood cells (macrophages)

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Mature Erythrocytes
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Red Blood Cells (RBCs)

• Hemoglobin (Hgb)
• Reported in grams per 100 mL of blood
• Normal hemoglobin for men is 13.5 to 18 g/100 mL
• In women a normal hemoglobin is 12 to 16 g/100 mL
• Number of RBCs is about 4.5 to 5 million
  cells/cubic millimeter
• Hematocrit (Hct)
• The fraction of the total volume of blood that
  consists of red blood cells, normally about 45
• Reticulocyte count
• Provides information about the rate of RBC
  production

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Hemoglobin Molecule
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White Blood Cells (WBCs)

• WBCs arise from the bone marrow and are released
  into the blood stream
• Function
• Destroy foreign substances (e.g., bacterium,
  virus)
• Clear the blood stream of debris
• Leukocyte production increases in response to
  infection
• Causes an elevated WBC count in the blood

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White Blood Cells (WBCs)

• Normal WBC count is about 5000 to 10,000
  cells/cubic millimeter
• Monocytes make up about 5 of the total white
  count and will increase with chronic infections
• Lymphocytes account for about 27.5 of the total
• Neutrophils about 65 of the total
• Eosinophils and basophils together comprise about
  2.5 of the total white cell count

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White Blood Cells (WBCs)

• Leukocyte disorders
• Leukemiaan increased number of WBCs in the
  tissues and/or in the blood
• Leukocytosisan abnormal increase in the number
  of circulating WBCs
• Leukopeniaan abnormal decrease in the number of
  WBCs

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The Inflammatory Process

• Inflammation is characterized by redness, heat,
  swelling, and pain
• When tissues are injured or irritated, injured
  cells release histamine and other substances
• Cause blood vessels in the injured tissue to
  dilate
• Increased blood flow also carries neutrophils and
  monocytes (phagocytic cells) to the site of injury

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The Inflammatory Process

• Histamine and other substances cause the walls of
  the blood vessels to leak
• The fluid that collects in the tissues contains
  fibrinogen (a clotting factor)
• Fluid and irritating chemicals accumulate at the
  injured site, stimulating pain receptors

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Immunity

• Cellular immunity
• Humoral immunity
• Autoimmune diseases
• Alterations in immunologic response

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Platelets (Thrombocytes)

• Platelets are small, sticky cells that play an
  important role in blood clotting
• When a blood vessel is cut, platelets travel to
  the site and swell into odd, irregular shapes and
  adhere to the damaged vessel wall
• Platelets plug the leak and allow other cells
  to stick to them and form a clot
• If the damage to the vessel is too great,
  platelets chemically signal the complex clotting
  process, the clotting cascade

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Platelets

• Clotting time is normally about 7 to 10 minutes
• Prothrombin time (PT time) is the time it takes
  plasma to clot
• Normally about 12 to 13 seconds

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Blood Groups

• When combined with foreign plasma, red blood
  cells either clump together (agglutinate), or do
  not
• Two distinct agglutinins (substances on red blood
  cells acting as antigens) are responsible for
  this clumping
• Based on possible combinations of these antigens,
  four types of human blood have been identified
  A, B, AB, and O
• Type A blood has anti-B antibodies in the plasma
  and will clump Type B blood
• Type B blood has anti-A antibodies and will clump
  Type A blood

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Blood Groups

• Type AB blood has neither antibody and can
  receive any of the four types of blood
• Universal recipient
• Type O blood has both anti-A and anti-B
  antibodies
• Cannot receive any type of blood other than Type
  O
• Type O blood has neither antigen, however, and
  can be given to patients with any blood type
• Type O blood is called the universal donor

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Rh Factor

• Refers to the presence or absence of the Rh
  antigen on the surface of red blood cells
• A person with the factor is Rh-positive
• A person without it is Rh-negative
• Antibodies to the Rh factor are acquired through
  exposure to Rh-positive blood

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Hemostasis

• Hemostasis is the process that stops bleeding
  after injury
• Involves the interaction of plasma and tissue
  factors with the platelets and vessels
• The process of hemostasis ensures that leaky
  vessels are sealed within minutes of injury
• Vascular components
• Coagulation mechanisms

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Anemia

• A condition in which the concentration of
  hemoglobin or erythrocytes in the blood is below
  normal
• Precipitating causes of anemia
• Chronic or acute blood loss
• Decreased production of erythrocytes
• Increased destruction of erythrocytes
• Two common forms of anemia
• Iron-deficiency anemia
• Hemolytic anemia

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Iron-deficiency Anemia

• Iron is the critical part of a hemoglobin
  molecules ability to bind oxygen
• The lack of iron in iron-deficiency anemia
  prevents the bone marrow from making sufficient
  hemoglobin for the red cells
• The cells produced are small and pale-centered,
  and have a reduced oxygen-carrying capacity
• Causes
• Signs and symptoms
• Treatment

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Hemolytic Anemia

• Caused by the premature destruction of red cells
  in the blood (hemolysis)
• May result from an inherited disorder inside the
  red cell or from a disorder outside the cell
• Is usually acquired later in life
• Signs and symptoms
• Treatment

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AnemiaSigns and Symptoms

• Fatigue and headaches
• Sometimes a sore mouth or tongue
• Brittle nails
• In severe cases, breathlessness and chest pain
• Other patient complaints may include
• Fatigue
• Lethargy
• Fever
• Cutaneous bleeding
• Bleeding from mucous membranes

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Anemia

• Treatment
• Directed at correcting, modifying, or diminishing
  the mechanism or process that is leading to
  defective red cell production or reduced red cell
  survival
• Diagnosis

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Leukemia

• Refers to any of several types of cancer in which
  there is usually a disorganized proliferation of
  WBCs in the bone marrow
• Incidence
• Causes
• Classifications
• Signs and symptoms
• Diagnosis
• Treatment

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Lymphomas

• Refers to a varied group of diseases that range
  from slowly-growing chronic disorders to rapidly
  evolving, acute conditions
• Hodgkins disease represents one type
• All others are commonly called non-Hodgkins
  lymphomas

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Hodgkins Disease

• A malignant disorder of lymphoid tissue (found
  mainly in the lymph nodes and spleen) in which
  there is a proliferation of its constituent cells
  and a resultant enlargement of the lymph nodes
• Left unchecked, these cancer cells multiply and
  eventually displace healthy lymphocytes,
  suppressing the immune system
• Sign and symptoms
• Diagnosis
• Treatment

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Non-Hodgkins Lymphomas

• Vary in their malignancy according the nature and
  activity of the abnormal cells
• At least 10 types of non-Hodgkins lymphoma have
  been identified
• Cause
• Signs and symptoms
• Treatment
• Radiation therapy
• Anticancer drugs
• Sometimes bone marrow transplantation

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Polycythemia

• A rare disorder characterized by overabundant
  production of RBCs, WBCs, and platelets
• May be a natural response to hypoxia (secondary
  polycythemia) or may occur for unknown reasons
  (primary polycythemia)
• Signs and symptoms
• Treatment

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Disseminated Intravascular Coagulopathy (DIC)

• A complication of severe injury, trauma, or
  disease
• A relatively common abnormal clotting disorder
• Most often seen in the critical care setting
• Disrupts the fine balance between procoagulants
  and inhibitors, thrombus formation and lysis
• Signs and symptoms
• Management

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Hemophilia

• Hemophilia (meaning love of blood) is an
  inherited bleeding disorder
• Hemophilia A
• Caused by a deficiency of factor VIII that is
  essential to the process of blood clotting
• Hemophilia B
• Less common form of hemophilia caused by a
  deficiency of factor IX
• Bleeding from hemophilia may occur spontaneously,
  after even minor injury, or during some medical
  procedures (e.g., tooth extraction)

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Hemophilia

• Hemorrhage can occur anywhere in the body
• Bleeding into joints, deep muscles, the urinary
  tract, and intracranial sites are the most common
• Hemophilia is controlled by infusions of
  concentrates of factor VIII that may be
  self-administered by the patient
• Most hemophiliacs seek emergency care only with
  complicated problems and trauma-related
  difficulties

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Sickle Cell Disease

• Also known as sickle cell anemia
• A debilitating and unpredictable recessive
  genetic illness that affects persons of African
  descent (and less commonly, persons of
  Mediterranean origin)
• Signs and symptoms
• Pathophysiology
• Management

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Clinical Manifestations of Sickle Cell Disease
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Sickle Cell versus Normal Erythrocyte
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Multiple Myeloma

• A malignant neoplasm of the bone marrow
• Incidence
• Pathophysiology
• Signs and symptoms
• Diagnosis
• Treatment

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Assessment and Management

• Most patients with hematologic disorders are
  knowledgeable about their disease
• May summon EMS to
• Help manage a change in their condition
• Arrange for transport to an emergency department
  for physician evaluation
• Situations that may initiate a call for emergency
  care will vary by patient and disease