Comprehensive Study Guide for the Hematopoietic System and Oncology

Defining the Hematopoietic System and the Process of Hematopoiesis

The hematopoietic system is the physiological system responsible for the creation of blood cells within the body. This process, known as hematopoiesis, occurs as stem cells located in the bone marrow differentiate into various specialized blood cells. A significant characteristic of mature blood cells is the absence of a nuclease, which means these cells cannot undergo division. Consequently, the hematopoietic system must engage in continuous renewal to maintain adequate blood cell levels. The primary significance of this system lies in its role in transporting oxygen ($O_2$), nutrients, and metabolic waste, as well as providing protection against pathogens and facilitating coagulation. The blood acts as a transport medium to move materials from the external environment to the body's internal cells. The components of blood include plasma, erythrocytes, leukocytes, and thrombocytes.

Erythrocytes: Primary Functions and Essential Nutrients

Erythrocytes, more commonly referred to as Red Blood Cells ($RBC$), serve two primary functions related to gas exchange: the transport of oxygen ($O_2$) from the lungs to the body tissues and the transport of carbon dioxide ($CO_2$) from the tissues back to the lungs. The production of erythrocytes is regulated by Erythropoietin, a hormone produced by the kidneys. The action of erythropoietin is to stimulate the bone marrow to increase blood cell production. To facilitate healthy erythrocyte formation, several nutrients are necessary, including Iron ($Fe$), Vitamin $B_{12}$, Folic Acid, and Protein ($\text{PRO}$). A reticulocyte count is used to measure immature Red Blood Cells in the system. Students should review Hoffman Table 33.7 for specific values. The life cycle of an $RBC$ is finite, and medications such as Procrit or Epogen are used to stimulate the bone marrow when more red blood cell production is required.

Leukocytes and Thrombocytes: Defense and Hemostasis

Leukocytes, or White Blood Cells ($WBC$), are primarily involved in the body's protection against infection and disease. They are classified into two main groups: Granulocytes and Agranulocytes. Adequate protein ($\text{PRO}$) intake is necessary for their development. Normal laboratory values can be found in Hoffman Table 33.1. A clinical phenomenon known as a "Left Shift" or "Shift to the Left" refers to the presence of an increased number of immature neutrophils (bands) in the blood, often signaling an acute infection.

Thrombocytes, also known as platelets, are actually cell fragments rather than whole cells. They have a lifespan of approximately $7$ to $10 \text{ days}$ and are often stored in the spleen. Their primary function is to control bleeding through coagulation. The normal value for platelets is approximately $150,000$ to $450,000 \text{ per microliter}$.

Bone Marrow Biopsy and Clinical Significance

Hematopoiesis occurs in the red marrow of the bone. In children, marrow is formed in nearly all bones. However, in adults, active marrow is primarily restricted to the pelvis (iliac crest), ribs, vertebrae, and the sternum. A bone marrow biopsy is often performed when there is a suspected malignancy. The iliac crest is the standard site for this procedure.

Nursing considerations for a bone marrow biopsy include several steps. Before the procedure, the nurse must ensure informed consent is obtained, check laboratory results, educate the patient, assist with positioning, and address patient anxiety. After the procedure, the nurse must apply pressure and a dressing to the site, handle the specimen correctly, provide medication for pain, and continue patient education regarding post-procedure care.

General Anemia Manifestations and Nutrient-Deficiency Anemias

Anemia is characterized by a lack of oxygen-carrying capacity in the blood. Clinical manifestations include cold hands and toes, pallor, and fatigue. To compensate for the lack of oxygen, the body utilizes two primary mechanisms: tachycardia (increased heart rate) and tachypnea (increased respiratory rate). Specific signs for different types of anemia can be found in Table 34-4.

Level 1 Anemias include those caused by deficiencies in Iron, $B_{12}$, and Folic Acid. Iron Deficiency Anemia is caused by a lack of iron and is often seen during periods of rapid growth, poor diet, or GI issues. Clinical manifestations include Pica (craving non-food items), Glossitis (inflammation of the tongue), Cheilosis (cracking at the corners of the mouth), and Koilonychia (spoon-shaped nails). Diagnostics include Hemoglobin and Hematocrit ($H\&H$), Ferritin, and Transferrin. Treatment involves Ferrous Sulfate combined with Vitamin C ($\text{Ascorbic Acid}$) to enhance absorption. Dietary sources include heme and non-heme iron.

Vitamin B12 and Folic Acid Deficiency Anemias

Vitamin $B_{12}$ Deficiency Anemia results from low levels of $B_{12}$, often due to diet or issues with gastric acid (intrinsic factor). A distinguishing clinical manifestation is the presence of neurological changes. Diagnostics include $H\&H$, $B_{12}$ levels, and elevated Methylmalonic Acid ($\text{MMA}$). Treatment involves $B_{12}$ supplementation via oral ($PO$) or subcutaneous ($SQ$) routes.

Folic Acid Anemia is caused by a folate deficiency, with risks including pregnancy, GI malabsorption, and alcohol abuse. It can manifest alongside pancytopenia. Diagnostics show low folate but normal $\text{MMA}$ levels. Treatment is folate supplementation. This deficiency is notably linked to Neural Tube Defects in developing fetuses.

Aplastic and Hemolytic Anemias

Aplastic anemia is caused by bone marrow damage, resulting in pancytopenia (a deficiency of all three blood cell types). This leads to infection (due to low $WBC$) and bleeding or bruising (due to low platelets). Diagnosis involves a $CBC$, coagulation studies, and bone marrow biopsy. Early treatment includes blood transfusions and growth factor stimulants, while severe cases may require a stem cell transplant.

Hemolytic anemia is defined as anemia due to the premature destruction of Red Blood Cells. Clinical manifestations include jaundice and dark urine. Severe cases can lead to renal insufficiency. Treatment depends on the underlying cause of the hemolysis.

Sickle Cell Anemia and Thalassemia

Sickle Cell Anemia is a genetic disorder affecting hemoglobin ($Hgb$), causing cells to take on a sickle shape. This reduces their oxygen-carrying capacity and flexibility, leading to thrombi (clots) and hemolytic anemia. It is most prevalent in the African American ($AA$) population. Diagnosis often occurs in childhood (around $6 \text{ months}$). There is no cure except for a stem cell transplant. Sickling of the cells is triggered by stressors like dehydration or cold. Manifestations include intense pain, organ damage, and jaundice. Management involves the use of Hydroxyurea and blood transfusions. A Sickle Cell Crisis is a sudden onset of pain treated with the "HOP" protocol: Hydration, Oxygen, and Pain management (with rest and transfusion).

Thalassemia Anemia is a genetic mutation of hemoglobin leading to hemolysis. It also presents with jaundice and dark urine. Treatment involves regular blood transfusions and stem cell transplants.

Polycythemia and Phlebotomy Therapy

Polycythemia is a condition characterized by an overproduction of red blood cells. Polycythemia Vera is a rare, primary form of the disease. Erythrocytosis is a more common secondary form. Clinical manifestations of polycythemia include vision changes, skin color changes (red or purple hue), and hyper-viscosity of the blood. Diagnostics include a $CBC$, genetic testing, and checking erythropoietin levels. Treatment involves therapeutic phlebotomy to reduce blood volume and the administration of Hydroxyurea to suppress marrow production.

Thrombocytopenia and Hemophilia

Thrombocytopenia is defined as a platelet count of less than $150,000/mm^3$. It occurs due to decreased production, increased utilization, or increased destruction of platelets. Types include Idiopathic Thrombocytopenia Purpura ($ITP$), which can be acute in children or chronic in adults, and Heparin-Induced Thrombocytopenia ($HIT$). Manifestations involve bleeding (hematemesis, hematuria, bruising, ecchymosis, and petechiae). Nurses must implement bleeding precautions and avoid medications like Aspirin or $NSAIDs$. If $HIT$ is the cause, heparin must be stopped immediately.

Hemophilia is a genetic bleeding disorder caused by inadequate clotting factors. Hemophilia A involves a deficiency in Factor VIII, while Hemophilia B involve a deficiency in Factor IX. There is no cure for hemophilia. Nursing care focuses on safety, monitoring vital signs, and fall precautions.

Blood Typing and Transfusion Protocols

Blood is classified via the ABO system and the Rh system. In the ABO system, the types are A, B, AB (Universal Recipient), and O (Universal Donor). The Rh system designates blood as Rh positive ($+$) or Rh negative ($-$). Cross-matching is performed to confirm the donor blood is safe for the recipient; an Agglutination Reaction indicates incompatibility and the blood must not be given.

Pre-administration steps include checking the physician's order and lab results, obtaining a signed consent form, and ensuring the presence of Normal Saline ($0.9\% \text{ NS}$). Blood administration requires specific tubing with a filter and a Y-connector. Vital signs must be taken before and during the transfusion. Transfusion steps involve priming the line with $NS$, beginning the infusion slowly, and staying with the patient for the first $15 \text{ minutes}$. The transfusion must be completed within a maximum of $4 \text{ hours}$. Vital signs are monitored every $15 \text{ minutes}$ twice, then every $30 \text{ minutes}$ once, then every $60 \text{ minutes}$, and finally at the conclusion of the transfusion. After completion, the line is flushed and the bag is discarded in biohazard waste.

Transfusion Reactions and Cancer Pathophysiology

If a transfusion reaction occurs, the nurse must STOP the infusion immediately, assess vital signs, maintain the IV line with $NS$, contact the PCP, and keep all tubing and blood bags for analysis. Frequent transfusions can lead to iron overload, which is managed with Chelation Therapy.

Cancer is defined as abnormal cells that divide and grow uncontrollably. Risk factors include modifiable factors (sedentary lifestyle, diet, smoking, alcohol) and non-modifiable factors (age, genetics). Hallmark signs include uncontrolled cell death (apoptosis evasion) and altered cell differentiation. Metastasis occurs when cancer cells move from the original site to other locations via cell-to-cell spread, the lymphatic system, or the hematogenous (blood) route. Warning signs are often categorized by the "CAUTION" acronym.

Cancer Prevention and Therapy

Cancer prevention is tiered: Primary prevention involves risk factor modification and immunization; Secondary prevention involves early detection through screening (refer to Hoffman Table 13.4 for guidelines); Tertiary prevention involves managing the disease, symptoms, and side effects after diagnosis. Diagnosis is aided by radiological imaging and biopsy. Staging uses the TNM system (Tumor size, Nodes involved, Metastasis) and is classified into Stages $I$ through $IV$.

Therapy categories include Surgery, Radiation Therapy, Chemotherapy, Targeted Therapy, and Immunotherapy. Nursing care involves pre- and post-operative management, education on mucosa care (frequent oral rinsing for mucositis), and medication administration. Essential medications include antiemetics such as Ondansetron and Phenergan, and analgesics/opioids such as Hydrocodone, Morphine, and Hydromorphone.

Leukemia, Multiple Myeloma, and Lymphoma

Leukemia is a hematological cancer characterized by the overproduction of immature leukocytes. It is classified by cell origin (Lymphoid or Myeloid) and whether it is Acute or Chronic. The four main types are:

1. Acute Lymphocytic (ALL): Peak age $2$ to $4 \text{ years}$; $90\%$ five-year survival rate.
2. Acute Myelogenous (AML): Peak age $12$ to $20 \text{ years}$ and over $55$; poor prognosis.
3. Chronic Lymphocytic (CLL): Peak age over $60 \text{ years}$; good prognosis ($> 10 \text{ years}$).
4. Chronic Myelogenous (CML): Peak age $30$ to $50 \text{ years}$; poor prognosis (death often within $5 \text{ years}$).

Manifestations of leukemia include enlarged organs, neutropenia, anemia, and thrombocytopenia. Multiple Myeloma is another hematological malignancy. Lymphoma is a tumor of the lymphocytes, categorized as Hodgkin’s (presence of Reed-Sternberg Cells) or Non-Hodgkin’s. "B Symptoms" of lymphoma include painless swelling of lymph nodes, low-grade fever, drenching night sweats, weight loss, and fatigue. Nursing care for these patients includes transfusions, medication administration, and maintaining IV fluids.