The Child with Hematologic or Immunologic Dysfunction



The Child with Hematologic or Immunologic Dysfunction


Rosalind Bryant



image


evolve.elsevier.com/wong/essentials





Hematologic and Immunologic Dysfunction


Several tests can be performed to assess hematologic function, including additional procedures to identify the cause of the dysfunction. The following discussion is limited to a description of the most common and one of the most valuable tests, the complete blood cell count (CBC). Other procedures, such as those related to iron, coagulation, and immune status, are discussed throughout the chapter as appropriate. The nurse should be familiar with the significance of the findings from the CBC (Table 26-1) and be aware of normal values for age, which are listed in Appendix B.



TABLE 26-1


TESTS PERFORMED AS PART OF A COMPLETE BLOOD COUNT



































































TEST (AVERAGE VALUE)* DESCRIPTION, COMMENTS
RBC count (4.5–5.5 million/mm3) Number of RBCs/mm3 of blood
Indirectly estimates Hgb content of blood
Reflects function of bone marrow
Hgb determination (11.5–15.5 g/dl) Amount of Hgb (g)/dl of whole blood
Total blood Hgb primarily depends on number of circulating RBCs but also on amount of Hgb in each cell
Hct (35%–45%) Percent volume of packed RBCs in whole blood
Indirectly measures Hgb content
Is approximately three times Hgb content
RBC indices  
MCV (77–95 fl) Average or mean volume (size) of a single RBC
MCV values are expressed as femtoliters (fl) or cubic microns (mm3)
MCH (25–33 pg/cell) Average or mean quantity (weight) of Hgb in a single RBC
MCH values are expressed as picograms (pg) or micromicrograms (mmcg)
Whereas MCV and MCH depend on accurate counts of RBCs, MCHC does not; therefore, MCHC is often more reliable
All indices depend on average cell measurements and do not show individual RBC variations (anisocytosis)
MCHC (31%–37% Hgb [g]/dl RBC) Average concentration of Hgb in a single RBC
MCHC values are expressed as percent Hgb (g)/cell or Hgb (g)/dl RBC
RBC volume distribution width (13.4% ± 1.2%) Average size of RBCs
Differentiates some types of anemia
Reticulocyte count (0.5%–1.5% erythrocytes) Percent reticulocytes in RBCs
Index of production of mature RBCs by bone marrow
Decreased count indicates depressed bone marrow function
Increased count indicates erythrogenesis in response to some stimulus
When reticulocyte count is extremely high, other forms of immature RBCs (normoblasts, even erythroblasts) may be present
Indirectly estimates hypochromic anemia
Usually elevated in patients with chronic hemolytic anemia
WBC count (4.5–13.5 × 103 cells/mm3) Number of WBCs/mm3 of blood
Total number of WBCs less important than differential count
Differential WBC count Inspection and quantification of WBC types present in peripheral blood
Values are expressed as percentages; to obtain absolute number of any type of WBC, multiply its respective percentage by total number of WBCs
Neutrophils (polys) (54%–62%) (3–5.8 × 103 cells/mm3) Primary defense in bacterial infection; capable of phagocytizing and killing bacteria
Bands (3%–5%) (0.15–0.4 × 103 cells/mm3) Immature neutrophil
Increased numbers in bacterial infection
Also capable of phagocytosis and killing
Eosinophils (1%–3%) (0.05–0.25 × 103 cells/mm3) Named for their staining characteristics with eosin dye
Increased in allergic disorders, parasitic diseases, certain neoplasms, and other diseases
Basophils (0.075%) (0.015–0.030 × 103 cells/mm3) Named for their characteristic basophilic stippling
Contain histamine, heparin, and serotonin; believed to cause increased blood flow to injured tissues while preventing excessive clotting
Lymphocytes (25%–33%) (1.5–3.0 × 103 cells/mm3) Involved in development of antibody and delayed hypersensitivity
Monocytes (3%–7%) Large phagocytic cells that are involved in early stage of inflammatory reaction
ANC (>1000/mm3) Percent neutrophils/bands times WBC count
Indicates body’s capability to handle bacterial infections
Platelet count (150–400 × 103/mm3) Number of platelets/mm3 of blood
Cellular fragments that are necessary for clotting to occur
Stained peripheral blood smear Visual estimation of amount of Hgb in RBCs and overall size, shape, and structure of RBCs
Various staining properties of RBC structures may be evidence of immature forms of erythrocytes
Shows variation in size and shape of RBCs: microcytic, macrocytic, poikilocytic (variable shapes)

ANC, Absolute neutrophil count; Hct, hematocrit; Hgb, hemoglobin; MCH, mean corpuscular hemoglobin; MCHC, mean corpuscular hemoglobin concentration; MCV, mean corpuscular volume; RBC, red blood cell; WBC, white blood cell.


*See Appendix B for normal values according to age.


As with any disorder, the history and physical examination are essential to identify hematologic dysfunction, and the nurse is often the first person to suspect a problem based on information from these sources. Comments by the parent regarding the child’s lack of energy, food diary of poor sources of iron, frequent infections, and bleeding that is difficult to control offer clues to the more common disorders affecting the blood. A careful physical appraisal, especially of the skin, can reveal findings (e.g., pallor, petechiae, bruising) that may indicate minor or serious hematologic conditions. Nurses need to be aware of the clinical manifestations of blood diseases to assist in recognizing symptoms and establishing a diagnosis.




Red Blood Cell Disorders


Anemia


The term anemia describes a condition in which the number of red blood cells (RBCs) or the hemoglobin (Hgb or Hb) concentration is reduced below normal values for age. This diminishes the oxygen-carrying capacity of the blood, causing a reduction in the oxygen available to the tissues. Anemia is the most common hematologic disorder of infancy and childhood and is not a disease itself but an indication or manifestation of an underlying pathologic process.



Classification


Anemias are classified in relation to (1) etiology or physiology, manifested by erythrocyte or Hgb depletion, and (2) morphology, the characteristic changes in RBC size, shape, or color (Box 26-1). Although the morphologic classification is more useful in terms of laboratory evaluation of anemia, the etiologic approach provides direction for planning nursing care. For example, anemia with reduced Hgb concentration may be caused by a dietary depletion of iron, and the principal intervention is replenishing iron stores. The classification of anemias is found in Fig. 26-1.





Consequences of Anemia


The basic physiologic defect caused by anemia is a decrease in the oxygen-carrying capacity of blood and consequently a reduction in the amount of oxygen available to the cells. When the anemia has developed slowly, the child usually adapts to the declining Hgb level.


The effects of anemia on the circulatory system can be profound. Because the viscosity of blood depends almost entirely on the concentration of RBCs, the resulting hemodilution of severe anemia decreases peripheral resistance, causing greater quantities of blood to return to the heart. The increased circulation and turbulence within the heart may produce a murmur. Because the cardiac workload is greatly increased, especially during exercise, infection, or emotional stress, cardiac failure may ensue.


Children seem to have a remarkable ability to function well despite low levels of Hgb. Cyanosis (the result of the quantity of deoxygenated Hgb in arterial blood) is typically not evident. Growth retardation, resulting from decreased cellular metabolism and coexisting anorexia, is a common finding in chronic severe anemia and is frequently accompanied by delayed sexual maturation in the older child.





Nursing Care Management


image The assessment of anemia includes the basic techniques that are applicable to any condition. The age of the infant or child provides some clues regarding the possible etiology of the anemia. For example, iron-deficiency anemia occurs more frequently in toddlers between 12 and 36 months of age and during the growth spurt of adolescence.


image Case Study—The Child with Anemia


Racial or ethnic background is significant. For example, the anemias related to abnormal Hgb levels are found in Southeast Asians and persons of African or Mediterranean ancestry. These same groups may be genetically deficient in the enzyme lactase after the period of infancy. Affected individuals are unable to tolerate lactose in the diet, with consequent intestinal irritation and chronic blood loss.


Special emphasis is placed on a careful history to elicit any information that might help identify the cause of the anemia. For example, a statement such as “My child drinks lots of milk” is a frequent finding in toddlers with iron-deficiency anemia. An episode of diarrhea may have precipitated temporary lactose intolerance in a young child.


Stool examination for occult (microscopic) blood (Hemoccult test) can identify chronic intestinal bleeding that results from a primary or secondary lactase deficiency. It is also important to understand the significance of various blood tests (see Table 26-1).



Prepare the Child and Family for Laboratory Tests

Usually, several blood tests are ordered, but because they are generally done sequentially rather than at one time, the child is subjected to multiple finger or heel punctures or venipunctures. Laboratory technicians frequently are not aware of the trauma that repeated punctures represent to a child. However, these invasive procedures need not be painful (see Blood Specimens, Chapter 22). For example, the topical application of EMLA (an eutectic mix of lidocaine and prilocaine) or 4% lidocaine (Ela-Max or LMX) before needle punctures can eliminate pain (see Pain Management, Chapter 7). Therefore, the nurse is responsible for preparing the child and family for the tests by:



Older children may appreciate the opportunity to observe the blood cells under a microscope or in photographs. This experience is especially important if a serious blood disorder, such as leukemia, is suspected because it serves as a foundation for explaining the pathophysiology of the disorder.


Bone marrow aspiration is not a routine hematologic test but is essential for definitive diagnosis of the leukemias, lymphomas, and certain anemias.




Decrease Tissue Oxygen Needs

Because the basic pathologic process in anemia is a decrease in oxygen-carrying capacity, an important nursing responsibility is to assess the child’s energy level and minimize excess demands. The child’s level of tolerance for activities of daily living and play is assessed, and adjustments are made to allow as much self-care as possible without undue exertion. During periods of rest, the nurse takes vital signs and observes behavior to establish a baseline of nonexertion energy expenditure. During periods of activity, the nurse repeats these measurements and observations to compare them with resting values.





Iron-Deficiency Anemia


Anemia caused by an inadequate supply of dietary iron is the most prevalent nutritional disorder in the United States and the most preventable mineral disturbance. The prevalence of iron-deficiency anemia has decreased during infancy in the United States, probably in part because of families’ participation in the Women, Infants, and Children (WIC) program, which provides iron-fortified formula for the first year of life and routine screening of Hgb levels during early childhood (Baker, Greer, and Committee on Nutrition American Academy of Pediatrics [AAP], 2010; Cusick, Mei, Freedman, and others, 2008). Preterm infants are especially at risk because of their reduced fetal iron supply. Children 12 to 36 months of age are at risk for anemia as a result of primarily cow milk intake and not eating an adequate amount of iron-containing food (Andrews, Ullrich, and Fleming, 2009; Baker, Greer, and Committee on Nutrition AAP, 2010; Richardson, 2007). Adolescents are also at risk because of their rapid growth rate combined with poor eating habits, menses, obesity, or strenuous activities.



Pathophysiology


image Iron-deficiency anemia can be caused by any number of factors that decrease the supply of iron, impair its absorption, increase the body’s need for iron, or affect the synthesis of Hgb. Although the clinical manifestations and diagnostic evaluation are similar regardless of the cause, the therapeutic and nursing care management depend on the specific reason for the iron deficiency. The following discussion is limited to iron-deficiency anemia resulting from inadequate iron in the diet.


image Case Study—Iron Deficiency Anemia


During the last trimester of pregnancy, iron is transferred from the mother to the fetus. Most of the iron is stored in the circulating erythrocytes of the fetus, with the remainder stored in the fetal liver, spleen, and bone marrow. These iron stores are usually adequate for the first 5 to 6 months in a full-term infant but for only 2 to 3 months in preterm infants and multiple births. If dietary iron is not supplied to meet the infant’s growth demands after the fetal iron stores are depleted, iron-deficiency anemia results. Physiologic anemia should not be confused with iron-deficiency anemia resulting from nutritional causes.


Although most toddlers with iron-deficiency anemia are underweight, many infants are overweight because of excessive milk ingestion (known as milk babies). These children become anemic for two reasons: milk, a poor source of iron, is given almost to the exclusion of solid foods, and 50% of iron-deficient infants fed cow’s milk have an increased fecal loss of blood.



Therapeutic Management


After the diagnosis of iron-deficiency anemia is made, therapeutic management focuses on increasing the amount of supplemental iron the child receives. This is usually done through dietary counseling and the administration of oral iron supplements.


In formula-fed infants, the most convenient and best sources of supplemental iron are iron-fortified commercial formula and iron-fortified infant cereal. Iron-fortified formula provides a relatively constant and predictable amount of iron and is not associated with an increased incidence of gastrointestinal (GI) symptoms, such as colic, diarrhea, or constipation. Infants younger than 12 months of age should not be given fresh cow’s milk because it may increase the risk of GI blood loss occurring from exposure to a heat-labile protein in cow’s milk or cow’s milk–induced GI mucosal damage resulting from a lack of cytochrome iron (heme protein) (Glader, 2007; Richardson, 2007). If GI bleeding is suspected, the child’s stool should be guaiac tested on at least four or five occasions to identify any intermittent blood loss.


Dietary addition of iron-rich foods is usually inadequate as the sole treatment of iron-deficiency anemia because the iron is poorly absorbed and thus provides insufficient supplemental quantities of iron. If dietary sources of iron cannot replace body stores, oral iron supplements are prescribed for approximately 3 months. Ferrous iron, more readily absorbed than ferric iron, results in higher Hgb levels. Ascorbic acid (vitamin C) appears to facilitate absorption of iron and may be given as vitamin C–enriched foods and juices with the iron preparation.


If the Hgb level fails to rise after 1 month of oral therapy, it is important to assess for persistent bleeding, iron malabsorption, noncompliance, improper iron administration, or other causes of the anemia. Parenteral (IV or intramuscular [IM]) iron administration is safe and effective but painful, expensive, and occasionally associated with regional lymphadenopathy, transient arthralgias or serious allergic reaction (Andrews, Ullrich, and Fleming, 2009; Glader, 2007; McKenzie, 2004). Therefore, parenteral iron is reserved for children who have iron malabsorption or chronic hemoglobinuria. Transfusions are indicated for the most severe anemia and in cases of serious infection, cardiac dysfunction, or surgical emergency when anesthesia is required. Packed RBCs (2–3 ml/kg), not whole blood, are used to minimize the chance of circulatory overload. Supplemental oxygen is administered when tissue hypoxia is severe.




Nursing Care Management


An essential nursing responsibility is instructing parents in the administration of iron. Oral iron should be given as prescribed in two divided doses between meals, when the presence of free hydrochloric acid is greatest, because more iron is absorbed in the acidic environment of the upper GI tract. A citrus fruit or juice taken with the medication aids in absorption.



An adequate dosage of oral iron turns the stools a tarry green color. The nurse advises parents of this normally expected change and inquires about its occurrence on follow-up visits. Absence of the greenish black stool may be a clue to poor administration of iron, either in schedule or in dosage. Vomiting or diarrhea can occur with iron therapy. If the parents report these symptoms, the iron can be given with meals and the dosage reduced and then gradually increased until tolerated.



If parenteral iron preparations are prescribed, iron dextran must be injected deeply into a large muscle mass using the Z-track method. The injection site is not massaged after injection to minimize skin staining and irritation. Because no more than 1 ml should be given in one site, the IV route should be considered to avoid multiple injections. Careful observation is required because of the risk of adverse reactions, such as anaphylaxis, with IV administration. A test dose is recommended before routine use. Recently, a new IV iron preparation (ferumoxytol) was approved in the United States that shows promise in complete replacement of iron with little toxicity (Auerbach, 2011).



Diet

A primary nursing objective is to prevent nutritional anemia through family education. Because breast milk is a low iron source, the nurse must reinforce the importance of administering iron supplementation to exclusively breastfed infants by 4 months of age (Baker, Greer, and Committee on Nutrition AAP, 2010; Lokeshwar, Mehta, Mehta, and others, 2011). The AAP recommends that preterm, marginally low and low–birth-weight infants, or infants with inadequate iron stores at birth receive iron supplements at approximately 2 months of age (Berglund, Westrup, and Domellof, 2010).


In formula-fed infants, the nurse discusses with parents the importance of using iron-fortified formula and of introducing solid foods at the appropriate age during the first year of life. Traditionally, cereals are one of the first semisolid foods to be introduced into the infant’s diet at approximately 6 months of age (Baker, Greer, and Committee on Nutrition AAP, 2010; Glader, 2007; Lokeshwar, Mehta, Mehta, and others, 2011). The best solid-food source of iron is commercial iron-fortified cereals. It may be difficult at first to teach the infant to accept foods other than milk. The same principles are applied as those for introducing new foods (see Nutrition, Chapter 10), especially feeding the solid food before the milk. Predominantly milk-fed infants rebel against solid foods, and parents are cautioned about this and the need to be firm in not relinquishing control to the child. It may require intense problem solving on the part of both the family and the nurse to overcome the child’s resistance.


A difficulty encountered in discouraging the parents from feeding milk to the exclusion of other foods is dispelling the popular myth that milk is a “perfect food.” Many parents believe that milk is best for infants and equate weight gain with a “healthy child” and “good mothering.” The nurse can also stress that overweight is not synonymous with good health.


Diet education of teenagers is especially difficult, especially because teenage girls are particularly prone to following weight-reduction diets. Emphasizing the effect of anemia on appearance (pallor) and energy level (difficulty maintaining popular activities) may be useful. (See Mineral Imbalances, Chapter 11.)

Jan 16, 2017 | Posted by in NURSING | Comments Off on The Child with Hematologic or Immunologic Dysfunction
Premium Wordpress Themes by UFO Themes