Health Promotion of the Newborn and Family



Health Promotion of the Newborn and Family


Barbara J. Wheeler



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evolve.elsevier.com/wong/essentials





Adjustment to Extrauterine Life


The most profound physiologic change required of neonates is transition from fetal or placental circulation to independent respiration. The loss of the placental connection means the loss of complete metabolic support, especially the supply of oxygen and the removal of carbon dioxide. The normal stresses of labor and delivery produce alterations of placental gas exchange patterns, acid–base balance in the blood, and cardiovascular activity in the infant. Factors that interfere with this normal transition or that interfere with fetal oxygenation (including conditions such as hypoxemia, hypercapnia, and acidosis) affect the fetus’s adjustment to extrauterine life.



Immediate Adjustments


Respiratory System


The most critical and immediate physiologic change required of newborns is the onset of breathing. The stimuli that help initiate the first breath are primarily chemical and thermal. Chemical factors in the blood (low oxygen, high carbon dioxide, and low pH) initiate impulses that excite the respiratory center in the medulla. The primary thermal stimulus is the sudden chilling of the infant, who leaves a warm environment and enters a relatively cooler atmosphere. This abrupt change in temperature excites sensory impulses in the skin that are transmitted to the respiratory center.


Tactile stimulation may assist in initiating respiration. Descent through the birth canal and normal handling during delivery help stimulate respiration in uncompromised infants. Acceptable methods of tactile stimulation include tapping or flicking the soles of the feet or gently rubbing the newborn’s back, trunk, or extremities. Slapping the newborn’s buttocks or back is a harmful technique and should not be done. Prolonged tactile stimulation, beyond one or two taps or flicks to the soles of the feet or rubbing the back once or twice, can waste precious time in the event of respiratory difficulty and can cause additional damage in infants who have become hypoxemic before or during the birth process.


The initial entry of air into the lungs is opposed by the surface tension of the fluid that filled the fetal lungs and the alveoli. Some lung fluid is removed during the normal forces of labor and delivery. As the chest emerges from the birth canal, fluid is squeezed from the lungs through the nose and mouth. After complete delivery of the chest, brisk recoil of the thorax occurs, and air enters the upper airway to replace the lost fluid. Remaining lung fluid is absorbed by the pulmonary capillaries and lymphatic vessels.


In the alveoli, the surface tension of the fluid is reduced by surfactant, a substance produced by the alveolar epithelium that coats the alveolar surface. The effect of surfactant in facilitating breathing is discussed in relation to respiratory distress syndrome (see Chapter 9).



Circulatory System


image As important as the initiation of respiration are the circulatory changes that allow blood to flow through the lungs. These changes, which occur more gradually, are the result of pressure changes in the lungs, heart, and major vessels. The transition from fetal to postnatal circulation involves the functional closure of the fetal shunts: the foramen ovale, the ductus arteriosus, and eventually the ductus venosus. (For a review of fetal circulation, see Chapter 25.) Increased blood flow dilates the pulmonary vessels, pulmonary vascular resistance decreases, and systemic resistance increases, thus maintaining blood pressure (BP). As the pulmonary vessels receive blood, the pressure in the right atrium, right ventricle, and pulmonary arteries decreases. Left atrial pressure increases above right atrial pressure, with subsequent foramen ovale closure. With the increase in pulmonary blood flow and dramatic reduction of pulmonary vascular resistance, the ductus arteriosus begins to close.


image Animation—Fetal Circulation


The most important factors controlling ductal closure are the increased oxygen concentration of the blood and the fall in endogenous prostaglandins. The foramen ovale closes functionally at or soon after birth. The ductus arteriosus is closed functionally by the fourth day. Anatomic closure takes considerably longer. Failure of the ductus arteriosus or foramen ovale to close results in persistence of fetal shunting of blood away from the lungs (see Chapter 25).


Because of the reversible flow of blood through the ductus during the early neonatal period, a functional murmur occasionally may be heard. In conditions such as crying or straining, the increased pressure shunts unoxygenated blood from the right side of the heart across the ductal opening, which may cause transient cyanosis.



Physiologic Status of Other Systems


Thermoregulation


Next to establishing respiration, heat regulation is most critical to the newborn’s survival. Although the newborn’s capacity for heat production is adequate, three factors predispose newborns to excessive heat loss:



The principal thermogenic sources are the heart, liver, and brain. An additional source, once believed to be unique to newborns (Zingaretti, Crosta, Vitali, and others, 2009), is known as brown adipose tissue, or brown fat. Brown fat, which owes its name to its larger content of mitochondrial cytochromes, has a greater capacity for heat production through intensified metabolic activity than does ordinary adipose tissue. Heat generated in brown fat is distributed to other parts of the body by the blood, which is warmed as it flows through the layers of this tissue. Superficial deposits of brown fat are located between the scapulae, around the neck, in the axillae, and behind the sternum. Deeper layers surround the kidneys, trachea, esophagus, some major arteries, and adrenals. The location of brown fat may explain why the nape of the neck often feels warmer than the rest of the infant’s body.


Because of these factors predisposing infants to loss of body heat, it is essential that newly born infants are quickly dried and either placed skin to skin with their mothers or provided with warm, dry blankets after delivery.


Although newborns’ ability to conserve heat is usually a matter of concern, they may also have difficulty dissipating heat in an overheated environment, which increases the risk of hyperthermia.




Fluid and Electrolyte Balance


Changes occur in the total body water volume, extracellular fluid volume, and intracellular fluid volume during the transition from fetal to postnatal life. At birth, the total weight of an infant is 73% fluid compared with 58% in an adult. Infants have a proportionately higher ratio of extracellular fluid than adults.


An important aspect of fluid balance is its relationship to other systems. An infant’s rate of metabolism is twice that of an adult in relation to body weight. As a result, twice as much acid is formed, leading to more rapid development of acidosis. In addition, immature kidneys cannot sufficiently concentrate urine to conserve body water. These three factors make infants more prone to dehydration, acidosis, and possible overhydration or water intoxication.



Gastrointestinal System


The ability of newborns to digest, absorb, and metabolize foodstuff is adequate but limited in certain functions. Enzymes are adequate to handle proteins and simple carbohydrates (monosaccharides and disaccharides), but deficient production of pancreatic amylase impairs use of complex carbohydrates (polysaccharides). Deficiency of pancreatic lipase limits absorption of fats, especially with ingestion of foods with high saturated fatty acid content such as cow’s milk. Human milk, despite its high fat content, is easily digested because the milk itself contains enzymes such as lipase, which assist in digestion.


The liver is the most immature of the gastrointestinal organs. The activity of the enzyme glucuronyl transferase is reduced, which affects the conjugation of bilirubin with glucuronic acid and contributes to physiologic jaundice of newborns. The liver is also deficient in forming plasma proteins. The decreased plasma protein concentration probably plays a role in the edema usually seen at birth. Prothrombin and other coagulation factors are also low. The liver stores less glycogen at birth than later in life. Consequently, newborns are prone to hypoglycemia, which may be prevented by early and effective feeding, ideally breastfeeding.


Some salivary glands are functioning at birth, but the majority do not begin to secrete saliva until about age 2 to 3 months, when drooling is frequent. Stomach capacity varies in the first few days of life, from about 5 ml on day 1 to about 60 ml on day 3 (Spangler, Randenberg, Brenner, and others, 2008); thus, infants require frequent small feedings. The colon also has a small volume; newborns may have a bowel movement after each feeding. Newborns who breastfeed usually have more frequent feedings and more frequent stools than infants who receive formula.


An infant’s intestine is longer in relation to body size than that of the adult. Therefore, there are a larger number of secretory glands and a larger surface area for absorption compared with an adult’s intestine. Infants have rapid peristaltic waves and simultaneous nonperistaltic waves along the entire esophagus, which propel nutrients forward. The relative immaturity of the peristaltic waves combined with decreased lower esophageal sphincter (LES) pressure, inappropriate relaxation of the LES, and delayed gastric emptying make regurgitation a common occurrence. Progressive changes in the stooling pattern indicate a properly functioning gastrointestinal tract (Box 8-1).



The neonatal gastrointestinal mucosa may perform an important function as a barrier to foreign antigens. Both immune and nonimmune factors may play a vital role in decreasing the absorption of antigens capable of causing serious neonatal illness; however, the functional capacity of this system may be immature or altered. Feeding an infant human milk increases the effectiveness of this defense mechanism (Le Huërou-Luron, Blat, and Boudry, 2010).




Integumentary System


At birth, all of the structures within the skin are present, but many of the functions of the integument are immature. The outer two layers of the skin, the epidermis and dermis, are loosely bound to each other and very thin. Rete pegs, which later in life anchor the epidermis to the dermis, are not developed. Slight friction across the epidermis, such as from rapid removal of adhesive tape, can cause separation of these layers and blister formation. The transitional zone between the cornified and living layers of the epidermis is effective in preventing fluid from reaching the skin surface.


The sebaceous glands are very active late in fetal life and in early infancy because of the high levels of maternal androgens. They are most densely located on the scalp, face, and genitalia and produce the greasy vernix caseosa that covers infants at birth. Plugging of the sebaceous glands causes milia.


The eccrine glands, which produce sweat in response to heat or emotional stimuli, are functional at birth, and palmar sweating on crying reaches levels equivalent to those of anxious adults by 3 weeks of age. The eccrine glands produce sweat in response to higher temperatures than those required in adults, and the retention of sweat may result in miliaria. The apocrine glands remain small and nonfunctional until puberty.


The growth phases of hair follicles usually occur simultaneously at birth. During the first few months, the synchrony between hair loss and regrowth is disrupted, and there may be overgrowth of hair or temporary alopecia.


Because the amount of melanin is low at birth, newborns are lighter skinned than they will be as children. Consequently, they are more susceptible to the harmful effects of the sun.




Defenses Against Infection


Infants are born with several defenses against infection. The first line of defense is the skin and mucous membranes, which protect the body from invading organisms. The mature neonatal intestinal mucosal (gut) barrier also plays a vital role as an important defense mechanism against antigens. The second line of defense is the macrophage system, which produces several types of cells capable of attacking a pathogen. The neutrophils and monocytes are phagocytes, which means they can engulf, ingest, and destroy foreign agents. Eosinophils also probably have a phagocytic property because they increase in number in the presence of foreign protein. The lymphocytes (T cells and B cells) are capable of being converted to other cell types, such as monocytes and antibodies. Although the phagocytic properties of the blood are present in infants, the inflammatory response of the tissues to localize an infection is immature.


The third line of defense is the formation of specific antibodies to an antigen. Exposure to various foreign agents is necessary for antibody production to occur. Infants are generally not capable of producing their own immunoglobulin (Ig) until the beginning of the second month of life, but they receive considerable passive immunity in the form of IgG from the maternal circulation and from human milk (see p. 214). They are protected against most major childhood diseases, including diphtheria, measles, poliomyelitis, and rubella, for about 3 months, provided the mother has developed antibodies to these illnesses.




Neurologic System


At birth, the nervous system is incompletely integrated but sufficiently developed to sustain extrauterine life. Most neurologic functions are primitive reflexes. The autonomic nervous system is crucial during transition because it stimulates initial respirations, helps maintain acid–base balance, and partially regulates temperature control.


Myelination of the nervous system follows cephalocaudal–proximodistal (head-to-toe–center-to-periphery) laws of development and is closely related to observed mastery of fine and gross motor skills. Myelin is necessary for rapid and efficient transmission of some, but not all, nerve impulses along the neural pathway. The tracts that develop myelin earliest are the sensory, cerebellar, and extrapyramidal tracts. This accounts for the acute senses of taste, smell, and hearing in newborns, as well as the perception of pain. All cranial nerves are present and myelinated except for the optic and olfactory nerves.



Sensory Functions


Newborns’ sensory functions are remarkably well developed and have a significant effect on growth and development, including the attachment process.



Vision

At birth, the eye is structurally incomplete. The fovea centralis is not yet completely differentiated from the macula. The ciliary muscles are also immature, limiting the eyes’ ability to accommodate and focus on an object for any length of time. The infant can track and follow objects. The pupils react to light, the blink reflex is responsive to minimal stimulus, and the corneal reflex is activated by a light touch. Tear glands usually do not begin to function until 2 to 4 weeks of age.


Newborns have the ability to focus momentarily on a bright or moving object that is within 20 cm (8 inches) and in the midline of the visual field. In fact, infants’ ability to fixate on coordinated movement is greater during the first hour of life than during the succeeding several days. Visual acuity is reported to be between 20/100 and 20/400, depending on the vision measurement techniques.


Infants also demonstrate visual preferences: medium colors (yellow, green, pink) over bright (red, orange, blue) or dim colors; black-and-white contrasting patterns, especially geometric shapes and checkerboards; large objects with medium complexity rather than small, complex objects; and reflecting objects over dull ones.



Hearing

After the amniotic fluid has drained from the ears, infants probably have auditory acuity similar to that of adults. Neonates react to loud sounds of about 90 decibels with a startle reflex. Newborns’ response to sounds of low frequency versus those of high frequency differs; whereas the former, such as the sound of a heartbeat, metronome, or lullaby, tends to decrease an infant’s motor activity and crying, the latter elicits an alerting reaction. There is also an early sensitivity to the sound of human voices, although not specifically speech sounds. For example, infants younger than 3 days of age can discriminate the mother’s voice from that of other women. As early as age 5 days, newborns can differentiate between stories repeated to them during the last trimester of pregnancy by their mother and the same stories recited after birth by a different woman.


The internal and middle ear is large at birth, but the external canal is small. The mastoid process and the bony part of the external canal have not yet developed. Consequently, the tympanic membrane and facial nerve are very close to the surface and can be easily damaged.






Nursing Care of the Newborn and Family


Assessment


Newborns require thorough, skilled observation to ensure a satisfactory adjustment to extrauterine life. Physical assessment after delivery can be divided into four phases:



image In addition, the nurse must be aware of behaviors that signal successful reciprocal attachment between the infant and parents. Awareness of the expected normal findings during each assessment process helps the nurse recognize any deviation that may prevent the infant from progressing uneventfully through the early postnatal period. With shorter hospitalizations, the accomplishment of thorough newborn assessment and parent teaching has become a challenge.


image Case Study—The Normal Newborn



Initial Assessment: Apgar Scoring


The most frequently used method to assess newborns’ immediate adjustment to extrauterine life is the Apgar scoring system, which is based on newborn heart rate, respiratory effort, muscle tone, reflex irritability, and color (Table 8-1). Each item is given a score of 0, 1, or 2. Evaluations of all five categories are made at 1 and 5 minutes after birth and repeated until the infant’s condition stabilizes. Total scores of 0 to 3 represent severe distress, scores of 4 to 6 signify moderate difficulty, and scores of 7 to 10 indicate absence of difficulty in adjusting to extrauterine life. The Apgar score is affected by the degree of physiologic immaturity, infection, congenital malformations, maternal sedation or analgesia, and neuromuscular disorders.



The Apgar score reflects the general condition of the infant at 1 and 5 minutes based on the five parameters described previously. The Apgar score is not a tool, however, that stands on its own to interpret past events, determine need for newborn resuscitation, or predict future events linked to the infant’s eventual neurologic or physical status. Considerable discussion and controversy have centered on Apgar scoring because of its misuse as an indicator for the presence or absence of perinatal asphyxia in the medicolegal field (American Academy of Pediatrics [AAP] Committee on Fetus and Newborn, and American College of Obstetricians and Gynecologists [ACOG], Committee on Obstetric Practice, 2006, reaffirmed 2008).



Clinical Assessment of Gestational Age


Assessment of gestational age is an important criterion because perinatal morbidity and mortality are related to gestational age and birth weight. A frequently used method of determining gestational age is the New Ballard Scale (NBS) by Ballard, Khoury, Wedig, and others (1991) (Fig. 8-1, A). This scale, an abbreviated version of the Dubowitz scale, assesses six external physical and six neuromuscular signs. Each sign has a number score, and the cumulative score correlates with a maturity rating of 20 to 44 weeks of gestation.



The NBS includes –1 and –2 scores that reflect signs of extremely preterm infants, such as fused eyelids; imperceptible breast tissue; sticky, friable, transparent skin; no lanugo; and square-window (flexion of wrist) angle of greater than 90 degrees (see Fig. 8-1, A, and the description of the tests in Box 8-2). For infants with a gestational age of at least 26 weeks, the examination may be performed up to 96 hours after birth; however, it is recommended that the initial examination be performed within the first 48 hours of life. In a study of preterm infants ranging from 29 to 35 weeks at birth, Ballard scores completed after 7 days after birth were found to either overestimate or underestimate gestational age by up to 2 weeks (Sasidharan, Dutta, and Narang, 2009). In a blinded Spanish study, Marín, Martín, Lliteras, and others (2006) compared estimations of gestational age using NBS versus ultrasonography or the mother’s last menstrual period. Researchers found general agreement between NBS and ultrasonography or last menstrual period; however, they noted that NBS tends to overestimate gestational age in very preterm newborns and in infants whose mothers had received prenatal corticosteroid therapy.



Box 8-2   Tests Used in Assessing Gestational Age




Posture—With infant quiet and in a supine position, observe degree of flexion in arms and legs. Muscle tone and degree of flexion increase with maturity.


    Full flexion of the arms and legs—4*


Square window—With thumb supporting back of arm below wrist, apply gentle pressure with index and third fingers on dorsum of hand without rotating infant’s wrist. Measure angle between base of thumb and forearm.


    Full flexion (hand lies flat on ventral surface of forearm)—4


Arm recoil—With infant supine, fully flex both forearms on upper arms, hold for 5 seconds; pull down on hands to fully extend and rapidly release arms. Observe rapidity and intensity of recoil to a state of flexion.


    A brisk return to full flexion—4


Popliteal angle—With infant supine and pelvis flat on a firm surface, flex lower leg on thigh and then flex thigh on abdomen. While holding knee with thumb and index finger, extend lower leg with index finger of other hand. Measure degree of angle behind knee (popliteal angle).


    An angle of less than 90 degrees—5


Scarf sign—With infant supine, support head in midline with one hand; use other hand to pull infant’s arm across the shoulder so that infant’s hand touches shoulder. Determine location of elbow in relation to midline.


    Elbow does not reach midline—4


Heel to ear—With infant supine and pelvis flat on a firm surface, pull foot as far as possible up toward ear on same side. Measure degree of knee flexion (same as popliteal angle).


    Knees flexed with a popliteal angle of less than 90 degrees—4



*Numeric ratings correspond with Fig. 8-1, A.



Weight Related to Gestational Age

The weight of the infant at birth also correlates with the incidence of perinatal morbidity and mortality. However, birth weight alone is a poor indicator of gestational age and fetal maturity. Maturity implies functional capacity—the degree to which the neonate’s organ systems are able to adapt to the requirements of extrauterine life. Therefore, gestational age is more closely related to fetal maturity than is birth weight. Because heredity influences a newborn’s size, noting the size of other family members is part of the assessment process.


Intrauterine growth curves are used to classify infants according to birth weight and gestational age. The primary intrauterine growth charts that provide national reference data include the work of Alexander, Himes, Kaufman, and others (1996), which is representative of more than 3.1 million live births in the United States, and Thomas, Peabody, Turnier, and others (2000). Olsen, Groveman, Lawson, and others (2010) published new intrauterine growth curves based on more than 257,000 infants in the United States, noting that use of a contemporary, large, and racially diverse U.S. sample has produced intrauterine growth curves that differ from those produced earlier. Thomas, Peabody, Turnier, and others (2000) concluded that intrauterine growth measured by head circumference, birth weight, and length varies according to race and gender. These researchers also found that altitude did not seem to significantly affect birth weight, as has been suggested by other authors. It is recommended that readers access and use the most current intrauterine growth chart specific to the referent population being evaluated.


Classification of infants at birth by both birth weight and gestational age provides a more satisfactory method for predicting mortality risks and providing guidelines for management of the neonate than estimating gestational age or birth weight alone. The infant’s birth weight, length, and head circumference are plotted on standardized graphs that identify normal values for gestational age (for birth weight see Fig. 8-1, B). Infants whose weight is appropriate for gestational age (AGA) (between the 10th and 90th percentiles) can be presumed to have grown at a normal rate regardless of the time of birth—preterm, term, or postterm. Infants who are large for gestational age (LGA) (above the 90th percentile) can be presumed to have grown at an accelerated rate during fetal life; small-for-gestational-age (SGA) infants (below the 10th percentile) can be assumed to have intrauterine growth restriction or delay.


When gestational age is determined according to a standardized gestational age scale such as the NBS, the newborn will fall into one of the following nine possible categories for birth weight and gestational age: AGA—term, preterm, postterm; SGA—term, preterm, postterm; LGA—term, preterm, postterm. Figure 8-2 illustrates the disparity between birth weights of three preterm infants of the same gestational age, 32 weeks. Birth weight and gestational age both influence morbidity and mortality; the lower the birth weight and gestational age, the higher the morbidity and mortality.




General Measurements

Several important measurements of newborns have significance when compared with each other and when recorded over time on a graph. For full-term infants, average head circumference is between 33 and 35.5 cm (13 and 14 inches). Head circumference may be somewhat less immediately after birth because of the molding process that occurs during vaginal deliveries. Usually by the second or third day, the skull is normal in size and contour.


Chest circumference is 30.5 to 33 cm (12–13 inches) but is not routinely performed in the healthy term infant. Head circumference is usually about 2 to 3 cm (≈1 inch) greater than chest circumference. Because of the molding of the head during delivery, these measurements may initially appear equal. However, if the head is significantly smaller than the chest, microcephaly or premature closure of the sutures (craniosynostosis) is a possibility. If the head is more than 4 cm (1.6 inches) larger than the chest and this remains constant or increases over several days, then hydrocephalus must be considered. Other causes of increased head circumferences are caput succedaneum, cephalhematoma, subgaleal hemorrhage, and subdural hematoma.


Head circumference may also be compared with crown-to-rump length, or sitting height. Crown-to-rump measurements are usually 31 to 35 cm (12.2–13.8 inches) and are approximately equal to head circumference. The relationship of the head and crown-to-rump measurements is more reliable than that of the head and chest. Neonatal head circumference and crown-to-rump length may provide a more accurate means for identifying infants at risk; head circumference has been shown to be equal to or up to 1 cm more than crown-to-rump length in 62% of the infants examined and determined to be normocephalic.


Abdominal circumference need not be routinely measured in newborns but should be done in the event of abdominal distention to determine changes in girth over time. Abdominal circumference is measured just above the level of the umbilicus because the umbilical cord is still attached, making measurements across the umbilicus too variable in newborns. Measuring the abdominal circumference below the umbilical region is unsuitable because bladder status may affect the reading.


Head-to-heel length is also measured. Because of the usual flexed position of infants, it is important to extend the legs completely when measuring total body length. The average length of newborns is 48 to 53 cm (19–21 inches) (Fig. 8-3). Foote and colleagues (2011) have developed an evidence-based practice guideline for measuring length in infants and children.



Body weight should be measured soon after birth because weight loss occurs fairly rapidly. Normally, neonates lose about 10% of their birth weight by 3 to 4 days of age because of loss of extracellular fluid and meconium, as well as limited food intake, especially in breastfed infants. The birth weight is usually regained by the tenth to fourteenth day of life. Most newborns weigh 2700 to 4000 g (6–9 pounds), the average weight being about 3400 g (7.5 pounds). Accurate birth weights and lengths are important because they provide a baseline for assessment of future growth.


Another category of measurements is vital signs. Axillary temperatures are taken because insertion of a thermometer into the rectum can potentially cause perforation of the mucosa if performed incorrectly (see Table 6-3 and Fig. 8-4). Core body temperature varies according to the periods of reactivity but is usually 36.5° to 37.6° C (97.7°–99.7° F). Skin temperature is slightly lower than core body temperature. Therefore axillary temperature is generally less than rectal temperature, measuring about 0.2° C lower (Hussink, van Berkel, and de Beaufort, 2008). Because brown adipose tissue is located in the axillary pocket, axillary readings may be elevated whenever NST occurs. However, axillary readings may be normal in cold-stressed infants when NST is not triggered or is overwhelmed.


Jan 16, 2017 | Posted by in NURSING | Comments Off on Health Promotion of the Newborn and Family
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