Preterm and Postterm Newborns

Important structural changes occur in the fetal lungs during the second half of the pregnancy. The alveoli, or air sacs, enlarge, which brings them closer to the capillaries in the lungs. The failure of this phenomenon to occur leads to many deaths attributed to previability (pre, “before,” vita, “life,” and able “capable of”). In addition, the muscles that move the chest are not fully developed; the abdomen is distended, creating pressure on the diaphragm; the stimulation of the respiratory center in the brain is immature; and the gag and cough reflexes are weak because of immature nerve supply. Oxygen may be required and can be administered via nasal catheter, incubator, or oxygen hood (Fig. 13.4). The oxygen must be warmed and humidified to prevent drying of the mucous membranes. Mechanical ventilation may be required. Oxygen saturation levels should be monitored. The infant is usually admitted to the NICU.

Respiratory Distress Syndrome

Respiratory distress syndrome (RDS), also called hyaline membrane disease, is a result of lung immaturity, which leads to reduced gas exchange. An estimated 60% to 80% of neonatal deaths of infants born before 28 weeks’ gestation, and 15% to 30% of infants born between 32 and 36 weeks’ gestation result from RDS or its complications (Ahlfeld, 2020). In this disease, there is a deficient synthesis or release of surfactant, a chemical in the lungs. Surfactant is high in lecithin, a fatty protein necessary for the absorption of oxygen by the lungs. Testing for the lecithin/sphingomyelin (L/S) ratio provides information about the amount of surfactant in amniotic fluid.

Manifestations

In general, the symptoms of respiratory distress are apparent after delivery, but they may not manifest for several hours (Fig. 13.5). Respirations increase to 60 breaths/minute or more. Rapid respirations (tachypnea) are accompanied by grunt-like sounds, nasal flaring, cyanosis, and intercostal and sternal retractions. Edema, lassitude, and apnea occur as the condition becomes more severe. Mechanical ventilation may be necessary. The treatment of these infants is ideally carried out in the NICU.

Treatment

Surfactant begins to appear in the fetal alveoli at approximately 24 weeks of gestation and is at a level to enable the infant to breathe adequately at birth by 34 weeks of gestation. If insufficient amounts of surfactant are detected through amniocentesis, it is possible to increase its production by giving the mother injections of corticosteroids, such as betamethasone. Administration 1 or 2 days before delivery may reduce the chances of RDS. In preterm newborns, surfactant can be administered via endotracheal (ET) tube at birth or when symptoms of RDS occur, with improvement of lung function seen within 72 hours. Surfactant production is altered during episodes of cold stress or hypoxia and when there is poor tissue perfusion, and such conditions are often present in the preterm infant in the first days of life.

Vital signs are monitored closely, arterial blood gases are analyzed, and the infant is placed in a warm incubator with gentle and minimal handling to conserve energy. The concept of cluster care involves combining and coordinating the handling required for assessment and treatments to provide adequate blocks of time for uninterrupted rest. Intravenous fluids are prescribed, and the nurse observes for signs of overhydration or dehydration. Oxygen therapy may be given via hood (see Fig. 13.4) or ventilator in concentrations necessary to maintain adequate tissue perfusion. Oxygen toxicity is a high risk for infants receiving prolonged treatment with high concentrations of oxygen. Bronchopulmonary dysplasia is the toxic response of the lung to oxygen therapy. Atelectasis, edema, and thickening of the membranes of the lung interfere with ventilation. This often results in prolonged dependence on supplemental oxygen and ventilators and has long-term complications.

Neonatal Hypoxia

Neonatal hypoxia is inadequate oxygenation at the cellular level in a newborn infant. A deficiency of oxygen in the arterial blood is known as hypoxemia. The degree of hypoxemia present can be detected by a noninvasive pulse oximetry reading. Pulse oximetry is defined as the measure of oxygen on the hemoglobin in the circulating blood divided by the oxygen capacity of the hemoglobin. A pulse oximeter saturation level of 92% or higher is normal (Skill 13.1). There must be at least 5 g/dL of desaturated hemoglobin (unoxygenated blood) to produce clinical cyanosis. Therefore the severely anemic infant may have severe hypoxia yet not manifest clinical cyanosis. If the hemoglobin present is an abnormal fetal hemoglobin, hypoxia can be present even when the pulse oximeter shows a normal reading because fetal hemoglobin does not readily release oxygen to the tissues and end organs (Rohan and Golombek, 2009).

Skill 13.1

Applying a Pulse Oximeter        

Purpose

To determine oxygen saturation of the blood

Steps

1. 1. Prepare the infant and explain procedure to the family.
2. 2. Turn on oximeter.
3. 3. Set alarm switch to minimum acceptable oxygen saturation (SaO₂) of approximately 92% to 95%.
4. 4. Apply the oximeter sensor to the toe or the side of the foot.

   

5. 5. The probe must be flush with the skin and secured firmly with the wing tapes.
6. 6. The sensors, a light-emitting diode and photo detector, must be lined up opposite each other to obtain an accurate reading. Use the circles on the external surface of the lead to align the sensors. A red light passes from one sensor on the toe or foot through the vascular bed and registers on the sensor on the opposite side.
7. 7. Check the monitor reading for level of oxygen saturation.
8. 8. Compare the heart rate reading on the monitor with the infant’s heart rate. Matching heart rates indicate the saturation level reading is accurate. If heart rates do not match, reapply or adjust sensors.
9. 9. Document time that oximetry is initiated, heart rate and oxygen saturation readings, and location of sensor on the infant’s body. Any oxygen administered and the method of administration should also be recorded.

Some pulse oximeters can also noninvasively measure the transcutaneous hemoglobin level and provide an accurate oxygen saturation level. Others can display oxygen saturation and total hemoglobin simultaneously. The devices can also be set to display the respiratory rate and the carboxyhemoglobin and methemoglobin levels, with additional sensors.

Keeping the preterm infant warm is a nursing challenge. Heat loss in the preterm infant results from the following factors:

These and other factors make the preterm newborn vulnerable to cold stress, which increases the need for oxygen and glucose. Early detection can prevent complications.

Hypoglycemia (hypo, “less than,” and glycemia, “sugar in the blood”) is common among preterm infants. They have not remained in the uterus long enough to acquire sufficient stores of glycogen and fat. This condition is aggravated by the need for increased glycogen in the brain, the heart, and other tissues as a result of asphyxia, sepsis, RDS, unstable body temperature, and similar conditions. Any condition that increases energy requirements places more stress on these already deficient stores. Plasma glucose levels lower than 40 mg/dL in a term infant and lower than 30 mg/dL in a preterm infant indicate hypoglycemia.

The brain needs a steady supply of glucose, and hypoglycemia must be anticipated and treated promptly. Any condition that increases metabolism increases glucose needs. Preterm infants may be too weak to suck and swallow formula and often require gavage or parenteral feedings to supply their need of 120 to 150 kcal/kg/day. Nursing responsibilities include frequent glucose monitoring and nasogastric or parenteral feedings.

Hypocalcemia (hypo, “below,” and calcemia, “calcium in the blood”) is also seen in preterm and sick newborns. Calcium is transported across the placenta throughout pregnancy, but in greater amounts during the third trimester. Early birth can result in infants with lower serum calcium levels.

In early hypocalcemia, the parathyroid fails to respond to the preterm infant’s low calcium levels. Infants stressed by hypoxia or birth trauma or who are receiving sodium bicarbonate are at high risk for this problem. Infants born to mothers who are diabetic or who have had a low vitamin D intake are also at risk for developing early hypocalcemia.

Late hypocalcemia usually occurs about age 1 week in newborn or preterm infants who are fed cow’s milk. Cow’s milk increases serum phosphate levels, which cause calcium levels to fall.

Administering intravenous calcium gluconate is the treatment for hypocalcemia. During intravenous therapy, the nurse should monitor the infant for bradycardia. Adding calcium lactate powder to the formula also lowers phosphate levels. (Calcium lactate tablets are insoluble in milk and must not be used.) When calcium lactate powder is slowly discontinued from the formula, the nurse should again monitor the infant for signs of neonatal tetany.

Retinopathy of prematurity (ROP) is a disorder of the developing retina in premature infants that can lead to blindness. The condition was formerly termed retrolental fibroplasia, but the term ROP is currently used because it is more precise. It is the leading cause of blindness in newborns weighing less than 1500 g (3.3 lb). The condition can be caused by many factors, but premature infants are more commonly at risk because their immature retinas are incompletely vascularized at birth.

After birth, often accompanied by high levels of oxygen required for the infant’s survival, the retina completes an abnormal vascularization process that causes fibrous tissue to form behind the lens of each eye, resulting in blindness and retinal detachment (Olitsky and Marsh, 2020). Full-term infants who have fully developed vascular systems in the retina at birth are usually not affected, but infants with an unstable course should be monitored for ROP. The American Academy of Pediatrics (AAP) standards recommend routine retinal examinations by certified ophthalmologists in the NICU for infants with a birth weight between 1500 and 2000 g or a gestational age less than 30 weeks. Examination at 4 weeks of age and at proper intervals for follow-up can result in early detection and prompt treatment. Retinal ablative therapy using laser photocoagulation of the fibrous tissue, or intravitreal injection of bevacizumab, has been used with success in preventing blindness (Olitsky and Marsh, 2020). Follow-up for other eye problems, such as strabismus, refractive errors, or cataracts, should be provided within 4 to 6 months after discharge from the NICU. The nurse must teach the parents the importance of follow-up care.

Prevention of preterm births and the problems that beset preterm infants is the key to preventing ROP. Careful monitoring of oxygen saturation in high-risk infants with a pulse oximeter continues to be a priority in the nursery (see Skill 13.1). It is the level of oxygen in the blood, rather than the amount of oxygen received, that is of importance in oxygen therapy. There is no “safe level” of oxygen. Infants must be provided with the level of oxygen required to sustain life and prevent neurological damage. Maintaining a sufficient level of vitamin E and avoiding excessively high concentrations of oxygen are important.

Necrotizing enterocolitis (NEC) is an acute inflammation of the bowel that leads to bowel necrosis. Preterm newborns are particularly susceptible to NEC. Factors implicated include a diminished blood supply to the lining of the bowel wall because of hypoxia or sepsis; this causes a decrease in protective mucus and results in bacterial invasion of the delicate tissues. A source for bacterial growth occurs when the infant is fed a milk formula or hypertonic gavage feeding.

Signs of NEC include abdominal distention, bloody stools, diarrhea, and bilious vomitus. Specific nursing responsibilities include observing vital signs, maintaining infection control techniques, and carefully resuming oral fluids as ordered. Measuring the abdomen and listening for bowel sounds are also important measures. Treatment includes antimicrobials and the use of parenteral nutrition to rest the bowels. Surgical removal of the necrosed bowel may be indicated.

The liver of the newborn is immature, which contributes to a condition called icterus, or jaundice. Jaundice causes the skin and the whites of the eyes to assume a yellow-orange cast. The liver is unable to clear the blood of bile pigments that result from the normal postnatal destruction of red blood cells. The amount of bile pigment in the blood serum is expressed as milligrams of bilirubin per deciliter (mg/dL). The higher the blood bilirubin level is, the deeper the jaundice and the greater the risk for neurological damage. An increase of more than 5 mg/dL in 24 hours or a bilirubin level greater than 12.9 mg/dL requires careful investigation (Shaughnessy and Goyal, 2020). Physiological jaundice is normal and is discussed in Chapter 12. Pathological jaundice is more serious, occurs within 24 hours of birth, and is secondary to an abnormal condition, such as ABO-Rh incompatibility (see Chapter 13). In preterm infants, the normal rise in bilirubin levels (icterus neonatorum) is slower than in full-term infants and lasts longer, which predisposes the infant to hyperbilirubinemia (hyper, “excessive,” bilirubin, “bile,” and emia, “blood”), or excessive bilirubin levels in the blood.

There is more evidence of jaundice in infants who are breastfed. Breastmilk jaundice begins to be seen about the fourth day, when the mother’s milk supply develops. The newborn usually does well but is carefully monitored to rule out problems. In early-onset jaundice of the breastfed infant, inadequate infant suckling at the breast causes jaundice and necessitates an increase in breastfeeding. Glucose water feedings should not be offered to the infant because this practice may reduce milk intake and can serve to further increase bilirubin levels. In late-onset jaundice of the breastfed infant, the breastmilk itself may inhibit conjugation of bilirubin, and therefore formula may be substituted for 24 to 48 hours to reduce bilirubin levels. The total serum bilirubin level typically peaks 3 to 5 days after birth. The early discharge of a newborn necessitates follow-up visits within 2 days to check total serum bilirubin and to prevent the development of kernicterus.

The goals of treatment for hyperbilirubinemia are to prevent kernicterus (a serious neurological complication that can cause brain damage, which is also known as bilirubin encephalopathy) and to avoid the continued increase of bilirubin levels in the blood. The nursing care for hyperbilirubinemia consists of observing the infant’s skin, sclera, and mucous membranes for jaundice. (Blanching of the skin over bony prominences enhances the evaluation for jaundice.) Observing and reporting the progression of jaundice from the face to the abdomen and feet is important because the progression may indicate increasing bilirubin blood levels. Treatment includes monitoring and reporting bilirubin laboratory values and documenting the response of the infant to phototherapy. (See Chapter 12 and Skill 12.4 for assessing jaundice.)

Thermoregulation (thermo, “heat,” and regulation, “maintenance of”) involves maintaining a stable body temperature and preventing hypothermia (low temperature) and hyperthermia (high temperature). A stable body temperature is essential to the survival and management of preterm infants.

Incubator

The preterm newborn is placed in an incubator designed to provide a neutral thermal environment—temperature, air, radiating surface temperatures, and humidity are controlled to maintain the infant’s temperature within a normal range with minimal oxygen consumption required. The incubator also provides isolation and protection from infection. The top of the incubator is transparent to enable personnel to view the newborn clearly at all times. Different models include alarms to indicate overheating or a lack of circulating air, facilities for positioning, and a scale to weigh the infant without removal from the warm environment. Nurses must understand how to use the incubators available in the nurseries to which they are assigned (Fig. 13.6). They should request assistance if needed.

The temperature of the incubator is adjusted to a level that will maintain an optimal body temperature in the infant. Smaller infants may require higher incubator temperatures. The nurse records the temperature of the infant and the incubator every 2 hours. The infant’s temperature is monitored with a heat-sensitive probe that is taped to the abdomen. The probe should not be placed over a bony prominence, areas of brown fat, the extremities, or an excoriated area of the body. Temporal artery or axillary temperatures may also be taken (see Chapter 22). A relative humidity of 60% or higher is desirable. Overheating should be avoided because it increases the infant’s oxygen and caloric requirements.

Kangaroo Care (Skin-to-Skin Contact)

Kangaroo care is a method of care for preterm infants that uses skin-to-skin contact. This method of holding the infant is similar to the way a kangaroo keeps its offspring warm in its pouch (Skill 13.2). The practice began in 1979 in Bogota, Colombia, in response to a shortage of incubators and staff and is currently a popular practice in the United States. The infant, wearing only a diaper and a small cap, rests on the mother’s or father’s naked chest. The skin provides warmth and calms the child, and the contact promotes bonding. Kangaroo care has been shown to be superior to holding a blanket-wrapped infant for enhancing the stabilization of infants and promoting later development (Mehler et al., 2020). Skin-to-skin contact is an important practice in hospitals that are designated as “baby friendly.”

Skill 13.2

Kangaroo Care        

Purpose

To maintain skin-to-skin contact to promote warmth and bonding

Steps

1. 1. Explain the rationale and principles of care to the parents.
2. 2. Provide a comfortable chair and privacy.
3. 3. Have parent wear a gown that opens in the front, leaving the chest bare.

   

   
   The mother provides kangaroo care for her preterm infants. Skin-to-skin contact is provided, with warmth maintained by the outer covering.
4. 4. Remove newborn’s clothes except for diaper.
5. 5. Place newborn in vertical position between the breasts of the parent’s bare chest.
6. 6. Place a blanket over the newborn.
7. 7. Monitor the temperature of the newborn throughout this form of care.
8. 8. Document the procedure, the infant’s vital signs, and responses.

The father can also provide effective kangaroo care. The infant shows a positive response to this contact.

(Courtesy Loma Linda University Medical Center, Loma Linda, CA.)

The nurse should observe and record bowel sounds and the passage of meconium, which indicate intestinal readiness for oral feedings. When the infant is gavage fed, the contents of the stomach should be aspirated before the feeding is started. If only mucus or air is aspirated, the feeding can be given as planned. If a residual of liquid contents is aspirated, the physician should be notified before proceeding to feed the infant. Infants older than 28 weeks of gestation usually have the digestive enzymes required for the digestion of breastmilk. Formulas designed for the term infant are not well tolerated by preterm infants because they are a burden to their kidneys and can cause central nervous system problems. Formulas designed for preterm infants are not well tolerated by infants older than 34 weeks of gestation or term infants because hypercalcemia may develop. Supplemental vitamins are usually prescribed for the preterm infant. If the infant is too premature or too ill to tolerate oral feedings, total parenteral nutrition (TPN) (intravenous infusion of lipids and nutrients) may be prescribed to meet the infant’s nutritional and growth needs. Gavage and gastrostomy tube feedings are discussed in Chapter 22.

The physician examines the preterm newborn and writes specific orders for treatment and nursing care. When the physician leaves the nursery, the nurse is responsible for reporting any significant changes in the infant’s condition. The experienced nurse in the preterm nursery observes and charts care and treatment in great detail. Table 13.1 lists the general observations to guide care of the preterm newborn. Sudden changes are reported immediately.

Positioning of the preterm infant should be compatible with the drainage of secretions and the prevention of aspiration. Propping the infant on the side or placing the infant prone can reduce respiratory effort, improve oxygenation, promote a more organized sleep pattern, and lessen physical activity that burns up energy needed for growth and development. An enclosed space, or nesting, can provide a calming, supportive environment that promotes body flexion for the preterm infant (Fig. 13.7). Infants should be gradually weaned from the prone position when the physical condition becomes stable, and they should be placed in the supine position well before discharge from the NICU.

It is important to teach the parent about the importance of the “back-to-sleep” concept to prevent sudden infant death syndrome (SIDS). The infant should not be left in one position for long periods because it is uncomfortable and may harm the lungs. Changing the position also prevents breakdown from pressure on the infant’s delicate skin. If such a breakdown should occur, the area is exposed to the air, and a suitable ointment is applied as prescribed by the health care provider. Alkaline-based soap, alcohol, and medicated wipes should not be used on the preterm infant’s thin and sensitive skin. Hydrocolloid adhesives or using gauze or cotton under adhesive tape is advisable.

Daily cleansing of the eyes, mouth, and diaper area, and baths two or three times weekly with the application of emollients such as Eucerin or Aquaphor, promote skin integrity (see Chapter 12 for a more extended discussion of the skin of the newborn).

Every effort should be made to maintain a quiet environment and organize nursing care so that overstimulation of the preterm infant is avoided. Blankets can be placed over the top of the incubator to reduce external stimulation and to establish a normal circadian rhythm (night-day sleep pattern), and dimmer switches on lights can encourage the infants to open their eyes and become responsive to the environment. Eye patches can be placed over the infant’s eyes to protect against the bright procedure lights. Observing the physical and behavioral responses of the preterm infant enables a developmentally appropriate care plan to be developed. The preterm infant should be awakened slowly and gently for procedures or nursing care and should be moved gently, maintaining flexion of the arms close to the midline of the infant’s body. Nonnutritive sucking is beneficial to the infant.

Some studies have shown that cobedding of twins (placing them together in one incubator) may improve their growth and development, but further research is needed to determine the risks related to the transmission of infection.