Maternal History

The newborn’s history begins with the mother’s history obtained during her prenatal care. Was the mother healthy before she was pregnant? Does she have chronic diseases? Is she taking medications or illicit drugs? If no prenatal care is noted, the RT should be on the alert for the potential of a high-risk delivery and possible postnatal complications.

The mother’s previous pregnancy history can give the RT or other clinician valuable information. Obstetricians note this information in the mother’s medical record using the terms gravida, para, and abortion. Gravida is a pregnant woman, para is a woman who delivers a live infant, and abortion is the delivery of a dead infant or embryo. These terms will most likely be abbreviated and followed by numbers (e.g., G2, P1, Ab0, which means this woman is in her second pregnancy, has delivered a living infant, and has not had any abortions). Abortions can be further subdivided into therapeutic and spontaneous; these are frequently abbreviated as TAb and SAb, respectively.

Other maternal factors that may indicate a high-risk pregnancy are listed in Table 12-1. Some of these factors will be discussed in the sections that follow.

Family History

It is important to inquire about family history as well as maternal history. Is there a history of spontaneous abortion during pregnancy? Is there a history of multiple early neonatal deaths? Multiple deaths during pregnancy or the early neonatal period may be clues for genetic diseases or the presence of other risks factors such as alcohol or drug abuse. Is there a history of prematurity? Have there been other infants with respiratory problems? It should be noted that the incidence and severity of diseases, such as respiratory distress syndrome (RDS), are similar among siblings. RDS is discussed later in the chapter. There may also be an increased tendency for the recurrence of pneumonias caused by group B β-hemolytic streptococcus in siblings.

Pregnancy History

In evaluating the infant with respiratory disease, valuable information can be found in the pregnancy, labor, and delivery histories. In the pregnancy history, the interviewer records information about the mother and the fetus. Did the mother have any illnesses during gestation? Congenital viral infections that profoundly affect the infant may have produced only mild or even no symptoms in the mother. Did the mother have any vaginal bleeding? The mother usually is the source of bleeding, but occasionally the baby is bleeding, and these infants must be evaluated at birth for hypovolemia or low hematocrit. Did the mother note any evidence of amniotic infection or urinary tract infection? An infant delivered in the presence of infection has an increased risk for respiratory difficulty and other complications. Did the mother have a traumatic injury? A traumatic injury may compromise the uteroplacental interface and thus decrease transfer of oxygen and other nutrients to the baby. Traumatic injuries can also lead to hemorrhage and low hemoglobin and hematocrit in the newborn infant. Did the mother’s uterus grow appropriately during pregnancy? If not, the infant may not have grown properly and could have pulmonary hypoplasia, severe malformations, a congenital infection, or intrauterine growth retardation (IGR), a conditioned explained later on this chapter. Any of these conditions may cause significant respiratory distress in the newborn.

The incidence of respiratory disease varies with different gestational ages, and determining when the infant was actually due is important. The interviewer should attempt to identify the date of the mother’s last menstrual period (LMP), her estimated date of delivery (this appears as the estimated date of confinement [EDC] on the mother’s chart), her obstetric record of uterine growth, and any reports from ultrasound examinations that she may have had.

Infants born prematurely are more susceptible to develop RDS, pulmonary interstitial emphysema (PIE), intraventricular hemorrhage (IVH), and bronchopulmonary dysplasia (BPD). Postterm infants are more susceptible to severe perinatal asphyxia, meconium aspiration, and the development of persistent pulmonary hypertension of the newborn (PPHN).

Labor and Delivery History

The labor and delivery (L&D) history is obtained to evaluate the well-being of the newborn during the transition from intrauterine to extrauterine life. The newborn must successfully deal with cyclic decreases in uterine blood flow caused by contraction and possible umbilical cord compression as well as compression of his or her body. The clinician should consider fetal heart rate tracings, fetal activity, biophysical profile, and fetal ultrasound as well as neonatal age in order to anticipate possible complications. Information that suggests perinatal asphyxia might include variable or late heart rate decelerations, low biophysical profile score, decrease in fetal movement, presence of meconium (first feces of an infant) in the amniotic fluid, long labor, and abnormal vaginal bleeding. The clinician should also look for information that might suggest an infection in the infant or the mother. This information might include maternal fever, high maternal white blood cell (WBC) count, tender uterus, rupture of the amniotic membranes for more than 24 hours, foul-smelling or colored amniotic fluid, and fetal tachycardia.

A healthy fetus is capable of withstanding the challenges of labor. However, when the fetus is compromised or the labor is dysfunctional, the fetus can be taxed beyond capacity. This stress can place the fetus at risk for further compromise, including but not limited to asphyxia and intrauterine death. Box 12-1 lists some of the more significant clinical manifestations signaling abnormal transition to extrauterine life.

The delivery history should include the method of delivery for the infant: vaginal or cesarean; spontaneous, forceps, or vacuum extraction; or low, middle, or high forceps. Newborns who successfully withstand the labor process are usually born by spontaneous or low forceps vaginal deliveries. Those who have trouble during labor and delivery are more likely to be delivered by vacuum extraction, middle or high forceps, or cesarean delivery. Some cesarean deliveries are performed because the infant is positioned in such a manner that vaginal delivery would be high risk, not because the infant is in trouble. These infants are at greater risk for respiratory diseases, such as transient tachypnea of the newborn (TTN), caused by a failure to reabsorb fetal lung fluid after birth. It is also helpful to know what type of anesthetic the mother had for delivery (e.g., narcotics, local, epidural, spinal, or general). Narcotics and general anesthetics may enter the fetus’s bloodstream and produce respiratory depression in the newborn. Spinal anesthetics may lower the mother’s blood pressure, thus compromising the oxygen supply to the fetus.

The most standard objective measurement of the newborn’s well-being during the perinatal period is the Apgar score.1,2 The Apgar score is a simple, quick, and reliable means to assess and document the newborn’s status immediately after birth. It assigns the infant points for the presence of five specific physical criteria (Table 12-2). Most infants are evaluated and assigned Apgar scores at 1 and 5 minutes. However, if the infant is having difficulty during the transition to extrauterine life, Apgar scores can be assigned more often and over a longer time span. For example, a sick infant may have 1-, 2-, 5-, 10-, 15-, and 20-minute Apgar scores. The process of assigning an Apgar score must not delay the initiation of resuscitative measures.

The Apgar score is useful in identifying neonates who may need further resuscitation and assistance. Those who are adjusting well to extrauterine life usually have 1-minute scores of 7 to 10 but may still show acrocyanosis (bluish coloration of hands and feet), irregular respirations, or hypotonia (decreased muscle tone). Such neonates usually require only routine newborn care such as drying, temperature maintenance, and clearing of the airway. These neonates may occasionally require supplemental oxygen or bag-mask ventilation (BVM) for a brief period. Moderately depressed infants with 1-minute scores of 4 to 6 may need more than routine care and often require an increased fraction of inspired oxygen (F_Io₂) with BVM ventilation. Most infants respond well to this therapy and improve in a few minutes. Infants who have 1-minute scores of 0 to 3 are severely depressed and need extensive medical resuscitation that may include intubation and mechanical ventilation.

Although the 1-minute Apgar score is a useful tool in screening infants who might require resuscitation, the 5-minute Apgar score is a better predictor of the infant’s neurologic outcome. For preterm and term infants, neonatal survival increases with increasing Apgar scores; low 5-minute scores (e.g., 0 to 3) are associated with the highest risk for neonatal morbidity and mortality.³

Postnatal History

After the delivery, the clinician should document the magnitude of the infant’s resuscitation, presence of disease, treatment of disease, length of the hospital stay, condition at discharge, and problems that have developed since the infant was last seen. For most infants, all of this information is normal, and the postnatal history is brief. All newborns require some form of resuscitation. The simplest resuscitation required is clearing the airway and drying the skin. It is important to document whether the infant required only this simple intervention; a more significant intervention with oxygen, manual ventilation with bag and mask, or intubation; or chemical resuscitation with the administration of drugs to support cardiac output. How did the infant respond to resuscitation? Was the response immediate or slow?

If the infant is still hospitalized, the only further information needed for an adequate assessment is what diseases the infant has, what treatment has been initiated, and what the response to treatment has been. If the infant has been discharged and is now being readmitted, seen again in a practice office, or seen at home, the clinician must inquire about the infant’s condition since discharge. Was the infant still sick at the time of discharge? Did the infant require continuing treatment at home? How is the infant doing with the current treatment? What kind of problem does the infant have now?

Fetal Assessment

Useful information about the future well-being of the infant can be determined from the prenatal assessment of the fetus. This information could include but it is not limited to the following:

Fetal movement monitoring is easily accomplished using three widely available tools: maternal observation, fetal ultrasound, and fetal Doppler ultrasound. The simplest of these tools is having the mother keep a log of the timing, strength, and duration of the fetal movements for a period of time. Fetal ultrasound and Doppler ultrasound provide more quantifiable data but for shorter periods. Having a history of decreased fetal movement should alert the clinician of the possibility of the fetus being in trouble. This could indicate prenatal asphyxia and impending death or the possibility of severe neuromuscular disease, in which the newborn will be unable to support spontaneous independent respiration after birth. See Figure 12-1 for a representation of the events leading to neonatal death.

The biophysical profile is an ultrasound evaluation of fetal breathing, body movement, tone, reactive heart rate, and amniotic fluid volume that predicts the presence or absence of fetal asphyxia and, ultimately, the risk for fetal death. Like the Apgar score, each of these parameters has a maximal score of 2 and a minimal score of 0. The score for a normal fetus is 8 to 10. With lower biophysical profile scores, the chance of significant fetal and newborn problems increases (Table 12-3). These potential problems include IGR, significant fetal acidosis, stillbirth, and neonatal death (see Fig-12-1).

Amniocentesis also allows for the evaluation of the L/S ratio to assess pulmonary lung maturity. The L/S ratio is the ratio of two surfactant phospholipids: lecithin and sphingomyelin. Increasing levels of lecithin indicate improving maturation of the lung’s surfactant system. Like lecithin, the presence of PI and PG is usually indicative of advancing lung maturation. In general, L/S ratios of less than 2:1 and the absence of PG are associated with high risks for RDS.⁴

Fetal monitoring is a continuous graphic method of recording the fetal heart rate and uterine contractions. Various patterns (fetal tachycardia, variable decelerations, and late decelerations) are signs that a fetus may be in trouble in the uterine environment. Knowing that a fetus has any of these heart rate patterns should alert the health care team that this infant may need a more extensive resuscitation and more careful evaluation after birth.

The fetal NST is a method of evaluating the stability of the fetus’s physiology within the uterine environment. The NST monitors the acceleration of the fetal heart rate in response to fetal movement. A healthy fetus has a minimum of an increase in heart rate of at least 15 beats/minute in response to fetal movement. To be considered reactive, the fetus needs to have a minimum of two accelerations exceeding 15 beats/minute in 20 minutes for term pregnancies. A fetus is considered nonreactive when it fails to have heart rate response in two consecutive 20-minute periods. Nonreactivity may be associated with prolonged fetal sleep states, immaturity, maternal ingestion of sedatives, and fetal cardiac or neurologic anomalies.⁵ A fetus that is nonreactive is at greater risk for serious complications and fetal death. This will prompt the obstetrician to consider the possibility of an accelerated or operative delivery (cesarean). Knowing that a fetus has a nonreactive NST should alert the health care team that this infant may need a more extensive resuscitation and more careful evaluation after birth.

Physical Examination of the Newborn and Infant

Unlike the adult patient, the nonverbal neonate communicates primarily by behavior. Through objective physical observations and evaluations, the clinician can interpret this behavior into information about the individual neonate’s condition during the postnatal period.

Examination of a newborn is based on three of the four classic principles of physical examination as described in Chapter 5: inspection, palpation, and auscultation. Percussion is rarely used in examining newborns because of their small cavity and organ sizes and the possibility of injury. Therefore, percussion is not described in this chapter. Careful inspection reveals clues about the type and severity of respiratory disease. It is important to inspect the overall appearance of the infant carefully because respiratory pathology in the newborn is often manifested by extrapulmonary signs. Palpation is useful in assessing growth and gestational age and in determining the cause of respiratory distress and the severity of side effects from the lung disease and its treatment. As in the adult, auscultation is used to define characteristics of the disease process occurring in the lung. However, statements about the internal location of the pathologic process must be made with greater caution in newborns because localization by auscultation is difficult in the small chest cavity.

Growth and Gestational Age Assessment

Preterm infants are also classified based on their birthweight, as follows:

• Low birthweight (LBW): less than 2500 g

• Very low birthweight (VLBW): less than 1500 g

• Extremely low birthweight (ELBW): less than 1000 g

Newborn classification based on birthweight and gestational age is a valuable tool in predicting possible complications in the postnatal period and neonatal diseases. In any gestation, the poorest outcome is seen in infants born with marked IGR.

Based on their weight and gestational age, newborn infants are further classified as:

• Appropriate for gestational age (AGA): weight is appropriate for the gestational age

• Small for gestational age (SGA): smaller than expected, the weight falls below the 10th percentile for the gestational age

• Large for gestational age (LGA): heavier than expected, the birthweight is above the 90th percentile for the gestational age

Gestational age is assigned by the maternal dates, fetal ultrasound, and gestational assessment examination. Assessment of gestational age should be done to assign a newborn classification, determine neonatal mortality risk, assess for possible morbidities, and quickly initiate the proper interventions to address the identified risk factors.

Most women know approximately when they conceive. This is frequently confirmed by an early fetal ultrasound examination. Sometimes, the mother does not know the date of conception, or there is significant disagreement between the maternal dates and the fetal ultrasound. In those situations, the gestational age assessment can be performed with a gestational assessment tool.

The original assessment tools were developed by Dubowitz and Dubowitz. These tools have been modified and validated over many years. Most nurseries currently use a Ballard examination (Fig. 12-2), which is a modification of the Dubowitz examination. Gestational age assessment should be performed for all newborns.

The Ballard examination is divided into two sections: neuromuscular maturity and physical maturity. The infant’s neuromuscular and physical characteristics are scored by matching the infant’s characteristics to the table’s descriptions and then marking the table. Each column of the table has a numerical value ranging from −1 to +5. The numerical values for all of the marked cells are added together. It is important that a cell is marked in each row. The sum is then compared with the maturity scale, and a gestational age is assigned. The Ballard examination is accurate to within 2 weeks of the gestational age.³

Vital Signs Assessment

Body Temperature

The range of normal body temperature in the newborn does not differ from that in the adult. Humans maintain body temperature by balancing heat production with heat loss. The newborn loses much more heat to the environment than the older child or adult, largely because heat loss is determined by the ratio of the surface area of the body to the total body mass (Table 12-4). The neonatal surface area-to-mass ratio is more than three times the surface area-to-mass ratio of an adult male. For premature neonates, the problem becomes even more significant owing to the lack of brown fat tissue and a very low surface area-to-mass ratio. Brown fat tissue, which is present in a full term neonate, is a major source of heat production for the newborn and helps to maintain internal body temperature. A 28-week gestational age neonate has a body surface area of approximately 0.15 m² and a body mass of 1 kg. This results in a surface area to mass ratio of 0.15 m²/kg, which is more than six times greater than that of an adult male. Therefore, newborn term and preterm infants lose heat easily and are extremely dependent on the environment to help them maintain a neutral thermal environment (NTE). An NTE is the environmental temperature at which the infant’s metabolic demands and therefore oxygen consumption are the least (Fig. 12-3).

TABLE 12-4

Ratio of Surface Area to Body Mass

	Surface Area (m2)	Mass (kg)	Area/Mass (m2/kg)
Adult male	1.7	80	0.02
Term infant	0.25	3.5	0.07
28-week-old infant	0.15	1.0	0.15

Neonates, like all physical objects, lose heat to the environment by one of four mechanisms: conduction (touching a cold or wet object), convection (gas blowing over the skin surface), evaporation (liquid evaporating from the skin surface), and radiation (attempting to warm a cold surface not in contact with the skin). All these mechanisms must be considered when helping newborns deal with their environment.

SIMPLY STATED

Newborns are very prone to heat loss because of their high ratio of surface area to body mass. Maintaining an NTE is essential to avoid stressing the infant and causing “cold stress.”

Hyperthermia is a core body temperature of more than 37.5° C or 99.5° F. Hyperthermia in the newborn usually is caused by environmental factors. The infant may be wrapped in too many clothes, placed too close to a heater, or placed in an isolette or radiant warmer that is too warm. It is uncommon, although not rare, for an infant with hyperthermia to have an infection.

Hypothermia is a core body temperature of less than 36.5° C or 97.7° F. Hypothermia is a more common and significantly more serious sign of infection in the newborn than in the older child or adult. Hypothermia probably occurs because the newborn is unable to maintain normal heat production or there is an increase in heat loss caused by environmental factors around the neonate. The newborn, in contrast to the adult, does not shiver when hypothermic.

Assessment of Body Temperature

The most common methods to measure temperature are axillary and rectal temperatures. In addition to noting body temperature, the RT or other clinician should also note the temperature of the infant’s environment. Most sick infants are placed in an NTE (see Fig. 12-3). If the environmental temperature leaves the neutral thermal range, the infant usually can maintain a stable body temperature, but at the cost of a significant increase in oxygen consumption. NTEs are defined for an infant based on weight and gestational and chronologic age.

Pulse

The normal pulse rate for newborns is between 100 and 160 beats/minute. Their heart rate is age and size dependent and is usually a function of the developmental age of the neonate. The normal resting heart rate is higher in premature infants than in a full-term newborn. The resting heart rate also decreases with increasing chronologic age. Newborns and infants cannot significantly change their cardiac output by increasing stroke volume (volume of blood ejected from the heart with ventricular contraction) because their stroke volume at rest is normally more than 90% of maximal stroke volume. Neonates and infants increase their cardiac output by increasing their heart rate. However, too high a rate (>180 beats/minute) may impede ventricular refill and lead to cardiovascular collapse and shock in the small infant or child.

Tachycardia in the newborn is a heart rate greater than 160 beats/minute, and bradycardia is a heart rate of less than 100 beats/minute. Tachycardia in the newborn can be caused by crying, pain, decrease in the circulating blood volume, drugs, hyperthermia, and heart disease. Bradycardia can be caused by hypoxia, Valsalva maneuver (often occurs during crying), heart disease, hypothermia, vagal stimulation (e.g., passing a nasogastric tube), critical congenital heart disease (CCHD), and certain drugs. In addition, there are a few infants with sinus bradycardia (a normal variant) and resting heart rates between 70 and 100 beats/minutes.

Assessment of Pulse Rate

The pulse usually is evaluated at the brachial or femoral artery because of the small size of the radial arteries. To evaluate the brachial pulse, the clinician places his or her index finger pad over the brachial artery just above the elbow, with the baby in a supine position. The femoral artery pulse can be assessed at the groin, about halfway across the thigh (Fig. 12-4). On a newborn, the pulse can also be felt at the base of the umbilical cord. This is the preferred site in the L&D room during resuscitation of the neonate.

Respiratory Rate

The normal respiratory rate for neonates and infants is between 30 and 60 breaths/minute and is a function of the developmental age of the infant. The normal respiratory rate decreases as gestational age increases. Infants’ respiratory rates are higher than those of older children and adults because of mechanical properties of their chest walls and airways. Infants’ chest walls are more compliant, leaving them more prone to excessive inward movement of the chest (retractions) on inhalation. As a result, infants normally breathe rapidly and shallowly to help avoid retractions and chest wall collapse.

Tachypnea is a respiratory rate greater than 60 breaths/minute, and bradypnea is a respiratory rate of less than 30 breaths/minute in an infant (<40 breaths/minute in a newborn). In newborns and infants, tachypnea can be caused by hypoxemia, metabolic and respiratory acidosis, CCHD, anxiety, pain, hyperthermia, and crying. Bradypnea is not a normal physiologic response in newborns. Bradypnea can be caused by certain medications (e.g., narcotics), hypothermia, and central nervous system diseases, and it may be an important clinical sign of the imminent decompensation from fatigue of the newborn with significant lung disease. Nonintubated infants with lung disease usually are tachypneic. As the disease progresses and the infant or child tires from the increasing work of breathing, bradypnea occurs just before ventilator respiratory failure.

All newborns display an irregular breathing pattern. Respiratory rates that exceed 60 breaths/minute but normalize over the next several hours may indicate TTN.

Another common respiratory pattern of infants is apnea, or the cessation of respiratory effort. Apnea is a pathologic condition in which breathing ceases for longer than 15 to 20 seconds. Apnea may be accompanied by cyanosis, bradycardia, pallor, and hypotonia. More than six events of apnea accompanied by bradycardia in an hour (A&Bs) should be further investigated and their cause properly treated or addressed. A phenomenon known as periodic breathing also exists in newborns. During periodic breathing, the infant has multiple episodes of respiratory pauses or short apnea interspersed with normal-appearing ventilation. This pattern of breathing may continue for several minutes to several hours. All episodes of apnea must be investigated to establish the cause.

Assessment of Respiratory Rate

The respiratory rate can be obtained by visually observing chest motion or counting respirations while listening with a stethoscope. Visual observation provides a respiratory rate closer to the infant’s resting rate. However, because the normal infant breathes rapidly with a small tidal volume, visualization of all of the true breaths may be difficult. If the RT or other member of the patient care team thinks this is a possibility, the respiratory rate should be assessed by listening with a stethoscope. The infant is likely to respond to the touch of the stethoscope with a temporary increase in respiratory rate.

The infant’s respirations are assessed for rate as well as for regularity and depth. Many premature infants have normal rates but very irregular breathing patterns, which may include brief periods of apnea as described before. In addition, infants with significant lung disease may have normal respiratory rates but tidal volumes so small that they have minimal effective ventilation. Gasping respiratory efforts are never to be considered normal respiratory patterns in newborns.

Blood Pressure

The normal values for blood pressure depend on the size of the infant or neonate, with pressures decreasing with lower weights (Table 12-5). Usually, a term neonate’s systolic blood pressure should be no higher than 70 mm Hg, with diastolic pressure no higher than 50 mm Hg. Normal pulse pressure (the difference between systolic and diastolic blood pressure) in a term infant is between 15 and 25 mm Hg.

TABLE 12-5

Normal Newborn Blood Pressures in the First Hours of Life

Birthweight (g)	Systolic (mm Hg)	Diastolic (mm Hg)
501-750	50-62	26-36
751-1000	48-59	23-36
1001-1250	49-61	26-35
1251-1500	46-56	23-33
1501-1750	46-58	23-33
1751-2000	48-61	24-35
2001-3000	59	35
>3000	66	41

Adapted from Hegyi T, Carbone MT, Anwar M, et al: Blood pressure changes in premature infants. I. The first hours of life. J Pediatr 124:627-633, 1994.

Assessment of Blood Pressure

There are two common methods of determining blood pressure in newborns: use of a blood pressure cuff (sphygmomanometer) and direct arterial pressure monitoring. The more common method is to use a blood pressure cuff. The other common method for obtaining blood pressure in newborns is the direct measurement of pressure through an arterial cannula, also known as an arterial pressure catheter (see Chapter 15). In the newborn, it is important to measure the blood pressure in all four extremities after birth. Difference in blood pressure between upper and lower extremities can be an indication of a CCHD such as coarctation of the aorta (a narrowing of the ascending or descending aorta in a newborn).

Lung Topography

The infant’s lungs are situated in the chest much as in the adult, but the infant’s chest has a greater anteroposterior (AP) diameter than the adult’s chest. The AP diameter of the infant’s chest decreases proportionally and becomes more like the adult configuration with growth (Fig. 12-5). The imaginary lines and thoracic cage landmarks are the same in infants as in adults (see Chapter 5).

Inspection is probably the most important and often the most neglected portion of the physical examination of a newborn. The infant should be unclothed and in a supine position initially in a quiet environment. The RT or other clinician should look first at the infant’s overall appearance to identify level of illness, presence of malformations, and whether the infant’s body position is appropriate for the gestational age (Fig. 12-6). The full-term neonate at rest flexes the arms and legs into a fetal position. Premature infants at earlier gestational ages have less muscle tone, and their extremities are less flexed at rest.

The RT should also look at the infant’s skin to see whether the infant is cyanotic. Some caution must be used in interpreting these findings. Infants with hypothermia or infants with polycythemia (hematocrit level > 65%) may have bluish extremities, yet they are not really hypoxemic. The mucosal color of infants who are preterm and immature with thin skin can look quite pink when they are really hypoxemic. The color of the mucous membranes in the mouth and tongue and the nail beds in the extremities give a more reliable indication of the infant’s true level of oxygenation. Acrocyanosis, which is peripheral cyanosis of the hands and feet during the first 24 to 72 hours of life, is normal and is due to immature development of peripheral capillary beds.

The effort involved in breathing and the breathing pattern should be noted, especially the regularity of respirations. An infant with respiratory distress characteristically exhibits tachypnea (discussed earlier), retractions, nasal flaring, and sometimes grunting.

Retractions

Sinking inward of the skin around the chest wall during inspiration (retractions) occurs when the lung’s compliance is less than the compliance of the chest wall or when there is a significant airway obstruction. Thus, retractions are a sign of an increase in the work of breathing. The diaphragm contracts during inspiration, lowering the negative pressure in the intrapleural space. In the normal respiratory system, the lung is the most compliant structure and will inflate to relieve this negative pressure. Furthermore, in a healthy infant, the chest wall is as compliant as the lungs. Any lung disease that causes a decrease in compliance can cause the lung to become less compliant than the chest wall. The chest wall then represents the most compliant structure in the respiratory system and collapses inward in response to the increasing negative intrathoracic pressure generated by diaphragmatic contraction.

Retractions tend to be in different locations, depending on the cause of the respiratory distress. Three common points of collapse are the intercostal area (between the ribs), the subcostal area (below the lower rib margin), and the substernal area (below the bottom of the sternum). A fourth point of collapse is the supraclavicular area (above the clavicles) (Fig. 12-7).

Infants with lung disease tend to have retractions toward the center of the body (substernal and subcostal). Infants with heart disease tend to have intercostal retractions on the sides of their bodies because their large hearts prevent backward motion of the sternum. Finally, infants with obstructed airways tend to have large suprasternal retractions due to the pronounced use of accessory respiratory muscles.

SIMPLY STATED

Retractions in the infant generally indicate a decrease in lung compliance, and a serious increase in the work of breathing or airway resistance, or both. Further assessment and monitoring of the infant are necessary.

Grunting

Grunting is a sound heard at the end of expiration just before rapid inspiration. Grunting is caused by closure of the glottis during expiration in an attempt to provide increased positive end-expiratory pressure and to maintain lung volume and functional residual capacity (FRC). The infant accomplishes this by occluding the airway with glottic closure and actively exhaling against the closed glottis after the end of inspiration. The grunting sound is produced when the infant suddenly opens the glottis and quickly exhales, inhales, and again closes the glottis (Fig. 12-8). Grunting is typically heard in infants with diseases that decrease lung volume (e.g., RDS).