Neonates are infants ≤1 month old, or preterm infants within 30 days of their term due date. Symptoms that precipitate ED visits in neonates are often vague and nonspecific. Signs are usually subtle and may not point to a specific diagnosis. For example, respiratory distress can be caused by pulmonary or cardiac disease, generalized sepsis, abdominal pathology, or metabolic disorders. Many visits occur because of caregiver concerns about normal variants of newborn vegetative functions. Such concerns must be distinguished from potentially life-threatening congenital and acquired conditions that can present in the first month of life. This chapter reviews normal neonatal vegetative patterns, life-threatening neonatal emergencies, and common neonatal problems.

FEEDING PATTERNS

In the first few weeks of life, expect variation in times between feedings, but by the end of the first month, the vast majority of newborns establish a regular feeding schedule. Most healthy, bottle-fed infants eat 2 to 4 ounces every 2 to 4 hours (six to nine feedings in 24 hours) by the end of the first week of life; breastfed infants prefer shorter intervals—feeding every 1 to 3 hours. Intake is adequate if the neonate gains weight appropriately and appears content between feedings. Feedings are progressing well if the infant is no longer losing weight by 5 to 7 days of age and is gaining weight by 12 to 14 days of age.

WEIGHT GAIN

Weigh neonates completely undressed. Normal newborns may lose up to 12% of their birth weight during the first 3 to 7 days of life, with earlier and slightly more accentuated weight loss in exclusively breastfed newborns. A weight loss of up to 10% is accepTable if the infant’s examination, stooling, and voiding frequency and behavior are normal. On average, infants gain between 20 and 30 grams per day in the first 3 months of life and between 15 and 20 grams per day for the next several months.

STOOL PATTERNS

The number, color, and consistency of bowel movements can vary greatly in the same infant and between infants, regardless of diet or environment (Table 114-1).

An excessive intake of human milk or maternal use of laxatives increases the water content of the infant’s stool. Overfeeding or use of formula that is too concentrated or too high in sugar content also can produce loose stools.

Stool color has no significance unless it is acholic or bloody. The first stool, which consists of meconium, is usually passed within the first 24 hours after birth and is thick, sticky, and black. Transitional stools, which are greenish brown, appear after initiation of milk feeding and are replaced by typical yellow, seedy milk stools 3 to 4 days later. Infrequent bowel movements do not necessarily mean constipation, because breastfed infants may occasionally go 5 to 7 days without a bowel movement. Failure to pass meconium in the first 48 hours of life may suggest Hirschsprung’s disease or cystic fibrosis.

BREATHING PATTERNS

The normal respiratory rate in neonates is 30 to 60 breaths/min. Newborn breathing is almost entirely diaphragmatic, and the soft front of the thorax is usually drawn inward during inspiration while the abdomen protrudes. Count the respiratory rate for a full minute with the infant resting or preferably asleep. Neonates increase minute ventilation almost entirely through an increase in respiratory rate rather than inspiratory volume; a neonate with a resting respiratory rate of >60 breaths/min during periods of regular, quiet breathing requires evaluation for the causes of tachypnea. Observe respirations to determine if breathing is thoracic or abdominal. Thoracic breathing or tachypnea usually signifies intrathoracic or intra-abdominal pathology. Check the nares and upper airway, as neonates are obligate nose breathers, and nasal congestion, or choanal stenosis or atresia, can cause respiratory distress.

Newborn infants, especially those born prematurely, may exhibit periodic breathing that is characterized by alternating periods of a normal or fast rate and periods of a markedly slow rate of respiration, with pauses of 3 to 10 seconds between breaths. Irregular respiratory patterns are seen in many premature babies during sleep, but are less common in term infants. Periods of apnea >20 seconds or apnea accompanied by bradycardia, cyanosis, or a change in muscle tone is abnormal and requires evaluation (see chapter 115, Sudden Infant Death Syndrome and Apparent Life-Threatening Event).

SLEEPING AND FEEDING PATTERNS

Infants are not born with the ability to sleep through the night. Instead, they awaken every 20 minutes to 6 hours, and sleep periods are spread evenly across the day and night. By 3 months of age, most sleep occurs at night, and by 6 months, most infants are sleeping through the night. Night waking is defined as waking and crying once or more between midnight and 5 A.M. for ≥4 nights per week, for ≥4 consecutive weeks. Night waking occurs in about 25% of bottle-fed infants and about 50% of breastfed infants <12 months old. When the child cries during the night, parents should make sure that there is no physical reason for crying. If there is no physical problem, parents may ignore the crying so that the child learns to fall asleep on his or her own. If parents usually feed the child at that time and the child is about ≥6 months old, the volume of the night feedings should be progressively tapered and then discontinued, so all nourishment is given during the daytime.

CRYING

The symptom complex of crying or irritability is fairly common yet difficult to treat, even in the presence of an identifiable cause. Most neonates exhibit varying degrees and periods of crying during a 24-hour period. Total crying time increases after birth, peaking at 3 to 5 months of age. Infants who present with an episode of acute, inconsolable crying, however, require careful evaluation for an underlying cause (Table 114-2).

Principles of basic life support, pediatric advanced life support, and the Neonatal Resuscitation Program are reviewed in chapter 108, Resuscitation of Neonates. A brief discussion of critical neonatal illness is presented here (Table 114-3), with further discussion of specific complaint-based differential diagnosis and management to follow.

For the neonate with respiratory and/or cardiovascular distress, pay primary attention to adequacy of the airway and breathing. There are more stresses and fewer compensatory responses available to the neonate. The neonate has a compliant chest wall and cannot increase inspiratory force; the neonatal airway is small; neonatal metabolism is characterized by high oxygen consumption; and abdominal distention can further impair ventilation. Consider the early use of positive-pressure ventilation or endotracheal intubation for respiratory insufficiency and nasogastric tube placement for gastric distention. Bradycardia in the neonate is almost always due to respiratory failure and hypoxia and usually corrects with restoration of adequate airway and breathing.

Tachypnea can be caused by minor problems, such as gaseous abdominal distention, or life-threatening illnesses, such as sepsis. True tachypnea (respiratory rate >60 breaths/min) or grunting is an emergency; admit for further investigations, monitoring, and therapy in all but the mildest cases.

Cardiorespiratory symptoms in neonates are nonspecific and may be due to cardiovascular or respiratory failure or to systemic diseases. Search for pathologic conditions in all organ systems. For example, sepsis, meningitis, gastroenteritis, and metabolic acidosis may cause respiratory distress as the predominant symptom. Regardless of the cause, assess and stabilize the cardiac and respiratory systems before, or simultaneously with, further diagnostic evaluation.

When a specific cause cannot be identified, initiate a full sepsis evaluation (see chapter 116, Fever and Serious Bacterial Illness in Infants and Children) and begin broad-spectrum antibiotics, and add IV acyclovir if there are any findings consistent with or suggestive of exposure to herpes simplex virus.

Conditions discussed in the following sections include common and uncommon symptom complexes in the critically ill neonate: neonatal sepsis; congenital heart disease; pneumonia; bronchiolitis; anatomic airway lesions; inborn errors of metabolism; congenital adrenal hyperplasia; neuromuscular disorders; intracranial hemorrhage; and abdominal catastrophe.

NEONATAL SEPSIS

Overwhelming neonatal sepsis is the most common cause of neonatal cardiorespiratory distress. Fever or hypothermia signals serious infection in the neonate. Fever in the first month of life is a rectal temperature ≥38°C (100.4°F), and hypothermia is a rectal temperature <36.5°C (97.7°F). Neonates have about twice the risk of serious bacterial infection as do infants 4 to 8 weeks of age. Neonatal sepsis tends to appear as an “early-onset” or a “late-onset” syndrome, with some overlap. Early-onset disease is seen in the first few days of life, tends to be fulminant, and is usually associated with maternal or perinatal risk factors, such as maternal fever, prolonged rupture of membranes, and fetal distress. Late-onset disease usually occurs after 1 week of age, tends to develop more gradually, and is less likely to be associated with risk factors. Septic shock and neutropenia are more common with early-onset syndrome, and meningitis is more common in late-onset disease.

Clinical signs of early- or late-onset sepsis are not specific. Septic infants may exhibit any of a variety of symptoms as described in Table 114-4. Tachypnea and respiratory distress may be a sign of sepsis, meningitis, or urinary tract infection. Localizing signs may be absent—for instance, nuchal rigidity and Kernig and Brudzinski signs are present in a small minority of neonates with meningitis.

Bacterial causes of neonatal sepsis reflect organisms that colonize the female genital tract and nasal mucosa of caregivers. In general, the two groups of pathogens most frequently encountered are gram-positive cocci, such as β-hemolytic streptococci, and enteric organisms, such as Escherichia coli and Klebsiella species, and Haemophilus influenzae. Listeria monocytogenes also causes sepsis and meningitis in neonates. Viral infections are another cause of fever and are most likely due to enteroviruses (coxsackievirus and echovirus) acquired at the time of delivery or respiratory syncytial virus and influenza A virus acquired postnatally. The height of the temperature does not distinguish a viral versus bacterial cause in neonates.

The clinical investigation for neonatal sepsis is similar to that of an older infant except that the threshold for a full sepsis workup, including cerebrospinal fluid analyses, is lower. Admit all neonates to the hospital and initiate treatment with empiric IV antibiotics. Initial treatment of a neonate with suspected bacterial septicemia or meningitis usually includes ampicillin (50 milligrams/kg to cover group B Streptococcus and Listeria) and an aminoglycoside (gentamicin, 2.5 milligrams/kg) to cover E. coli and other gram-negative organisms and possible gram-negative meningitis. Avoid ceftriaxone in neonates as it can cause kernicterus. When gram-negative meningitis is strongly suspected, replace gentamicin with cefotaxime or ceftazidime (50 milligrams/kg), which have better CNS penetration. Add IV acyclovir for neonates with a maternal history of herpes or suspicious cerebrospinal fluid findings (predominance of lymphocytes and erythrocytes in a nontraumatic lumbar puncture) and all neonates who are ill appearing.³ For further detailed discussion, see chapter 116.

CONGENITAL HEART DISEASE

Suspect congenital heart disease in a well-developed neonate who presents with unexplained cardiorespiratory collapse, cyanosis, and or tachypnea, especially without chest retractions or use of accessory muscles for breathing (see chapter 126, Congenital and Acquired Pediatric Heart Disease). Undiagnosed congenital heart disease may be first identified after discharge from the newborn nursery and typically becomes symptomatic at one of two distinct time frames: in the first week of life or after the second week of life (see also chapter 126, Congenital and Acquired Pediatric Heart Disease). In the first week of life, lesions dependent on pulmonary or systemic blood flow through the ductus arteriosus (e.g., hypoplastic left heart syndrome, critical coarctation of the aorta) present with shock and acidosis as the duct begins to close. Lesions that involve left-to-right shunting of blood (ventricular and atrial septal defects) typically present after the second week of life with congestive heart failure as pulmonary vascular resistance falls, allowing pulmonary overcirculation and the onset of congestive heart failure.

PNEUMONIA

The lungs are the most common site of infection in neonates. Neonatal pneumonia contributes to significant mortality in developing countries, whereas the incidence of neonatal pneumonia in full-term infants in developed countries is lower. Table 114-5 displays the various causes, the associated clinical picture, and suggested management of neonatal pneumonia.⁴ Chapter 125, Pneumonia in Infants and Children, further addresses pneumonia after the neonatal period.