Weight

A normal neonate may lose up to 10% of birth weight during the first week of life. By the end of the second week, the infant should have returned to birth weight or a little above it. Weight gain from this point through the first month should be about 30 g (1 oz) per day. It is essential that the weight (undressed) of any neonate be measured accurately in the ED.

Feeding

The feeding schedules of neonates are quite variable, and the same child can exhibit significant variability within a 24-hour period. The average neonate eats between six and nine times a day. Intervals between feeding may range from 2 to 4 hours. Breastfed infants tend to eat more often than formula-fed infants.

Sleeping

Newborns sleep 16 to 18 hours per day, with almost equal amounts of day and night sleep. Awake periods are generally about 1 to 2 hours in duration.

Vital Signs

A normal neonatal pulse is in the range of 120 to 160 beats/min, but it rises if the child is stimulated. The heart rate slows during sleep.

The normal respiratory rate is between 40 and 60 breaths/min. Some irregularity and pauses of less than 20 seconds are normal in the neonatal period. Respiratory pauses should not be associated with any change in color or hypotonia. Because of this irregularity in respiratory rate, accurate measurements can be obtained only if breaths are counted for at least 30 seconds.

Measuring blood pressure in a newborn can be frustrating and time-consuming. A Doppler probe can facilitate the procedure. A systolic blood pressure of less than 60 mm Hg is abnormal in a neonate.

The core temperature in an infant is the same as that in an adult. Fever is generally recognized as a temperature higher than 38° C (100.4° F). Any temperature lower than 36.1° C (97° F) should raise concern for hypothermia. Because of limited thermoregulatory ability, neonates should be examined and treated in a warm ambient environment. See Table 15.1 for normal neonatal vital signs.

Table 15.1 Normal Vital Signs in Neonates

Epidemiology

General estimates suggest that between 0.5% and 6.0% of infants will experience an apparent life-threatening event (ALTE). A prospective Austrian study conducted from 1993 to 2001 revealed an incidence of 2.46 per 1000 live births.² In this study more than 60% of the events occurred in infants 2 months or younger.

Pathophysiology

ALTE is not a single disease entity but rather a constellation of signs and symptoms of numerous diseases that can have lethal consequences. The 1986 National Institutes of Health Consensus Development Conference on Infantile Apnea and Home Monitoring defined ALTE as “an episode that is frightening to the observer and is characterized by some combination of apnea (central or occasionally obstructive), change in color (usually cyanotic or pallid, but occasionally erythematous or plethoric), marked change in muscle tone (usually marked limpness), choking, or gagging.”³

The conventional definition of apnea is absence of breathing for 20 seconds or for a shorter period if associated with clinical signs such as cyanosis, hypotonia, and bradycardia. Because periods of apnea of up to 30 seconds have been observed in normal, healthy, asymptomatic term and preterm infants, the duration of apnea does not seem to be as clinically important as apnea associated with signs and symptoms.⁴ Apnea should be distinguished from the normal periodic breathing of newborns, which is characterized by irregular breathing and episodes of pauses. This latter pattern is more commonly seen in premature infants during sleep. Although similarities exist, ALTE is now considered a different pathophysiologic entity from sudden infant death syndrome.

Presenting Signs and Symptoms

The majority of neonates who have experienced an ALTE have a normal appearance at the time of arrival at the ED. Stratton et al. reported a prehospital study of 60 cases of ALTE in which 83% of the infants were asymptomatic by the time that emergency medical service personnel arrived.⁵ A comprehensive history and a thorough physical examination should be performed. One study showed that the history and physical examination were helpful in diagnosing the cause of ALTE in 70% of cases.⁶ The history should consist of a detailed description of the event, a prenatal and perinatal history, a review of systems, and a family history (especially child deaths, neurologic diseases, cardiac diseases, and congenital problems). Box 15.1 lists essential historical questions in these cases. A detailed physical examination should pay particular attention to the neurologic, respiratory, cardiac, and developmental components. Evidence of child abuse should be sought, including a funduscopic examination for retinal hemorrhage.

Differential Diagnosis and Medical Decision Making

ALTEs and apnea are clinical manifestations that have many causes, as summarized in Box 15.2. The most common organ systems involved (in order of decreasing frequency) are the gastrointestinal, neurologic, respiratory, cardiac, metabolic, and endocrine systems. The cause of ALTE in an individual patient is likely to be discovered only about 50% of the time.

Diagnostic testing is best guided by the history and physical examination. Laboratory tests have been shown to be contributory to the diagnosis only 3.3% of the time if the results of the history and physical examination were noncontributory.⁶ An Israeli study concluded that diagnostic testing has low yield in infants with normal perinatal histories and normal findings on physical examination.⁷

Disposition

Historically it has been the practice that all infants with apnea or ALTE be admitted for observation. Some studies suggest that certain low-risk infant groups might be able to be discharged home from the ED.^8,9 Box 15.3 lists low-risk criteria for ALTE. An infant meeting all the criteria in this box would have a very low probability of experiencing an adverse outcome. Otherwise, it is prudent to admit the infant for observation and in-patient evaluation by a pediatric specialist.

Epidemiology

Crying peaks in infancy at 6 weeks of age with an average crying time of 3 hours per day. More of the crying time is clustered in the late afternoon and evening. Forty percent of these infants cry for 30 minutes or longer at one time, 75% of whom have the longest crying spells between 6 and 12 PM.¹⁰ The prevalence of excessive crying varies between 1.5% and 11.9%, depending on the definition of excessive crying.¹¹

Pathophysiology

Crying is a form of communication by the neonate. It signals some form of infant discomfort from hunger to lack of attention to other causes of pain, some that can be serious.

Presenting Signs and Symptoms

Box 15.4 lists important questions to ask the caregiver of an afebrile infant with excessive crying. Table 15.2 lists possible physical findings in these infants.

Table 15.2 Potential Abnormalities in Crying Infants Found on Physical Examination

Differential Diagnosis and Medical Decision Making

The first differentiation that the clinician must make is whether the child is febrile (see the section “Fever”). In an afebrile infant the chronicity of the crying is important. Is the crying an acute single episode, or has it been an ongoing problem for some time?

The latter describes colic, which affects a large subgroup of excessively crying infants. Classically, colic has been described by the rule of threes—crying for 3 hours per day, for at least 3 days per week, for 3 weeks. Scores of theories concerning the etiology of colic have been proposed; such theories range from physiologic disturbances (cow’s milk allergies, gastrointestinal reflux, hypocontractile gallbladder, and other gastrointestinal disturbances), to infant temperament and maternal response, to deficiencies in parenting practices.¹² No single cause has been identified.

No pharmacologic agent has been listed as being both safe and efficacious for the treatment of colic. Anticholinergic agents have been found to be more effective than placebo but are associated with apnea and should not be administered to infants younger than 6 months.¹³ Many other interventions have been proposed for colic, such as having the infant in a car, specific ways to hold the infant, use of white noise, crib vibrators, and herbal teas. None have been shown to be particularly beneficial, however. The EP should reassure parents that there is no ideal treatment of colic, that their child is normal, that the infant will outgrow the colic, and that colic has no long-term sequelae.

A retrospective study involving 237 afebrile children younger than 1 year brought to the ED with the chief complaint of crying or fussiness revealed that 5.1% had a serious underlying etiology. The final diagnosis in the 237 patients was made by the history and physical examination alone in 66% of cases. Only 0.8% of the diagnoses were made by diagnostic evaluation alone. These authors concluded that afebrile crying infants younger than 1 month should undergo urinalysis.¹⁴

A suggested approach to the ED evaluation of an excessively crying child is presented in Figure 15.2.

Fig. 15.2 Evaluation of a crying neonate.

CBC, Complete blood count.

Treatment

Treatment is determined by the underlying condition causing the crying.

Disposition

Afebrile crying infants may be discharged home if they are consolable, if they have a negative history and physical examination, and if the clinician has a low index of suspicion for a “sick” child.

Pathophysiology

Cyanosis is the result of either deoxygenated hemoglobin or abnormal hemoglobin (methemoglobin). Cyanosis occurs with the presence of 4 to 5 g of deoxygenated (unsaturated or reduced) hemoglobin per 100 mL of blood. This is an absolute quantity and not a percentage of unsaturated hemoglobin. A cyanotic, polycythemic infant with a hemoglobin value of 18 g/100 mL might have no tissue hypoxia if the total amount of unsaturated hemoglobin is only 5 g/100 mL because the oxygen content of the blood would still be adequate. Conversely, an anemic infant with a hemoglobin value of 7 g/100 mL would have severe tissue hypoxia because at least 4 to 5 g/100 mL of the total is deoxygenated hemoglobin.

Presenting Signs and Symptoms

Cyanosis in a neonate may be persistent or transient, central or peripheral (acrocyanosis). The EP can best evaluate cyanosis clinically by looking at the tongue and mucous membranes. Duskiness or blueness in these areas defines central cyanosis, a pathologic condition. In peripheral cyanosis, or acrocyanosis, the extremities are blue but the oral mucosa and tongue remain pink; this pattern is frequently a normal finding in a neonate but can be associated with pathologic oxygenation.

Differential Diagnosis and Medical Decision Making

An easy method of classifying cyanosis is by causative organ system (Box 15.5). The cardiac and respiratory systems are responsible for the large majority of cases of neonatal cyanosis. Distinguishing between these two categories can be difficult but is necessary for optimal management of the patient.