eMedicine Specialties > Emergency Medicine > Pediatric

Pediatrics, Apnea

Author: Elizabeth B Jones, MD, Assistant Professor, Department of Emergency Medicine, University of Texas Health Science Center at Houston
Coauthor(s): Brent R King, MD, Associate Professor of Emergency Medicine and Pediatrics, University of Texas Health Science Center at Houston; Chair, Department of Emergency Medicine, Memorial Hermann Hospital, Lyndon B Johnson General Hospital; Isaac Grate Jr, MD, Assistant Clinical Professor, Department of Emergency Medicine, University of Texas Health Science Center at Houston
Contributor Information and Disclosures

Updated: Nov 29, 2007

Introduction

Background

Infant apnea is defined by the American Academy of Pediatrics as "an unexplained episode of cessation of breathing for 20 seconds or longer, or a shorter respiratory pause associated with bradycardia, cyanosis, pallor, and/or marked hypotonia."¹ Apnea is more common in preterm infants. Apnea in preterm infants requires specific treatment, which is not discussed in this article. Apnea is rare among full-term, healthy infants and generally resolves with age. For the ED physician or general pediatrician, the real problem is when an infant's caregiver reports that an infant has stopped breathing. This is an apparent life-threatening event (ALTE).

ALTE was defined by the 1986 National Institutes of Heath Consensus Development Conference on Infantile Apnea and Home Monitoring as follows:

"An episode that is frightening to the observer and is characterized by some combination of apnea (central or occasionally obstructive), color change (usually cyanotic or pallid but occasionally erythematous or plethoric), marked change in muscle tone (usually marked limpness), choking or gagging. In some cases, the observer fears that the infant has died. Previously used terminology, such as 'aborted crib death' or 'near miss SIDS' should be abandoned as it implies a, possibly, misleading close association between this type of spell and SIDS."

ALTE is not a diagnosis. It is the description of an event or a presenting complaint. The episodes described vary tremendously, and the potential diagnoses are diverse. In most cases, the emergency physician examines a well-appearing infant who has experienced an ALTE before his or her arrival at the ED, or the physician encounters an infant who is being monitored for apnea and bradycardia and now has a history of frequent monitor alarms. The challenge lies in scrutinizing the patient's history to identify potentially important episodes and evaluating the findings on physical examination to make a presumptive diagnosis and an appropriate referral.

Pathophysiology

ALTE has many potential causes. These include central apnea, obstructive apnea, gastroesophageal reflux (GER), cardiac arrhythmia, and seizure disorder. ALTE is also a common complaint for parents with Munchausen syndrome by proxy, and it may be a secondary manifestation of certain types of child abuse. Apnea may be a part of the presentation of infants with sepsis and other severe illnesses. These infants will not be well appearing and should be managed as the specific condition indicates.

The usual cause of central apnea is often presumed to be immaturity of the respiratory center, with a weak respiratory response to hypercapnia. Studies of cases followed up in apnea centers have shown increased respiratory pauses in patients with apnea compared with age-matched control subjects. However, these events were not apparently correlated with low oxygen levels. Studies of hypercapnia in infants with known apnea have not demonstrated an abnormal response to carbon dioxide.

Frequency

United States

Estimates of the incidence of ALTE in the general population are 0.5-6%. However, the studies on which these estimates are based have methodologic flaws that make the findings hard to interpret.

International

The worldwide incidence of ALTE is unknown. One report from Sweden places the incidence of apnea during the first 4 days of life at 0.35 case per 1,000 population.

Mortality/Morbidity

• Perhaps the most important question yet to be answered regarding ALTEs is the degree to which they are associated with sudden infant death syndrome (SIDS). A recent retrospective study from Sweden found a much higher incidence of the combination of prone sleeping and maternal smoking among SIDS victims versus ALTE patients.²
• Some reports suggest that 5-10% of patients dying of SIDS had a previous ALTE. In 8 studies of mortality among patients with a history of ALTE, the death rate was 1%, and some, but not all, patients died of SIDS. On the contrary, most patients dying of SIDS did not have a previous ALTE. At present, a causal relationship between ALTE and SIDS has not been proven. Indeed, many circumstantial factors suggest that no relationship exists.
• Although little true morbidity is associated with ALTE, psychological morbidity certainly occurs. Most children who experience an ALTE are ultimately given a home monitoring device. The period of monitoring may last a year or more. This monitoring can be stressful for the family because a family member must be relied on to respond to monitor alarms at all times. Some ED visits by monitored infants probably result from the demands of caring for a baby on a home monitoring device.

Sex

Data are variable, but most studies demonstrate a male predilection. In some studies, the male-to-female ratio among infants with ALTE is as high as 2:1.

Age

The typical infant presenting after an ALTE is aged 8-14 weeks. Approximately 7% of these infants were born prematurely.

Clinical

History

Careful medical history taking is the best way to make a presumptive diagnosis. Sophisticated (and expensive) testing can be judiciously ordered after the examining physician obtains a good history. A detailed history is essential to establish the severity of the episode and to suggest a specific diagnosis. Risk factors for medical interventions after an ALTE are prematurity, a positive medical history, and age >60 days.

• In most cases, caretakers have observed that the child changed colors and/or stopped breathing, or they may find the child limp. In addition or as an alternative, the infant may have experienced a notable episode of coughing, choking, or gagging.
• The child's caretakers should be asked to describe the events in as much detail as possible. Ascertaining the following information is especially important:
  • Was vomitus or fluid found on the infant or his or her bedclothes?
  • Was any coughing or choking associated with the event?
  • Did any associated color change occur, and, if so, what was the infant's color?
  • Was the infant breathing, and was his or her heart beating?
  • Was the infant making respiratory efforts?
  • Did the infant move during the event, and, if so, what were the movements? Did any abnormal eye movements occur?
  • How long did the event last? Was stimulation required to terminate the event and, if so, what type?
  • Were mechanical factors (eg, the child being pinned in the crib) involved?
• Premature infants are at increased risk for ALTE. Respiratory syncytial virus (RSV) is a common culprit among these babies, and a history of recent illness and exposure to ill contacts may be present. The formerly premature infant who has had general anesthesia is at increased risk for ALTE for 2-4 months after the procedure for which it was given.
• Examining physician should ask how the infant is fed (breast vs bottle) and about his or her feeding habits. Babies who feed rapidly, cough frequently, or choke during feedings may be at increased risk for ALTE.
• Events occurring shortly after feedings, particularly if associated with the finding of stomach contents on the infant or on the bedclothes, are likely to represent severe gastroesophageal reflux (GER). Similarly, if the baby is an aggressive feeder who chokes frequently during feedings, he or she may have GER with or without laryngospasm as a cause. Frequent choking may also represent the rare H-type tracheoesophageal fistula.
• Infants who are found asleep and not moving are likely to have idiopathic central apnea or a cardiac arrhythmia. On the other hand, strange or stereotypic movements or abnormal eye movements are suggestive of seizures. Apparent respiratory efforts suggest upper airway obstruction, although infants with primary cardiac arrhythmias may also be found breathing.
• Color change is particularly important. Cyanosis suggests a clinically significant episode. Most often, the baby is observed turning red.
• The actual length of the episode may be difficult to determine. Most physicians are familiar with the phenomenon of time expansion in which frightening events seem to last far longer than they actually lasted.
• The examiner may be most successful by trying to get the person to relate the elapsed time to something familiar. For example, the family can be asked if the event lasted as long as a television commercial. The duration may help establish the etiology.
• Healthy infants may have respiratory pauses as long as 20 seconds. If the episode lasted fewer than 20 seconds and was not associated with vomiting, abnormal movements, or color change, it may have been a normal respiratory pause.
• The infant's response to stimulation is important. The baby who did not cry or move after being picked up probably had a clinically significant event. The infant's response must be distinguished from the parent's response. Many infants who would have responded to simply being picked up may have unnecessarily received intervention ranging from having water splashed in his or her face to receiving CPR.
• Finally, a subset of patients present not because of a primary ALTE but because their home monitoring device triggered an alarm.
  • In the vast majority of cases, the monitor malfunctioned or was improperly used; however, full evaluation is still warranted. During observation in the ED, the infant should be connected to the home monitor and to one of the cardiorespiratory monitors in the ED for comparison.
  • Home monitoring devices are simple, single-channel machines that monitor the patient's heart rate and chest-wall movements. Comparing events recorded on the home monitor with the recordings on the sophisticated equipment in the ED, particularly the pulse oximeter, is often useful. Newer home monitors have an event-recording feature that allows the episode to be played back.

Physical

In 50% of cases, the infant appears well, and the examination findings are normal. The other 50% have physical findings that may suggest a diagnosis. Therefore, a complete physical examination with the patient undressed is essential. Infants who do not appear well may have a variety of serious disorders (see Differential Diagnosis below). Therefore, it is most important to identify infants who appear sick.

• Vital signs and temperature: All abnormalities must be investigated. About 25% of patients have pyrexia, and 25% have an infection.
• Height and weight: Deviation from growth charts suggests child abuse or inborn errors of metabolism.
• Head, eyes, ears, nose, and throat examination
  • A bulging fontanelle suggests raised intracranial pressure.
  • The physician must look for pupillary abnormalities and, if possible, for retinal hemorrhages.
  • Oronasal hemorrhage has been associated with trauma but not with benign causes of ALTE.
• Neck examination
  • Infants may have meningitis without nuchal rigidity, but this sign is worrisome.
  • The examiner should listen to the neck for stridor, which suggests laryngomalacia.
• Chest examination
  • The patient's respiratory pattern should be observed to identify an exaggerated periodic breathing pattern.
  • Retractions and grunting suggest lower-airway pathology.
  • The examiner should listen for abnormal breath sounds and for heart murmurs.
• Neurologic examination
  • Any abnormal neurologic findings should be noted. It is important to remember that the normal neurologic findings in the newborn are substantially different from those of the older child.
  • Seizure activity, muscle rigidity, and abnormal eye movements are important indicators of a neurologic etiology.

Causes

• In the infant who appears well after an ALTE, one of the following causes is likely.
  • Idiopathic central apnea (most common): The usual cause of central apnea is often presumed to be immaturity of the respiratory center, with a weak respiratory response to hypercapnia. Studies of cases followed up in apnea centers have shown increased respiratory pauses in patients compared with age-matched control subjects. However, these events were not apparently correlated with low levels of oxygen. Studies of hypercapnia in infants with known apnea have not demonstrated an abnormal response to carbon dioxide.
  • Toxin-related central apnea (eg, carbon monoxide poisoning): Certain drugs are known to cause central apnea; however, in most cases, the patient has no history of drug exposure. The examining physician to ask about the mother's use of drugs, particularly when the mother might be smoking drugs or when the infant is being breastfed. Carbon monoxide poisoning must also be considered because it is more likely to affect young infants (because of fetal hemoglobins) than adults.
  • GER: Although apnea due to GER usually has another cause, in some cases GER causes laryngospasm and obstructive apnea. Infants with severe GER may have apnea due to stimulation of chemoreceptors around the larynx that results in central apnea, bradycardia, and pallor. In older patients with GER, ALTE is most likely to result from laryngospasm.
  • Seizure: Neonatal seizures are often different from those observed in older children. Although apnea may result from seizures, it is usually not the only symptom. Most patients with seizures also have abnormal movements or posturing, and lateralizing eye movements.
  • Primary arrhythmia: Cardiac arrhythmias cause ALTEs for obvious reasons. Infants with previous cardiac surgery or known congenital defects near the conducting system may have arrhythmia. In most cases, the cause is obscure. The infant with a cardiac cause for ALTE is less likely than others to present with primary apnea.
  • Laryngomalacia or tracheomalacia: The cause is a thin, floppy upper airway and trachea, which are prone to collapse with the negative pressure of inspiration. Infants with these conditions may also have stridorous breathing.
  • Misinterpretation of normal periodic breathing is a pitfall.
  • A choking episode might be possible.
• In an ill-appearing infant, ALTE may have many potential causes, including the following:
  • Infection (eg, sepsis, meningitis, infant botulism)
  • Inborn error of metabolism
  • Congenital adrenal hyperplasia
  • Dehydration or renal tubular acidosis
  • Child abuse, including aborted infanticide, Munchausen syndrome by proxy, and physical abuse
    • Abuse should be considered when infants do not appear well on arrival.  Careful physical examination should be performed to look for other signs of abuse.
    • Munchausen syndrome by proxy may be suspected in the infant who has recurrent or bizarre ALTEs, particularly when the family has been to several EDs and/or physicians with the same complaint and when "no one can find the cause." A previous SIDS death in the family also increases the risk of Munchausen by proxy. Although not found in all cases, family dynamics may include a father who is somewhat distant or uninvolved and a mother (usually the perpetrator) who has a healthcare background and who seems to identify with members of the healthcare team.
• The most common discharge diagnoses are seizure, febrile seizure, GER, and lower respiratory infection.
• Home monitor alarm: Causes may include worn or faulty leads, improper placement of leads, a damaged monitor, failure to adjust the limits of the alarm to account for a decreasing normal pulse and respiratory rate as the infant ages.

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