An apparent life-threatening event (ALTE) is the sudden appearance of certain alarming symptoms (eg, apnea, change in color or muscle tone, coughing, gagging, choking). The caregiver may fear that the child is dead. It typically occurs in children < 1 yr with peak incidence at 10 to 12 wk. Causes may be digestive, neurologic, respiratory, infectious, cardiac, metabolic, or traumatic (eg, resulting from abuse). Treatment is aimed at specific causes when identified.

An ALTE is not a diagnosis but a group of symptoms that occur acutely in young children.

Etiology

The most common causes include

• Digestive: Gastroesophageal reflux disease or swallowing difficulty when associated with laryngospasm or aspiration
• Neurologic: Neurologic disorders (eg, seizures, brain tumors, breath holding or abnormal brain stem neuroregulation of cardiorespiratory control, hydrocephalus, brain malformations)
• Respiratory: Infections (eg, respiratory syncytial virus, influenza, pertussis)
• Infectious: Sepsis, meningitis

Less common causes include

• Cardiac disorders
• Metabolic disorders
• Upper airway obstruction (eg, obstructive sleep apnea)
• Other (eg, drug-related, anaphylaxis, abuse)

Causes may be genetic or acquired. About 50% of cases are considered idiopathic. If an infant is under the care of one person and has repeated episodes with no clear etiology, child abuse should be considered.

Symptoms and Signs

An ALTE usually is characterized by an unexpected, acute change in an infant's breathing that alarms the parent or caretaker. Features of an event include some or all of the following:

• Apneic episode
• Color change
• Change in muscle tone
• Choking or gagging

Many infants appear well by the time they present. Ongoing symptoms are concerning but help suggest a cause and guide evaluation.

Diagnosis

Evaluation initially involves a thorough history, including

• Observations by the caregiver who witnessed the event, particularly a description of changes in breathing, color, muscle tone, and eyes; noises made; length of episode; and any preceding signs such as respiratory distress or hypotonia
• Interventions taken (eg, gentle stimulation, mouth-to-mouth breathing, CPR)
• Prenatal (maternal) and current family use of drugs, tobacco, and alcohol
• Information about the infant's birth (eg, gestational age, perinatal complications)
• Feeding habits (whether gagging, coughing, vomiting, or poor weight gain has occurred)
• Developmental history (eg, milestones)
• Prior history of ALTE or recent trauma
• Family history of ALTE, early deaths, or possible causative disorders

Physical examination is done to check for obvious malformations, neurologic abnormalities (eg, posturing, inappropriate head lag), and signs of infection or trauma (particularly including retinal hemorrhage on funduscopy).

Laboratory and imaging tests (see Table 1: Miscellaneous Disorders in Infants and Children: Diagnostic Tests for Causes of Apparent Life-Threatening Event (ALTE)) are done to check for possible causes. Some are routinely done, and others are done based only on history and physical examination findings, including whether the infant is still symptomatic or has required medical intervention.

Table 1
PrintOpen table in new window
Diagnostic Tests for Causes of Apparent Life-Threatening Event (ALTE) Tests Possible Causes Typical initial testing Blood tests, typically including CBC and differential Electrolytes (Mg, Ca, Na, K), bicarbonate, and glucose Liver function tests Lactate Acidosis Anemia Dehydration Infection Liver disorders Metabolic disorders Chest x-ray Echocardiography Cardiomegaly Infection Cultures (blood, stool, urine, CSF) Infection ECG Cardiac monitoring in hospital Arrhythmias QT abnormalities Lumbar puncture Meningitis Skeletal survey Fractures Toxicology screen Overdose Urinalysis Infection Additional tests based on clinical suspicion ABGs Acidosis Brain imaging (head CT, MRI) Trauma, hemorrhage, tumor EEG Seizures Esophageal pH monitoring* Gastroesophageal reflux disease Nasal swab Respiratory syncytial virus infection Pertussis blood tests and cultures Pertussis Serum lactate Hereditary enzyme defects (eg, glycogen storage disease type I, fatty acid oxidation defects, multiple carboxylase deficiency, methylmalonicaciduria) Hypoxia Toxins (eg, salicylates, ethylene, glycol, ethanol, methanol) Upper GI with radioisotope milk scanning* Gastroesophageal reflux disease *In infants with a history of spitting up, gagging, vomiting, coughing, or difficulty feeding. Diagnostic Tests for Causes of Apparent Life-Threatening Event (ALTE) Tests Possible Causes Typical initial testing Blood tests, typically including CBC and differential Electrolytes (Mg, Ca, Na, K), bicarbonate, and glucose Liver function tests Lactate Acidosis Anemia Dehydration Infection Liver disorders Metabolic disorders Chest x-ray Echocardiography Cardiomegaly Infection Cultures (blood, stool, urine, CSF) Infection ECG Cardiac monitoring in hospital Arrhythmias QT abnormalities Lumbar puncture Meningitis Skeletal survey Fractures Toxicology screen Overdose Urinalysis Infection Additional tests based on clinical suspicion ABGs Acidosis Brain imaging (head CT, MRI) Trauma, hemorrhage, tumor EEG Seizures Esophageal pH monitoring* Gastroesophageal reflux disease Nasal swab Respiratory syncytial virus infection Pertussis blood tests and cultures Pertussis Serum lactate Hereditary enzyme defects (eg, glycogen storage disease type I, fatty acid oxidation defects, multiple carboxylase deficiency, methylmalonicaciduria) Hypoxia Toxins (eg, salicylates, ethylene, glycol, ethanol, methanol) Upper GI with radioisotope milk scanning* Gastroesophageal reflux disease *In infants with a history of spitting up, gagging, vomiting, coughing, or difficulty feeding.

Risk factors for child abuse should be sensitively assessed (see Child Maltreatment: Overview of Child Maltreatment). Recurrent ALTEs that are concerning for abuse are those that occur only in the presence of a parent or caretaker but not the hospital staff or when the infant is alone (eg, sleeping while attached to a monitor).

Clinical Calculator

Prognosis

Prognosis depends on the cause of ALTE. For example, risk of death is higher if the cause is a serious neurologic disorder. The relationship of ALTE to SIDS (see Miscellaneous Disorders in Infants and Children: Sudden Infant Death Syndrome (SIDS)) is unclear. About 4 to 10% of infants who die of SIDS have a history of ALTE, and the risk of SIDS is higher if an infant has had 2 or more ALTEs. Also, infants who have had an ALTE share many of the same characteristics with infants who die of SIDS. However, incidence of ALTE, unlike that of SIDS, has not decreased in response to the Back to Sleep campaign.

There seem to be no long-term effects on development.

Treatment

• Treatment of cause
• Sometimes home monitoring devices

The cause, if identified, is treated. If the infant required resuscitation or if evaluation detected any abnormalities, the infant is hospitalized for evaluation that includes respiratory and cardiac monitoring and some of the tests listed in Table 1: Miscellaneous Disorders in Infants and Children: Diagnostic Tests for Causes of Apparent Life-Threatening Event (ALTE) as indicated.

Parents and caregivers should be trained in CPR for infants and in safe infant care.

Home monitoring devices may be considered for infants with the following increased risk factors for recurrence:

• An ALTE episode requiring CPR
• Prematurity
• A sibling who died of SIDS

Monitors should be equipped with event recorders and used for a predetermined period of time. Parents should be taught how to use the monitor and be advised that home monitoring has not been shown to reduce the mortality rate. Also, exposure to tobacco smoke must be eliminated.

Key Points

• ALTEs have many possible causes; often no etiology is found.
• Most children should have testing for respiratory, neurologic, infectious, and GI disorders and clinical screening for possible abuse; other testing is done based on history and physical examination findings.
• Prognosis depends on cause; risk of death is increased in children with a neurologic disorder, who have had 2 or more ALTEs, who have experienced nonaccidental trauma, or who are > 6 mo and have had an ALTE of longer duration, especially if they have heart disease.
• Children with abnormal examination findings or laboratory results or who required intervention or had a worrisome history are hospitalized.
• Treatment is directed at the cause; home monitoring may be done but has not been shown to decrease mortality.

Last full review/revision May 2012 by Elizabeth J. Palumbo, MD

Content last modified May 2012