An apparent life-threatening event (ALTE) is the sudden occurrence of certain alarming symptoms such as prolonged periods of no breathing (apnea), change in color or muscle tone, coughing, and gagging in children under 1 year of age.

• Known causes include nervous system disorders and infections.
• The diagnosis is based on a discussion with caregivers, a physical examination, and the results of certain laboratory tests.
• The prognosis depends on the cause of the apparent life-threatening event.
• Treatment is aimed at specific causes when they can be identified.

ALTE is not a specific disorder; it is a group of symptoms that occur suddenly in young children.

Causes

The most common causes of ALTE include gastroesophageal reflux disease, nervous system disorders (such as seizures, meningitis, or brain tumors), and infections. Less common causes include heart disorders, metabolic disorders, child abuse, and narrowing or complete blockage of the airways. A cause cannot be determined in about 50% of cases.

Symptoms

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

• Not breathing for 20 seconds or more
• Color change, usually blue or pale, but sometimes red
• Change in muscle tone, usually floppy
• Choking or gagging

Diagnosis

When an ALTE occurs, the doctor asks several key questions:

• What was observed by the caregiver who witnessed the event (including a description of changes in breathing, color, muscle tone, and eyes, noises made, and length of the episode)?
• What interventions were taken (such as gentle stimulation, mouth-to-mouth breathing, or cardiopulmonary resuscitation [CPR])?
• Has the mother used drugs while pregnant? Do members of the family currently use drugs, tobacco, and alcohol?
• What is the child's gestational age (length of time spent in the uterus after the egg is fertilized)? Were there any complications at birth?
• While feeding, does the child gag, cough, or vomit? Has poor weight gain been an issue?
• Has the child reached all age-appropriate developmental milestones?
• Has the child had an ALTE before or experienced a recent trauma?
• Have there been any other ALTEs in the family or early death?

The doctor does a physical examination to check for obvious defects, particularly nervous system abnormalities such as being too stiff (posturing) or being too floppy (poor muscle tone), and signs of trauma.

The doctor may do laboratory tests (such as liver function, blood, stool, and urine tests), imaging tests (such as a chest x-ray or CT scan of the head), electrocardiography, or a combination based on the examination findings. Tests (such as electroencephalography [see Diagnosis of Brain, Spinal Cord, and Nerve Disorders: Electroencephalography]) to check for other possible causes also may be done.

Prognosis

The prognosis depends on the cause. Some causes, such as neurologic disorders, are more dangerous than others. If the ALTE was not caused by a serious disorder, children do not seem to have any long-term consequences. The relationship of ALTE to sudden infant death syndrome (SIDS) is unclear. However, most doctors no longer think infants who had an ALTE are at increased risk of SIDS.

Treatment

The cause, if identified, is treated. Infants who have required cardiopulmonary resuscitation (CPR) or have had any abnormalities identified on examination or initial laboratory testing are hospitalized for monitoring and further evaluation.

Parents and caregivers should be trained in CPR for infants and in general safe infant care (such as sleeping on the back and eliminating exposure to tobacco smoke). Doctors sometimes recommend home apnea monitoring devices for a limited period of time. Monitors that can record the infants' breathing pattern and heart rate are preferred to those that simply sound an alarm. Recording monitors may help doctors distinguish false alarms from real events.

Last full review/revision February 2009 by Elizabeth J. Palumbo, MD