Diseases & Conditions

Apparent Life-Threatening Event

Overview, Causes, & Risk Factors

An apparent life-threatening event, or ALTE, is sometimes referred to as a prolonged infant apnea spell. It is an episode in which an infant has apnea, or stops breathing for a short time. The episode lasts long enough to cause:

  • choking and gagging
  • color change in the skin and lips, first bright red then blue
  • muscle weakness and limpness
  • Babies often breathe in cycles. That is, they alternate rapid breathing with slow breathing. This can be normal. Apnea, however, occurs when the baby has an episode of not breathing at all that lasts for more than 20 seconds.

    What is going on in the body?

    What occurs in the body during an ALTE depends on the cause of the episode. A heart or lung problem may cause an infant to temporarily stop breathing. As the lack of breathing continues, the infant may start to struggle for air, cough, and gag. Eventually, as the oxygen level in the blood decreases, the infant may become limp and pale and then may turn blue. This can occur both when an infant is sleeping or when the baby is playing and active. Sometimes simply touching the infant or picking the infant up will make him or her start breathing again. In other cases, advanced medical support may be needed.

    What are the causes and risks of the condition?

    Potential causes of ALTE include:

  • a viral infection such as respiratory syncytial virus, also known as RSV
  • a bacterial infection such as pneumonia
  • something blocking the infant's airway, such as food that was inhaled into the windpipe or an abnormally narrow airway
  • cardiac arrhythmia, which is an abnormal heart rhythm
  • cardiomyopathy, which is an abnormal growth of the heart muscle
  • gastrointestinal conditions, such as gastroesophageal reflux disorder, also known as GERD
  • respiratory conditions, such as whooping cough
  • neurological disorders, such as seizures, meningitis, or brain tumors
  • Munchausen syndrome by proxy, a parenting disorder in which a parent fabricates symptoms in the child
  • In approximately 50% of cases of ALTE, the cause is not found.

    Infants who are born prematurely may be at greater risk for an ALTE. Infants who have a history of respiratory or cardiac problems, such as congenital heart disease, may also be at greater risk for ALTE. Infants with other family members who have had episodes of ALTE may also be more at risk.

    Symptoms & Signs

    What are the signs and symptoms of the condition?

    When an infant arrives at an emergency department, he or she may appear well or may appear extremely ill. The infant's caregiver can tell the doctors whatever symptoms have occurred. Symptoms of ALTE may include:

  • bluish lips, nail beds, and skin
  • coughing or choking
  • limpness or floppy muscles
  • a temporary stop in breathing
  • If there is an underlying illness causing the ALTE, other symptoms will often be present. These can vary widely. For example, the infant may have symptoms such as:

  • convulsions
  • fever
  • high-pitched cry
  • lethargy
  • rapid breathing or slow breathing
  • rapid, irregular, or slow heartbeat
  • vomiting

  • Diagnosis & Tests

    How is the condition diagnosed?

    The diagnosis of ALTE begins with a thorough physical exam and a full medical history. The infant may appear fine and healthy. Various lab tests will usually be normal.

    The healthcare provider will want information on how the baby was before and after the episode. He or she will ask a variety of questions including:

  • Were there any signs of illness before or after the episode, such as fever, vomiting, diarrhea, cough, rapid or labored breathing, rapid heartbeat, or slow heartbeat?
  • Does the infant breast-feed or take a bottle? Does the infant eat quickly? Is there any choking or spitting up?
  • Has the infant been exposed to any toxic substances or poisons?
  • Is there any family history of sudden infant death syndrome (also called SIDS), death in infancy, or genetic disorders?
  • How active does the infant usually seem?
  • Does the infant have a painful or high-pitched cry?
  • How long did the ALTE seem to last?
  • Were there any abnormal movements of the arms, legs, or eyes during the episode?
  • If the infant appears ill, a variety of lab tests may be done to find the underlying cause of the ALTE. The tests done depend on the infant's symptoms. For example, a spinal tap may be done on an infant who has an episode of ALTE along with a fever in order to test for meningitis, a serious infection. If a heart murmur is heard, further cardiac testing may be done, such as an electrocardiogram or echocardiogram. A chest X-ray may be done if the doctor suspects pneumonia or whooping cough.

    Prevention & Expectations

    What can be done to prevent the condition?

    ALTE cannot necessarily be prevented. Preventing illness and infections when possible may decrease the likelihood of an episode of ALTE. However, most normal babies do not experience ALTE.

    What are the long-term effects of the condition?

    The long-term effects of ALTE vary depending on the cause. If there was an episode of ALTE and no other symptoms, there will often be no long-term effects. If the ALTE was caused by an infection that can be easily treated, there may be no other long-term effects. If the ALTE has another underlying cause, long-term effects may vary. They could range from treatable causes to life-threatening problems or even death.

    The caregiver may also have some long-term effects. Witnessing an ALTE in an infant can be a very frightening experience. The caregiver often worries that the child may stop breathing again. Learning CPR can often help ease the caregiver's fears.

    What are the risks to others?

    ALTE is not contagious, although the underlying cause may be contagious. For example, if the ALTE was triggered by an infection, the infection may be contagious.

    Treatment & Monitoring

    What are the treatments for the condition?

    The first priority during an ALTE episode is to get the infant to breathe again. This may be as simple as gently stimulating the infant by picking the baby up and calling out the baby's name. If the infant does not start to breathe, rubbing his back or the bottom of his foot may cause him to breathe. If the infant still does not start breathing, paramedics should be called and resuscitation should be started, including mouth-to-mouth breathing and CPR.

    After the baby starts breathing, he or she will be monitored for further episodes. If the infant is not ill and diagnostic tests and monitoring do not reveal an underlying cause, there may be no need for further treatment.

    If an underlying cause is found, the treatment will depend on that cause. For example, an infant who has an infection will need to be treated for that infection. An infant who has a congenital heart disease may need medicine or surgery, depending on the cause. Treatment and diagnosis may require a medical team that includes specialists in different areas.

    What are the side effects of the treatments?

    Side effects of treatment also depend on the cause of the illness. If no cause for the ALTE is found and the infant is healthy, there are no side effects. Antibiotics for infection may cause stomach upset or allergic reaction. Surgery poses a risk for infection, bleeding, or allergic reaction to anesthesia.

    What happens after treatment for the condition?

    What happens after treatment depends on the cause of the ALTE.

  • If no cause is found and the infant appears healthy, the infant can often be sent home.
  • Sometime an underlying cause is treated but there are concerns that the infant will have more ALTE episodes. In these cases, the infant may need to stay at a hospital to be monitored. Or, the infant may be sent home on an apnea monitor, a device that alerts the caregiver if the infant stops breathing.
  • If the underlying cause is a disease or condition that needs continuous follow-up or treatment, treatment may be ongoing.
  • It may also be helpful for a caregiver to receive training in CPR before leaving the hospital.
  • How is the condition monitored?

    ALTE may not need any further monitoring once the infant leaves the hospital. If the infant is healthy and there is no further concern regarding the possibility of more ALTE episodes, monitoring can be done at home by the caregiver.

    Sometimes an infant will be sent home with an apnea monitor. This monitors the infant's breathing and alerts the caregiver to any further ALTE episodes. Any new or worsening symptoms should be reported to the doctor.


    Author:Eileen McLaughlin, RN, BSN
    Date Written:
    Editor:Crist, Gayle P., MS, BA
    Edit Date:07/19/02
    Reviewer:Lama Rimawi, MD
    Date Reviewed:07/13/01


    Current Pediatric Diagnosis & Treatment, Appleton and Lange, 1993.