Apparent Life-Threatening Event

An apparent life-threatening event (ALTE), is the term sometimes given to a prolonged infant apnea spell. It is an episode in which an infant has apnea, or stops breathing for 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 and is known as "periodic breathing." Apnea, however, is defined as an episode in which an infant does not breathe at all for more than 20 seconds. An apparent life-threatening event is also sometimes called apnea spell, infant apnea, and acute life-threatening episode.

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. Reflux (when the stomach contents flow back into the esophagus) may also cause some babies to stop breathing for a while.

As the seconds go by without a breath, 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 either when an infant is sleeping or when the baby is playing and active.

Sometimes simply touching or picking the infant up will make him or her start breathing again. In other cases, advanced medical support may be needed.

Signs and Symptoms

When an infant arrives at an emergency department following an episode of apnea, he or she may appear well or may appear extremely ill. The infant's caregiver can tell the healthcare professionals 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:

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

Causes and Risks of the Condition

Potential causes of ALTE include:

  • a viral infection such as respiratory syncytial virus (RSV), especially in infants under 6 months
  • 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, an abnormal heart rhythm
  • cardiomyopathy, an abnormal growth of the heart muscle
  • gastrointestinal conditions, such as gastroesophageal reflux disorder (GERD)
  • respiratory conditions, such as whooping cough
  • neurological disorders, such as seizures, meningitis, or brain tumors

On rare occasions, a reported episode of infant apnea may actually not have occurred at all. It may represent a case of Munchausen syndrome by proxy, an unusual 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, or 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 at higher risk.

Preventing ALTE

ALTE usually cannot 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.

Diagnosis

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 professional 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 life-threatening infection of the nervous system.

If a heart murmur is heard, further cardiac testing may be done, such as an electrocardiogram (ECG) or echocardiogram. A chest X-ray may be done if the healthcare professional suspects pneumonia or whooping cough.

Long-term Effects

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, ranging from treatable conditions to life-threatening illnesses 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.

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.

Treatments

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.

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 can be complicated by infection, bleeding, or an allergic reaction to the anesthetic.

After Treatment
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.

Monitoring ALTE

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 device monitors the infant's breathing and alerts the caregiver to any further ALTE episodes. Any new or worsening symptoms should be reported to the healthcare professional.