Apparent Life Threatening Event In Infant (ALTE)

Apparent life threatening event refers to the sudden appearance of dangerous symptoms in otherwise healthy babies below one year of age. Apnea or a prolonged absence of breathing, gagging and coughing fits, change of muscle tone or skin color, are the usual symptoms associated with an apparent life-threatening event or ALTE.

  • Certain infections and disorders of the nervous system are the usual causes of ALTEs.
  • Feedback from parents and caregivers of the baby followed by a thorough physical examination, and certain diagnostic tests, help diagnose the condition.
  • The cause of the ALTE determines the prognosis.
  • Treatment depends on the cause, if it is identified.

Apparent life threatening event is not a disease, but often the symptom of some underlying disease in the baby which needs to be investigated.


Infections, brain tumors, meningitis, and other such disorders of the nervous system, and gastroesophageal reflux disease, are the usual causes of Apparent life threatening event. Less commonly, abnormalities of the heart, metabolic disorders, and narrowing of the airways or a complete blockage, may result in an ALTE. Occasionally, it may have resulted from child abuse. In about half the cases, it may not be possible to detect the exact cause.


An Apparent life threatening event often occurs without any warning, and the alarming symptoms shock the child’s parents or other caregivers. Some of the commonly occurring symptoms are:

  • Absence of breathing for over 20 seconds
  • Sudden change in color to blue or red, or becoming pale
  • Muscle tone changes, usually the body becoming floppy, and less commonly, developing stiffness
  • Gagging, choking or sudden fits of severe coughing


Feedback from parents and caregivers play an important part in diagnosis. On bringing the child who has suffered an Apparent life threatening event to the doctor, the parents or other caregivers may be asked to explain the following in detail:

  • The observation of the baby’s parents or caregivers who were present at the time of the Apparent life-threatening event regarding the changes which occurred in the breathing pattern, muscle tone, skin color, eyes and the general appearance.
  • Whether the baby has had previous episodes of ALTE.
  • The duration of the episode, and how it got resolved.
  • Whether any first-aid procedures such as cardiopulmonary resuscitation, mouth-to-mouth breathing, or other methods of stimulation were done to revive the baby, and what they were.
  • The drugs the baby’s mother had used during pregnancy, her current use of alcohol and drugs and the family’s tobacco usage.
  • The gestational age of the baby, and whether the baby had prematurity or post maturity at birth.
  • Whether there were any complications during delivery.
  • Whether the baby has any feeding difficulties, and whether incidents of gagging, coughing fits, or bringing up food, occur frequently at the time of feeding.
  • Whether the weight gain has been normal or poor.
  • Whether the baby had any developmental delays or growth retardation.
  • Whether the baby had suffered any physical trauma recently.
  • Whether any other family member had an ALTE or whether any sudden death had occurred in the family.

A thorough physical examination is done with special emphasis on identifying abnormalities of the nervous system such as changes of muscle tone, either stiffness, which is termed posturing, or floppiness, referred to as poor muscle tone. Doctor may look for signs and symptoms of trauma also.

In addition to blood tests, urine and stool tests, liver function tests and imaging tests also may be done. A chest x-ray, ECG and a CT scan of the head are usually done. An electroencephalography is also done, if required.


If the cause of Apparent life threatening event is identified, it can be treated. If the infant has required CPR for revival, or if any abnormality is detected by physical examination or by laboratory testing, hospitalization may be necessary to monitor the infant and evaluate the condition.

The parents of a child who has had ALTE should get trained in CPR, as well as safe infant care, including, how to place the infant on its back for sleeping, and ways to avoid exposing the infant to tobacco smoke. Other caregivers of the infant also should have proper training. An apnea monitoring device designed for home use may be recommended by the doctor. The apnea monitor sounds an alarm when there is a disruption in the breathing. Some monitors can record breathing pattern and heart beat as well, and they may help the doctor evaluate the ALTE better and distinguish it from false alarms

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Yasser Elnahas

MD, PHD, Professor Of CardioVascular Surgery
Dr. Yasser Elnahas, Is an associate Professor of Cardiovascular Surgery. Dr. Elnahas was trained as a fellow At Texas Heart Institute And Mayo Clinic Foundation.Dr. Elnahas is dedicated to educating the general public about different disease conditions and simplifying the medical knowledge in an easy to understand terminology.

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