Apparent life-threatening events in infants: high risk in the out-of-hospital environment

Ann Emerg Med. 2004 Jun;43(6):711-7. doi: 10.1016/S0196064403011193.


Study objective: The purpose of this study is to define the prevalence and significance of apparent life-threatening events among infants in the out-of-hospital setting.

Methods: This was a retrospective, cohort, outcome study of infants for whom a caregiver activated the emergency medical services (EMS) system. For purposes of the study, an apparent life-threatening event was defined as an episode of apnea, skin color change, or change in muscle tone. Study data characteristics included initial physical appearance, work of breathing, circulation skin signs, pulse rate, respiratory rate, and overall concern for the chief complaint as interpreted by EMS personnel.

Results: Sixty (7.5%) of 804 infants encountered by EMS during the study period met our criteria for apparent life-threatening event. Mean age was 3.1+/-3.3 months, and 55% were boys. Of the infants with apparent life-threatening event, 50 (83.3%) infants appeared to be in no distress, 8 (13.3%) infants were in mild distress, and 2 (3.3%) infants were in moderate distress. General physical appearance, work of breathing, circulatory signs, respiratory rate, and pulse rate were not clinically abnormal in the study group as a whole. Critical conditions associated with apparent life-threatening event included pneumonia or bronchiolitis (12%), seizure (8%), sepsis (7%), intracranial hemorrhage (3%), bacterial meningitis (2%), dehydration (2%), and severe anemia (2%). Limitations of the study included retrospective design and inability to follow up study patients beyond hospital discharge.

Conclusion: An apparent life-threatening event in an infant can present without signs of acute illness and is commonly encountered in the EMS setting. It is often associated with significant medical conditions, and EMS personnel should be aware of the clinical importance of an apparent life-threatening event. Infants meeting criteria for an apparent life-threatening event should receive a timely and thorough medical evaluation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Anemia / physiopathology
  • Apnea*
  • Cohort Studies
  • Cyanosis*
  • Dehydration / physiopathology
  • Emergencies*
  • Emergency Medical Services
  • Female
  • Heart Rate
  • Humans
  • Infant
  • Intracranial Hemorrhages / physiopathology
  • Male
  • Meningitis, Bacterial / physiopathology
  • Muscle Hypotonia*
  • Muscle Rigidity*
  • Respiration
  • Respiratory Tract Infections / physiopathology
  • Retrospective Studies
  • Risk
  • Seizures / physiopathology
  • Sepsis / physiopathology