Brief resolved unexplained event

(Redirected from ALTE)


  • Abbreviation: BRUE
  • BRUE was formerly known as Apparent life-threatening event (ALTE)[1]
  • BRUE definition has a strict age limit (<1 y/o) and should only be considered if no other likely explanation
  • Peak incidence: 1 wk - 2 mo
  • BRUE is a symptom and requires evaluation for the actual diagnosis causing the event
  • Only 10% have repeat events
  • BRUE is not related to SIDS


BRUE diagnosis is only made by a clinician based on the features and is not based on the caregiver's perception of what happened. BRUE is an event occurring in an infant <1 year of age when an observer reports a sudden, brief ( <1 minute but typically <20–30 seconds), and now resolved episode of ≥1 of the following:[1]

  • Cyanosis or pallor
  • Absent, decreased, or irregular breathing
  • Marked change in tone (hyper or hypotonia)
  • Altered level of responsiveness
  • Must have returned to baseline

A BRUE should only be diagnosed when there is no alternative explanation for a the event after completing full history and physical.

ALTE to BRUE Definiton Changes

  • BRUE has a strict age limit < 1yo
  • There must be no other explanation for the event (not something as simple as nasal congestion, choking, viral infection or vomiting)
  • Caregiver's perception of a BRUE does not make an event a BRUE without clinical suspicion
  • Altered responsiveness is a new criteria

Risk Factors

  • RSV infection
  • Prematurity
  • Recent anesthesia
  • GERD
  • Airway/maxillofacial anomalies
  • Age < 10 wks
  • History of apnea
  • Pallor, cyanosis, feeding difficulties
  • Family hx of sudden cardiac death

Clinical Features

See definition above

Past Medical History

The history in an BRUE should focus extensively on the details surrounding the event, need for resuscitation, prior events, possible related medical conditions, or historic findings that may indicate prior events.

  • Prematurity, history of apnea, prior resp/feeding difficulties
  • Immunization status (particularly pertussis)

Family History

  • History of SIDS, cardiac abnormalities, seizures, or metabolic disease


  • Duration of the BRUE
  • Was resuscitation with CPR and rescue breaths required?
  • Temporal relationship with feeding, sleeping, crying, vomiting, or choking
  • Any episodes concerning for central versus obstructive patterns of apnea
  • Any progressive or episodic changes in mental status

Differential Diagnosis

The differential diagnosis is extensive, and although a broad workup is often started in the ED including evaluation for sepsis, occult infection, and metabolic disorders, a cause is infrequently found[2]


  • Idiopathic (~50%)
  • GERD
  • Seizure
  • Respiratory tract infection (e.g. bronchiolitis)
  • Misinterpretation of benign process (e.g. periodic breathing)
  • Vomiting/choking episode

Less Common




Low Risk

Individualize testing by history and exam. These are generally not needed for the low risk patients.

  • Consider:
    • Obtain pertussis
    • ECG
    • Briefly observe on pulse oximetry (e.g. 1-3 hours)

Moderate or Higher Risk


See Definition in Background section

Low Risk Criteria[1]

  • Age >60 days
  • Gestational age > 32 weeks and post-conceptional age >= 45 weeks
  • First BRUE ever
    • No prior BRUE or BRUE in clusters
  • BRUE duration <1 minute
  • No CPR by a medical provider
  • No concern for child abuse, family history of sudden unexplained death,or toxic exposures
  • No abnormal physical findings: (bruising, cardiac murmurs, organomegaly)


Low Risk

Low Risk infants can be safely discharged but there should be shared decision making with parents.

  • Also offer the family CPR training resources
  • Consider pertussis swab, ECG, and brief monitored observation in the ED.
  • No other consults, metabolic or hematologic labs or medications are necessary for discharge


Low Risk

  • Discharged with shared parental decision making, CPR instructions, and close outpatient follow-up

Not Low Risk

Admission in most cases

Especially for:

  • <30 weeks preterm[4]
  • Ill-appearing or abnormal vitals (including pulse ox)[5]
  • Bronchiolitis or pertussis with apnea
  • >1 event in past 24hr or multiple BRUE
  • Abnormalities in past medical history
  • Prolonged central apnea >20 seconds
  • Need for resuscitation
  • Family history of SIDS

Current Research

  • Neither of these decision rules have been validated

Mittal ALTE Decision Rule[6]

  • 300 Infants in a single center with 76% admission rate with 37 (12%) required significant intervention
Predictors for requiring intervention
  • Prematurity
  • Abnormal physical examination
  • Color change to cyanosis,
  • Absence of upper respiratory infection symptoms and the absence of choking
  • Negative predictive value: 96%
  • Specificity of 70.5%
  • 7 out of the 184 (3.8%) were incorrectly discharged

Kaji ALTE Decision Rule[7]

  • 832 patients from 4 different study sites, with a 79.2% admission rate
Predictors for requiring admission

See Also

External Links


  1. 1.0 1.1 1.2 1.3 1.4 Tieder et al. Brief Resolved Unexplained Events (Formerly Apparent Life-Threatening Events) and Evaluation of Lower-Risk Infants. Pediatrics. May 2016, Vol. 137(5)
  2. McGovern MC. et al. Smith MB. Causes of apparent life threatening events in children: a systemic review. Arch Dis Child. 2004;89(11):1043-1048
  3. Okada K et al. Discharge Diagnoses in infants with apparent life threatening event admissions and gastroesophageal reflux disease. Pediatric Emergency Care. 2012;28(1):17-21
  4. Claudius I, Keens T. Do all infants with apparent life-threatening events need to be admitted? Pediatrics. 2007;119(4):679–683pmid:17403838
  5. Hunt CE et al. Collaborative Home Infant Monitoring Evaluation (CHIME) Study Group. Longitudinal assessment of hemoglobin oxygen saturation in healthy infants during the first 6 months of age. J Pediatr. 1999;135(5):580–586pmid:10547246
  6. Mittal M. et al. A clinical decision rule to identify infants with apparent life-threatening events who can be safely discharged from the emergency department. Pediatric Emergency Care. 2012;28(7): 599-605
  7. Kaji A et al. Apparent life-threatening event: multicenter prospective cohort study to develop a clinical decision rule for admission to the hospital. Ann Emerg Med. 2013;61(4):379-387