BRUE - Brief Resolved Unexplained Events

Formerly (ALTE) Apparent Life-Threatening Events.


The term BRUE is an event occurring in an infant (<1 year) when the observer reports a sudden, brief and now resolved episode of ≥1 of:

  • cyanosis or pallor
  • absent, decreased, or irregular breathing
  • marked change in tone (hyper- or hypotonia)
  • altered level of responsiveness

A BRUE is diagnosed only when there is no explanation for a qualifying event after conducting an appropriate history and physical examination.

Using the above definition, and after history and examination you should categorise the patient into A) High risk - need further investigations or B) Low risk - no further intervention at this time.

BRUE definition
Includes Excudes
Brief Duration <1 min Duration ≥1 min
Resolved Back to baseline health
Normal vitals
Normal appearance
Recent fever
↑ or ↓ resp rate
↑ or ↓ HR or BP
Somnolence/Δ mentation
ANY sign injury
Abnormal Wt, growth, head circumference
Noisy breathing
Recurrent events
Unexplained Event consistent with GOR, swallow dysfunction, nasal congestion etc
ANY concern child abuse
Cyanosis/pallor Central colour changes Acrocyanosis or perioral cyanosis
Absent, ↓ or irreg. breathing Central apnoea
Obstructive apnoea
Periodic breathing of newborn
Breath-holding spell
Marked Δ tone Hypertonia
Hypertonia assoc. with crying, choking, gagging or problems
Δ tone assoc. with breath-holding
Tonic eye deviation or nystagmus
Tonic-clonic activity
Infantile spasms
Δ responsiveness LOC
Mental status Δ
Post ictal phase
LOC assoc. with breath-holding spell


A careful history and physical examination are necessary to characterise the event, assess the risk of recurrence, and determine the presence of an underlying disorder.


Consider NAI:

  • Inconsistent Hx
  • Hx inconsistent with developmental stage
  • Unexplained bruising
  • Unexplained attitude to child

History of the event:

  • Who reported the event?
  • Witness of the event?
  • State immediately before the event
  • Location of event
  • Awake or asleep?
  • Position: supine, prone, upright, sitting, moving?
  • Feeding?
  • Possibility FB ingestion/inhalation

State during the event:

  • Choking or gagging noise?
  • Active/moving or flaccid?
  • Conscious? Able to see you or respond to voice?
  • Muscle tone increased or decreased?
  • Repetitive movements?
  • Appeared distressed or alarmed?
  • Breathing: yes/no, struggling to breathe?
  • Skin color: normal, pale, red, or blue?
  • Bleeding from nose or mouth?
  • Color of lips: normal, pale, or blue?

End of event:

  • Approximate duration of the event?
  • How did it stop: with no intervention, picking up, positioning, rubbing or clapping back, mouth-tomouth, chest compressions, etc?
  • End abruptly or gradually?
  • Treatment provided by parent/caregiver (eg, glucose-containing drink, call 112/999)?

State after event:

  • Back to normal immediately/gradually/still not there?
  • Before back to normal, was quiet, dazed, fussy, irritable, crying?

Recent history

  • Illness in preceding days?
  • If yes, detail signs/symptoms (fussiness, decreased activity, fever, congestion, rhinorrhea, cough, vomiting, diarrhea, decreased intake, poor sleep)
  • Injuries, falls, previous unexplained bruising?

Past medical history

  • Pre-/perinatal history
  • Gestational age
  • Newborn screen normal (for inborn errors of metabolism, congenital heart disease)?
  • Previous episodes/BRUE?
  • Reflux? If yes, obtain details, including Mx
  • Breathing problems? Noisy ever? Snoring?
  • Growth patterns normal?
  • Development normal? Assess a few major milestones across categories, any concerns about development or behavior?
  • Illnesses, injuries, emergencies?
  • Previous hospitalization, surgery?
  • Recent immunization?
  • Use of over-the-counter medications?

Family history

  • Sudden unexplained death (including unexplained car accident or drowning) in first- or second degree family members before age 35, and particularly as an infant?
  • Apparent life-threatening event in sibling?
  • Long QT syndrome?
  • Inborn error of metabolism or genetic disease?
  • Developmental delay?

Environmental history

  • Housing: general, water damage, or mold problems?
  • Exposure to tobacco smoke, toxic substances, drugs?

Social history

  • Family structure, individuals living in home?
  • Housing: general, mold?
  • Recent changes, stressors, or strife?
  • Exposure to smoke, toxic substances, drugs?
  • Recent exposure to infectious illness, particularly upper respiratory illness, paroxysmal cough, pertussis?
  • Support system(s)/access to needed resources?
  • Current level of concern/anxiety; how family manages adverse situations?
  • Potential impact of event/admission on work/family?
  • Previous child protective services or law enforcement involvement (eg, domestic violence, animal abuse), alerts/reports for this child or others in the family (when available)?
  • Exposure of child to adults with history of mental illness or substance abuse?


Appearance Craniofacial abnormalities
Age appropriate response to environment
Growth variables Length, weight
occipitofrontal circumference
Vitals Temp, pulse, RR, BP, O2 sats
Skin Colour, perfusion
evidence of injury
Head Shape, fontanelles
bruising or injury
Eyes General, movements
pupillary responses
Conj. haemorrhage
Retinal exam
Ears TMs
Nose & mouth Congestion/coryza
Blood in nares/oropharynx
Trauma or obstruction
Torn frenulum
Neck Mobility
Chest Auscultation
rib tenderness
crepitus, irregularity
Heart Rhythm, rate, auscultation
Abdomen Organomegaly, masses
Genitalia Any abnormality
Extremities Muscle one, injuries
Deformity (?#)
Neurological Alertness, responsiveness
Response to sound/visual stimuli
General tone
Pupilary response
Symmetrycal reflexes
Symmetrical move/tone/power


Risk assessment

High risk

  • infants <2 months of age
  • Hx of prematurity
  • More than 1 event
  • CPR instigated by trained person

Lower risk

  • Age >60 days (congenital or infection less likely)
  • Prematurity: gestational age ≥32 weeks and postconceptional age >45 weeks
  • First BRUE (no previous BRUE ever and not occurring in clusters)
  • Duration of event <1 minute
  • No CPR required by trained medical provider
  • No concerning historical features (see table above)
  • No concerning physical examination findings (see table above)

Content by Prof Ronan O' Sullivan, Dr Íomhar O' Sullivan 20171002. Last review Dr ÍOS 31/08/22.