The term Apparent Life Threatening Event (ALTE) is one that is very familiar to those of us that have worked in paediatrics for any length of time. The term ALTE originated from a 1986 National Institutes of Health Consensus on Infantile Apnoea and was intended to replace the term “near miss sudden infant death syndrome”.

An ALTE was defined as: “an episode that is frightening to the observer and that is characterized by some combination of apnoea (central or occasionally obstructive), color change (usually cyanotic or pallid but occasionally erythematous or plethoric), marked change in muscle tone (usually marked limpness), choking, or gagging. In some cases, the observer fears that the infant has died.”


BRUE is the new ALTE

In 2016 a clinical practice guideline from the American Academy of Paediatrics (AAP) recommended the replacement of the term ALTE with a new term, Brief Resolved Unexplained Event (BRUE).

Whilst ALTE was a descriptive term, BRUE has stricter criteria and only applies to an episode that occurs in an infant that is less than 12-months-old, that is:

  • Brief (<1 minute, but typically 2-30 seconds)
  • Resolved (must have returned to baseline)
  • Not explained by an identifiable medical condition
  • Characterised by > 1 of the following:
    • Cyanosis or pallor
    • Absent, decreased, or irregular breathing
    • Marked change in tone (hyper- or hypotonia)
    • Altered level of responsiveness


A BRUE should only be diagnosed when there is no explanation for the event after a full history and physical examination of the infant has been undertaken.


Assessing the affected infant

A BRUE is usually a very frightening and distressing event for the caregiver that witnessed it. The history should ideally be taken from a person that directly observed the event, and should be taken as soon as possible after the event.

A clear description of the event should be elucidated, with careful attention paid to features such as the duration, the colour of the infant, whether any choking or gagging occurred, the tone of the infant during the episode, whether or not any abnormal or seizure-like movements occurred, and the conscious state of the infant during the event.

The circumstances leading up to the event are also of great importance and special attention should be paid to the position of the infant (e.g. prone or supine), preceding feeding difficulties or vomiting, preceding illness or fever, and proximity to objects that could be swallowed and cause choking. Other important history points include past medical history, birth history, immunization status (particularly pertussis), and family history of note (particularly a history of SIDS).

The following are considered to be risk factors for the development of a BRUE:

  • Prematurity
  • Age less than 10 weeks
  • Recent anaesthesia
  • Airway or maxillofacial abnormalities
  • History of gastro-oesophageal reflux disease
  • Previous history of apnoeic episode
  • Infection with RSV
  • History of feeding difficulties


A detailed and thorough clinical examination should be undertaken, with possible differential diagnoses borne in mind.


Risk stratification

If the infant has recovered fully, has a normal examination, and the event is deemed to have met the criteria for a BRUE, the event can then be risk stratified. This risk stratification can then be used to guide further management.

A BRUE is considered to be LOW risk if the infant has recovered fully, there are no concerning history or physical examination features, and the following criteria are met:

  • Age >60 days
  • Born >32 weeks gestation and corrected gestational age >45 weeks
  • No CPR was performed by a trained healthcare professional
  • This was a first event
  • The event lasted <1 minute


Low risk infants can be safely discharged with early outpatient follow-up (within 24 hours), however decision-making should be shared with the parents/caregivers. It can be explained to the parents that a low-risk BRUE is unlikely to represent a presentation of a severe underlying disorder and the event is unlikely to reoccur.

Consider performing an ECG, a brief period of monitored observation, and a pertussis swab before the infant is discharged. The family and caregivers should also be offered CPR training resources. No other investigations or treatments are required prior to discharge.


How to manage the non low-risk infant

The following investigations are recommended for infants that fail to meet the low-risk criteria:

  • Full blood count
  • Urea & electrolytes
  • Blood glucose
  • Nasopharyngeal sample for viruses and pertussis
  • ECG (measure QT interval)


Infants with a non low-risk BRUE may still have a benign cause for their symptoms, but should be referred for admission under the Paediatric team for observation and cardiorespiratory monitoring.


In summary

The term BRUE is, at present, mainly being used in the USA, and is still not widely used in the UK. Its use is becoming more commonplace however, and the low-risk criteria are being increasingly embraced by paediatricians and emergency physicians in the UK.

It is important to recognize that many infants with a low-risk BRUE will still be admitted because of parent/caregiver and/or physician anxiety, and that all infants that have presented following an apnoeic episode should be taken very seriously and have a very thorough history and physical examination performed. It is also worth noting that even for low-risk infants that are being discharged, follow-up by a paediatrician for a repeat history and examination is recommended within 24 hours.


Thank you to the joint editorial team of for this article.

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