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Brief resolved unexplained event

Last updated: November 25, 2025

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Summarytoggle arrow icon

Brief resolved unexplained events (BRUE) are sudden, brief, resolved events characterized by transient cyanosis, pallor, change in muscle tone, altered level of responsiveness, and/or absent, decreased, or irregular breathing in an infant less than 1 year of age. If the cause is identified, the event is no longer considered a BRUE. Management is based on risk category. Infants with low-risk BRUE criteria can often be managed as outpatients with minimal early testing. Management for infants with high-risk BRUE criteria includes admission, expert consultation, feeding evaluation, and laboratory studies. Most BRUE remain unexplained even after investigation.

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Definitionstoggle arrow icon

Brief resolved unexplained event (BRUE) [1]

  • A sudden, brief, and resolved event in a child < 1 year that includes ≥ 1 of the following features:
    • Cyanosis
    • Pallor
    • Absent, decreased, or irregular breathing
    • Change in muscle tone (i.e., hypertonia or hypotonia)
    • Altered level of responsiveness
  • No explanation for the event after history and physical examination

BRUE is a diagnosis of exclusion and is no longer applicable once the cause has been identified. [1]

Apparent life-threatening event (ALTE) [1][2]

  • An episode of apnea, color or muscle tone change, choking, and/or gagging that is frightening to the observer
  • A historical term that is no longer recommended by the American Academy of Pediatrics
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Epidemiologytoggle arrow icon

Epidemiological data refers to the US, unless otherwise specified.

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Classificationtoggle arrow icon

BRUE risk criteria accurately identify patients at low risk for serious underlying pathology, but even high-risk infants are unlikely to have a serious underlying pathology. [4]

Low-risk BRUE criteria [1]

A BRUE is classified as low-risk if it fulfills all of the following criteria:

High-risk BRUE criteria [5]

A BRUE is classified as high-risk if it fulfills any of the following criteria:

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Differential diagnosestoggle arrow icon

The following conditions may initially present as a BRUE:

The differential diagnoses listed here are not exhaustive.

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Approach [1][5][6]

Maintain a low threshold for admission and specialist consultation in infants with high-risk BRUE, as they have more adverse outcomes, more frequent recurrences, and a higher risk of a serious underlying condition than low-risk patients. [4]

Management of low-risk BRUE [1]

Use shared decision-making with parents and/or guardians when determining management.

Diagnosis

Disposition

Home cardio-respiratory monitoring is not recommended for low-risk BRUE. [1]

Management of high-risk BRUE [5]

All patients require further diagnostic testing and continuous pulse oximetry monitoring for ≥ 4 hours.

Diagnosis

Consultations and disposition

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Acute management checklisttoggle arrow icon

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