A Brief Resolved Unexplained Event (BRUE) is a clinical diagnosis used in pediatric medicine to describe a specific type of episode that occurs in infants. The term applies to a sudden, short-lived event in a baby less than one year old where the cause of the episode is not immediately apparent after an initial evaluation. The American Academy of Pediatrics introduced this definition to standardize the approach to these occurrences. While the event can be alarming for parents and caregivers, the BRUE designation focuses on the fact that the episode has fully concluded and the infant has returned to their normal state of health.
Defining the Brief Resolved Unexplained Event
The formal definition of a BRUE requires the infant to be under one year of age. An observer must report a sudden, brief, and resolved episode that involves at least one of four specific signs:
- A notable change in the infant’s color, such as turning cyanotic (blue) or pallid (pale).
- A disturbance in breathing, specifically absent, decreased, or irregular respiratory patterns.
- A marked change in muscle tone, presenting as either excessive stiffness (hypertonia) or marked limpness (hypotonia).
- An altered level of responsiveness, indicating the baby was not reacting normally to their surroundings.
The event is categorized as “brief” because it typically lasts for less than one minute, often only 20 to 30 seconds. Crucially, the episode must be “resolved,” meaning the infant is back to their baseline health status and appears well at the time a medical professional examines them. The diagnosis is one of exclusion, meaning the event is only deemed “unexplained” if a thorough history and physical examination fail to identify a clear medical cause for the episode. If a plausible explanation is found, such as choking on an object or a seizure, the event is no longer classified as a BRUE.
The Clinical Shift from ALTE to BRUE
The introduction of BRUE in 2016 by the American Academy of Pediatrics represented a significant departure from the previous terminology, Apparent Life-Threatening Event (ALTE). ALTE was a more subjective diagnosis, defined as an event that was frightening to the observer and involved a combination of color change, breathing abnormalities, or changes in tone. The phrase “life-threatening” in the older term often caused substantial anxiety for parents and led to overly aggressive medical workups.
The shift to BRUE was a deliberate effort to use more precise, objective, and less emotionally charged language. By emphasizing that the event is brief and resolved, the new term aims to mitigate parental fear and reduce the number of unnecessary hospital admissions and invasive diagnostic tests. This change in terminology has resulted in a more measured, risk-based approach to managing infants who experience these episodes.
Evaluation and Risk Stratification
The initial evaluation after a suspected BRUE begins with a comprehensive history and physical examination to confirm the event meets all BRUE criteria and to exclude any immediate, identifiable causes. Once the diagnosis of BRUE is established, the infant is immediately categorized into one of two groups: low-risk or high-risk, a process called risk stratification. This distinction guides the remainder of the medical investigation and management.
An infant is classified as low-risk if they meet a specific set of criteria that indicate a very low chance of a serious underlying condition or a recurrent event. These criteria include:
- Being over 60 days of age.
- Born at 32 weeks gestation or later, with a post-conceptional age of at least 45 weeks.
- The event must be the infant’s first.
- The event lasted for less than one minute.
- The event did not require cardiopulmonary resuscitation (CPR) by a trained professional.
For infants meeting all low-risk criteria, the evaluation is minimal and focused, often involving a short period of observation in the emergency department, typically one to four hours. Routine diagnostic testing, such as extensive blood work, imaging, or hospitalization solely for cardiorespiratory monitoring, is generally not recommended because it rarely yields an explanation. Infants who do not meet every single low-risk criterion are automatically classified as high-risk.
High-risk infants require a more comprehensive and targeted evaluation to determine the event’s cause, which often necessitates admission to the hospital for observation and monitoring. This extensive workup may include an electrocardiogram (ECG) to check the heart’s electrical activity or blood tests to look for infection or metabolic issues. The decision for specific testing is driven by the clinical concerns raised during the history and physical examination, rather than a broad, standardized panel of tests.
Management and Follow-Up Care
Management for infants diagnosed with a low-risk BRUE centers on caregiver education and a safe discharge plan. Clinicians emphasize shared decision-making with the parents to ensure they are comfortable with the plan and understand the benign nature of the event. A significant component of this education is advocating for caregivers to receive CPR training, which empowers them to respond effectively should a future event occur.
Infants with low-risk BRUE are typically discharged home after the brief observation period, with instructions for prompt follow-up with their primary care provider within 24 to 72 hours. Hospitalization is discouraged unless the clinician or family has unresolved concerns. For high-risk infants who are admitted, the management involves continuous monitoring and targeted testing, with discharge occurring once any potential underlying issues have been investigated or ruled out.
Home cardiorespiratory monitoring is generally not recommended for either risk group unless specific medical conditions are identified that warrant it. The long-term management focuses on reassurance and ongoing support for the family, as the prognosis for low-risk infants is excellent, with a very low likelihood of recurrence or serious outcome. Close communication between the hospital team and the infant’s pediatrician ensures a smooth transition to ongoing outpatient care.