A Brief Resolved Unexplained Event (BRUE) is a medical term describing a sudden, brief episode in an infant younger than one year old that is frightening to an observer. It involves noticeable changes in the baby’s appearance or behavior but must be fully resolved by the time a medical professional evaluates the child. BRUE is a diagnosis of exclusion, applied only after a thorough examination fails to identify an underlying cause for the episode. This term replaced the older, more alarming phrase, Apparent Life-Threatening Event (ALTE), to better reflect the transient nature of the episode.
Understanding the Characteristics of a BRUE
For an event to be classified as a BRUE, it must be sudden, brief, resolved, and feature one or more of four core clinical characteristics. The first is a marked change in skin color, such as pallor or central cyanosis (bluish discoloration). The second involves a change in the infant’s breathing pattern, manifesting as a complete absence of breath, decreased respiration, or an irregular rhythm.
The third characteristic is a marked change in muscle tone, reported as either hypertonia (rigidity) or hypotonia (limpness). The final component is an altered level of responsiveness, where the infant appears less aware or conscious. The entire episode must be brief, typically lasting less than one minute, followed by a complete return to the infant’s baseline state. If the infant requires ongoing treatment or presents with symptoms like fever or persistent changes in vital signs, it is not considered a BRUE.
How Doctors Determine Risk Level
After determining an event meets the BRUE definition, clinicians perform risk stratification to guide management. Infants are categorized as Low-Risk BRUE or High-Risk BRUE based on established criteria. Low-Risk BRUE is assigned only if the infant meets all five specific criteria, indicating a lower likelihood of a serious underlying condition or recurrent event.
The criteria for Low-Risk status are:
- Being older than 60 days of age.
- Being born at or after 32 weeks gestation.
- Having a corrected gestational age of at least 45 weeks.
- The event must be the infant’s first episode.
- The event lasted less than one minute and did not require cardiopulmonary resuscitation (CPR) by a trained medical professional.
If the infant fails to meet even one of these five criteria, they are automatically classified as High-Risk.
The classification process is important because the “U” in BRUE stands for unexplained, meaning a serious underlying cause must be ruled out. A thorough diagnostic workup is performed to exclude conditions that can mimic a BRUE, such as seizures, cardiac arrhythmias, infections, or gastroesophageal reflux. High-Risk infants typically undergo a more comprehensive evaluation, which may include blood tests, an electrocardiogram (ECG) to check heart rhythm, and imaging studies, depending on the event’s features.
Post-Diagnosis Monitoring and Follow-Up
The management plan for a BRUE diagnosis depends entirely on the risk stratification. For infants categorized as Low-Risk BRUE, intervention is often limited to observation in the emergency department for one to four hours, with continuous monitoring of oxygen levels and heart rate. Routine laboratory testing or imaging is generally not required for these infants.
A primary element of the low-risk management plan is extensive parent education, including guidance on safe sleep practices and advocacy for cardiopulmonary resuscitation (CPR) training. Parents are discharged with instructions to follow up with their primary medical provider within 24 to 48 hours.
In contrast, infants with a High-Risk BRUE are typically admitted to the hospital for closer observation and more extensive investigations. Hospital admission allows for prolonged cardiorespiratory monitoring, often for 24 hours, and a tailored diagnostic workup to identify the underlying cause. Parents of any infant diagnosed with a BRUE should seek immediate medical attention if the child experiences a repeat event, develops a fever, or shows signs of respiratory distress or other new symptoms.