Brief Resolved Unexplained Event (BRUE)

A four-month-old male arrives to the emergency department (ED) via EMS for an episode of possible cyanosis. Per the patient’s mother, the baby was sleeping and was noted to have an abnormal breathing pattern, described as intermittent “slow breaths” and “pauses.” He appeared to become pale and blue. He was promptly stimulated by his mother and reportedly returned to baseline in “a few seconds.”

The birth history reveals that he was born at 38.5 weeks’ gestation by spontaneous vaginal delivery without complications. He is gaining weight appropriately and there are no concerns from the pediatrician per maternal report. No fever, cough, or congestion is reported. He has had no sick contacts and continues to have normal oral intake with no change in urination or stooling. He is up-to-date with his vaccinations. The baby’s vital signs are within normal limits. He is alert, moving all extremities, and tracking well on your exam. The mother states that he has returned to baseline.

Initial Impression

The emergency assessment of any potentially ill infant, including those with a possible BRUE, starts with the initial impression. The initial impression is an observational assessment based on the first encountered visual and auditory presentation. It precedes the ABCDEs of the primary assessment. The Pediatric Assessment Triangle (PAT) is a tool designed to provide health care professionals a standardized means to generate an initial impression. It is composed of three components: work of breathing, circulation to the skin, and appearance. Characteristics of each component allow health care professionals to quickly assess if the component is normal or abnormal.

• Appearance: Tone, interactiveness, gaze, cry, consolability (e.g. lack of spontaneous movement, does not interact, won't stop crying with comforting, does not track or make eye contact, weak cry).
• Work of Breathing: Breath sounds, positioning, retractions, nasal flaring (e.g. stridor/grunting, sniffing position, supraclavicular or substernal retractions).
• Circulation: Pallor, mottling, cyanosis (e.g. pale skin, irregular/patchy skin appearance, blue appearance of skin and/or mucous membranes).

Once each component is assessed, combining the components provides an initial impression of the patient’s cardiovascular, pulmonary, and central nervous system status. The initial impression is not designed to provide a diagnosis, rather it identifies the general category of physiologic derangement, severity, and provides a point from which to initiate critical interventions.

Primary Assessment

The primary assessment is a structured physical assessment conducted by the healthcare team that proceeds in a specific order. As significant pathologies can often present with features of a BRUE, it is important to perform a primary survey and promptly address any concerning findings.

• Airway: Assess patency - evaluate for obstruction, partial obstruction, pooling of secretions or blood.
• Breathing: Assess respiratory rate, breath sounds with auscultation, oxygen saturation.
• Circulation: Assess heart rate, pulse quality (distal and proximal), capillary refill time, blood pressure.
• Disability: Assess level of consciousness, motor activity, pupillary response.
• Exposure: Appropriate exposure of patient is necessary for complete assessment.

A BRUE is a brief event consisting of at least one of the following features: apnea, color change, change in muscle tone, and/or altered responsiveness. The episode is typically frightening to the observer and may prompt observer attempts to resuscitate the infant. By definition, the event is limited in duration and the infant is asymptomatic at emergency department (ED) arrival. Once identified, a BRUE can be divided into low- and high-risk, which stratifies for potential recurrent events or undiagnosed serious underlying causes. To be considered low-risk, ALL of the following criteria must be met:

• Over 60 days old.
• If premature, gestational age was > 32 weeks and the post-conceptual age at time of the event is > 45 weeks.
• First BRUE (no previous and did not occur in clusters).
• Event duration less than one minute.
• No CPR required by a trained medical provider.
• No concerning historical features (see below).
• No concerning findings on physical examination (see below).

Patients that do not have any high-risk criteria are unlikely to have a serious underlying cause. Those that are high-risk have an increased risk for recurrent BRUEs and underlying pathology. It is important to note that, despite risk stratification, the term BRUE should only be used for a patient that meets all defining features and is asymptomatic with a normal physical examination at presentation. If the history and physical examination indicate a diagnosis or explanation for the event (e.g. a seizure), the term BRUE should not be applied.

When evaluating a patient with potential BRUE, many questions can be helpful in identifying an alternative diagnosis.

• When did the episode occur?
• Who witnessed the episode?
• What were the events immediately preceding the episode?
• When was the last feeding?
• Did the infant have any symptoms prior to the episode?
• Was the infant at his/her baseline state of health prior to the episode?
• What did the episode look like?
• Were there any color changes? Where?
• How long was the episode?
• What (if any) interventions did the observer perform?
• What happened, or how did the infant appear, immediately after the episode?

The majority of patients presenting with a BRUE do not meet low-risk criteria. High-risk BRUE patients are considered to be at greater risk to have a serious underlying disorder, subsequent event, or adverse outcome.

Concerning Historical Features in a Patient Presenting with a BRUE

• Social/Environmental: Social or historical risk factors for abuse or neglect, exposure to smoke or toxic substances, previous child protective services or law enforcement involvement.
• Past Medical History: Abnormalities on newborn screen, previous episodes, developmental delay, congenital anomalies.
• Recent Illness: Respiratory illness or exposure, fevers, vomiting, diarrhea.
• Family History: Sudden unexplained death in young first-degree relative, history of Long-QT syndrome, history of arrhythmias, history of genetic condition.
• Other: Medication access (accidental ingestion) or recent use.

Concerning Physical Examination Findings in a Patient Presenting with a BRUE

• General: Fever, toxic appearance.
• HEENT: Evidence of trauma (bleeding or bruising, hemotympanum, bulging fontanelle, frenulum injury, conjunctival hemorrhage), nasal congestion, rhinorrhea.
• Respiratory: Tachypnea, hypoxia, abnormalities on auscultation.
• Cardiovascular: Murmur, abnormal rhythm or rate, weak pulses, poor capillary refill.
• Gastrointestinal: Abdominal distension, abdominal tenderness, hepatomegaly, splenomegaly.
• Neurologic: Altered mental status, abnormal tone, asymmetric movement/strength.
• Musculoskeletal: Bruising, findings suggesting fracture.

A thorough physical examination with particular attention to the cardiovascular, respiratory, and neurological systems, and signs suggestive of non-accidental trauma, should follow the history. Vital signs (including oxygen saturation) should be carefully reviewed for abnormalities. Signs suggesting an alternative diagnosis must be noted and evaluated. Height, weight, and head circumference measurements should be plotted on appropriate growth charts. The developmental stage should be assessed.

• Gastrointestinal: GERD, volvulus, intussusception, swallowing abnormalities.
• Neurologic: Afebrile/febrile seizures, intracranial bleed, CNS infection, vasovagal reflexes, hydrocephalus, Budd-Chiari malformation, hindbrain malformation, brainstem malformation, CNS malignancy, ventriculoperitoneal shunt malfunction.
• Respiratory: Breath-holding spells, laryngotracheomalacia, prematurity, central hypoventilation, vocal cord abnormalities, respiratory syncytial virus/bronchiolitis, pertussis, pneumonia, foreign body aspiration, croup.
• Cardiovascular: Dysrhythmias, congenital heart disease, cardiomyopathy, myocarditis.
• Metabolic: Inborn errors of metabolism, thyroid disorders, hypoglycemia.
• Renal: Electrolyte abnormalities (hypocalcemia, hypomagnesemia, hyponatremia), urinary tract infections.
• Hematologic: Anemia.
• Infectious: Sepsis, CNS infections (meningitis, encephalitis), respiratory infections (bronchiolitis, croup, pertussis, pneumonia), UTI.
• Non-accidental trauma: Munchausen syndrome by proxy, suffocation, abusive head trauma, shaken baby syndrome.
• Toxicological: Accidental drug ingestions, carbon monoxide, other toxic ingestions/exposures.

Treatment starts with addressing any emergent issues identified. Patients with cardiopulmonary instability or other significant acute physiologic abnormalities should be immediately resuscitated and stabilized. Patients with an acute event for which there is an identifiable cause should be treated accordingly. Patients meeting criteria for a BRUE should be treated based on risk stratification. Additionally, underlying disorders identified by diagnostic testing should be addressed in a timely and appropriate manner.

Recommendations for the management of low-risk BRUE patients include:

• Admission is no longer recommended for cardiopulmonary monitoring in low-risk infants.
• Guidelines suggest observation for one-four hours with continuous pulse oximetry as an option.
• Consider observing post-feeding for recurrence of the event.
• All children with BRUE should have a social risk assessment.
• Provide parents with education on BRUEs and offer CPR training resources.
• Ensure close follow-up with the patient's primary physician.

Infants that do not meet low-risk criteria are typically admitted to the hospital for observation and diagnostic testing, and potential sub-specialist evaluation. Serious underlying disorders identified during the diagnostic evaluation should be treated appropriately. One study found that 4% of BRUE patients had a serious underlying disorder, with the most common diagnoses being seizures, airway abnormalities, and abusive head trauma.

• Recognize that a BRUE is comprised of one ore more features that must include respiratory changes (apnea or decreased breathing), cyanosis or pallor, changes in tone, and a change in responsiveness.
• Understand that infants presenting to the ED following a BRUE will appear asymptomatic; this does not mean a significant event did not occur.
• All low-risk criteria must be met to designate an event as a low-risk BRUE.
• Patients that do not meet the low-risk criteria have a higher risk of subsequent events and serious underlying conditions.
• All patients that are stratified as a high-risk BRUE warrant further workup and likely admission to the hospital.

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3. Merritt JL II, Quinonez RA, et al. A Framework for Evaluation of the Higher-Risk Infant After a Brief Resolved Unexplained Event. Pediatrics. 2019 Aug.
4. National Institutes of Health Consensus Development Conference on Infantile Apnea and Home Monitoring. 1986 Sep 29-Oct 1. Pediatrics.
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