Many infants have experienced an episode of apnea, defined as a pause in respiration of 20 seconds or more. Most episodes remain unexplained, and no underlying cause can be found. Historically, these were referred to as “near-miss SIDS,” episodes, but that label suggested that all of these events would have ended in death had someone not intervened. New descriptive terminology was needed.
In the mid-1980s, the term “apparent life-threatening event” (ALTE) was adopted. But that term, too, was an overstatement, because although scary for parents, these brief apnea episodes were not, in most cases, truly life-threatening.
In 2013, authors of a systematic review coined the term “brief resolved unexplained event” (BRUE). This review also addressed the history and physical exam features associated with risk for a subsequent episode. It was felt that hospitalization and testing might be warranted if certain infants could be identified as high risk for recurrence.
What Is Considered a BRUE?
In the current working definition of BRUE, the child must be < 1 year old. The episode must be a sudden, brief, and resolved, with one or more of these characteristics:
- Cyanosis or pallor (but not turning red)
- A change in breathing (absent, decreased, or irregular)
- A change in tone (hypertonia or hypotonia)
- A change in responsiveness.
Furthermore, to qualify as a BRUE, no explanation can be found for the event based on the history and physical examination but before any laboratory testing is done. The definition also excludes children with known potential explanatory diagnoses (such as gastroesophageal reflux or bronchiolitis) and those who are otherwise symptomatically ill at the time of the event.
Decision to Admit and Recurrence Risk
An apnea event in an otherwise healthy infant, regardless of what it’s called, puts providers and parents in a difficult position. Should the infant be hospitalized for further monitoring and potentially more invasive testing to determine the cause of the episode? And what are the chances that the episode will be repeated?
A clinical practice guideline (CPG) for BRUE, widely adopted in 2016, resulted in significant reductions in healthcare utilization. The CPG attempted to identify low-risk infants who could safely be discharged from the emergency department. Although the CPG improved outcomes, experts acknowledged that an underlying problem was not likely to be identified even among infants deemed high risk, and these infants would be hospitalized unnecessarily.
Available data were simply insufficient to support this decision. So, with the goal of identifying factors that could help predict recurrent BRUE risk, a 15-hospital collaborative study was undertaken, followed by the development and validation of a clinical decision rule for predicting the risk for a serious underlying diagnosis or event recurrence among infants presenting with BRUE.
Here’s what we learned from more than 3000 cases of BRUE.
First, it turns out that it’s not easy to determine whether an infant is at low or high risk for recurrence of BRUE. Initially, 91.5% of patients enrolled in the study would have been labeled high risk.
Furthermore, a BRUE recurred in 14.3% of the cohort, and 4.8% of high-risk infants were found to have a serious undiagnosed condition. Seizures, airway anomalies, and gastroesophageal reflux were the top three causes of BRUE, but the spectrum of underlying pathology was quite considerable.
The problem was that 4.6% of the entire cohort were found to have a serious underlying condition, nearly identical to the proportion of high-risk infants with these conditions. This prompted the question of whether simply labeling infants “high risk” was really appropriate any longer.