As educators, we love—and are always humbled by—those moments when we get to say, “I don’t know.” For some of these questions, you may already know the answers. For others, you may never have thought to ask the question. For all, questions, comments, concerns, and critiques are encouraged. Welcome to the Kids Korner.

While it may have been warm outside a few weeks ago, the cold days to have returned, which means the bronchiolitics and croupers are on their way, too.

Question: Under what age (in months) is there a significant association with central apnea in respiratory syncytial virus (RSV)-positive bronchiolitis?

The association between RSV-positive bronchiolitis and central apnea was recognized as early as the late 1960s.^1,2 In an early multicenter retrospective study of 274 infants younger than 6 months with RSV-positive bronchiolitis, the overall incidence of apnea was found to be 20.4 percent (95% CI, 16.1–25.6%).¹ While this study provided no p-values, the data suggested that the highest-risk group for apnea was infants under three months of age. Additionally, the authors recognized that premature infants were more likely to develop apnea. Since then, there have been other studies that have found similar results, with an association between RSV-positive bronchiolitis and central apnea, but the overall incidence varies widely. The incidence ranges from ^1.2 percent to 23.8 percent, with more recent studies in the 5 percent to 10 percent range.^3,4 So why do we care? Ultimately, the reason we care about this topic is because studies recurrently recognize that apnea can be the first sign of RSV-positive bronchiolitis.

A retrospective study by Kneyber et al looked at 185 infants under 12 months of age who were admitted with RSV-positive bronchiolitis over a four-year period.⁵ They found that age was a statistically significant independent risk factor for RSV-associated apnea and that infants younger than 2 months were the highest-risk group.⁵ Along with age, a number of studies have identified prematurity (commonly defined as <37 weeks gestation) as a significant risk factor as well.^2,3

A retrospective study by Kneyber et al looked at 185 infants under 12 months of age who were admitted with RSV-positive bronchiolitis over a four-year period.5 They found that age was a statistically significant independent risk factor for RSV-associated apnea and that infants younger than 2 months were the highest-risk group.⁵

Recent studies continue to demonstrate an association between bronchiolitis and central apnea or need for a significant medical intervention in children younger than 2 months of age. A 2014 study by Pruikkonen et al retrospectively reviewed the cases of 353 children younger than 6 months of age with bronchiolitis and found that 19 percent of hospitalized infants with bronchiolitis required a major medical intervention—defined as supplemental oxygen, intravenous fluids or antibiotics, or admission to the ICU.⁴ While not all of these interventions were secondary to apnea, all apneic events occurred in children younger than 2 months. Ninety-two percent of patients requiring medical interventions were RSV-positive, and the largest majority of these interventions were necessary within the first five days of symptom onset.