Consideration of Cough Reflex Development When Ordering Modified Barium Swallow Studies in Infants

Infants < 51 weeks post-menstrual age (< 51 PMA) are often referred for modified barium swallow (MBS) studies for suspected silent aspiration (SA) given a possible association between SA and aspiration pneumonia. Infants this young are unlikely to have developed a mature laryngeal cough reflex, most likely rendering SA an expected finding in those who aspirate. The aims of this retrospective review were to (1) determine if SA resolves in a significant proportion of infants around the expected emergence of the laryngeal cough reflex, (2) determine which factors or characteristics are associated with and without SA resolution in these infants, and (3) determine if SA, or any aspiration, is associated with increased rates of lower respiratory infection (including aspiration pneumonia) in these infants. Results from the chart review revealed that 79/148 (53.4%) infants had SA on MBS < 51 PMA. 16/48 (33.3%) infants assessed for SA by the time of the expected emergence of the cough reflex had resolution. SA resolution was less common in infants with obstructive sleep apnea (p = 0.037). A total of 50/70 (71.4%) infants with a follow-up MBS had eventual SA resolution. Aspiration was not significantly associated with LRI, including aspiration pneumonia. The results suggested that the laryngeal cough reflex might develop later than reported in the literature and there is no association between aspiration and LRI. These findings may indicate that age should be considered before ordering an MBS solely to assess for SA in this population. The study provides preliminary evidence for future prospective research regarding SA resolution.