Faculty Bibliography

Introduction: The assessment of dysphagia in preterm infants has been limited to clinical bedside evaluation followed by videofluoroscopic swallow study (VFSS) in selected patients. Recently, fiberoptic endoscopic evaluation of swallowing (FEES) is being described more in literature for preterm infants. However, it is unclear if one test has a better diagnostic utility than the other in this population. Furthermore, it is also unclear if performing FEES and VFSS simultaneously will increase the sensitivity and specificity of detecting dysphagia compared to either test performed independently. Objectives: The primary objective of this study is to evaluate the feasibility of performing VFSS and FEES simultaneously in preterm infants. Our secondary objective is to determine whether simultaneously performed VFSS-FEES improves the diagnostic ability in detecting dysphagia in preterm infants compared to either test done separately. Methods: In this pilot study, we describe the process involved in performing simultaneous VFSS-FEES in five preterm infants (postmenstrual age ≥36 weeks) with dysphagia. A total of 26 linked VFSS-FEES swallows were analyzed, where the same bolus during the same swallow was compared using simultaneous fluoroscopy and endoscopy. The sensitivity and specificity of detecting penetration and aspiration were evaluated in simultaneous VFSS-FEES compared with each test done independently. Results: Our results demonstrated that performing simultaneous VFSS-FEES is feasible in preterm infants with dysphagia. All patients tolerated the procedures well without any complications. Our pilot study in these five symptomatic preterm infants demonstrated a low incidence of aspiration but a high incidence of penetration. Simultaneous VFSS-FEES (26 linked swallows) improved the ability to detect penetration compared to each test done separately. Conclusion: To our knowledge, this study is the first to demonstrate the feasibility of performing VFSS and FEES simultaneously in symptomatic preterm infants with dysphagia resulting in potentially higher diagnostic yield than either procedure done separately.

Gestational age-dependent immune intolerance at the maternal-fetal interface might be a contributing factor to placental pathology and adverse pregnancy outcomes. Although the intrauterine setting is highly choreographed and considered to be a protective environment for the fetus, unscheduled inflammation might overwhelm the intrauterine milieu to cause a cascade of events leading to adverse pregnancy outcomes. The old paradigm of a sterile intrauterine microenvironment has been challenged, and altered microflora has been detected in gestational tissues and amniotic fluid in the absence of induction of significant inflammation. Is there a role for endotoxin tolerance at the maternal-fetal interface? Endotoxin tolerance is a phenomenon in which tissues or cells exposed to the bacterial product, particularly lipopolysaccharide, become less responsive to subsequent exposures accompanied by decreased expression of pro-inflammatory mediators. This could also be related to trained or experienced immunity that leads to the successful outcome of subsequent pregnancies. Adaptation to endotoxin tolerance or trained immunity might be critical in preventing rejection of the fetus by the maternal immune system and protecting the fetus from excessive maternal inflammatory responses to infectious agents; however, to date, the exact mechanisms contributing to the establishment and maintenance of tolerance at the maternal-fetal interface remain incompletely understood. There is now extensive evidence suggesting that microRNAs (miRNAs) play important roles in the maintenance of a healthy pregnancy. miRNAs not only circulate freely in extracellular fluids but are also packaged within extracellular vesicles (EVs) produced by various cells and tissues. The placenta is a known, abundant, and transient source of EVs; therefore, our proposed model suggests that repeated exposure to infectious agents induces a tolerant phenotype at the maternal-fetal interface mediated by specific miRNAs mostly contained within placental EVs. We hypothesize that impaired endotoxin tolerance or failed trained immunity at the maternal-fetal interface will result in a pathological inflammatory response contributing to early or late pregnancy maladies.

Cold stimulation reduces airway compromise in adults with dysphagia. However, there is no sufficient evidence to support its use in the pediatric population. The primary goal of this pilot study is to assess the effect of cold liquid on the pharyngeal swallow mechanism in preterm infants with dysphagia. We hypothesized that thermal stimulation from cold liquid will decrease the risk of airway compromise in dysphagic preterm infants. Nine preterm infants with clinical symptoms of dysphagia were included. Video fluoroscopic swallow studies were used to assess the swallowing mechanism of each participant. The occurrence of swallow dysfunctions under room temperature liquid swallows (RTS) vs. short period cold liquid swallows (CS) was compared. Paired t test was used to test significance. The occurrence of deep penetration (p = 0.007) and aspiration (p = 0.002) decreased significantly in the CS condition compared with the RTS condition. There was a trend of less nasopharyngeal reflux with CS but did not reach statistical significance (p = 0.084). No differences were noted for mild penetration (p = 0.824). CS reduced airway compromise in dysphagic preterm infants compared to RTS. These data provide important information regarding the immediate effects of CS on pharyngeal swallowing in preterm infants with dysphagia. However, further investigation regarding its sustained effects is required before introducing to clinical practice.