Sa1454 Correlation of the Threshold Volume to Trigger Reflexive Pharyngeal Swallow With the Hypopharyngeal Safe Volume in Awake State Can Predict Aspiration During Sleep

Abstract

BACKGROUND: Cough and swallowing are important protective mechanisms that maintain the integrity of the aero-digestive tract across the age spectrum. Premature neonates commonly experience swallowing and breathing problems. Consequently, anterograde or retrograde aspiration is a frequent concern in neonates with chronic lung disease such as bronchopulmonary dysplasia (BPD). AIMS: Our aims were to define the cough-initiating and subsequent post-tussive mechanisms that restore aero-digestive normalcy (defined as return of respiratory rhythm to baseline along with esophageal quiescence) in human premature infants suffering from BPD. METHODS: Ten premature neonates (born at 25.5 ± 0.6 wks gestation, studied at 42.2 ± 1.2 wks post-menstrual age), diagnosed with BPD underwent concurrent pharyngo-esophageal manometry, respiratory inductance plethysmography (using Respitrace) and nasal air flow (using thermistor) methods to determine the relationships between esophageal motility and respiratory phases using a specially designed manometric catheter with upper and lower esophageal sphincter (UES and LES) sleeves and 5 recording pressure ports from pharynx, proximal-, middle-, and distalesophagus, and stomach. Cough was recognized as forceful exhalation preceded by deep inhalation on the respiratory waveforms along with audible cough marked during the study. The dynamic characteristics were analyzed preceding and following cough events defined by manometry and Respitrace. RESULTS: 1) Cough initiating mechanisms during 59 cough episodes are shown (Table). 2) Post-tussive mechanisms that restored aero-digestive normalcy were primary peristalsis in 81.4% (48/59), secondary peristalsis in 15.3 % (9/59), and not recognizable in 3.4 % (2/59). CONCLUSIONS: 1) In premature neonates with BPD, non-propagating swallows and UES contractile reflexes are the dominant reasons for the origin of the cough reflex, indicating the majority of cough events have upper aero-digestive origins. 2) Primary peristalsis is the most important clearance mechanism for post-tussive restoration of respiratory normalcy and pharyngo-esophageal quiescence. 3) These phenomena underscore the importance of postnatal development of esophagus-airway reciprocal communications mediated by Glossopharyngeal and Vagal nerves in human premature neonates with BPD. *Supported by PPG-PO1 DK 068051 Mechanisms triggering cough in neonates.