The Effects of Vestibular Stimulation Rate and Magnitude of Acceleration on Central Pattern Generation for Chest-Wall Kinematics in Preterm Infants. by
چکیده
Date Approved: __________ iii ABSTRACT The vestibular system of the fetus is responsive to accelerations in utero by 25 weeks gestational age (Hooker, 1969). However, the restrictive environment of the crib/isolette in the neonatal intensive care unit (NICU) and decreased positional changes limits vestibular experience and associated neural activity among preterm infants. This project was developed to test a set of hypotheses concerning the role of vestibular inputs on respiratory and oromotor systems during suck and early feeding development in preterm infants. Linear acceleration of the vestibular otoliths was achieved using a customized glider chair, the VestibuGlide System, developed in the Communication Neuroscience Laboratories at the University of Kansas. The VestibuGlide system features an integrated position-servo motor and a digital controller to generate physiologically appropriate sinusoidal displacements of the glider chair in the horizontal plane at specified rates and accelerations (.21, .36, and .51 m/s 2). It was hypothesized that providing this type of input to the vestibular apparatus will modify the central patterning of chest wall motion, and secondarily may alter suck and feed development during a critical period of brain development. Twelve preterm infants (7F/5M, birth GA 32; 6, BW 1927g) were recruited from the NICU at Stormont-Vail Regional Hospital in Topeka. Each infant received the 15 minute gliding protocol starting at 32 wks PMA, 3x/day before a scheduled feed for 10 days. Infants were fitted with two soft cloth Respitrace™ inductance bands around the rib cage and abdomen to measure respiratory rate. The gliding protocol alternates between baseline and stimulus conditions every minute. During baseline conditions, the glider chair was stationary. Respiration, suck dynamics, and pulse-oximetry were recorded and monitored throughout the study. iv On average, infants received 24 VestibuGlide sessions. Stimulus condition had a significant effect for the in rib cage [F (7, 77) = 25.53, p < 0.01] and abdominal [F (7, 77) = 23.60, p < 0.01] breaths per minute (BPM). In general, infants increased their respiratory rate in response to the VestibuGlide stimulus. Stimulus number 7 provided the highest acceleration to the infant and induced significantly higher BPM than stimuli 1, 4, and 5 for the rib cage and stimuli 1 and 4 for the abdomen. It is clear that acceleration has the largest influence over the respiratory central pattern generator (rCPG) and is capable of inducing significant changes in chest wall kinematics. In spite of the increases in BPM during vestibular stimulation, …