Patterned auditory stimulation and suck dynamics in full-term infants

Abstract

Aim: To determine whether patterned auditory stimuli, designed to mimic the natural burst-pause pattern evident in non-nutritive suck (NNS) with variations to the intraburst frequency, alter infants' NNS and cardiorespiratory patterning.

Methods: Sixteen healthy full-term infants participated in this study. Infants were fitted with electrocardiogram electrodes and a respiratory belt to measure cardiorespiratory patterning. Infants were offered a custom pacifier attached to a pressure transducer to measure NNS. Prior to the start of the study, a two-minute NNS and cardiorespiratory baseline was attained. Next, three auditory stimulation conditions were presented in the form of sucking clicks at interburst frequencies of 1, 2 and 4 Hz. Each of the three frequencies was played for two minutes.

Results: Separate repeated-measures ANOVAs revealed significant differences in NNS burst duration (p = 0.013), NNS cycles/burst (p = 0.010) and NNS bursts/minute (p = 0.005) across auditory stimulation conditions. No significant differences were evident in the cardiorespiratory outcomes.

Conclusion: We found that patterned auditory stimulation significantly reduced NNS dynamics and had no effect on cardiorespiratory patterning. The findings further suggest that infants attempted to modulate their suck pattern to the patterned acoustic stimuli by shortening their burst durations with fewer cycles per burst.

Keywords: Acoustic stimulation; Feeding; Infants; Non-nutritive suck.

Figure 1

An example of the patterned auditory stimuli. These sounds were essentially suck sound clicks that were presented to the infant. The patterned stimuli mimicked the burst/pause pattern that is characteristic of NNS and all stimuli were 7 cycles/burst with a 6.5 second inter-burst pause period. The stimuli conditions differed in their intra-burst frequency and burst duration.

Figure 2

NNS is organized in bursts (black brackets) of sucking and pause periods for breathing. Each burst contains approximately 6–12 cycles (black circles). The suck pressure amplitude is measured in cmH₂O. The suck dynamics included in our study included the following: NNS burst duration, NNS cycles per burst, NNS cycles per minute, NNS bursts per minute, NNS intra-burst frequency (Hz), and NNS amplitude (cmH₂O).