Focus & Scope

Swallow-Breath Interaction and Phase of Respiration with Swallow During Nonnutritive Suck in Term Infants and Preterm Infants Approaching Term Adjusted Age

Eric W. Reynolds¹*, Cynthia S. Bell², Debbie Grider³

¹University of Texas Health Science Center at Houston, McGovern Medical School, Department of Pediatrics, Division of Neonatology Houston, TX

²University of Texas Health Science Center at Houston, McGovern Medical School, Department of Pediatrics, Houston, TX

³University of Kentucky, Department of Pediatrics, Division of Neonatology, Lexington, KY

Introduction: During nonnutritive suck, infants must intermittently swallow. When a swallow occurs, it must interact with respiration in 2 main ways. We have previously labeled HOW the interaction occurs as “swallow-breath interaction” (SwBr), and WHERE in the respiratory cycle the swallow occurs as “phase of respiration incident to swallow” (POR). We have described SwBr and POR in preterm infants with and without bronchopulmonary dysplasia and term infants with neonatal abstinence syndrome.

Objective: The objective of this work is to describe SwBr and POR in term infants (TRM) and compare those findings to our previous study of low-risk preterm (LRP) infants.

Method: Suckle, swallow, nasal airflow and chest movement were recorded during nonnutritive suck in 12 TRM infants, collecting 94 swallows. SwBr and POR for each swallow were characterized by our previously described method. Generalized estimating equations were developed to relate the 3 types of SwBr and 5 types of POR to gender, birth weight, gestational age, postmenstrual age (PMA), and weeks post-first nipple feed. The percentages of SwBr and POR were compared to 16 LRP infants, with 176 swallows over 35 encounters.

Results: TRM infants had more swallows with attenuated respiration (AR) with advancing weeks post-first nipple feed and fewer swallows occurring with obstructive apnea (OA) in males and with increasing birth weight. More swallows occurred at mid-expiration (ME) with increasing gestational age, PMA, and male gender and at mid-inspiration (MI) with increasing weeks post-first nipple feed. Fewer swallows occurred at MI in males. Infants in the LRP group studied before 35 weeks PMA were different from TRM infants but become indistinguishable from TRM infants as PMA approached 40 weeks. SwBr and POR in LRP infants progress towards improved feeding efficiency and safety. These results are similar to studies of nutritive feeding.

Conclusion: SwBr and POR during nonnutritive suck in LRP infants become more like TRM infants with advancing PMA. Because the same brainstem centers are activated in both nutritive and nonnutritive suck, investigation of swallow during nonnutritive suck may provide similar information as nutritive feeding with easier analysis.