This study describes swallow-breath interaction and phase of respiration with swallow during nonnutritive suck (NNS) in low-risk preterm infants. Suckle and swallow, thoracic motion, and airflow were measured in 16 infants during NNS. Logistic regression models were used to describe swallow-breath interaction and phase of respiration with swallow. One hundred seventy-six swallows occurred in 35 NNS periods. Swallow-breath interaction occurred as: central apnea (CA), obstructive apnea (OA), or attenuated respiration (AR). AR was associated with increased weeks post-first nipple feeding. OA occurred less often in males and with increased weeks post-first nipple feeding. In looking at the phase of respiration, more swallows occurred at beginning expiration with increased gestational age, increased weeks post-first nipple feed, and increased weeks before first nipple feed. More swallows occurred at midexpiration with more swallows per study, increased birth weight (BWT), and weeks before first nipple feed. Fewer swallows occurred at end expiration with increased weeks before first nipple feed. Fewer swallows occurred at midinspiration with increased swallows per study. Fewer swallows occurred at apnea with increasing BWT, more occurred with increased swallows per study. In low-risk preterm infants, swallow-breath interaction progresses from CA and OA to AR. The phase of respiration with swallow shows a maturation progression.

BackgroundThe development of suck–swallow–breath rhythms during non-nutritive suck (NNS) may be an indicator of neurologic integrity. We have described swallow–breath (SwBr) interaction and phase of respiration (POR) with swallow during NNS in low-risk preterm (LRP) infants. NNS in infants with neonatal abstinence syndrome (NAS) has not been described with our method.MethodSuckle, swallow, thoracic motion, and nasal airflow were measured during NNS in 10 infants with NAS and 12 unaffected infants (control). Logistic regression models were fit to describe the three types of SwBr and five types of POR in terms of the independent variables (gender, gestational age, birth weight, postmenstrual age, weeks postfirst nipple feed and swallows per study). We also compared the NAS group to 16 LRP infants.ResultsIn the NAS group, there were 94 swallows in 18 studies. In the control group, there were 94 swallows in 12 studies. There were statistical differences between groups for all three types of SwBr. The distribution of SwBr in NAS was similar to LRP infants with NAS having fewer swallows with attenuated respiration and more with central apnea. For POR, there were few differences. Over time, the distribution of SwBr in NAS infants approaches that of control infants.DiscussionVariability in SwBr and POR during NNS may represent neurologic dysfunction in infants with NAS. Specifically, term infants with NAS display an immature pattern of SwBr making them more similar to preterm infants, rather than a unique pathology. The distribution of SwBr and POR in NAS infants becomes more like term infants, possibly representing catch-up development as the NAS symptoms resolve.ConclusionSwBr in babies with NAS is different from that of unaffected term infants, actually being similar to preterm infants. Infants with NAS exhibit a dysmature pattern of NNS development which resolves over time.

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 "swallowbreath 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.