Vanessa S. Sakalidis

Oxygen Saturation and Suck-Swallow-Breathe Coordination of Term Infants during Breastfeeding and Feeding from a Teat Releasing Milk Only with Vacuum

Background. Vacuum is an important factor in milk removal from the breast, yet compression is the predominant component of milk removal from bottle teats. Since bottle-feeding infants have lower oxygen saturation, vacuum levels, and different suck-swallow-breathe (SSwB) coordination to breastfeeding infants, we hypothesised that when infants fed from a teat that required a vacuum threshold of −29 mmHg for milk removal, that oxygen saturation, heart rate, and suck-swallow-breathe (SSwB) patterns would be similar to those of breastfeeding. Study Design. Infants (n = 16) were monitored during one breastfeed and one feed from the experimental teat. Simultaneous recordings were made of oxygen saturation, heart rate, vacuum, tongue movement, respiration, and swallowing. Results. There were no differences in oxygen saturation and heart rate between the breast and the teat. Infants displayed fewer sucks and breaths per swallow during nutritive sucking (NS) compared to non-nutritive sucking (NNS). The number of sucks per breath was similar for NS and NNS although respiratory rates were slower during NS. These patterns did not differ between the breast and the teat. Conclusion. These results suggest that vacuum may be conducive to safe and coordinated milk removal by the infant during both breast and bottle-feeding.

Tongue movement and intra-oral vacuum of term infants during breastfeeding and feeding from an experimental teat that released milk under vacuum only

BACKGROUND Recent literature supports the theory that vacuum is integral to the removal of milk from the breast rather than peristaltic compression of the breast. AIM We aimed to determine if breastfed infants could remove breast milk from an experimental teat designed to release milk only when a vacuum is applied. METHODS Submental ultrasound images and intra-oral vacuum measurements were recorded simultaneously during both a breastfeed and a feed with the experimental teat. RESULTS Infants placed the nipple and teat a similar distance from the nipple hard-soft palate junction when the tongue was lowered (4.7 mm vs 5.3 mm). As the tongue lowered the nipple and teat expanded evenly although the nipple expanded more than the teat (3.1mm vs 1.5 mm). Both baseline (-31 mm Hg vs -12 mm Hg) and peak vacuum (-122 mm Hg vs -67 mm Hg) applied to the breast were significantly higher than for the teat. CONCLUSION Breastfed infants are able to remove milk from a teat using only vacuum with a similar tongue movement to that of breastfeeding. This evidence supports the theory that vacuum is a critical factor in the removal of milk from the breast.

Ultrasound Imaging of Infant Sucking Dynamics during the Establishment of Lactation

Background: Infant sucking problems are frequently implicated in early weaning during breastfeeding, yet our understanding of early sucking dynamics is limited. Objective: This study aimed to describe infant sucking patterns during breastfeeding at secretory activation and determine whether they changed by the time of established lactation. Methods: Sucking patterns and milk intake of 15 breastfeeding infants were assessed on day 3.2 ± 0.8 and later at follow-up, 16.0 (11.3-22.8) days postpartum. Nipple diameters, tongue movement, nipple position, and suck rate during nutritive sucking (NS) and non-nutritive sucking (NNS) were measured from ultrasound scans of the intra-oral cavity during breastfeeding. Milk intake and LATCH scores were also recorded. Results: As the tongue lowered during a suck cycle, the nipple increased in size (P < .001), milk flowed into the intra-oral space and the nipple moved closer to the hard-soft palate junction (P < .001). During NS, nipple diameters and the mid-tongue movement were greater than during NNS (P < .001). As the infant aged, the mid-tongue lowered further (P = .002), suck rates became faster (P < .001) and milk intake increased (P = .004), however, no differences were seen for LATCH scores (P = .34). Conclusion: Differences in tongue movement between NS and NNS suggest that there is an altered sucking action when milk flow is absent. Similar sucking patterns at day 3 and during established lactation imply that infants have a mature sucking pattern in the early postpartum period.

Validation of Nipple Diameter and Tongue Movement Measurements with B-Mode Ultrasound During Breastfeeding

Infant feeding problems are extremely common during breastfeeding establishment. To objectively assess infant sucking, consistent methods to analyze ultrasound images of the infants oral cavity are required. We developed and assessed the reliability of an extensive ultrasound measurement protocol by measuring nipple diameter and placement. Midline submental ultrasound scans of 30 term breastfed infants were analyzed by two raters. Nipple diameter, nipple hard-soft palate junction distance and tongue hard-soft palate junction distance were measured on two frames: tongue-up and tongue-down. No evidence of measurement bias was found between raters and inter-rater agreement and consistency scores were high. The changes in nipple diameter and placement were consistent with previous descriptions; however, the diameter of the nipple was not consistent in either position. This method provides objective measurements representative of tongue movement, and further investigation is required to ensure usefulness when examining sucking difficulties.

Longitudinal changes in suck-swallow-breathe, oxygen saturation, and heart rate patterns in term breastfeeding infants.

Background: Despite the differences in breastfeeding and bottle-feeding, our understanding of how suck-swallow-breathe (SSwB), oxygenation, and heart rate patterns change as the infant ages is based predominantly on bottle-feeding studies. Therefore, this study aimed to measure how SSwB, oxygenation, and heart rate patterns changed during the first 4 months of lactation in term breastfeeding infants. Methods: Infants less than 1 month postpartum (n = 15) were monitored early in lactation and again later in lactation (2-4 months postpartum). Simultaneous recordings of vacuum, tongue movement, respiration, swallowing, oxygen saturation, and heart rate were made during both nutritive sucking and non-nutritive sucking during breastfeeding. Results: Infants transferred a similar amount of milk (P = .15) over a shorter duration later in lactation (P = .04). Compared to early lactation, suck bursts became longer (P < .001), pauses became shorter (P < .001), vacuum levels decreased (all P < .05), oxygen saturation increased (P < .001), and heart rate decreased (P < .001) later in lactation. Conclusion: This study confirmed that term infants become more efficient at breastfeeding as they age, primarily by extending their suck bursts and pausing less. Although infants demonstrated satisfactory SSwB coordination during early lactation, they showed a level of adaption or conditioning at later lactation by applying weaker vacuum levels and demonstrating improved cardiorespiratory responses.

A comparison of early sucking dynamics during breastfeeding after cesarean section and vaginal birth.

BACKGROUND The impact of cesarean section (CS) birth and pethidine for post-CS epidural analgesia on early breastfeeding behavior is unclear. This study aimed to measure infant sucking and breastfeeding behavior in infants of mothers who delivered by CS (CS group) and used pethidine patient-controlled epidural analgesia (PCEA) after CS with that of infants who were delivered by vaginal birth (V group), during secretory activation and again after the establishment of lactation. SUBJECTS AND METHODS Sucking dynamics and milk intake of breastfeeding infants were assessed on approximately 3 and 20 (follow-up) days postpartum (CS group, n=19; V group, n=15). Nipple diameters, tongue movement, and nipple position during sucking were measured from ultrasound scans of the intra-oral cavity during breastfeeding. Time of the first breastfeed and day of breast fullness were recorded, and infant neurobehavior was assessed. RESULTS CS infants displayed more anterior tongue movement on Day 3 than at follow-up compared with the V group, which showed a similar amount of movement at each assessment (p for interaction<0.001). Compared with the V group, the CS group showed faster suck rates, especially on Day 3 (p<0.001), later times to first breastfeed (p=0.01) and breast fullness (p=0.03), and lower neurobehavioral scores (p=0.047). Breastfeeding duration and milk intake were similar between groups. CONCLUSIONS Although the observed effect of CS birth followed by pethidine PCEA after CS during the period of secretory activation was small, our results indicate that successful initiation of lactation may require additional breastfeeding support and monitoring at Day 3 postpartum for mothers who undergo CS.

Suck-Swallow-Breathe Dynamics in Breastfed Infants

Despite the importance of the suck-swallow-breathe reflex during breastfeeding, a large proportion of our understanding is derived from bottle-feeding studies. Given the differences in the delivery of milk during breast and bottle feeding, it is imperative that a more general view of the suck-swallow-breathe and milk removal process during breastfeeding is available. This systematic review aimed to assess the evidence for the mechanism of milk removal during breastfeeding; evaluate how the term infant coordinates sucking, swallowing, breathing (SSwB) and cardiorespiratory patterns; and how these patterns change with maturation during breastfeeding. A literature search of PubMed and MEDLINE was performed to assess the mechanism of milk removal and patterns of sucking, swallowing, breathing, and cardiorespiratory control during breastfeeding in healthy term infants. Seventeen studies were selected and a narrative synthesis was performed. Nine studies assessing the infant sucking mechanism consistently provided evidence that vacuum is essential to milk removal from the breast. The limited data on swallowing and breathing and cardiorespiratory control showed mixed results. Overall, results highlighted the high variability in breastfeeding studies and suggested that swallowing, breathing, and cardiorespiratory patterns change with maturation, and within a breastfeed. These findings show potential for devising breastfeeding interventions for populations at risk of SSwB problems. However, consistent methods and definitions of breastfeeding parameters are required before interventions can be adequately developed and tested.

Vacuum characteristics of the sucking cycle and relationships with milk removal from the breast in term infants

BACKGROUND The importance of an infants intra-oral vacuum in milk removal from the breast has been established. However, the relationship between the vacuum curve and milk transfer is not well understood. AIMS To investigate the parameters of the infant suck cycle in relation to the volume of milk removed from the breast. STUDY DESIGN Cross-sectional study to elucidate the role of infant intra-oral vacuum in efficient milk removal from the breast. SUBJECTS Nineteen fully breastfed term infants. METHODS Intra-oral vacuum was recorded during monitored breastfeeds using a pressure transducer. Ultrasound imaging (milk flow) and respiratory inductive plethysmography (swallowing) were used to determine the nutritive sucking (NS) portion of the feed. Milk intake was determined by weighing infants before and after feeds. Vacuum traces of the first and next 2min of NS from the first breast were analysed. RESULTS The volumes of milk removed during both NS periods were negatively associated with peak vacuum (p<0.001) and rate of vacuum application (p<0.001), and positively related to area under first half of the suck cycle (p<0.001). Most parameters changed significantly from the first 2min of NS to the next 2min including significant reduction in peak vacuum and area under first half of the suck cycle. CONCLUSION These results further support the role of intra-oral vacuum, specifically optimal peak vacuum, in effective and efficient milk removal during breastfeeding. It also appears that infants modify their sucking dynamics to adapt to changes in milk flow during milk ejection as the breast empties.

Evidence of Improved Milk Intake After Frenotomy: A Case Report

Ankyloglossia (tongue tie) is a well-recognized cause of breastfeeding difficulties and, if untreated, can cause maternal nipple pain and trauma, ineffective feeding, and poor infant weight gain. In some cases, this condition will result in a downregulation of the maternal milk supply. Milk-production measurements (24-hour) for a breastfeeding infant with ankyloglossia revealed the ineffective feeding of the infant (78 mL/24 hours), and a low milk supply (350 mL/24 hours) was diagnosed. Appropriate management increased milk supply (1254 mL/24 hours) but not infant milk intake (190 mL/24 hours). Test weighing convincingly revealed the efficacy of frenotomy, increasing breastfeeding milk transfer from 190 to 810 mL/24 hours. Postfrenotomy, breastfeeding almost completely replaced bottle-feeding of expressed breast milk. This case study confirms that ankyloglossia may reduce maternal milk supply and that frenotomy can improve milk removal by the infant. Milk-production measurements (24-hour) provided the evidence to confirm these findings.

House mouse abundance and Ross River virus notifications in Victoria, Australia

OBJECTIVES The number of emerging and re-emerging infectious diseases is increasing. As such, understanding the fundamental ecology of infectious disease is critical. Short-lived highly fecund amplification hosts are implicated to influence disease prevalence, but few empirical examples exist. We examined the relationship between mouse (Mus musculus) abundance and Ross River virus (RRV) incidence in northwest Victoria, Australia. METHODS We determined a biologically plausible distribution overlap of M. musculus, humans, and vector mosquitoes in our study region. We compared M. musculus abundance with human RRV notifications seasonally between 1997 and 2000. RESULTS Trends in M. musculus and RRV were similar during summer, autumn, and summer plus autumn, but unrelated during winter, spring, and winter plus spring, coinciding with the seasonal abundance and relative absence of the vector, Culex annulirostris. CONCLUSIONS Our results demonstrate a plausible association between M. musculus and RRV incidence, suggesting that short-lived highly fecund amplification hosts may profoundly influence disease transmission. Our results are supported by theoretical studies and empirical evidence from other systems. Further research is warranted to establish a causal relationship between amplification hosts and RRV, and in other infectious disease systems. Implications for the management of infectious disease may exist.