Ultrasonographic Study of Sucking and Swallowing by Newborn Infants

SIRWeber and colleagues (DMCN, 28, 19-24) included in their results on bottle-fed babies a trace (their Fig. 2) drawn from a video screen showing suck-swallow cycles and a respiratory trace recorded from a Graseby Dynamics Apnoea Alarm. Commenting on the co-ordination of swallowing and breathing, the authors state: ‘In some of the babies the swallows occurred consistently in the end-expiratory pause (between expiration and inspiration). This was noted particularly in fourand five-day-old babies. In others, notably babies at two days of age, the breath was held during either inspiration or expiration, in association with a swallowing motion’. In our series of observations on bottle-fed babies, made on a much larger sample than that reported by Weber et al. and using different techniques to record sucking, swallowing and respiration, we have found that the pattern for two-day-old babies is commonly a form which we have called ‘immature’. It later develops, over about five to eight days, into a more ‘mature’ pattern. We were disturbed to find that the patterns we had observed over many measurements did not agree with those of Weber et al. In particular, our recordings show that the swallow of a mature infant is almost always preceded by an inspiration and followed by an expiration. In those cases when swallowing occurs on expiration, the expiratory flow is arrested as a swallow takes place and then ccntinues before an inspiration. We have no record, from over 100 recordings, of an infant swallowing at end-expiration. To confirm our findings we have Fig. 1. Signals from three transducers recorded simultaneously from eight-day-old baby during resting respiration. Upper trace: thermistor anemometer held at naris. Centre trace: pressure drop across naris, indicating direction of nasal airflow. Bottom trace: Graseby Apnoea Monitor output (E = expiration, I = inspiration). Difference in height of anemometer trace is partly due to inhaled air more easily avoiding the transducer.