Frequency and significance of swallowing during prolonged apnea in infants.

To better document and describe the phenomenon of swallowing during apneic spells, we compared the frequency of swallowing during epidsodes of prolonged apnea with nonapnea control periods in 9 preterm and 1 term infant. Infants with a history of idiopathic prolonged apnea were studied for 2 to 3 h by monitoring, electrocardiogram, nasal air flow, oral CO2, abdominal respiratory movements, chin electromyogram, pharyngeal pressure, and pH. In 7 of the infants, additional observations were performed without the intrapharyngeal recording devices. One or more swallows occurred during 75% of the 100 spells observed. Swallows were far more common during apneic spells than during nonapnea control periods, and were more frequent during mixed and obstructive apnea than during central apnea (p less than .01). Asphyxia, regurgitation, and the intrapharyngeal recording devices did not appear to cause the increased frequency of swallows during apneic spells. Swallowing was temporally related to spontaneous recovery from apnea, with a swallow usually preceding recovery by 5 to 6 s. During apneic spells, we observed that swallows were often associated with a brief obstructed inspiratory effort ("swallow-breath"), a normal component of nonfeeding swallows in infants. These swallow-breaths were interspersed with higher amplitude "ordinary" obstructed breaths during apneic episodes. Thus, 2 distinctly different types of obstructed inspiratory efforts were identified during mixed and obstructive apnea episodes in infants. The sequence of events during apneic spells in the term and preterm infants was similar.