Coordination of respiration and swallowing: effect of bolus volume in normal adults

Abstract

The coordination of swallowing and respiration, as measured by nasal airflow, and the effect of changes in the volume of the swallow bolus (0-20 ml) were investigated in 12 normal subjects. Both nonbolus and bolus swallows were usually preceded and followed by expiratory airflow. Swallows followed by inspiratory airflow accounted for 20% of nonbolus swallows but decreased further in frequency in the presence of a bolus. Swallowing was associated with an apneic period lasting 1.90 +/- 0.26 s for nonbolus swallows. Based on the apneic period response to bolus volume, the subjects were divided into two groups. The apneic period decreased by 60% in seven of the subjects regardless of bolus volume. The remaining five subjects gradually increased swallow apnea as bolus volume was increased. At larger bolus volumes, the latter group also exhibited an earlier onset of the swallow apnea and an increase in the number of swallows preceded by inspiration. The duration of the swallow-associated respiratory cycle was similarly prolonged by an increase in bolus volume in both groups. The results indicate that the respiratory pattern associated with swallowing is modulated by the volume of the swallow bolus. Within the normal population, at least two different patterns of response to bolus volume are identified.

Effects of Age, Gender, Bolus Volume, and Trial on Swallowing Apnea Duration and Swallow/Respiratory Phase Relationships of Normal Adults

“…The findings of this study demonstrated that normal elderly female mean SAD on a 25 ml bolus was 1.32 s whereas normal young female mean SAD on a 10 ml bolus was .77 s. Thus, if a researcher or clinician obtains a SAD value from a participant/patient without respect to age or bolus volume an incorrect assumption may be made as to the increased or decreased nature of its duration. The lack of a significant bolus volume effect on SAD reported by Martin et al [2] and Preiksaitis et Swallowing Apnea Duration 13 al. [13] may be a consequence of employing a small sample size and limited bolus volumes.…”

“…Klahn and Perlman [21] reported similar percentages where apneic onset occurred during expiration 93% of the time and was succeeded by expiration 100% of the time across 5-ml water and applesauce boluses. In contrast, however, Preiksaitis, et al [13] reported a marked smaller percentage of 71.4% of swallows exhibited an exhale-swallow-exhale pattern. Moreover, Preiksaitis and Mills [14] reported the pattern of exhale-swallow-exhale was present in 77% of 100 swallows, yet this pattern decreased Klahn and Perlman [21] acknowledged the disparity in the reported data relating to SA and called for a larger body of normative data from a larger number of participants to confirm their findings.…”

“…Martin et al [2] reported SAD was not a function of bolus volume (i.e., 3, 10, or 20 ml) among 13 healthy adults. In 1992, Preiksaitis et al [13] similarly failed to find a definitive relationship between bolus volume with a small sample of 12 participants. Preiksaitis et al reported that a bolus volume effect was present for some but not all participants.…”

“…with increasing bolus volumes have been repeatedly documented [2,7,8,9,10,11,12,13,14,15,16,17]. Unfortunately, the effect of bolus size on SAD is inexplicit.…”

“…That is, the large majority of studies have employed 1, 5, and 10 ml boluses. Only a few studies have applied a bolus size as large as 20 ml [2,13,14], yet, Swallowing Apnea Duration 5 even a 20 ml bolus size does not reflect a normal bolus volume swallow for most adults.…”