Am. J. Respir. Crit. Care Med., Vol 150, No. 5, Nov 1994, 1274-1278.
Control of ventilation during continuous swallowing
FG Issa and S Porostocky
Faculty of Medicine, University of Calgary, Alberta, Canada.
The upper airway performs three distinct functions that must be coordinated
to allow maximal operation of each individual system. We tested the
ventilatory response to progressive hypercapnia in seven normal adults
during continuous swallowing. Swallowing was induced by oral infusion of
water while the subject breathed through the nose. Infusion of 40 ml/min
resulted in repetitive swallows (rate: 8.1 +/- 4.1 swallows/min, mean +/-
SD), but this did not cause a single incidence of coughing or aspiration.
Swallows interrupted inspiration and expiration and resulted in
compensatory changes in tidal volume and breathing frequency. Continuous
drinking did not significantly change the slope of the ventilatory response
to hypercapnia. The test was repeated in three subjects swallowing water
infused at 60, 80, and 100 ml/min. The slope of the response was also not
significantly different from control in these tests. We conclude that
continuous swallowing does not override ventilatory control mechanisms in
human adults.
