Journal of Applied Physiology, Vol 55, Issue 2 368-376, Copyright © 1983 by American Physiological Society
Airway anesthesia effects on hypercapnic breathing pattern in humans
T. Y. Sullivan and P. L. Yu
Minute ventilation (VE) and breathing pattern during an abrupt increase in
fractional CO2 were compared in 10 normal subjects before and after airway
anesthesia. Subjects breathed 7% CO2-93% O2 for 5 min before and after
inhaling aerosolized lidocaine. As a result of airway anesthesia, VE and
tidal volume (VT) were greater during hypercapnia, but there was no effect
on inspiratory time (TI). Therefore, airway anesthesia produced an increase
in mean inspiratory flow (VT/TI) during hypercapnia. The increase in VT/TI
was compatible with an increase in neuromuscular output. There was no
effect of airway anesthesia on the inspiratory timing ratio or the shape
and position of the curve relating VT and TI. We also compared airway
resistance (Raw), thoracic gas volume, forced vital capacity, forced
expired volume at 1s, and maximum midexpiratory flow rate before and after
airway anesthesia. A small (0.18 cmH2O X l-1 X s) decrease in Raw occurred
after airway anesthesia that did not correlate with the effect of airway
anesthesia on VT/TI. We conclude that airway receptors accessible to airway
anesthesia play a role in hypercapnic VE.
