TY - JOUR
T1 - Effects of airway anesthesia on ventilatory responses to graded dead spaces and CO2
AU - Shindoh, C.
AU - Hida, W.
AU - Kikuchi, Y.
AU - Chonan, T.
AU - Inoue, H.
AU - Takishima, T.
PY - 1988
Y1 - 1988
N2 - Ventilatory response to graded external dead space (0.5, 1.0, 2.0, and 2.5 liters) with hyperoxia and CO2 steady-state inhalation (3, 5, 7, and 8% CO2 in O2) was studied before and after 4% lidocaine aerosol inhalation in nine healthy males. The mean ventilatory response (ΔV̇E/ΔPET(CO2), where V̇E is minute ventilation and PET(CO2) is end-tidal PCO2) to graded dead space before airway anesthesia was 10.2 ± 4.6 (SD) l·min-1·Torr-1, which was significantly greater than the steady-state CO2 response (1.4 ± 0.6 l·min-1·Torr-1, P < 0.001). Dead-space loading produced greater oscillation in airway PCO2 than did CO2 gas loading. After airway anesthesia, ventilatory response to graded dead space decreased significantly, to 2.1 ± 0.6 l·min-1·Torr-1 (P < 0.01) but was still greater than that to CO2. The response to CO2 did not significantly differ (1.3 ± 0.5 l·min-1·Torr-1). Tidal volume, mean inspiratory flow, respiratory frequency, inspiratory time, and expiratory time during dead-space breathing were also depressed after airway anesthesia, particularly during large dead-space loading. On the other hand, during CO2 inhalation, these respiratory variables did not significantly differ before and after airway anesthesia. These results suggest that in conscious humans vagal airway receptors play a role in the ventilatory response to graded dead space and control of the breathing pattern during dead-space loading by detecting the oscillation in airway PCO2. These receptors do not appear to contribute to the ventilatory response to inhaled CO2.
AB - Ventilatory response to graded external dead space (0.5, 1.0, 2.0, and 2.5 liters) with hyperoxia and CO2 steady-state inhalation (3, 5, 7, and 8% CO2 in O2) was studied before and after 4% lidocaine aerosol inhalation in nine healthy males. The mean ventilatory response (ΔV̇E/ΔPET(CO2), where V̇E is minute ventilation and PET(CO2) is end-tidal PCO2) to graded dead space before airway anesthesia was 10.2 ± 4.6 (SD) l·min-1·Torr-1, which was significantly greater than the steady-state CO2 response (1.4 ± 0.6 l·min-1·Torr-1, P < 0.001). Dead-space loading produced greater oscillation in airway PCO2 than did CO2 gas loading. After airway anesthesia, ventilatory response to graded dead space decreased significantly, to 2.1 ± 0.6 l·min-1·Torr-1 (P < 0.01) but was still greater than that to CO2. The response to CO2 did not significantly differ (1.3 ± 0.5 l·min-1·Torr-1). Tidal volume, mean inspiratory flow, respiratory frequency, inspiratory time, and expiratory time during dead-space breathing were also depressed after airway anesthesia, particularly during large dead-space loading. On the other hand, during CO2 inhalation, these respiratory variables did not significantly differ before and after airway anesthesia. These results suggest that in conscious humans vagal airway receptors play a role in the ventilatory response to graded dead space and control of the breathing pattern during dead-space loading by detecting the oscillation in airway PCO2. These receptors do not appear to contribute to the ventilatory response to inhaled CO2.
UR - http://www.scopus.com/inward/record.url?scp=0023947301&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0023947301&partnerID=8YFLogxK
U2 - 10.1152/jappl.1988.64.5.1885
DO - 10.1152/jappl.1988.64.5.1885
M3 - Article
C2 - 3391890
AN - SCOPUS:0023947301
VL - 64
SP - 1885
EP - 1892
JO - Journal of Applied Physiology
JF - Journal of Applied Physiology
SN - 8750-7587
IS - 5
ER -