TY - JOUR
T1 - The role of chemical (CO2) drive in the apnea induced by high frequency ventilation in the cat
AU - Thompson-Gorman, Susan L.
AU - Fitzgerald, Robert S.
AU - Mitzner, Wayne
N1 - Funding Information:
Acknowledgements. The authors are grateful to Dr. Allyn Kimball for his help in choosing and applying this unique statistical approach to our study. We also thank David Westcott for technical assistance. This work was supported by National Heart, Lung, and Blood Institute Grants HL10342 and HL07534.
PY - 1990
Y1 - 1990
N2 - The purpose of the present study was to compare the relative roles of PaCO2 and pulmonary mechanoreceptors in the generation of apnea during high frequency ventilation (HFV) and conventional mechanical ventilation (CMV) in the anesthetized cat. Our hypothesis was that PaCO2 primarily determines the appearance of apnea, while mechanoreceptor input plays an important but secondary role. We calculated the tidal volume which would have a 50% chance of inducing apnea (Vt50) for each combination of ventilator settings, and used it as a standard for comparison of mechanical dynamic inputs. When either 2% or 5% CO2 was added to the bias flow during HFV, the Vt50 was significantly increased over that seen with a room air bias flow. Apnea was observed during either mode of ventilation only when PaCO2 was reduced below normocapnic levels. The mean tidal volume associated with each apnea group was larger than that for the corresponding nonapnea group. There was no difference in the PaCO2 for apnea between HFV and CMV, but the EMG of the diaphragm did differ. With HFV-apnea tonic activity was observed, while CMV-apnea showed abolition of all activity. We conclude that both HFV- and CMV-induced apnea depend primarily on lowering the chemical drive (PaCO2), and secondarily on inhibitory mechanical input (Vt). The excitation of rapidly adapting receptors during HFV could explain the tonic EMG activity.
AB - The purpose of the present study was to compare the relative roles of PaCO2 and pulmonary mechanoreceptors in the generation of apnea during high frequency ventilation (HFV) and conventional mechanical ventilation (CMV) in the anesthetized cat. Our hypothesis was that PaCO2 primarily determines the appearance of apnea, while mechanoreceptor input plays an important but secondary role. We calculated the tidal volume which would have a 50% chance of inducing apnea (Vt50) for each combination of ventilator settings, and used it as a standard for comparison of mechanical dynamic inputs. When either 2% or 5% CO2 was added to the bias flow during HFV, the Vt50 was significantly increased over that seen with a room air bias flow. Apnea was observed during either mode of ventilation only when PaCO2 was reduced below normocapnic levels. The mean tidal volume associated with each apnea group was larger than that for the corresponding nonapnea group. There was no difference in the PaCO2 for apnea between HFV and CMV, but the EMG of the diaphragm did differ. With HFV-apnea tonic activity was observed, while CMV-apnea showed abolition of all activity. We conclude that both HFV- and CMV-induced apnea depend primarily on lowering the chemical drive (PaCO2), and secondarily on inhibitory mechanical input (Vt). The excitation of rapidly adapting receptors during HFV could explain the tonic EMG activity.
KW - Animal, cat
KW - Apnea
KW - Artificial ventilation, high ventilation
KW - Control of breathing, pulmonary mechanoreceptors
KW - Pulmonary mechanoreceptor
KW - Receptor
KW - Ventilation, by high frequency
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U2 - 10.1016/0034-5687(90)90091-C
DO - 10.1016/0034-5687(90)90091-C
M3 - Article
C2 - 2120755
AN - SCOPUS:0025193713
VL - 80
SP - 307
EP - 321
JO - Respiratory Physiology and Neurobiology
JF - Respiratory Physiology and Neurobiology
SN - 1569-9048
IS - 2-3
ER -