Dynamic characteristics of ventilatory depression in man on abrupt administration of O.

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Abstract
The dynamic response characteristics of the O2 sensitive peripheral chemoreflex component of the human respiratory control system were measured by determining the magnitude and time course respiratory depression following the abrupt, sustained course of respiratory depression following the abrupt, sustained administration of oxygen at a fixed, elevated arterial CO2 pressure (PACO2). In 6 subjects, inhalation of CO2 in 16% O2 resulted in an average control VE of 22.6 l/min. at a PACO2 of 49 mm Hg and PAO2 of 104 mm Hg. The FIO2 was then abruptly changed from 0.16 to 0.94 while PACO2 was held constant by adjustment of FICO2 [fractional concentration of CO2 ion inspired gas]. VE [minute volume of expired gas], VT [tidal volume], F [breathes/unit tissue] and PAcO2 were determined on a breath-by-breath basis. A depression of VE induced by oxygen became evident, on the average, 2.8 sec after the rise in FIO2, and reached an average maximal depression of 12.3% below control VE with an average time constant of 5.3 sec. At a higher constant PACO2 of 55 mm Hg an average depression of VE to 13.2% below the control level occurred. Values for average delay time and time constant were similar to those observed at the lower PCO2. The data indicate the contribution and time course of O2 sensitive component of respiratory control in resting man.