Respiratory acclimatization to carbon dioxide

Abstract

Twenty-one subjects were exposed to 1.5% CO2 in 21% O2 for 42 days with pre- and postexposure periods on air for 9 days. Respiratory minute volume (Ve) and alveolar pCO2 were increased throughout the exposure to CO2. After transition to air Ve decreased, while pCO2 remained elevated for 9 days. CO2 retention with uncompensated respiratory acidosis lasted for 23 days. CO2 excretion was increased during the 9-day recovery period indicating release of CO2 from the CO2 stores. Oxygen consumption did not change significantly during the experiment. Respiratory acclimatization to CO2 involved a continuous increase in tidal volume while the respiratory rate declined slowly after an initial increase. Changes in respiratory pattern were associated with an increase in physiological and anatomical dead space. A significant increase in the arterial-alveolar pCO2 and alveolar-arterial pO2 gradient indicated the development of an alveolar dead space. The ventilatory response to 5% CO2 was markedly reduced at the end of CO2 exposure. chronic CO2 exposure; chronic hypercapnia; chronic respiratory acidosis Submitted on August 31, 1961

Ventilatory roll off during sustained hypercapnia is gender specific in pekin ducks

“…These results support previous findings in adult male ducks (Dodd and Milsom, 1987), which demonstrated the remarkably rapid respiratory acclimation of male ducks during prolonged hypercapnia. In contrast, respiratory acclimation in humans and other mammals occurs over a period of days (Schaefer et al, 1963;Lai et al, 1981) if it happens at all (Kondo et al, 2000;Crosby et al, 2003). Interestingly, prolonged hypercapnia in adult female ducks did not result in a decline in respiration, at least over the time course of this study.…”

Adaptation to Co2 With Particular Relation to Co2 Retention in Diving

“…Printed with permission of Science period as shown in C0 2 sensitivity tests in eight tank instructors (Schaefer, 1961). Blood gas and electrolyte changes observed at the end of a longer period of water work were similar to those noted during adaptation to prolonged exposure to C0 2 (Schaefer, 1963). They consisted in a decrease in pH, increase in P COi and bicarbonate levels commensurate with an increase in hematocrit and a red cell cation exchange, e.g.…”

“…x -",_ v.,. Supporting evidence for this notion was obtained in a study of 21 subjects exposed to 1.5 per cent C0 2 for 42 days (Schaefer et al, 1963). Figure 3 shows changes in respiratory pattern during acclimatization to 1.5 per cent C0 2 .…”

Carbon Dioxide Tolerance: A Review

“…Utilizing differences in alveolar-arterial CO 2 gradients, Schaefer et al (47) estimated that there was a 4% increase in nonperfused alveoli associated with the increase in tidal volume in this study. Thisreturnedto control value 4 weeks after the study.…”

“…and remained elevated during the followup control period (47). Ventilatory response to breathing 5% (21 mm.…”