THE CARBON DIOXIDE RESPONSE CURVE OF THE DOG AT SEA LEVEL AND AT ALTITUDE
Abstract
Carbon dioxide response curves were measured in three trained dogs before, during, and after an 18-day sojourn at 12,470 ft altitude. The effects of sedation on CO2 sensitivity were studied in two dogs, using scopolamine and scopolaminethiopental. In addition, tests were made for the presence of an hypoxic drive component in resting ventilation at altitude by measuring the effect on ventilation of a sudden change in alveolar O2 tension from 55 mm Hg to 110 mm Hg. Reductions occurred in resting alveolar O2 and CO2 tensions to 53 and 71% of sea level control, respectively. On the average, CO2 sensitivity was increased during the first 10 days to 160% of sea level control. The CO2 response curve was shifted horizontally to the left by about 8 mm Hg. This decrease in CO2 threshold was statistically significant (P <0.01). Sedation increased the variability of the results. However, there was some evidence that CO2 sensitivity was reduced by sedation. These effects were more pronounced at altitude than at sea level. Tests for an hypoxic drive component showed a transitory reduction in alveolar ventilation occurring 1 minute after the increase in alveolar O2 tension. In subjects under sedation with scopolaminethiopental, 40% of resting ventilation was attributable to peripheral chemoreflexes.
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 01, 1964
- Accession Number
- AD0615967
Entities
People
- Erwin R. Archibald
Organizations
- University of California, Berkeley