Effects of Combined Breathing Impediments on Diver's Respiratory Performance
Annual progress rept. 1 Feb 1993-31 Jan 1994
STATE UNIV OF NEW YORK AT BUFFALO DEPT OF PHYSIOLOGY
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Combinations of flow resistance R, elastance E and static lung loading are present to varying degrees in all breathing gear for divers. We have, in earlier studies, determined the maximal acceptable levels for two of these loads, when acting alone, to be E 7 cm H20L, R such that the external work of breathing equals 1.5 to 2.0 JL. Fractions of the acceptable levels of R and E when acting alone were combined such that the total fraction was 1. The subjects were exposed to five of these combinations RE 1000, 7525, 50 50, 2575, 0100. No static lung load was imposed. Results are from 3, in an ongoing series of 12, submerged, air-breathing divers exposed in a hyperbaric chamber to 1.45 and 6.8 ATA exercise was performed in the prone position at 60 of VO2. The mean end-tidal CO2 values were 46.7 mm Hg at the shallow depth and 52.4 mm Hg at the great depth but were unaffected by the RE combination. VE was not affected differently by the RE combinations, but the tidal volumes were reduced 8-20 by increased E. The ERV was reduced by about 20 with the higher E. Similarly, the VC was reduced by about 15. The TiTtot was not affected by the RE combinations but it increased from 0.45 to 0.47 with depth. The dyspnea scores were not different for the different loads. Conclusion R and E are additive in their effects on divers respiratory performance.
- Stress Physiology