Effects of Combined Breathing Impediments on Diver's Respiratory Performance
Abstract
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 H20/L, R: such that the external work of breathing equals 1.5 to 2.0 J/L. 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 (%R/%E): 100/0, 75/25, 50/ 50, 25/75, 0/100. 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 VO(2). The mean end-tidal CO(2) values were 46.7 mm Hg at the shallow depth and 52.4 mm Hg at the great depth but were unaffected by the R/E combination. V(E) was not affected differently by the R/E 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 Ti/T(tot) was not affected by the R/E 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.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 31, 1994
- Accession Number
- ADA277437
Entities
People
- Claes Lundgren
Organizations
- University at Buffalo