Decompression Theory.

Abstract

CONTENTS: Introduction; Section I. Historical Development of the U.S. Navy's Decompression Model and Its Operational Limits; History of Decompression Theory - R. C. Bornmann; Current Problems with the Neo-Haldanian Model - T. E. Berghage; Safer Air Decompression Schedules Developed During a Two-Year Salvage Diving Operation - H. Yano and E. L. Beckman; Section II. Current Status of Neo-Haldanian Assumptions; Gas Uptake Assumptions: 1. Multiple tissues or tissue compartments must be used to describe whole-body gas exchange; 2. Tissue gas uptake is described by the following: exposure time, pressure differential, and tissue half times; 3. Only the inert gas partial pressures need be considered in the decompression problem; 4. Breathing multiple inert gases appears to provide some decompression advantages; 5. Compression procedures have no effect on decompression; Pressure Reduction Assumptions: 6. Tissue supersaturation limits are best described by a series of pressure-reduction ratios; 7. The pressure-reduction ratio for nitrogen-saturated tissues increases with increasing depth; the ratio remains constant for helium-saturated tissues.; 8. Tissue supersaturation limits increase with increasing depth.; 9. Pressure differentials during decompression can be maintained indefinitely; Gas Elimination Assumptions: 10. Gas uptake and elimination are symmetrical relationships; 11. Oxygen breathing enhances gas elimination by increasing the pressure differential between the tissues and alveolar air; 12. The concept of residual nitrogen time is sufficient to handle repeated exposures; Section III. Workshop Contributions; Workshop Comments - A. R. Behnke; Gas Uptake, Gas Elimination - A. A. Buehlmann; VMRC's Data Relevant to Current Assumptions Used in USN Decompression Calculation - B. G. D'Aoust; Comment on Use of Different Gases - R. W. Hamilton, Jr. and D. J. Kenyon; Effect of Duration of Exposure to M Values on Their Validity - R. W. Hamilton, Jr., D. J. Kenyon, and R. E. Peterson; Importance of Oxygen in Mixed-Gas Decompression - R. W. Hamilton, Jr., D. J. Kenyon, M. R. Powel" and M. Freitag; The Alternating Bubble Theory of Decompression - B. A. Hills; Responses to the Twelve Assumptions Presently Used for Calculating Decompression Schedules - D. E. Yount; Comments - R. D. Vann; Symmetry of Inert Gas Uptake and Elimination - P. K. Weathersby