Varying Permeability Model

The Varying Permeability Model, Variable Permeability Model or VPM is an algorithm that is used to calculate the decompression stops needed for ambient pressure dive profiles using specified breathing gases. It was developed by D.E. Yount and others for use in professional diving and recreational diving. It was developed to model laboratory observations of bubble formation and growth in both inanimate and in vivo systems exposed to pressure. In 1986, this model was applied by researchers at the University of Hawaii to calculate diving decompression tables.[citation needed]

Theoretical basis

The VPM presumes that microscopic bubble nuclei always exist in water and tissues that contain water. Any nuclei larger than a specific "critical" size, which is related to the maximum dive depth (exposure pressure), will grow upon decompression when the diver ascends. The VPM aims to minimize the total volume of these growing bubbles by keeping the external pressure large, and the inspired inert gas partial pressures low during decompression. The model depends on the assumptions that different sizes of bubbles exist within the body; that the larger bubbles require less reduction in pressure to begin to grow than smaller ones; and that fewer large bubbles exist than smaller ones. These are used to construct an algorithm that provides decompression schedules designed to allow the larger, growing bubbles to be eliminated before they can cause problems.

Bibliography

This bibliography list was compiled by E.B. Maiken and E.C. Baker as reference material for the V-Planner web site in 2002.

Primary Modeling Sources

  • Yount, D.E.; Hoffman, D.C. (1984). Bachrach, Arthur J.; Matzen, M.M. (eds.). Decompression theory: A dynamic critical-volume hypothesis. Underwater physiology VIII: Proceedings of the eighth symposium on underwater physiology. Bethesda: Undersea and Hyperbaric Medical Society. pp. 131–146.</ref>
  • Yount, D.E.; Hoffman, D.C. (1986). "On the use of a bubble formation model to calculate diving tables". Aviat Space Environ Med. 57 (2): 149–156. ISSN 0095-6562. PMID 3954703.
  • Yount, D.E.; Hoffman, D.C. (1989). "On the use of a bubble formation model to calculate nitrogen and helium diving tables". In Paganelli, C.V.; Farhi, L.E. (eds.). Physiological functions in special environments. New York: Springer-Verlag. pp. 95–108.
  • Yount, D.E.; Maiken, E.B.; Baker, E.C. (2000). Lang, M.A.; Lehner, C.E. (eds.). Implications of the Varying Permeability Model for Reverse Dive Profiles. Proceedings of the Reverse Dive Profiles Workshop. Washington, D.C.: Smithsonian Institution. pp. 29–61.

VPM Research and Development Sources

VPM Dive Planning Software

  • V-Planner: VPM-B & VPM-B/E, VPM-B/FBO.
  • MultiDeco: VPM-B & VPM-B/E, VPM-B/FBO, ZHL-B, ZHL-C, GF, and GFS.
  • Ultimate Planner: VPM-B, VPM-B/U, VPM-B (Dec-12), VPM-B/U (Dec-12), ZHL-B, ZHL-C, ZHL-D, GF and GF/U.
  • DecoPlanner: VPM-B.
  • HLPlanner: VPM-B.
  • JDeco: VPM-B.
  • PalmVPM: VPM.
  • DivePlan: VPM.
  • Baltic Deco Planner: VPM-B.
  • Subsurface: VPM-B.

VPM Dive computers

  • V-Planner Live: VPM-B & VPM-B/E.
  • MultiDeco-X1: VPM-B & VPM-B/E, VPM-B/FBO, ZHL-C, GF, and GFS.
  • MultiDeco-DR5: VPM-B & VPM-B/E, VPM-B/FBO, ZHL-C, GF, and GFS.
  • Shearwater Research Predator, Petrel, Perdix and NERD models: GF, VPM-B plus GFS.
  • RATIO Computers: iX3M series and iDive (Tech and Reb) series VPM-B and ZHL16-B.
  • TDC-3 with MultiDeco-TDC: VPM-B & VPM-B/E, VPM-B/FBO, ZHL-C, GF, and GFS.
  • HeinrichsWeikamp OSTC4: VPM-B

See also


This page was last updated at 2023-12-13 00:01 UTC. Update now. View original page.

All our content comes from Wikipedia and under the Creative Commons Attribution-ShareAlike License.


Top

If mathematical, chemical, physical and other formulas are not displayed correctly on this page, please useFirefox or Safari