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Varying Permeability Model

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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.[1] In 1986, this model was applied by researchers at the University of Hawaii to calculate diving decompression tables.[citation needed]

Theoretical basis[edit]

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.[2][3]


This bibliography list was compiled by E.B. Maiken and E.C. Baker as reference material for the V-Planner web site in 2002.[4]

Primary Modeling Sources[edit]

  • 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[edit]

VPM Dive Planning Software[edit]

  • V-Planner: VPM-B & VPM-B/E, VPM-B/FBO.[4]
  • MultiDeco: VPM-B & VPM-B/E, VPM-B/FBO, ZHL-B, ZHL-C, GF, and GFS.[5]
  • 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.[6]
  • DecoPlanner: VPM-B.[7]
  • HLPlanner: VPM-B.[8]
  • JDeco: VPM-B.[9]
  • PalmVPM: VPM.[10]
  • DivePlan: VPM.[11]
  • Baltic Deco Planner: VPM-B.[12]
  • Subsurface: VPM-B.[13]

VPM Dive computers[edit]

  • V-Planner Live: VPM-B & VPM-B/E.[14]
  • MultiDeco-X1: VPM-B & VPM-B/E, VPM-B/FBO, ZHL-C, GF, and GFS.[15]
  • MultiDeco-DR5: VPM-B & VPM-B/E, VPM-B/FBO, ZHL-C, GF, and GFS.[16]
  • 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.[17]
  • TDC-3 with MultiDeco-TDC: VPM-B & VPM-B/E, VPM-B/FBO, ZHL-C, GF, and GFS.[18]
  • HeinrichsWeikamp OSTC4: VPM-B

See also[edit]


  1. ^ Yount, DE (1991). "Gelatin, bubbles, and the bends". In: Hans-Jurgen, K; Harper Jr, DE (Eds.) International Pacifica Scientific Diving... 1991. Proceedings of the American Academy of Underwater Sciences Eleventh Annual Scientific Diving Symposium held 25–30 September 1991. University of Hawaii, Honolulu, Hawaii. Archived from the original on January 13, 2013. Retrieved 2011-10-14.{{cite journal}}: CS1 maint: unfit URL (link)
  2. ^ Bonuccelli, Corrado (10 March 2004). "Calculating deco schedule with VPM" (PDF). Retrieved 8 June 2016.
  3. ^ Watts, Kevin (19 March 2007). "VPM For Dummies". Rebreather World. Retrieved 8 June 2016.
  4. ^ a b "V-Planner dive decompression planning software". HHS Software. Retrieved 8 June 2016.
  5. ^ "MultiDeco VPM & VPM-B & VPM-B/E & ZHL GF dive decompression software for technical divers".
  6. ^ "Tech Diving Mag - Free online technical diving magazine - Ultimate Planner".
  7. ^ "DecoPlanner". Archived from the original on 10 January 2006.
  8. ^ "HLPlanner". Archived from the original on 2008-03-15. Retrieved 2008-04-16.
  9. ^ "JDeco - Dive Decompression Software for JAVA Mobile Devices (Buhlmann and VPM-B)".
  10. ^ "Yahoo! Groups - PalmVPM".
  11. ^ Roach, Greg. "DivePlan - Decompression software for SymbianOS".
  12. ^ Olsen, Eskil. "baltic deco planner - iPhone deco planning app".
  13. ^ Willem Ferguson; et al. "13.2.2. Non-recreational open circuit dives, including decompression". Subsurface 4.5 User Manual. Retrieved 10 November 2016.
  14. ^ "V-Planner Live VPM-B, VPM-B/E dive deco computer firmware".
  15. ^ "MultiDeco-X1 VPM-B VPM-B/E ZHL-GF dive computer firmware".
  16. ^ "MultiDeco-DR5/DRX VPM-B VPM-B/E ZHL-GF dive computer firmware".
  17. ^ "Ratio Dive Computers".
  18. ^ "Technical Dive Computers TDC-3".

External links[edit]