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 a particular dive profile. 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.

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 again). 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.

VPM model description articles:

• VPM Explained by Corrado Bonuccelli. An illustrated, easy to follow description of VPM principles and operation.
• VPM for Dummies by Kevin Watts. This article, published in both English and French in the International Cave Diving Magazine Plongeesout, provides divers a good working understanding of VPM.

See also

• Decompression (diving)
• Reduced Gradient Bubble Model
• Bühlmann tables

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 References

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

VPM Research and Development References

• Kunkle, T.D. 1979. Bubble nucleation in supersaturated fluids. Univ. of Hawaii Sea Grant Technical Report UNIHI-SEAGRANT-TR-80-01. Pp. 108.
• Yount, D.E. 1979. Multiple inert-gas bubble disease: a review of the theory. In: Lambertsen, C.J. and Bornmann, R.C. eds. Isobaric Inert Gas Counterdiffusion Workshop. Undersea Medical Society, Bethesda, 90-125.
• Yount, D.E. and Hoffman, D.C. 1983. On the use of a cavitation model to calculate diving tables. In: Hoyt, J.W., ed. Cavitation and multiphase flow forum-1983. New York: American Society of Mechanical Engineers, 65-68. ISSN: 9993289434

VPM Dive Planning Software

• 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
• MultiDeco VPM-B & VPM-B/E, VPM-B/FBO, ZHL-B, ZHL-C, GF, and GFS
• V-Planner VPM-B & VPM-B/E, VPM-B/FBO
• DecoPlanner VPM-B
• HLPlanner VPM-B
• JDeco VPM-B
• PalmVPM VPM
• DivePlan VPM
• Baltic Deco Planner 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 and Petrel models GF, VPM-B plus GFS

External links

• VPM web site
• VPM development time line