# Bühlmann decompression algorithm

The Bühlmann decompression algorithm is a mathematical model (algorithm) of the way in which inert gases enter and leave the human body as the ambient pressure changes.[1] It is used to create Bühlmann tables. These are decompression tables which allow divers to plan the depth and duration for dives and show decompression stops when necessary.

The algorithm was developed by Swiss physician Dr. Albert A. Bühlmann, who did research into decompression theory at the Laboratory of Hyperbaric Physiology at the University Hospital in Zürich, Switzerland.[2][3] The results of Bühlmann's research that began in 1959 were published in a 1983 German book whose English translation was entitled Decompression-Decompression Sickness.[1] The book was regarded as the most complete public reference on decompression calculations and was used soon after in dive computer algorithms.

## Principles

Building on the previous work of John Scott Haldane and Robert Workman,[4][5] and working off funding from Shell Oil Company,[6] Bühlmann designed studies to establish the longest half-times of nitrogen and helium in human tissues.[1] These studies were confirmed by the Capshell experiments in the Mediterranean sea in 1966.[6][7]

The naming convention he used to describe his algorithms, for example, ZH-L16, comes from Zürich (ZH), limits (L) and the number of tissue compartments or M-value sets used (16).

## Tables

Max Hahn first used Bühlmann's algorithm to develop dive tables for the Swiss Underwater Sport Association. In 1987, the SAA Bühlmann System was developed by Bob Cole. This system used the dive tables and a set of rules so that people could dive safely and stay below their no-decompression limit.[8] The tables are still used today and are very popular; many dive computers still use the ZHL-8 algorithm and many tables are based on the ZHL-16 algorithm. These calculations also include considerations for repetitive and altitude diving.[1][9][10][11][12][13]

## References

1. ^ a b c d Bühlmann, Albert A (1984). Decompression-Decompression Sickness. Berlin New York: Springer-Verlag. ISBN 0-387-13308-9.
2. ^ Bühlmann, Albert A (1982). "[Experimental principles of risk-free decompression following hyperbaric exposure. 20 years of applied decompression research in Zurich]". Schweizerische Medizinische Wochenschrift (in German) 112 (2): 48–59. PMID 7071573.
3. ^ Wendling, J; Nussberger, P; Schenk, B (1999). "Milestones of the deep diving research laboratory Zurich". South Pacific Underwater Medicine Society Journal 29 (2). ISSN 0813-1988. OCLC 16986801. Retrieved 2009-04-02.
4. ^ Boycott, AE; Damant, GCC; Haldane, John Scott (1908). "Prevention of compressed air illness". Journal of Hygiene (Cambridge University Press) 8 (3): 342–443. doi:10.1017/S0022172400003399. PMC 2167126. PMID 20474365. Retrieved 2009-06-12.
5. ^ Workman, Robert D (1957). "Calculation of air saturation decompression tables". Navy Experimental Diving Unit Technical Report. NEDU-RR-11-57. Retrieved 2009-06-12.
6. ^ a b Völlm, Ernst B; Götte, Georg (1994). "Leading diving researcher dies unexpectedly: Albert A Bühlmann, 1923 - 1994". Pressure, newsletter of the Undersea and Hyperbaric Medical Society 23 (3): 1–3. ISSN 0889-0242.
7. ^ Bühlmann, Albert A; Frei, P; Keller, Hannes (October 1967). "Saturation and desaturation with N2 and He at 4 atm". Journal of Applied Physiology 23 (4): 458–62. PMID 6053671. Retrieved 2009-06-13.
8. ^ Powell, Mark (2008). Deco for Divers. Southend-on-Sea: Aquapress. p. 18. ISBN 1-905492-07-3.
9. ^ Bühlmann, Albert A (1987). "Decompression after repeated dives". Undersea Biomedical Research 14 (1): 59–66. ISSN 0093-5387. OCLC 2068005. PMID 3810993. Retrieved 2008-04-25.
10. ^ Böni, M; Schibli, R; Nussberger, P; Bühlmann, Albert A (1976). "Diving at diminished atmospheric pressure: air decompression tables for different altitudes". Undersea Biomedical Research 3 (3): 189–204. ISSN 0093-5387. OCLC 2068005. PMID 969023. Retrieved 2008-04-24.
11. ^ Bühlmann, Albert A; Schibli, R; Gehring, H (March 1973). "[Experimental studies on decompression following diving in mountain lakes at reduced air pressure]". Schweizerische Medizinische Wochenschrift (in German) 103 (10): 378–83. PMID 4144210.
12. ^ Bühlmann, Albert A (1989). "[Decompression problems in diving in mountain lakes]". Schweizerische Zeitschrift fur Sportmedizin (in French) 37 (2): 80–3; discussion 99–102. PMID 2799365.
13. ^ Bühlmann, Albert A (1984). "[Decompression during lowered air pressure]". Schweizerische Medizinische Wochenschrift (in German) 114 (26): 942–7. PMID 6087447.