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Building on the previous work of [[John Scott Haldane]]<ref name="haldane" /> (The Haldane model, Royal Navy, 1908) and Robert Workman<ref name="Workman65" /> (M-Values, US-Navy, 1965) and working off funding from [[Shell Oil Company]],<ref name=Pressure94/> Bühlmann designed studies to establish the longest [[Half time (physics)|half-times]] of nitrogen and helium in human tissues.<ref name="AAB1984" /> These studies were confirmed by the ''Capshell'' experiments in the [[Mediterranean Sea]] in 1966.<ref name="Pressure94" /><ref name="pmid6053671" />
===
Inert gas exchange in haldanian models is assumed to be perfusion limited and is governed by the ordinary differential equation▼
The Bühlmann model uses a simplified version of the [[alveolar gas equation]] to calculate alveolar inert gas pressure
<math>\dfrac{\mathrm{d}P_t}{\mathrm{d}t} = k(P_{alv} - P_t)</math>▼
<math>P_{alv} = [P_{amb} - P_{H_{2}0} + \frac{1 - RQ}{RQ} P_{CO_{2}}]\cdot Q</math>▼
This equation can be solved for constant <math>P_{alv}</math> to give the so-called Haldane equation▼
Where <math>P_{H_{2}0}</math> is the water vapour pressure at 37 degrees centigrade (conventionally defined as 0.0627 bar), <math>P_{CO_{2}}</math> the carbon dioxide pressure (conventionally defined as 0.0534 bar), <math>Q</math> the inspired inert gas fraction, and <math>RQ</math> the respiratory coefficient: the ratio of carbon dioxide production to oxygen consumption. The Buhlmann model sets <math>RQ</math> to 1, simplifying the equation to▼
<math>P_t(t) = P_{t}(0) + (P_{t}(0) - P_{alv}(t)) \cdot e^{-kt}</math>▼
<math>P_{alv} = [P_{amb} - P_{H_{2}0}]\cdot Q</math>▼
▲Inert gas exchange in haldanian models is assumed to be perfusion limited and is governed by the ordinary differential equation
▲<math>\dfrac{\mathrm{d}P_t}{\mathrm{d}t} = k(P_{alv} - P_t)</math>
▲This equation can be solved for constant <math>P_{alv}</math> to give the
▲<math>P_t(t) = P_{t}(0) + (P_{t}(0) - P_{alv}(t)) \cdot e^{-kt}</math>
▲===Alveolar inert gas pressure===
<math>
▲<math>P_{alv} = [P_{amb} - P_{H_{2}0} + \frac{1 - RQ}{RQ} P_{CO_{2}}]\cdot Q</math>
▲
</math>
▲Where <math>P_{H_{2}0}</math> is the water vapour pressure at 37 degrees centigrade (conventionally defined as 0.0627 bar), <math>P_{CO_{2}}</math> the carbon dioxide pressure (conventionally defined as 0.0534 bar), <math>Q</math> the inspired inert gas fraction, and <math>RQ</math> the respiratory coefficient: the ratio of carbon dioxide production to oxygen consumption. The Buhlmann model sets <math>RQ</math> to 1, simplifying the equation to
▲<math>P_{alv} = [P_{amb} - P_{H_{2}0}]\cdot Q</math>
===Tissue inert gas limits===
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where <math>a_{N_2}</math> and <math>a_{He}</math> are the tissue's <math>a</math> Nitrogen and Helium coefficients and <math>R</math> the ratio of dissolved Helium to total dissolved inert gas.
==Ascent rates==▼
Ascent rate is intrinsically a variable, and may be selected by the programmer or user for table generation or simulations, and measured as real-time input in dive computer applications.▼
The rate of ascent to the first stop is limited to 3 bar per minute for compartments 1 to 5, 2 bar per minute for compartments 6 and 7, and 1 bar per minute for compartments 8 to 16. Chamber decompression may be continuous, or if stops are preferred they may be done at intervals of 1 or 3 m.<ref name="Buhlmann 1984" />▼
===Versions===
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* ZH-L 8 ADT MB PDIS: [[Decompression practice#Profile determined intermediate stops|Profile-Determined Intermediate Stops]].<ref name="dykcen">{{cite web|url=http://www.dykcen.dk/PDF/Instruktor%20info/PDIS_Algorithm.pdf|title=Diving with PDIS (Profile-Dependent Intermediate Stop)|last=Staff|work=Dykkercentret website|publisher=Dykkercentret ApS|access-date=5 March 2016|___location=Frederiksberg|archive-url=https://web.archive.org/web/20161017170523/http://www.dykcen.dk/PDF/Instruktor%20info/PDIS_Algorithm.pdf|archive-date=17 October 2016|url-status=dead|df=dmy-all}}</ref>
* ZH-L 8 ADT MB PMG: Predictive Multi-Gas.<ref name="Scubapro-Luna-PMG" />
▲==Ascent rates==
▲Ascent rate is intrinsically a variable, and may be selected by the programmer or user for table generation or simulations, and measured as real-time input in dive computer applications.
▲The rate of ascent to the first stop is limited to 3 bar per minute for compartments 1 to 5, 2 bar per minute for compartments 6 and 7, and 1 bar per minute for compartments 8 to 16. Chamber decompression may be continuous, or if stops are preferred they may be done at intervals of 1 or 3 m.<ref name="Buhlmann 1984" />
==References==
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