Professor Professor (commonly abbreviated as Prof.) is an academic rank at universities and other post-secondary education and research institutions in most countries. Literally, ''professor'' derives from Latin as a "person who professes". Professo ...

Albert Alois Bühlmann (16 May 1923 – 16 March 1994) was a Swiss

physician A physician (American English), medical practitioner (Commonwealth English), medical doctor, or simply doctor, is a health professional who practices medicine, which is concerned with promoting, maintaining or restoring health through th ...

who was principally responsible for a number of important contributions to decompression science at the Laboratory of Hyperbaric Physiology at the University Hospital in

Zürich , neighboring_municipalities = Adliswil, Dübendorf, Fällanden, Kilchberg, Maur, Oberengstringen, Opfikon, Regensdorf, Rümlang, Schlieren, Stallikon, Uitikon, Urdorf, Wallisellen, Zollikon , twintowns = Kunming, San Francisco Z ...

, Switzerland. His impact on diving ranged from complex

commercial Commercial may refer to: * a dose of advertising conveyed through media (such as - for example - radio or television) ** Radio advertisement ** Television advertisement * (adjective for:) commerce, a system of voluntary exchange of products and s ...

and

military A military, also known collectively as armed forces, is a heavily armed, highly organized force primarily intended for warfare. It is typically authorized and maintained by a sovereign state, with its members identifiable by their distinct ...

diving to the occasional

recreational diver Recreational diving or sport diving is diving for the purpose of leisure and enjoyment, usually when using scuba equipment. The term "recreational diving" may also be used in contradistinction to "technical diving", a more demanding aspect of r ...

. He is held in high regard for his professional ethics and attention to his research subjects.

Background

After completing his education at the

University of Zürich The University of Zürich (UZH, german: Universität Zürich) is a public research university located in the city of Zürich, Switzerland. It is the largest university in Switzerland, with its 28,000 enrolled students. It was founded in 1833 f ...

, Bühlmann specialized in

pathophysiology Pathophysiology ( physiopathology) – a convergence of pathology with physiology – is the study of the disordered physiological processes that cause, result from, or are otherwise associated with a disease or injury. Pathology is ...

of the respiratory and circulatory systems. He was particularly interested in

respiratory physiology In physiology, respiration is the movement of oxygen from the outside environment to the cells within tissues, and the removal of carbon dioxide in the opposite direction that's to the environment. The physiological definition of respiration di ...

at high altitudes and

high pressure In science and engineering the study of high pressure examines its effects on materials and the design and construction of devices, such as a diamond anvil cell, which can create high pressure. By ''high pressure'' is usually meant pressures of th ...

environments.

Bühlmann decompression algorithm

The Bühlmann decompression algorithm is used to create

decompression tables There are several categories of decompression equipment used to help divers decompress, which is the process required to allow divers to return to the surface safely after spending time underwater at higher ambient pressures. Decompression o ...

. In 1959,

Hannes Keller Hannes Keller (September 20, 1934 – ) was a Swiss physicist, mathematician, deep diving pioneer, and entrepreneur. In 1962, he reached a depth of in open ocean. In the 1970s through the 1980s, Keller made himself a name as an entrepreneur in th ...

became interested in deep diving and developed tables for mixed-gas decompression. Not a diver himself, Bühlmann was intrigued by project and suggested suitable

breathing gases A breathing gas is a mixture of gaseous chemical elements and compounds used for respiration. Air is the most common and only natural breathing gas, but other mixtures of gases, or pure oxygen, are also used in breathing equipment and enclosed h ...

. Keller successfully tested his idea in the

Lake Zurich __NOTOC__ Lake Zurich ( Swiss German/ Alemannic: ''Zürisee''; German: ''Zürichsee''; rm, Lai da Turitg) is a lake in Switzerland, extending southeast of the city of Zürich. Depending on the context, Lake Zurich or ''Zürichsee'' can be used t ...

where he reached a depth of 400 feet and then

Lake Maggiore Lake Maggiore (, ; it, Lago Maggiore ; lmo, label=Western Lombard, Lagh Maggior; pms, Lagh Magior; literally 'Greater Lake') or Verbano (; la, Lacus Verbanus) is a large lake located on the south side of the Alps. It is the second largest l ...

where he reached a depth of 728 feet. Building on the previous work of

John Scott Haldane John Scott Haldane (; 2 May 1860 – 14/15 March 1936) was a British physician and physiologist famous for intrepid self-experimentation which led to many important discoveries about the human body and the nature of gases. He also experime ...

and Robert Workman, and with funding from

Shell Oil Company Shell USA, Inc. (formerly Shell Oil Company, Inc.) is the United States-based wholly owned subsidiary of Shell plc, a UK-based transnational corporation " oil major" which is amongst the largest oil companies in the world. Approximately 18,0 ...

, Bühlmann designed studies to establish the longest half-times of nitrogen and helium. These studies were confirmed by the ''Capshell'' experiments in the

Mediterranean Sea The Mediterranean Sea is a sea connected to the Atlantic Ocean, surrounded by the Mediterranean Basin and almost completely enclosed by land: on the north by Western and Southern Europe and Anatolia, on the south by North Africa, and on ...

in 1966. 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). In 1962, Keller set a new world record when he reached a depth of 1000 feet off the coast of

California California is a state in the Western United States, located along the Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the most populous U.S. state and the 3rd largest by area. It is also the m ...

utilizing Bühlmann's algorithm in a study funded by the

United States Navy The United States Navy (USN) is the maritime service branch of the United States Armed Forces and one of the eight uniformed services of the United States. It is the largest and most powerful navy in the world, with the estimated tonnage ...

. Two out of eight Swiss military divers suffered decompression sickness following dives 1800 meters above sea level in

Lake Silvaplana Lake Silvaplana (german: Silvaplanersee; rm, Lej da Silvaplauna) is a lake in the Upper- Engadine valley of Grisons, Switzerland. It takes its name from the village of Silvaplana. The lake is also connected to the nearby Lej da Champfèr. Togethe ...

. Bühlmann recognized the problems associated with

altitude diving Altitude diving is underwater diving using scuba or surface supplied diving equipment where the surface is or more above sea level (for example, a mountain lake). Altitude is significant in diving because it affects the decompression requireme ...

, and proposed a

method Method ( grc, μέθοδος, methodos) literally means a pursuit of knowledge, investigation, mode of prosecuting such inquiry, or system. In recent centuries it more often means a prescribed process for completing a task. It may refer to: *Scien ...

which calculated maximum nitrogen loading in the tissues at a particular ambient pressure. The tables developed were adopted by the Swiss military in 1972. An expedition to

Lake Titicaca Lake Titicaca (; es, Lago Titicaca ; qu, Titiqaqa Qucha) is a large freshwater lake in the Andes mountains on the border of Bolivia and Peru. It is often called the highest navigable lake in the world. By volume of water and by surface area, i ...

at 3800 meters above sea level in 1987 revealed no decompression issues while utilizing Bühlmann's ZH-L16 algorithm. In addition to altitude diving, his calculations also include considerations for repetitive

dive profile A dive profile is a description of a diver's pressure exposure over time. It may be as simple as just a depth and time pair, as in: "sixty for twenty," (a bottom time of 20 minutes at a depth of 60 feet) or as complex as a second by second gra ...

s. The results of Bühlmann's research that began in 1959, was published in a 1983 German book entitled ''Dekompression-Dekompressionskrankheit'' (Decompression-Decompression Sickness). An English version of this book became available in 1984. The book was regarded as the most complete public reference on decompression calculations and was used soon after in coding

dive computer A dive computer, personal decompression computer or decompression meter is a device used by an underwater diver to measure the elapsed time and depth during a dive and use this data to calculate and display an ascent profile which according to th ...

algorithm In mathematics and computer science, an algorithm () is a finite sequence of rigorous instructions, typically used to solve a class of specific problems or to perform a computation. Algorithms are used as specifications for performing ...

s. Two follow-up books were published in 1992 and 1995. Versions of Bühlmann's ZHL-16 model have been used to generate the standard diving tables for a number of sports diving associations.

Max Hahn Max or MAX may refer to: Animals * Max (dog) (1983–2013), at one time purported to be the world's oldest living dog * Max (English Springer Spaniel), the first pet dog to win the PDSA Order of Merit (animal equivalent of OBE) * Max (gorilla) (1 ...

used Bühlmann's model to develop the Deco '92 Tables used by the Swiss Underwater Sport Association and the Association of German Sports Divers, and Bob Cole and Bühlmann developed the

Sub-Aqua Association The Sub-Aqua Association or SAA is a diver training organization for scubadivers in the United Kingdom. The SAA and other UK-based diving groups have traditionally used a club-based system with unpaid instructors, while other training agencies ...

(SAA) Bühlmann System in 1987, which used the tables and a set of instructions for their use in recreational diving without decompression stops. The tables are still used in the 2020s and remain popular, while many

s use variations of the ZHL-8, ZH-L12, or ZHL-16 algorithm.

Death

Bühlmann died unexpectedly of

heart failure Heart failure (HF), also known as congestive heart failure (CHF), is a syndrome, a group of signs and symptoms caused by an impairment of the heart's blood pumping function. Symptoms typically include shortness of breath, excessive fatigue, ...

on 16 March 1994.

Awards

The

Undersea and Hyperbaric Medical Society The underwater environment is the region below the surface of, and immersed in, liquid water in a natural or artificial feature (called a body of water), such as an ocean, sea, lake, pond, reservoir, river, canal, or aquifer. Some charac ...

gave Bühlmann the

Oceaneering Oceaneering International, Inc. is a subsea engineering and applied technology company based in Houston, Texas, U.S. that provides engineered services and hardware to customers who operate in marine, space, and other environments. Oceaneering' ...

award in 1977. In 1993, the

Divers Alert Network Divers Alert Network (DAN) is a group of not-for-profit organizations dedicated to improving diving safety for all divers. It was founded in Durham, North Carolina, United States, in 1980 at Duke University providing 24/7 telephonic hot-line div ...

presented Bühlmann with an award for his life's work in the service of decompression science.

References

External links