Albert A. Bühlmann
Encyclopedia
Professor
Albert A. Bühlmann (16 May 1923 – 16 March 1994) was a Swiss
physician
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
, Switzerland
. His impact on diving ranged from complex commercial and military
diving to the occasional recreational diver
. He is held in high regard for his professional ethics and attention to his research subjects.
, Bühlmann specialized in pathophysiology
of the respiratory and circulatory systems. He was particularly interested in respiratory physiology
at high altitudes and high pressure
environments.
In 1959, Hannes Keller
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. Keller successfully tested his idea in the Lake Zurich
where he reached a depth of 400 feet and then lake Maggiore
where he reached a depth of 728 feet.
Building off the previous work of John Scott Haldane and Robert Workman, and working off funding from Shell Oil Company
, 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
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
utilizing Bühlmann's algorithm in a study funded by the United States Navy
.
Two out of eight Swiss military divers suffered decompression sickness following dives 1800 meters above sea level in Lake Silvaplana
. Bühlmann recognized the problems associated with altitude diving
, and proposed a method
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
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
s.
The results of Bühlmann's research that began in 1959, was published in a 1983 German book entitled 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 dive computer
algorithm
s. Two follow-up books were published in 1992 and 1995.
In 1987 the SAA
Bühlmann System was developed. This system used the dive tables and a set of rules so that people could dive safely and stay below their no-decompression limit. 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.
gave Bühlmann the Oceaneering
award in 1977.
In 1993, the Divers Alert Network
presented Bühlmann with an award for his life’s work in the service of decompression science.
Professor
A professor is a scholarly teacher; the precise meaning of the term varies by country. Literally, professor derives from Latin as a "person who professes" being usually an expert in arts or sciences; a teacher of high rank...
Albert A. Bühlmann (16 May 1923 – 16 March 1994) was a Swiss
Switzerland
Switzerland name of one of the Swiss cantons. ; ; ; or ), in its full name the Swiss Confederation , is a federal republic consisting of 26 cantons, with Bern as the seat of the federal authorities. The country is situated in Western Europe,Or Central Europe depending on the definition....
physician
Physician
A physician is a health care provider who practices the profession of medicine, which is concerned with promoting, maintaining or restoring human health through the study, diagnosis, and treatment of disease, injury and other physical and mental impairments...
who was principally responsible for a number of important contributions to decompression
Decompression
Decompression has several meanings:* Decompression , the release of pressure and the opposition of physical compression* Decompression sickness, a condition arising from the precipitation of dissolved gases into bubbles inside the body on depressurization* Decompression , a procedure used to treat...
science at the Laboratory of Hyperbaric Physiology at the University Hospital in Zürich
Zürich
Zurich is the largest city in Switzerland and the capital of the canton of Zurich. It is located in central Switzerland at the northwestern tip of Lake Zurich...
, Switzerland
Switzerland
Switzerland name of one of the Swiss cantons. ; ; ; or ), in its full name the Swiss Confederation , is a federal republic consisting of 26 cantons, with Bern as the seat of the federal authorities. The country is situated in Western Europe,Or Central Europe depending on the definition....
. His impact on diving ranged from complex commercial and military
Frogman
A frogman is someone who is trained to scuba diving or swim underwater in a military capacity which can include combat. Such personnel are also known by the more formal names of combat diver or combatant diver or combat swimmer....
diving to the occasional recreational diver
Scuba diving
Scuba diving is a form of underwater diving in which a diver uses a scuba set to breathe underwater....
. 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 ZürichUniversity of Zurich
The University of Zurich , located in the city of Zurich, is the largest university in Switzerland, with over 25,000 students. It was founded in 1833 from the existing colleges of theology, law, medicine and a new faculty of philosophy....
, Bühlmann specialized in pathophysiology
Pathophysiology
Pathophysiology is the study of the changes of normal mechanical, physical, and biochemical functions, either caused by a disease, or resulting from an abnormal syndrome...
of the respiratory and circulatory systems. He was particularly interested in respiratory physiology
Respiratory physiology
Respiratory physiology is the branch of human physiology focusing upon respiration.Topics include:-Volumes:* lung volumes* vital capacity* functional residual capacity* dead space* spirometry* body plethysmography* peak flow meter-Mechanics:...
at high altitudes and high pressure
Diving medicine
Diving medicine, also called undersea and hyperbaric medicine , is the diagnosis, treatment and prevention of conditions caused by humans entering the undersea environment...
environments.
Bühlmann decompression algorithm
The Bühlmann decompression algorithm is used to create decompression tables.In 1959, Hannes Keller
Hannes Keller
Hannes Keller is a Swiss physicist, mathematician, deep diving pioneer, and entrepreneur. In 1962, he reached a depth of 1000 feet in open ocean....
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. Keller successfully tested his idea in the Lake Zurich
Lake Zurich
Lake Zurich is a lake in Switzerland, extending southeast of the city of Zurich. It is also known as Lake Zürich and Lake of Zürich. It lies approximately at co-ordinates ....
where he reached a depth of 400 feet and then lake Maggiore
Lake Maggiore
Lake Maggiore is a large lake located on the south side of the Alps. It is the second largest of Italy and largest of southern Switzerland. Lake Maggiore is the most westerly of the three great prealpine lakes of Italy, it extends for about 70 km between Locarno and Arona.The climate is mild...
where he reached a depth of 728 feet.
Building off the previous work of John Scott Haldane and Robert Workman, and working off funding from Shell Oil Company
Shell Oil Company
Shell Oil Company is the United States-based subsidiary of Royal Dutch Shell, a multinational oil company of Anglo Dutch origins, which is amongst the largest oil companies in the world. Approximately 22,000 Shell employees are based in the U.S. The head office in the U.S. is in Houston, Texas...
, Bühlmann designed studies to establish the longest half-times
Half time (physics)
The half time is the time taken by a quantity to reach one half of its final value, where the rate of change is proportional to the difference between the present value and the final value....
of nitrogen and helium. These studies were confirmed by the Capshell experiments in the Mediterranean sea
Mediterranean Sea
The Mediterranean Sea is a sea connected to the Atlantic Ocean surrounded by the Mediterranean region and almost completely enclosed by land: on the north by Anatolia and Europe, on the south by North Africa, and on the east by the Levant...
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
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...
utilizing Bühlmann's algorithm in a study funded by the United States Navy
United States Navy
The United States Navy is the naval warfare service branch of the United States Armed Forces and one of the seven uniformed services of the United States. The U.S. Navy is the largest in the world; its battle fleet tonnage is greater than that of the next 13 largest navies combined. The U.S...
.
Two out of eight Swiss military divers suffered decompression sickness following dives 1800 meters above sea level in Lake Silvaplana
Lake Silvaplana
Lake Silvaplana 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....
. Bühlmann recognized the problems associated with altitude diving
Altitude diving
Altitude diving is scuba diving where the surface is 300 meters or more above sea level . The U.S. Navy tables recommend that no alteration be made for dives at altitudes lower than 91 meters and dives between 91 meters and 300 meters correction is required for dives over 44 meters sea water...
, and proposed a method
Bühlmann tables
The Bühlmann decompression algorithm is a mathematical model of the way in which inert gases enter and leave the body as the ambient pressure changes. It is used to create Bühlmann tables. These are decompression tables which allow divers to plan the depth and duration for dives and show...
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
Lake Titicaca is a lake located on the border of Peru and Bolivia. It sits 3,811 m above sea level, making it the highest commercially navigable lake in the world...
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
Dive profile
A dive profile is a two dimensional graphical representation of a dive showing depth and time.It is useful as an indication of the risks of decompression sickness and oxygen toxicity and also the volume of open-circuit breathing gas needed for a planned dive as these depend in part upon the depth...
s.
The results of Bühlmann's research that began in 1959, was published in a 1983 German book entitled 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 dive computer
Dive computer
A dive computer or decompression meter is a device used by a scuba diver to measure the time and depth of a dive so that a safe ascent profile can be calculated and displayed so that the diver can avoid decompression sickness.- Purpose :...
algorithm
Algorithm
In mathematics and computer science, an algorithm is an effective method expressed as a finite list of well-defined instructions for calculating a function. Algorithms are used for calculation, data processing, and automated reasoning...
s. Two follow-up books were published in 1992 and 1995.
In 1987 the SAA
Sub-Aqua Association
The Sub-Aqua Association or SAA is a diver training organization for scubadivers in the United Kingdom. The association and some other UK-based diving groups have traditionally used a club-based system with unpaid instructors, while the other principal training agency, PADI, organises most of its...
Bühlmann System was developed. This system used the dive tables and a set of rules so that people could dive safely and stay below their no-decompression limit. 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.
Awards
The Undersea and Hyperbaric Medical SocietyUndersea and Hyperbaric Medical Society
The Undersea and Hyperbaric Medical Society is the primary source of information for diving and hyperbaric medicine physiology worldwide.-History:The Undersea Medical Society grew from the close associations of a small group of scientists...
gave Bühlmann the Oceaneering
Oceaneering International
Oceaneering International Inc. is an applied technology company based in Houston, Texas, U.S.A. that provides engineered services and hardware to customers who operate in marine, space, and other environments...
award in 1977.
In 1993, the Divers Alert Network
Divers Alert Network
The Divers Alert Network is a non-profit 501 organization devoted to assisting divers in need. The Research department conducts significant medical research on recreational scuba diving safety...
presented Bühlmann with an award for his life’s work in the service of decompression science.
External links
- An Explanation of Professor A.A. Buehlmann's ZH-L16 Algorithm - An in-depth treatment of the mathematics involved
- DIY Decompression - describes the steps involved in using the algorithm to write a decompression program
- On-line calculator on the basis of the model