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John B. West - One of the best experts on this subject based on the ideXlab platform.
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Early history of high-Altitude Physiology.
Annals of the New York Academy of Sciences, 2015Co-Authors: John B. WestAbstract:High-Altitude Physiology can be said to have begun in 1644 when Torricelli described the first mercury barometer and wrote the immortal words "We live submerged at the bottom of an ocean of the element air." Interestingly, the notion of atmospheric pressure had eluded his teacher, the great Galileo. Blaise Pascal was responsible for describing the fall in pressure with increasing Altitude, and Otto von Guericke gave a dramatic demonstration of the enormous force that could be developed by atmospheric pressure. Robert Boyle learned of Guericke's experiment and, with Robert Hooke, constructed the first air pump that allowed small animals to be exposed to a low pressure. Hooke also constructed a small low-pressure chamber and exposed himself to a simulated Altitude of about 2400 meters. With the advent of ballooning, humans were rapidly exposed to very low pressures, sometimes with tragic results. For example, the French balloon, Zenith, rose to over 8000 m, and two of the three aeronauts succumbed to the hypoxia. Paul Bert was the first person to clearly state that the deleterious effects of high Altitude were caused by the low partial pressure of oxygen (PO2), and later research was accelerated by high-Altitude stations and expeditions to high Altitude.
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Joseph Barcroft's studies of high-Altitude Physiology.
American journal of physiology. Lung cellular and molecular physiology, 2013Co-Authors: John B. WestAbstract:Joseph Barcroft (1872-1947) was an eminent British physiologist who made contributions to many areas. Some of his studies at high Altitude and related topics are reviewed here. In a remarkable experiment he spent 6 days in a small sealed room while the oxygen concentration of the air gradually fell, simulating an ascent to an Altitude of nearly 5,500 m. The study was prompted by earlier reports by J. S. Haldane that the lung secreted oxygen at high Altitude. Barcroft tested this by having blood removed from an exposed radial artery during both rest and exercise. No evidence for oxygen secretion was found, and the combination of 6 days incarceration and the loss of an artery was heroic. To obtain more data, Barcroft organized an expedition to Cerro de Pasco, Peru, Altitude 4,300 m, that included investigators from both Cambridge, UK and Harvard. Again oxygen secretion was ruled out. The protocol included neuropsychometric measurements, and Barcroft famously concluded that all dwellers at high Altitude are persons of impaired physical and mental powers, an assertion that has been hotly debated. Another colorful experiment in a low-pressure chamber involved reducing the pressure below that at the summit of Mt. Everest but giving the subjects 100% oxygen to breathe while exercising as a climber would on Everest. The conclusion was that it would be possible to reach the summit while breathing 100% oxygen. Barcroft was exceptional for his self-experimentation under hazardous conditions.
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Joseph Barcroft's studies of high-Altitude Physiology.
American Journal of Physiology-lung Cellular and Molecular Physiology, 2013Co-Authors: John B. WestAbstract:Joseph Barcroft (1872–1947) was an eminent British physiologist who made contributions to many areas. Some of his studies at high Altitude and related topics are reviewed here. In a remarkable expe...
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Adventures in high-Altitude Physiology
Advances in experimental medicine and biology, 2006Co-Authors: John B. WestAbstract:I have probably had more fun doing high-Altitude Physiology than most people. Some 45 years ago I applied to be a member of Sir Edmund Hillary’s Silver Hut expedition and was accepted in spite of having no previous climbing experience. On this project a group of physiologists wintered at an Altitude of 5800 m just south of Everest and carried out an extensive research program. Subsequently measurements were extended up to an Altitude of 7440 m on Makalu. In fact the Altitude of these field measurements of \( \dot VO_{2max} \) has never been exceeded. This led to a long interest in high-Altitude medicine and Physiology which culminated in the 1981 American Medical Research Expedition to Everest during which 5 people reached the summit and the first physiological measurements on the summit were made. Among the extraordinary findings were an extremely low alveolar PCO2 of 7–8 mmHg, an arterial pH (from the measured PCO2 and blood base excess) of over 7.7, and a \( \dot VO_{2max} \) of just over one liter/min. More recently a major interest has been the pathogenesis of high Altitude pulmonary edema which we believe is caused by damage to pulmonary capillaries when the pressure inside some of them increases as a result of uneven hypoxic pulmonary vasoconstriction (“stress failure”). Another interest is improving the conditions of people who need to work at high Altitude by oxygen enrichment of room air. This enhances well-being and productivity, and is now being used or planned for several high-Altitude telescopes up to Altitudes of 5600 m. Other recent high-Altitude projects include establishing an international archive on high-Altitude medicine and Physiology at UCSD, several books in the area including the historical study High Life, and editing the journal High Altitude Medicine & Biology.
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HIGH Altitude, Physiology AND DISEASES
Encyclopedia of Respiratory Medicine, 2006Co-Authors: John B. WestAbstract:Exposure to high Altitude causes generalized hypoxia throughout the body because the reduction in barometric pressure reduces the inspired partial pressure of oxygen. Physiological consequences include impairment of physical performance, mental performance, and sleep. The deleterious effects of high Altitude are reduced by the process of acclimatization, the most important feature of which is an increase in ventilation. Other features include polycythemia, changes in oxidative enzymes in cells, and reduced intercapillary distances in some tissues. However acclimatization does not return the body to its sea level status. Three principal high-Altitude diseases affect people who normally live near sea level. Acute mountain sickness causes headache, fatigue, insomnia, and anorexia but is generally a self-limiting disease that resolves after 2–3 days. High-Altitude pulmonary edema is a much more serious condition characterized by severe dyspnea, which may progress to coughing up frothy fluid. The pulmonary hypertension that occurs at high Altitude because of the alveolar hypoxia damages some pulmonary capillaries, a condition known as stress failure. High-Altitude cerebral edema is uncommon but potentially fatal and causes confusion, ataxia, and eventually coma. Permanent residents of high Altitude sometimes develop chronic mountain sickness characterized by severe polycythemia and a constellation of neurological symptoms.
Hanns-christian Gunga - One of the best experts on this subject based on the ideXlab platform.
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Nathan Zuntz: His Life and Work in the Fields of High Altitude Physiology and Aviation Medicine
2008Co-Authors: Hanns-christian GungaAbstract:This book focuses on the life and work of Nathan Zuntz (1847-1920), a German physiologist, who made significant contributions to high Altitude Physiology and aviation medicine. He achieved fame for his invention of the Zuntz-Geppert respiratory apparatus in 1886 and the first treadmill (Laufband) in 1889. He also invented an X-ray apparatus to observe cardiac changes during exercise and constructed a climate chamber to study exercise under varying and sometimes extreme climates. * Focuses on Zuntz's contribution to high Altitude Physiology and aviation medicine
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nathan zuntz 1847 1920 a german pioneer in high Altitude Physiology and aviation medicine part i biography
Aviation Space and Environmental Medicine, 1995Co-Authors: Hanns-christian Gunga, K A KirschAbstract:Nathan Zuntz (1847-1920) was a key person in the history of high Altitude Physiology and aviation medicine. As a professor of animal Physiology at the Landwirtschaftliche Hochschule (Agricultural University) in Berlin from 1881 until 1918, he carried out laboratory studies on the changes in metabolism at rest and during exercise. To this end he, together with August Julius Geppert, developed the famous "Zuntz-Geppert'schen Respirationsapparat" (Zuntz-Geppert respiratory apparatus) in 1885. In the early 1890's, Zuntz extended his research to the field of high Altitude Physiology. In view of the variety of questions, and despite considerable methodological problems, Zuntz first studied the effects of lowered PO2 on the human body in a Pneumatischen Kammer (hypobaric chamber). In 1893 the newly completed Capanna Regina Margherita, an international research station at the top of Monte Rosa, Italy (4,500 m), became the site of Zuntz's extensive field studies, where he worked together with his close co-worker Adolf Loewy (1862-1936), the Italian Angelo Mosso (1846-1910), and the Austrian Arnold Durig (1872-1961). For their investigations Zuntz invented the transportable Gasuhr (a gas exchange measuring device). In 1902 Zuntz and the Austrian Hermann von Schroetter (1870-1928) made two balloon ascents up to 5,000 m in Berlin. A synopsis of these studies was published by Zuntz in 1906: his famous book "Hohenklima und Bergwanderungen" (High Altitude climate and mountain-touring). A few years later Zuntz undertook further expeditions to the Canary Islands (Pico de Teide), conducting studies in airships and planes until 1914. Zuntz retired in 1916 and died in Berlin on March 22, 1920.
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nathan zuntz 1847 1920 a german pioneer in high Altitude Physiology and aviation medicine part ii scientific work
Aviation Space and Environmental Medicine, 1995Co-Authors: Hanns-christian Gunga, K A KirschAbstract:For over 52 years, the work of Nathan Zuntz (1847-1920) covered an amazingly wide spectrum of research fields; metabolism, nutrition, respiration, blood gases, exercise, and high Altitude Physiology were the main themes. Zuntz achieved fame for his invention of the Zuntz-Geppert respiratory apparatus in 1886 and the first Laufband (treadmill) in 1889. To this experimental setup Zuntz later added an X-ray apparatus in 1914 to determine the changes in heart volume during exercise. Moreover, he constructed a climate chamber to study exercise under varying and sometimes extreme climates. For field studies Zuntz invented a transportable Gasuhr (dry gas measuring device). Zuntz was the first to describe the difference between laboratory data gained in a hypobaric chamber and the measurements at high Altitude. He found that the barometric formula is not applicable in the field. Two balloon expeditions in 1902 by Zuntz and his pupil, v. Schroetter, marked the step from terrestrial Physiology towards aviation medicine. An outile of the development of scientific aviation in Berlin from 1880-1918 elucidates how closely the aviation union, army and scientific departments were connected with and dependent upon each other. In cooperation with these institutions Zuntz and v. Schroetter constructed an oxygen supply system and planned a pressure cabin for extreme Altitudes above 10,000 m, a forerunner of modern systems in aviation and astronautics. in 1912, Zuntz and v. Schroetter each published papers on aviation medicine, both publications internationally unique in style and extents. Zuntz's work in its empirical approach was the counterpart to the established formal mathematical-physical reductionism of the German Physiological Society. Outside of Germany, applied or integrative Physiology works in the German-speaking countries. His scientific universality was matched by a decided accuracy to detail
Bruce D. Johnson - One of the best experts on this subject based on the ideXlab platform.
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Incidence and Symptoms of High Altitude Illness in South Pole Workers: Antarctic Study of Altitude Physiology (ASAP).
Clinical medicine insights. Circulatory respiratory and pulmonary medicine, 2011Co-Authors: Paul J. Anderson, Andrew D. Miller, Kathy A. O'malley, Maile L. Ceridon, Kenneth C. Beck, Christina M. Wood, Heather J. Wiste, Joshua J. Mueller, Jacob B. Johnson, Bruce D. JohnsonAbstract:Introduction: Each year, the US Antarctic Program rapidly transports scientists and support personnel from sea level (SL) to the South Pole (SP, 2835 m) providing a unique natural laboratory to quantify the incidence of acute mountain sickness (AMS), patterns of Altitude related symptoms and the field effectiveness of acetazolamide in a highly controlled setting. We hypothesized that the combination of rapid ascent (3 hr), accentuated hypobarism (relative to Altitude), cold, and immediate exertion would increase Altitude illness risk. Methods: Medically screened adults (N = 246, age = 37 ± 11 yr, 30% female, BMI = 26 ± 4 kg/m2) were recruited. All underwent SL and SP physiological evaluation, completed Lake Louise symptom questionnaires (LLSQ, to define AMS), and answered additional symptom related questions (eg, exertional dyspnea, mental status, cough, edema and general health), during the 1st week at Altitude. Acetazolamide, while not mandatory, was used by 40% of participants. Results: At SP, the barometric pressure resulted in physiological Altitudes that approached 3400 m, while T °C averaged -42, humidity 0.03%. Arterial oxygen saturation averaged 89% ± 3%. Overall, 52% developed LLSQ defined AMS. The most common symptoms reported were exertional dyspnea-(87%), sleeping difficulty-(74%), headache-(66%), fatigue-(65%), and dizziness/lightheadedness-(46%). Symptom severity peaked on days 1–2, yet in .20% exertional dyspnea, fatigue and sleep problems persisted through day 7. AMS incidence was similar between those using acetazolamide and those abstaining (51 vs. 52%, P = 0.87). Those who used acetazolamide tended to be older, have less Altitude experience, worse symptoms on previous exposures, and less SP experience. Conclusion: The incidence of AMS at SP tended to be higher than previously reports in other geographic locations at similar Altitudes. Thus, the SP constitutes a more intense Altitude exposure than might be expected considering physical Altitude alone. Many symptoms persist, possibly due to extremely cold, arid conditions and the benefits of acetazolamide appeared negligible, though it may have prevented more severe symptoms in higher risk subjects.
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Physical Activity and the Incidence of Acute Mountain Sickness in United States Antarctic Program Participants Following Rapid Transport to the South Pole: Antarctic Study of Altitude Physiology (ASAP)
The FASEB Journal, 2010Co-Authors: Maile L. Ceridon, Paul J. Anderson, Andrew D. Miller, Kathy A. O'malley, Kenneth C. Beck, Jacob B. Johnson, Bruce D. JohnsonAbstract:BackgroundPhysical activity has been proposed as a risk factor for Altitude illness however it is unclear whether the total amount or intensity of activity determines illness. PurposeTo examine act...
K A Kirsch - One of the best experts on this subject based on the ideXlab platform.
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nathan zuntz 1847 1920 a german pioneer in high Altitude Physiology and aviation medicine part i biography
Aviation Space and Environmental Medicine, 1995Co-Authors: Hanns-christian Gunga, K A KirschAbstract:Nathan Zuntz (1847-1920) was a key person in the history of high Altitude Physiology and aviation medicine. As a professor of animal Physiology at the Landwirtschaftliche Hochschule (Agricultural University) in Berlin from 1881 until 1918, he carried out laboratory studies on the changes in metabolism at rest and during exercise. To this end he, together with August Julius Geppert, developed the famous "Zuntz-Geppert'schen Respirationsapparat" (Zuntz-Geppert respiratory apparatus) in 1885. In the early 1890's, Zuntz extended his research to the field of high Altitude Physiology. In view of the variety of questions, and despite considerable methodological problems, Zuntz first studied the effects of lowered PO2 on the human body in a Pneumatischen Kammer (hypobaric chamber). In 1893 the newly completed Capanna Regina Margherita, an international research station at the top of Monte Rosa, Italy (4,500 m), became the site of Zuntz's extensive field studies, where he worked together with his close co-worker Adolf Loewy (1862-1936), the Italian Angelo Mosso (1846-1910), and the Austrian Arnold Durig (1872-1961). For their investigations Zuntz invented the transportable Gasuhr (a gas exchange measuring device). In 1902 Zuntz and the Austrian Hermann von Schroetter (1870-1928) made two balloon ascents up to 5,000 m in Berlin. A synopsis of these studies was published by Zuntz in 1906: his famous book "Hohenklima und Bergwanderungen" (High Altitude climate and mountain-touring). A few years later Zuntz undertook further expeditions to the Canary Islands (Pico de Teide), conducting studies in airships and planes until 1914. Zuntz retired in 1916 and died in Berlin on March 22, 1920.
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nathan zuntz 1847 1920 a german pioneer in high Altitude Physiology and aviation medicine part ii scientific work
Aviation Space and Environmental Medicine, 1995Co-Authors: Hanns-christian Gunga, K A KirschAbstract:For over 52 years, the work of Nathan Zuntz (1847-1920) covered an amazingly wide spectrum of research fields; metabolism, nutrition, respiration, blood gases, exercise, and high Altitude Physiology were the main themes. Zuntz achieved fame for his invention of the Zuntz-Geppert respiratory apparatus in 1886 and the first Laufband (treadmill) in 1889. To this experimental setup Zuntz later added an X-ray apparatus in 1914 to determine the changes in heart volume during exercise. Moreover, he constructed a climate chamber to study exercise under varying and sometimes extreme climates. For field studies Zuntz invented a transportable Gasuhr (dry gas measuring device). Zuntz was the first to describe the difference between laboratory data gained in a hypobaric chamber and the measurements at high Altitude. He found that the barometric formula is not applicable in the field. Two balloon expeditions in 1902 by Zuntz and his pupil, v. Schroetter, marked the step from terrestrial Physiology towards aviation medicine. An outile of the development of scientific aviation in Berlin from 1880-1918 elucidates how closely the aviation union, army and scientific departments were connected with and dependent upon each other. In cooperation with these institutions Zuntz and v. Schroetter constructed an oxygen supply system and planned a pressure cabin for extreme Altitudes above 10,000 m, a forerunner of modern systems in aviation and astronautics. in 1912, Zuntz and v. Schroetter each published papers on aviation medicine, both publications internationally unique in style and extents. Zuntz's work in its empirical approach was the counterpart to the established formal mathematical-physical reductionism of the German Physiological Society. Outside of Germany, applied or integrative Physiology works in the German-speaking countries. His scientific universality was matched by a decided accuracy to detail
Maile L. Ceridon - One of the best experts on this subject based on the ideXlab platform.
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Incidence and Symptoms of High Altitude Illness in South Pole Workers: Antarctic Study of Altitude Physiology (ASAP).
Clinical medicine insights. Circulatory respiratory and pulmonary medicine, 2011Co-Authors: Paul J. Anderson, Andrew D. Miller, Kathy A. O'malley, Maile L. Ceridon, Kenneth C. Beck, Christina M. Wood, Heather J. Wiste, Joshua J. Mueller, Jacob B. Johnson, Bruce D. JohnsonAbstract:Introduction: Each year, the US Antarctic Program rapidly transports scientists and support personnel from sea level (SL) to the South Pole (SP, 2835 m) providing a unique natural laboratory to quantify the incidence of acute mountain sickness (AMS), patterns of Altitude related symptoms and the field effectiveness of acetazolamide in a highly controlled setting. We hypothesized that the combination of rapid ascent (3 hr), accentuated hypobarism (relative to Altitude), cold, and immediate exertion would increase Altitude illness risk. Methods: Medically screened adults (N = 246, age = 37 ± 11 yr, 30% female, BMI = 26 ± 4 kg/m2) were recruited. All underwent SL and SP physiological evaluation, completed Lake Louise symptom questionnaires (LLSQ, to define AMS), and answered additional symptom related questions (eg, exertional dyspnea, mental status, cough, edema and general health), during the 1st week at Altitude. Acetazolamide, while not mandatory, was used by 40% of participants. Results: At SP, the barometric pressure resulted in physiological Altitudes that approached 3400 m, while T °C averaged -42, humidity 0.03%. Arterial oxygen saturation averaged 89% ± 3%. Overall, 52% developed LLSQ defined AMS. The most common symptoms reported were exertional dyspnea-(87%), sleeping difficulty-(74%), headache-(66%), fatigue-(65%), and dizziness/lightheadedness-(46%). Symptom severity peaked on days 1–2, yet in .20% exertional dyspnea, fatigue and sleep problems persisted through day 7. AMS incidence was similar between those using acetazolamide and those abstaining (51 vs. 52%, P = 0.87). Those who used acetazolamide tended to be older, have less Altitude experience, worse symptoms on previous exposures, and less SP experience. Conclusion: The incidence of AMS at SP tended to be higher than previously reports in other geographic locations at similar Altitudes. Thus, the SP constitutes a more intense Altitude exposure than might be expected considering physical Altitude alone. Many symptoms persist, possibly due to extremely cold, arid conditions and the benefits of acetazolamide appeared negligible, though it may have prevented more severe symptoms in higher risk subjects.
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Physical Activity and the Incidence of Acute Mountain Sickness in United States Antarctic Program Participants Following Rapid Transport to the South Pole: Antarctic Study of Altitude Physiology (ASAP)
The FASEB Journal, 2010Co-Authors: Maile L. Ceridon, Paul J. Anderson, Andrew D. Miller, Kathy A. O'malley, Kenneth C. Beck, Jacob B. Johnson, Bruce D. JohnsonAbstract:BackgroundPhysical activity has been proposed as a risk factor for Altitude illness however it is unclear whether the total amount or intensity of activity determines illness. PurposeTo examine act...