John Snow: Anesthesiologist, Epidemiologist, Scientist, and Hero.

A 19th century physician was crucial to the establishment of 2 medical specialties-anesthesiology and public health. Everyone whose interest in public health has increased in the last year will be amazed at Dr John Snow's career in anesthesiology. Those who recognize him as the first full-time physician anesthetist will be struck by his development of medical mapping during the Cholera Pandemic of 1848, resulting in one of the fundamental techniques of epidemiology and public health that has continued through today. Snow's accomplishments in anesthesiology and epidemiology reflected a concatenation of science, focus, and creativity. His training in the early 19th century integrated science, medicine, and his keen interest in respiratory physiology. His early clinical exposure to colliery workers in Newcastle was likely influenced by the earlier development of pneumatic medicine. He was committed to the notion that chemistry, especially the use of medicinal gases, would be transformative for medicine. Thus, he was "primed" when the news of the American anodyne ether reached London in 1846. When the third cholera pandemic reached London shortly thereafter, in the fall of 1848, his academic and practical understanding of gas chemistry and pharmacology, respiratory physiology, and anesthetic agents led him to question the popularly promulgated miasma-based theories of transmission. His methodical investigations, research, and perseverance were mirrored in his scholarly work, numerous presentations, and public advocacy. He articulated many scientific principles essential to the early practice of anesthesia-anesthetic potency, quantitative dosing of anesthetic agents, engineering principles required for conserving the latent heat of vaporization, and minimizing the contribution of anesthetic equipment to airway resistance. He moved easily and methodically between these worlds of physiology, chemistry, engineering, clinical medicine, and public health. In his role as the first medical epidemiologist, Snow understood the power of medical mapping and the graphic presentation of data. He was a pioneer in 2 nascent fields of medicine that were historically and remain contemporarily connected.