Adolf Eugen Fick (1829-1901) - The Man Behind the Cardiac Output Equation.

Adolf Fick was a German physiologist, born in Kassel in 1829, who studied medicine at the University of Marburg and graduated in 1851. He worked first in Zurich and then in Wurzburg. Most of his studies were based on physics and mathematics, and deep analysis, and only later were proven by experiments. Fick's name in physics is associated to the laws of diffusion of solutions, and in medicine to the principle of cardiac output calculation. In 1855, he proposed Fick's laws on gas diffusion. In 1870, he devised Fick's principle, which allows the measurement of cardiac output and calculations of intracardiac shunts from the arteriovenous oxygen difference. The method was later generalized to the Fick principle, according to which the flow of an indicator taken up or released by an organ corresponds to the difference between the indicator flows in the inflow and outflow tracts. Fick invented several devices most of them aimed to improve precision in his physiologic experiments. In 1868, he invented the plethysmograph, for recording the speed of blood in the human artery. In 1888, the tonometer for measuring from outside the hydrostatic pressure inside the eyeball. After 3 decades as Professor in Wurzburg, he retired. Fick died at Blankenberge, Belgium in 1901 age 71 years old.
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