Measurement of cardiac output by the foreign gas method using nitrous oxide.

Abstract

Although he apparently never used it himself, Fick in 1870 elaborated the well known principle, bearing his name, for measuring cardiac output. He expressed it in the same form as it is presently used, i.e. that if one knows the amount of oxygen taken up by the lungs per unit time (or the amount of carbon dioxide eliminated also per unit time) and the difference in concentrations of oxygen (or carbon dioxide) between the arterial and the venous blood, then one can calculate the amount of blood flowing through the lung during that time. [...