Oxygen conductance equation in septic patient: a preliminary report

xA model of the metabolic internal power ((E) over dot(int)) during cycling, which includes the gravity acceleration (a(g)) as a variable, is presented. This model predicts that (E) over dot(int) is minimal in microgravity (0 g; g = 9.81 m s(-2)), and increases linearly with a(g), whence the hypothesis that the oxygen uptake ((V) over dot O-2) during cycling depends on a(g). Repeated (V) over dot O-2 measurements during steady-state exercise at 50, 75 and 100 W on the cycle ergometer, performed in space (0 g) and on Earth (1 g) on two subjects. validated the model. (V) over dot O-2, was determined from the time course of decreasing O-2 fraction during rebreathing. The gas volume during rebreathing was determined by the dilution principle. using an insoluble inert gas (SF6). Average (V) over dot O-2 for subject 1 at each power was 0.99, 1.22 and 1.52 L min(-1) at 1 g (n = 3) and 0.91, 1.13 and 1.32 L min(-1) at 0 g (n = 5). For subject 2 it was 0.90. 1.12 and 1.42 L min(-1) at 1 g, and 0.76, 0.98 and 1.21 L min(-1) at 0 g. These values corresponded to those predicted from the model. Although resting (V) over dot O-2 was lower at 0 g than at 1 g, the net (total minus resting) exercise (V) over dot O-2 was still smaller at 0 g than at 1 g. This difference reflects the lower (E) over dot(int) at 0 g.