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To investigate the mechanisms of CO2 transport during constant flow ventilation, we measured arterial blood gases using air, 80% He-20% O2 (He) or 80% SF6-20% O2 (SF6) as the insufflating gas. At any given flow rate (0.2 to 1.0 L/s), PaCO2 was greatest with He and lowest with SF6. Data for all gases could be described by the equation PaCO2/Pb = 0.044 V-0.64 v0.23, where Pb = barometric pressure, PaCO2 is in mm Hg, V = insufflated flow in L/s, and v = kinematic viscosity (cm2/s). At any given flow rate, the AaPO2 was greater using SF6 than using He. These results are consistent with a 2-zone model of gas transport in which the enhancement of gas transport as V increases may be due to an increase in the turbulent diffusivity in zone I (the region affected by the jet). The decreased gas transport with He compared to air and SF6 at any V may be due to either the decreased penetration depth of zone I caused by the greater kinematic viscosity of He, or the decreased rate of gas transport in the region affected by cardiogenic oscillations (zone II) secondary to the higher molecular diffusivity of He.
J Watson, and
R D Kamm, and
D R Burwen, and
R Brown, and
E Ingenito, and
A S Slutsky
January 1990,
Journal of applied physiology (Bethesda, Md. : 1985),
J Watson, and
R D Kamm, and
D R Burwen, and
R Brown, and
E Ingenito, and
A S Slutsky
October 1989,
Journal of applied physiology (Bethesda, Md. : 1985),
J Watson, and
R D Kamm, and
D R Burwen, and
R Brown, and
E Ingenito, and
A S Slutsky
February 1987,
Journal of applied physiology (Bethesda, Md. : 1985),
J Watson, and
R D Kamm, and
D R Burwen, and
R Brown, and
E Ingenito, and
A S Slutsky
August 1987,
Journal of applied physiology (Bethesda, Md. : 1985),
J Watson, and
R D Kamm, and
D R Burwen, and
R Brown, and
E Ingenito, and
A S Slutsky
May 1988,
Journal of applied physiology (Bethesda, Md. : 1985),
J Watson, and
R D Kamm, and
D R Burwen, and
R Brown, and
E Ingenito, and
A S Slutsky
March 1987,
Journal of applied physiology (Bethesda, Md. : 1985),
J Watson, and
R D Kamm, and
D R Burwen, and
R Brown, and
E Ingenito, and
A S Slutsky
January 1985,
Clinical physiology (Oxford, England),
J Watson, and
R D Kamm, and
D R Burwen, and
R Brown, and
E Ingenito, and
A S Slutsky
November 1981,
The American review of respiratory disease,
J Watson, and
R D Kamm, and
D R Burwen, and
R Brown, and
E Ingenito, and
A S Slutsky
January 1989,
Acta anaesthesiologica Scandinavica. Supplementum,
J Watson, and
R D Kamm, and
D R Burwen, and
R Brown, and
E Ingenito, and
A S Slutsky
March 1982,
Respiration physiology,
