Journal of Applied Physiology, Vol 45, Issue 5 818-822, Copyright © 1978 by American Physiological Society
Mixing technique for study of oxygen-hemoglobin equilibrium: a critical evaluation
P. Scheid and M. Meyer
In the mixing technique for study of oxygen-hemoglobin equilibrium, the O2
saturation (SO2) of a blood mixture is calculated from the volume ratio at
which an oxygenated sample is mixed with a deoxygenated sample, and the PO2
in the mixture is measured polarographically. Any predetermined level of
SO2 may be obtained by proper choice of the volume ratio. It is shown that
the volume and oxygen saturation of the mixed samples are by far the most
critical parameters in calculating SO2, and a method is suggested by which
the volume ratio is accurately measured by weighing the blood samples
before mixing. Other parameters that influence determination of SO2, e.g.,
the O2 capacity of the blood, are much less important. The method has been
applied to establish the O2 dissociation curve in human blood, and good
reproducibility and agreement with standard curves were obtained.
Measurements in rabbit blood yielded similarly satisfactory results. The
technique is particularly applicable to problems that require exact
adjustment of SO2 to a predetermined value, such as determination of the
half-saturation pressure or of the Bohr effect at various levels of O2
saturation.
