Simultaneous puncture of both jugulars and an artery is necessary for measuring carbon dioxide content, respiratory quotient, or oxygen-glucose ratios, but not for oxygen A-V differences alone.
Supports symmetric cerebral metabolism except in select psychosis or left-sided epilepsy; leaves open whether bilateral jugular sampling is routinely required.
Blood was drawn simultaneously from an artery and the two internal jugular veins in 25 subjects. The oxygen A-V difference was approximately the same on the two sides, except in 4 patients with psychosis, and in 4 epileptics with left-sided cerebral pathology. In the latter the oxygen A-V difference on the affected side was relatively great, suggesting a diminished blood flow. In all but 3 of the 25 cases the respiratory quotient approached unity, the average in these 22 being .995 on the right side and .994 on the left side. Variations in the A-V differences in oxygen, as between both individuals and the two sides, did not cause a shift in the value of the respiratory quotient. The average ratio of the A-V difference of oxygen (in volumes percent) to the A-V difference of glucose (in milligrams percent) was equal, 1.63 on the right side and 1.62 on the left. In 7 cases hyperpnea produced the usual increase in the oxygen A-V difference, with-out consistent differences on the two sides, even in the presence of unilateral brain pathology. Simultaneous puncture of the jugulars and artery is not necessary if A-V differences in the oxygen content of the blood are being measured, but it is necessary if the carbon dioxide content, the respiratory quotient, or the oxygen-glucose ratios are being measured.
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Gibbs et al. (1945) studied this question.
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