The oxygen tension field within a discrete volume of cerebral cortex

The purpose of this investigation was to experimentally determine with oxygen microelectrodes the characteristics of the oxygen tension field in a discrete volume of rabbit cortex. Over 20,000 measurements were made in 40 New Zealand white rabbits. These measurements were analyzed: (a) graphically, by plotting oxygen tension versus cortex depth; (b) statistically, by constructing oxygen tension histograms; and (c) mathematically, by calculating the arithmetic mean and standard deviation. The majority of values were between 0 and 40 mm Hg. Often sharp changes occurred within small distances. The measured oxygen tension values ranged from near 0 to 90 mm Hg, but 50% of the values occurred between 5 and 20 mm Hg and 70% of all values were below 35 mm Hg. The arithmetic mean was calculated to be 24.54 mm Hg with a standard deviation of 17.98. The oxygen tension histogram was characterized by a concentration of values between 10 and 20 mm Hg and was skewed toward the higher oxygen tension values.