A Study of Cerebrospinal Fluid Oxygen Tension

Abstract

The circulation of the brain has been the object of more speculation and study than any other part of the body. All present methods of estimating cerebral blood flow, however, leave much to be desired. Since, for many practical purposes we are not in-terested in the blood flow per se but in whether or not the oxygenation of the brain is adequate, we have attempted to approach the problem of quantitative brain oxygen tension directly.The prime consideration was "what" to measure that might justifiably be called "mean tissue oxygen tension." As pointed out by Bronk et al.1 and Bloor et al.2 the spatial resolution of the oxygen electrode is such that the absolute value obtained from the cortex varies greatly with its position relative to blood vessels. Other obvious problems arise in using the exposed cortex, such as pulsation, movement, variations in electrode pressure, etc. However, fluid in equilibrium with the tissue obviates most of these problems, and the brain is fortuitously bathed and filled with readily accessible fluid. Inasmuch as the work of Bering3 in¬ dicated a rapid water exchange in the cere¬ brospinal fluid, it did not seem unreasonable to expect equally rapid changes in the oxygen tension of the fluid. To explore this thesis and to determine the relationship be¬ tween brain, blood, and cerebrospinal fluid oxygen tension, the following study^v as undertaken. MethodsAll oxygen tension studies were carried out with an oxygen microelectrode based on the polarographic principle. The electrode is 2\/i in. in length with an O.D. of 0.038 in., which allows it to be introduced through an 18-gauge thin-walled needle. The assembly can be cold sterilized for aseptic use. The flow artifact is less than 1'% ; temperature coefficient is 3.2% per degree centigrade; readings with known oxygen tensions are reproducible to within 3% or less ; and the electrode is linear from 0 to over 700 mm. Hg oxygen tension.* Observations were made on 51 mongrel dogs and 4 monkeys (African Green). Light thiamylal sodium (Surital) anesthesia was used for the period of surgical preparation. During the experi¬ mental period the animals were intubated, im¬ mobilized with intramuscular succinylcholine, and mechanically respi rated so that the general anes-

Direct Measurements of the Partial Oxygen Tension in Different Cortical and Subcortical Structures of the Brain and in Gliomas during Stereotactic Operation

“…The mean value of the CS-fluid (34.518.9 mm Hg) lies within the range of values reported by J arn u m et al [11], R ossanda and G ordon [21] and B loor et al [2], However, in our series we have noted that pre cisely for the fluid there is a high degree of dependency of the PO, on en vironmental conditions, such as 0 2 content of the respiratory air and of the surrounding tissue. A direct proportional relationship exists between changes in the 0 2 consumption of the brain and changes of the PO, in the fluid.…”

Acid-Base and Gas Tension Measurements in Cerebrospinal Fluid

“…The oxygen tension in cerebrospinal fluid of man has been the subject of a number of studies (Bloor et al, 1961;Mollaret et al, 1964;Dunkin and Bondurant, 1966) but has found a much more limited place in clinical research than has c.s.f. acid-base balance.…”

Measurement of cerebrospinal fluid oxygen partial pressure in humans using MRI

“…Using invasive means, P csf O 2 has been measured to be between 25–53 mmHg in humans, roughly 25% its room air level (160 mmHg) (2–5, 9). Previous studies in humans have suggested that P csf O 2 changes occur in the setting of abnormal brain oxygen metabolism (1, 4, 5).…”

“…Cerebrospinal fluid (CSF) oxygen partial pressure ( P csf O 2 ) has been proposed as a surrogate marker for brain or spinal cord tissue oxygenation, given the passive nature of oxygen diffusion (1–5). Historically, investigators have measured P csf O 2 by analyzing fluid obtained by direct cisternal or lumbar puncture, or using implanted oxygen microelectrodes.…”