Direct mass spectrographic measurement of regional intracerebral oxygen, carbon dioxide, and argon

Abstract

✓ During 10 operative procedures on eight patients with various intracranial lesions a membrane mass spectrometer was used to measure the regional partial pressure of oxygen (pO2), carbon dioxide (pCO2), and argon (pA) in subcortical white matter. The pO2 varied from 12 to 49 mm Hg, and the pCO2 from 31 to 123 mm Hg. Lowering intracranial pressure to 0 by ventricular drainage increased the pO2 and argon washout values (except in necrotic brain where no increase occurred) and decreased the pCO2 values. In one patient restoration of intraventricular pressure to the initial level of 220 mm H2O resulted in a 20% decrease in pCO2, a 15% decrease in argon washout rate, and a 21% increase in pCO2. These data suggest that regional cerebral blood flow, pO2, and pCO2 are influenced by intracranial hypotension as well as the condition of local brain tissue.