지속적 과환기에 따른 뇌척수액과 혈액가스치의 변화

Abstract

Acid-base balance in CSF have been reported by a number of groups during past 20 years. CSF contained only negligible concentration of buffer anion other than HCO₃. Acid-base balance in the CSF depend mainly on arterial PCO₂ because arterial CO₂ diffuses easily into the blood brain barrier to form H₂CO₃ in CSF. This study was undertaken to observe the changes of PH, PCO₂,base excess and actual HCO₃, values in CSF in the controlled hyperventilation. The changes in pH and actual HCO₃, Base Excess in CSF of anesthetized , non-curarized 7 dogs during continous controlled hyperventilation were compared with those changes when the blood acid-base parameters were kept at normal level. Both groups were mechanically ventilated to maintain a constant PaCO₂ 20 torr. The PH , PCO₂, actual「HCO₃」,and Base Excess in cisternal CSF and arterial blood were determined at normal condition as a control group shortly after induction of controlled hyperventilation thereafter, were measured at 0.5, 1.0, 1.5, 3.5, 5.5 and 7.5 hours. The results were as follows : 1) The pH of CSF in the controlled group was significantly lower than that of arterial blood and the Pcsf CO₂ was 10 torr higher than PaCO₂. 2) The standard 「HCO₃」and BE seemed to be compenasting after continous hyperventilation of 3.5 hours and reached to the values of the controlled group. 3) The Pcsf CO₂ decreased rapidly during hyperventilation and than, was maintained in a parallel distance with PaCO₂.