Korean J Anesthesiol.  1984 Dec;17(4):295-299.

Changes of Gas Values in the CSF by Acute Hyperventilation

• Jeon JK
• Choi KT

Abstract

Acid-base balances in the CSF have been reported by a number of groups during the past 20 years. The CSF contains only neligilbe concentrations of buffer anions other than HCO3(-). Acid-base balances in the CSF depend mainly on arterial PCO2 because arterial CO2 diffuses easily into the blood-brain barrier to form H2CO2 in the CSF. This study was primarily undertaken to observe the changes of pH, CO2 and HCO3(-) values in the CSF in the acute stage of hyperventilation. We have studied relatively healthy patients who were scheduled for surgery for cerebral aneuryams. Prior to induction of anesthesia, the radial artery was cannulated for and arterial line and blood samples taken and lumbar tapping was performed at the level of L3-4 using at 14 gause long needle, then a 18 gauze catheter was inserted through the needle. Pre-operative samples for gases were taken, then the patient was anesthetized and his repiration was controlled and maintained at the PaCO2 of 30 torr. The samples in both blood and CSF for gases were obtained at intervals of 15, 30, 45 and 60 minutes and observed and compared. The results were as follows: The PCO2 in CSF decreased as rapidly as the arterial PCO2 decreased by hyperventilation. The data obtained after hyperventilation of 45 minutes showed a significant decrease of CO2 value in the CSF as compared to the control group. The pH in the CSF increased as rapidly as the pH of the arterial blood. The arterial HCO3(-) decreased significantly in the groups of 15, 30 and 45 minutes and it was highly significant in the 60 minutes group, despite this the HCO3(-) in the CSF showed no significant changes in any of the groups. In conclusion as a result of this study, no visible metabolic compensation in the CSF for respiratory alkalosis was observed in an acute stage of hyperventilation.

MeSH Terms

Alkalosis, Respiratory
Anesthesia
Anions
Blood-Brain Barrier
Catheters
Compensation and Redress
Gases
Humans
Hydrogen-Ion Concentration
Hyperventilation*
Needles
Radial Artery
Vascular Access Devices
Anions
Gases