The CBF-PaCO2 relationship curves in chronic cerebrovascular disease

The purpose of the present study was to know the correlation between cerebrovascular CO2 reactivity and the hypertensive organ changes in cases of cerebrovascular disease. The subjects of the present study were 45 patients with cerebral infarction confirmed by CT scan and cerebral angiogram. Of 45 patients, 31 cases (Group N) had no occlusion in the major cerebral arteries, and the other 14 cases (Group M) had occlusions in the stem of the middle cerebral artery. Measurements of cerebrovascular CO2 reactivity were made at least more than a month after the attack. The cerebral blood flow (CBF) was determined by using the Argon inhalation method. The changes of CBF during hyperventilation, 3% CO2, 5% CO2 and 7% CO2 inhalations, were estimated by using the method of cerebral arteriovenous oxygen difference. The individual CBF-PaCO2 relationship curves of the patients were calculated by the following equations by Olesen et al. In CBF=K·PaCO2+A The cerebrovascular CO2 reactivity was represented as K value which was a slope index of the In CBF-PaCO2 relationship curve. The severities of hypertensive and arteriosclerotic involvements in organs were estimated according to the classification of hypertension severity (IKEDA et al, 1984). Results were summarized as follows : 1) There was a strong negative correlation between K values and the scores of the hypertension severity in Group N (r=-0.86, p