Abstract
The range of autoregulation of cerebral blood flow (CBF) was investigated by the stepwise lowering of blood pressure with head-up tilting and/or with infusion of trimetaphan camsilate in the 52 patients with cerebral infarction of old stage. Changes of CBF were calculated by the method of cerebral arterio-venous oxygen difference. Fifty-two cases included 24 patients (Group N) which had no occlusion in the major cerebral arteries, 17 cases (Group E) which had one or more complete extracranial arterial occlusions, and the other 11 cases (Group M) which had occlusions in the stem of middle cerebral artery. CBF measurements were made at least more than a month after the onset.
Results obtained were as follows :
1) The ranges of autoregulation of CBF (control mean blood pressure (MABP) minus MABP at the lower limit of autoregulation) were 21.2 mmHg in Group N, 16.9 in Group E, and 12.0 in Group M respectively. There was a statistically significant difference between Group N and M (p<0.005).
2) Ratios of the MABP at lower limit of autoregulation to the control value of MABP were 82.7%, 85.3%, and 88.7% in groups N, E and M, respectively.
3) Dysautoregulation of CBF was most frequently encountered in Group M (45%).
From these observations, it is suggested that the adequate range at the time of the relatively rapid blood pressure reduction for hypertensive patients with ischemic cerebrovascular diseases is preferable within 20% in cases with no arterial occlusion and 10% in cases of occlusions in the middle cerebral arteries.
