Pressure-flow relationships in isolated canine cerebral circulation

Abstract

As a result of anatomic studies on the cerebral arteries and veins in the dog using vascular cast preparations, a surgical procedure was developed by which a) the cerebral arterial circulation can be completely isolated from the systemic circulation and b) the perfusion blood will flow only to the intracranial regions. Also devised was a servomechanism which controls the donor dog's body weight and thus prevents a blood volume shift between the donor and recipient dogs, within ± 5 cc of the original value. The cerebral perfusion pressure (C.P.P.) was controlled by a Starling's resistance and was altered stepwise from 140 to 0 mm Hg. At each C.P.P. level the cerebral blood flow (C.B.F.) was measured by a stromuhr. The mean and the standard deviation of C.B.F. values at 100 mm Hg C.P.P. in 10 dogs was 67.1 ± 19.5 cc/100 gm brain/min. Pressure-flow relationship over the C.P.P. range from 140 to 0 mm Hg did not show any evidence of autoregulation of the cerebral vessels, but instead suggested a linear proportional relationship.