Mechanism of arterial pressure oscillations caused by compressing the cerebral artery.

Abstract

The effect of adding a side pressure of isotonic character upon the carotid artery, a method originally reported by MIYAKAWA to create sustained oscillations in the mean arterial pressure level of rabbits, was reinvestigated with minor technical modifications in dogs. The expected oscillation was brought about successfully in all dogs. By recording the cerebral perfusion pressure (i. e. the pressure at the point distal to the side pressure loading site) and the cerebral blood flow simultaneously with the systemic arterial pressure, the roles of the Starling's resistance used to add side pressure were clearly demonstrated:(1) it operates as a sort of limiter for cerebral perfusion pressure or blood flow, and thus amplifies the changes of the cerebral arterial pressure in a nonlinear fashion 2 to 12 times as large as that in the systemic arterial pressure, and (2) it also biases the mean operating level of the effective cerebral arterial pressure toward zero from the ordinary systemic arterial pressure level. Both roles increase the over-all gain and time lag of the system response and render the system quite unstable. Thus, the present experiment reveals the feedback nature of arterial pressure oscillation elicited by adding the side pressure upon the cerebral arterial pressure.