a device and method for maintaining a constant average pressure difference between the inlet and outlet of a pump for a body fluid , leading to an adequate flow for different pathological conditions . the device and method allow for automatic adjustment of the pump to meet the physiological demand of the patient . the device and method also allow the physiological constraints on the pump to be accounted for , preventing suction and minimizing back flow of the body fluid . the device and method allow implicit synchronization of the pump with the natural regulatory mechanism for meeting patient &# 39 ; s demand . thus , the pump can be continually adjusted to an optimal level in response to the patient &# 39 ; s physiological condition .