A medical device is disclosed comprising a diaphragm having at least one slit valve disposed therein, and a valve housing configured to secure the diaphragm at a peripheral portion of the diaphragm, wherein a central portion of the diaphragm is positioned relative to the peripheral portion of the diaphragm such that compressive forces acting on the peripheral portion of the diaphragm create moment forces which bias the slit valve in a closed position. A method is disclosed for using the device in connection with a catheter for regulation of fluids to and from a patient.