Abstract: A peristaltic pump in which fluid is displaced towards the outlet of the pump by a rotating member which engages a section of tubing. The tubing comprises an outer tubing and an inner tubing with an annular airspace maintained therebetween and vented to atmosphere. When a positive hydrostatic head is maintained above the pump head level, the inner tubing will expand and fill. When the fluid level drops below the pump head level, the inner tube collapses, closing off the tube so there is no fluid volume to displace and the pump output stops to prevent entrainment of air into the patient's circulation. An occluding valve having a normlly closed position may also be provided at the inlet to the pumping section.