Abstract: A dialyser has a membrane assembly (14) comprising two U-shaped conduits partially defined, and separated, by a transfer membrane wall. The walls of the conduits are provided with furrowing at an inclination to the direction of flow through the conduit. Blood is pumped through one conduit by a roller pump (16) in series with a reciprocatory pump (18) and dialysate is pumped in counter current through the other conduit by a roller pump (23) in series with a reciprocatory pump (25). The reciprocatory pumps (18,25) are operated in phase so that the resulting pulsatile component in the two conduits is in phase. This pulsatile flow, in conjunction with the furrows, produces vortexes in, and good mixing of, the blood and dialysate in their respective conduits and hence enhanced contact of each of these liquids with the transfer membrane wall.

Abstract: A conduit assembly (23) for an artificial lung is formed from two sheets (30) of thermoplastic transfer membrane material which are sealed together along sinuous lines (24) to provide a unitary assembly of tubular conduits (26) each having longitudinally spaced hollows (27) which promote eddies in, and mixing of, blood when passed through the conduits with a pulsatile flow.

Abstract: A dialyser has a membrane assembly (12) comprising two superposed conduits partially defined, and separated, by a transfer membrane wall. The walls of the conduit are provided with furrowing (38 or 39) extending with a component along the conduits. Blood is pumped through one conduit by a roller pump (21) and dialysate is pumped in counter current through the other conduit by a roller pump (24). The conduits communicate with separate chambers in flexible bladders (16) along each side edge of the conduits and the bladders are alternately compressed by rollers (27) to provide a superimposed reciprocatory flow component on the blood and dialysate in a direction transverse to the length of the conduits. This reciprocatory flow component, in conjunction with the furrows, produces vortexes in, and good mixing of, the blood and dialysate in their respective conduits and hence enhanced contact of each of these liquids with the transfer membrane wall.

Abstract: A prosthetic valve, suitable for use as a mitral valve replacement, has a D-shaped annular seat-forming member and obturating flap, the flap having a major area formed by a rigid sheet of similar D-shape and extent for direct support on the seat when the valve is closed, and a flexible sheet hinge connecting the flap and annular member as a hinge along their straight edge portions. The rigid sheet is preferably scalloped around its free edge, with a flexible skirt being located across the incursions of this shaping, and is also preferably dished inwardly towards the valve.

Abstract: The oxygenation and removal of carbon dioxide from blood by simultaneous mass transfer through a microporous membrane is improved by pulsing the flow of oxygenating gas over the membrane. This avoids the progressive reduction in carbon dioxide transfer rate which otherwise occurs with steady gas flow and allows such transfer rate to be maintained at an acceptable level.