A dialysis bloodline set includes an arterial chamber with upper, lower and central portions, in which the maximum section area of the upper and central portions is less than that of the lower portion. The venous chamber may be completely filled with blood in use. The reduced volume of air within the bloodline provides, ceteris paribus, more rapid sensing of fault conditions during dialysis, while the smaller upper portion of the arterial chamber provides a useful medication point and makes manufacture easier.
