Membranes for use in medical apparatus made of synthetic or regenerated polymers in form of films, hollow fibers, tubings and pipings for separation processes, as well as bundles of the aforesaid hollow fibers, tubings and pipings in combination with textile threads; medical apparatus and instruments, namely, modules for use in medical apparatus equipped with the aforesaid membranes and bundles, especially hemodialysers, hemofiltration modules, hemodiafiltration modules, endotoxin filtration ...