A blood treatment device, in particular a dialysis machine, which permits both single-needle and dual-needle operation. A flexible membrane defines the top of an air cushion that captures the patient’s foot in the neutral position when the air pillow is inflated. The invention likewise relates to a method for producing such a lamp. Framework comprises a first section located generally along the periphery of the inwardly-directed surface and further can include an interconnect section extending between the first section.