PROBLEM TO BE SOLVED: To provide a regulator for flow rate modulation during blood collection capable of properly controlling the flow rate out of a blood vessel of a patient.SOLUTION: A regulator for in-line modulation of the flow rate of fluid during blood collection includes a fluid transfer device for transferring fluid from a patient to a collection device. The fluid transfer device comprises: a fluid passageway defined by a tubular sidewall； a flexible member associated with a portion of the tubular sidewall； and a venturi channel associated with the flexible member and adapted to accelerate a flow of fluid through an area adjacent to the flexible member upon exposure to the differential pressure. The flexible member is configured for movement with respect to the fluid passageway upon exposure of the fluid transfer device to the differential pressure during a blood collection procedure so as to prevent collapse of a blood vessel of the patient. The flexible member of the regulator can be a frame surrounding a flexible diaphragm. Alternatively, the flexible member can include a flexible material integrally formed within the tubular sidewall of the pressure regulator.SELECTED DRAWING: Figure 2A
