Pressure isolator

Apparatus for isolating a pressure-sensitive device from blood flowing in an extra-corporeal blood system and for transmitting the blood pressure from a blood flow line coupled to the pressure sensing device through the isolating apparatus, including a pressure chamber having an inlet coupled to the blood flow line and an outlet coupled to the pressure sensing device, and a membrane disposed transverse said chamber and surrounded by the chamber to segregate an inlet side of said chamber from an outlet side of said chamber, said membrane being fluid-impermeable and having its outer peripheral portion connected to the surrounding housing, comprising:

• said inlet coupled to the blood flow line being in communication with said inlet side and including an inlet fitting which extends generally perpendicular to the axis of said pressure chamber;
• and said outlet coupled to the pressure sensing device being in communication with said outlet side and including an outlet fitting which extends generally perpendicular to the axis of said pressure chamber;
• said membrane having a generally planar, circular central portion lying in a plane between the outer peripheral portion and the outlet side;
• said membrane having an intermediate portion contiguous with and between the central portion and the outer peripheral portion, said intermediate portion having a generally U-shaped cross-sectional configuration with one side of the U being contiguous with said outer peripheral portion, the other side of the U being contiguous with the central portion and the bight of the U being located in a plane between said outer peripheral portion and said inlet side;
• and
• said central portion having a substantially greater thickness than the thickness of said intermediate portion.