Pressure measuring device and extracorporeal circulator

An extracorporeal circulator for use in extracorporeal circulation of blood, the circulator comprising:

• a circulation circuit having a conduit through which the blood is transferred;
• and
• a pressure measuring device comprising:
• a main body portion adapted to mount onto the conduit;
• an elastically-deformable pressure receiver body within the main body portion adapted to deform according to the pressure of the blood;
• a polarizer disposed in the main body portion so that light oscillating in a specific direction passes therethrough;
• an image acquisition unit disposed in the main body portion to acquire image information of the pressure receiver body through the polarizer as the pressure receiver body is deformed in response to the pressure of the blood;
• and
• a control unit configured to convert the image information acquired by the image acquisition unit into pressure information.

A method of detecting blood pressure in a tube conveying pumped blood in an extracorporeal circulator, comprising the steps of:

• capturing a portion of the tube in a pressure measuring device having a main body portion, a polarizer disposed in the main body portion so that light oscillating in a specific direction passes therethrough, and an image acquisition unit disposed in the main body portion to acquire image information of a pressure receiver body through the polarizer, wherein the pressure receiver body is arranged to deform according to a pressure of the pumped blood;
• pumping the blood through the tube;
• capturing image information of the pressure receiver body through the polarizer as the pressure receiver body is deformed;
• and
• comparing the image information acquired by the image acquisition unit with stored reference image information to determine the blood pressure, wherein the reference image information defines a relationship between deformation represented by the reference image information and corresponding pressure information.