The present invention discloses a pressure sensing device (1) adapted to cause a liquid to flow through and to sense the pressure of the liquid. The pressure sensing device has a casing (2) which is fluid-tightly divided into a first chamber (3) and a second chamber (4) by a flexible and impermeable wall (5). The first chamber 3 has a first opening 6 for the liquid and the first opening is located at the bottom of the first chamber 3 and the first chamber has a second opening 7 for liquid , And the second opening is disposed in the upper part of the first chamber (3). The second chamber 4 has a measuring port 8 which is connected to the pressure transducer 9 to allow the second chamber 4 to communicate with the pressure transducer 9 in a gas- Lt； / RTI >； The pressure sensing device has a first orifice (10) for liquid into and out of the pressure sensing device (1), the first orifice being disposed on top of the pressure sensing device at a higher level than the second opening (7). The first channel (11) connects the first orifice (10) with the first opening (6). A second orifice (12) for liquid into and out of the pressure sensing device (1) is arranged at the lower part of the pressure sensing device at a level lower than the first opening (6). The second channel 13 connects the second opening 7 with the second orifice 12. In the first embodiment, the highest level of the first chamber 3 is at the same level as or higher than the highest level of the second channel 13. The present invention also includes the use of such pressure sensing devices in connection structures for extracorporeal blood treatment devices.Pressure sensing device, measuring port, pressure transducer, extracorporeal blood treatment device본 발명은, 액체가 관통하여 유동하도록 하고 상기 액체의 압력을 감지하도록 되어 있는 압력 감지 장치(1)를 개시한다. 상기 압력 감지 장치는, 가요성이고 불투과성인 벽(5)에 의해 제1 챔버(3) 및 제2 챔버(4)로 유체 밀봉식으로 분할되는 케이싱(2)을 구비한다. 제1 챔버(3)는 상기 액체를 위한 제1 개구(6)를 구비하며, 상기 제1 개구는 제1 챔버(3)의 하부에 배치되고, 제1 챔버는 액체를 위한 제2 개구(7)를 구비하며, 상기 제2 개구는
