This disclosure provides apparatus and methods for detecting pressure changes within a cavity of a patient. A pressure-sensing catheter comprises an elongate member and a monitor lumen. The pressure-sensing catheter may have a hollow pressure-compliant member in fluid communication with the monitor lumen and thereby define a fluid column. A connector apparatus can be in fluid communication with the monitor lumen, and can comprise a first complementary connector and a second complementary connector. One of the first complementary connector and the second complementary connector can have a pressurizing device that can displace a volume of fluid located within a bore of the other complementary connector into the fluid column, wherein the ratio of the volume of displaced fluid to the volume of the fluid column ranges from about 1:2 to about 1:4. The pressure catheter can comprise a radio-opaque band circumscribing the exterior of the elongate member.