A connector apparatus for a pressure sensing catheter, the pressure sensing catheter comprising one or more hollow pressure compliant members, comprising: a first complementary connector in fluid communication with the one or more hollow pressure compliant members, the first complementary connector having an aligning portion and a charging portion along a central axis of the first complementary connector with a resilient member located between the aligning portion and the charging portion, the aligning portion having a cross-sectional area, normal to the central axis, and less than a cross-sectional area normal to the central axis of the charging portion; a second complementary connector having a proximal coupler with an alignment section and a charging section along a central axis thereof, the alignment section having a cross-sectional area complementary to the cross-sectional area of the aligning portion to receive the aligning portion therein, the charging section having a cross-sectional area complementary to receive the charging portion and the resilient member therein and form a fluid tight seal therebetween, the first complementary connector being configured to displace a predetermined volume of fluid, from within the proximal coupler into the one or more hollow pressure compliant members when the alignment section receives the aligning portion, the charging section receives the charging portion, and the resilient member forms the fluid tight seal within the charging section; and a pressure detection device fluidly coupled to the one or more hollow pressure compliant members so as to detect a pressure associated with the one or more hollow pressure compliant members, characterised in that the proximal coupler comprises an engagement section, the engagement section having a cross-sectional area complementary to an engagement portion of the first complementary connector, and one of the engagement portion and the engagement section has a protrusion and the other of the engagement portion and the engagement section has a complementary recess for frictionally receiving the protrusion, the protrusion and recess forming a snap fit to retain the first complementary connector within the second complementary connector when the protrusion and recess are aligned. a first complementary connector in fluid communication with the one or more hollow pressure compliant members, the first complementary connector having an aligning portion and a charging portion along a central axis of the first complementary connector with a resilient member located between the aligning portion and the charging portion, the aligning portion having a cross-sectional area, normal to the central axis, and less than a cross-sectional area normal to the central axis of the charging portion; a second complementary connector having a proximal coupler with an alignment section and a charging section along a central axis thereof, the alignment section having a cross-sectional area complementary to the cross-sectional area of the aligning portion to receive the aligning portion therein, the charging section having a cross-sectional area complementary to receive the charging portion and the resilient member therein and form a fluid tight seal therebetween, the first complementary connector being configured to displace a predetermined volume of fluid, from within the proximal coupler into the one or more hollow pressure compliant members when the alignment section receives the aligning portion, the charging section receives the charging portion, and the resilient member forms the fluid tight seal within the charging section; and a pressure detection device fluidly coupled to the one or more hollow pressure compliant members so as to detect a pressure associated with the one or more hollow pressure compliant members, characterised in that the proximal coupler comprises an engagement section, the engagement section having a cross-sectional area complementary to an engagement portion of the first complementary connector, and one of the engagement portion and the engagement section has a protrusion and the other of the engagement portion and the engagement section has a complementary recess for frictionally receiving the protrusion, the protrusion and recess forming a snap fit to retain the first complementary connector within the second complementary connector when the protrusion and recess are aligned.