embodiments of the presently disclosed implantable access device will now be described in detail with reference to the drawings wherein like reference numerals designate identical or corresponding elements in each of the several views . fig1 - 6 illustrate one embodiment of the presently disclosed access device shown generally as 10 . access device 10 includes a housing 12 having an upper body portion 14 , a lower body portion 16 ( fig6 ) an upper collar 18 , a lower collar 20 , a biasing member 24 and a septum 26 . upper body portion 14 of housing 12 defines a cavity 28 dimensioned to receive the various components of device 10 as will be described in further detail below . a cam assembly 22 is formed along the inner wall 15 of upper body portion 14 of housing 12 . lower body portion 16 defines an outlet channel 30 ( fig6 ) that fluidly communicates a bottom of cavity 28 with a catheter 32 . referring to fig3 - 6 , upper collar 18 has a substantially cylindrical body 34 which defines a throughbore 34 a . alternatively , it is envisioned that upper collar 18 may have a variety of different configurations . septum 26 is supported in an upper end of throughbore 34 a using any known fastening technique , e . g ., adhesives , welding , press - fitting , etc . see fig6 . a proximal end of upper collar 18 includes a series of angled protrusions 36 and a plurality of guide ribs 37 . angled protrusions 36 can have a substantially triangular shape and are configured and dimensioned to interact with lower collar 20 to effect rotation of lower collar 20 within housing 12 as will be described in further detail below . guide ribs 37 rotatably fix upper collar 18 within cavity 28 of housing 12 and define the uppermost or extended position of upper collar 18 as will also be described in further detail below . lower collar 20 is substantially cylindrical and defines a throughbore 38 . a series of longitudinal ribs 40 are positioned about the external surface of collar 20 . an upper end 40 a of each of ribs 40 is positioned to engage angled projections 36 of upper collar 18 to effect rotation of lower collar 20 as will be described in detail below . upper end 40 a of ribs 40 may be tapered or angled . referring to fig3 and 5 , cam assembly 22 includes a series of retaining members 44 positioned annularly about cavity 28 of upper body portion 14 . each of retaining members 44 is separated from adjacent retaining members 44 by channels 46 . each retaining member 44 includes a lower end which defines an angled , recessed surface 50 , a vertical stop portion 52 and an angled or sloped guide surface 53 . in an alternative embodiment , the cam assembly may be provided on an annular cam member 22 which is separate from housing 12 and is fixedly positioned within housing 12 and dimensioned to be positioned about a lower end of upper collar 18 and lower collar 20 . when upper collar 18 and lower collar 20 are assembled within cavity 28 of upper body portion 14 of housing 12 , guide ribs 37 of upper collar 18 and longitudinal ribs 40 of lower collar 20 are slidably positioned within channels 46 of cam assembly 22 . as illustrated in fig3 , an upper end of each of channels 46 is closed and defines an abutment surface 55 which engages guide ribs 37 to define the extended position of upper collar 18 and prevent separation of collar 18 from housing 12 . referring to fig3 - 6 , biasing member 24 , which may be a coil spring , is positioned within cavity 28 between lower body portion 16 ( fig6 ) and a lower end of lower collar 20 such that lower collar 20 is urged upwardly towards upper collar 18 . when ribs 40 of lower collar 20 are aligned with channels 46 of cam assembly 22 , biasing member 24 urges lower collar 20 upwardly into a lower end of upper collar 18 to move the upper collar 18 to its extended or high profile position . see fig4 and 5 . as discussed above , when upper collar 18 is in its extended position , abutment surface 55 is engaged with a top surface of guide ribs 37 . it is also noted that when the upper collar 18 is in its extended position , the upper end 40 a of rib 40 engages the lower end of angled protrusions 36 of upper collar 18 . referring to fig7 - 10 , when upper collar 18 is pressed downwardly in the direction indicated by arrow “ a ” in fig7 , lower collar 20 is urged downwardly against biasing member 24 and angled protrusions 36 press against the top surface of ribs 40 to torque lower collar 20 . when ribs 40 of lower collar 20 exit channels 46 of cam assembly 22 , the torque applied by angled protrusions 36 on the upper end of ribs 40 rotates lower collar 20 in the direction indicated by arrow “ b ” in fig8 causing the upper end 40 a of ribs 40 to move into recessed surfaces 50 of retaining members 44 and abut against stop portion 52 of retaining members 44 . when this occurs , lower collar 20 and , thus , upper collar 18 are retained in a retracted or low profile position . see fig9 and 10 . referring to fig4 , 5 , 11 and 12 , when upper collar 18 is in its retracted position and it is pressed downwardly in the direction indicated by arrows “ c ” in fig1 , the upper end 40 a of rib 40 is moved downwardly and passes under stop portion 52 of cam assembly 22 ( fig1 ) and lower collar 18 rotates in the direction of arrow “ d ” in fig1 as discussed above . when lower collar 20 rotates , ribs 40 once again align with channels 46 of cam assembly 22 and biasing member 24 urges lower collar 20 upwardly to move upper collar 18 and septum 26 to the extended position . it is noted that sloped guide surfaces 53 of retaining members 44 in combination with biasing member 24 guides ribs 40 into channels 46 . referring to fig3 and 6 and as discussed above , septum 26 is secured to an underside of upper collar 18 . in one embodiment , a sleeve 60 has a first end 60 a secured to a bottom surface of septum 26 and a second end 60 b secured to lower body portion 16 . sleeve 60 provides a sealed passage 80 from septum 26 to outlet channel 30 of lower body portion 16 . sleeve 60 has an extendable configuration to facilitate movement of upper collar 18 to its extended position . in one embodiment , sleeve 60 has a flexible bellows - like construction . it is envisioned that other extendable sleeve configurations may be used . it is also envisioned that upper body portion 14 of housing 12 may have an o - ring or other sealing means to prevent the entry of substances found beneath the surface of the skin into cavity 28 along a path between upper collar 18 and a side wall of cavity 28 . in use , implantable access device 10 is implanted beneath the skin ( fig1 ) in a known manner with upper collar 18 in its retracted position . when medical personnel would like to inject or withdraw a fluid from device 10 , the general area of skin near access device 10 can be pressed downwardly to press upper collar 18 into housing 12 . as discussed above , when this occurs , rib 40 ( fig3 ) of lower collar 20 moves under stop portion 52 of cam assembly 22 and lower collar 20 is rotated to align ribs 40 of lower collar 20 with channels 46 of cam assembly 22 . when this occurs , lower collar 20 and upper collar 18 are urged upwardly by biasing member 24 such that upper collar 18 and septum 26 move to the extended , high profile position . in this position , a top surface of upper collar 18 will press against an undersurface of the skin such that the location of septum 26 will be apparent to medical personnel . see fig2 . after a medical procedure has been performed , upper collar 18 can be returned to the retracted position in the manner discussed above by pressing downwardly on upper collar 18 . alternatively , it is envisioned that upper collar 18 may be pressed downwardly during a medical procedure , such as while inserting a needle through septum 26 , to return the upper collar to the retracted position . it will be understood that various modifications may be made to the embodiments disclosed herein . therefore , the above description should not be construed as limiting , but merely as exemplifications of preferred embodiments . those skilled in the art will envision other modifications within the scope and spirit of the claims appended hereto .
an implantable access device for intravenous delivery and / or withdrawal of fluids is described herein . the access device includes a septum which is movably supported within a housing of the access device from a retracted , low profile position to an extended , high profile position to facilitate easy identification of the location of the septum by medical personnel .