fig1 is an external perspective view of a syringe 10 of the instant invention having the electronics housed in the plunger 11 , a thumb ring 12 affixed to the proximal end of the plunger 11 for control of fluid pressure syringe 10 . the plunger 11 is enveloped at least partially by a rotatable sleeve 16 with a captivated thread mechanism 13 capable of rotating independent of the plunger end cap 19 ( see fig4 ), a locking mechanism housing 17 and a sliding thread locking mechanism 18 . the syringe barrel 14 is similar to one known in the art and incorporates rings 15 and 15 a for the index finger and the middle finger . the triangular arrangement of the plunger thumb ring 12 and barrel rings 15 and 15 a facilitates one - handed operation of the syringe . this is a great advantage for any physician or technician performing any procedure in which fluid pressure is directly or indirectly applied to any human body part including a spinal disk or an artery . it is typically advantageous to have one free hand for accomplishing other tasks during any operation of a syringe . the syringe barrel has a luer lock or a slip socket 20 for a bonded extension line . the locking mechanism housing 17 is molded to attach to the proximal end of the syringe 10 and captivates a sliding thread locking mechanism 18 that engages or releases the threads of rotatable sleeve 16 . sliding this mechanism to one side allows the plunger 11 to travel free in the barrel 14 , sliding to the other side locks the mechanism and requires that the thumbwheel 23 be rotated to generate minute movement of the plunger 11 and associated volume or pressure change in the syringe lumen . as illustrated in fig2 , the cutout 25 in the body of the sliding thread locking mechanism 18 is a keyhole - shaped opening with a minor width such that it will engage with the threads of the threaded rotatable sleeve 16 ( see fig3 ), and has sufficient relief in its major diameter to allow free travel of the plunger 11 when threads of the rotatable sleeve 16 are disengaged . rapid disengagement is very desirable since many procedures may require an instantaneous release of fluid pressure to prevent or minimize some damage to a body part being treated or investigated . the plunger of the syringe illustrated in fig3 has a smooth inner bore 26 and outer bore 27 . the outer bore 27 becomes the supporting surface for the rotation of the threaded rotatable sleeve 16 . when the sliding thread locking mechanism 18 is engaged with the threads of the threaded sleeve , displacement of the plunger 11 is generated by rotation of the thumbwheel 23 which forces the distal end of the rotatable sleeve 16 against a flange , such as provided by plunger end cap 19 adjacent the distal end of the plunger 11 . the axial advancement or retraction of the plunger 11 effected by rotation of thumbwheel 23 is very slight , thus minute adjustments of fluid pressure are readily accomplished . also advantageous is the location of the thumbwheel 23 since its position vis - a - vis rings 15 and 15 a and thumb ring 12 readily permits an operator &# 39 ; s thumb to be removed from thumb ring 12 and placed upon thumbwheel 23 to rotate thumbwheel 23 to achieve minute fluid pressure adjustments . this continuous one - handed operation of the syringe is very advantageous for a variety of reasons . the plunger end cap 19 receives an electronic transducer , similar to those described and illustrated in the u . s . patents to wallace , cited hereinabove , which is retained by the transducer retainer 31 . the friction reduction washer 30 is placed on the plunger &# 39 ; s smooth outer bore 27 after the threaded rotatable sleeve 16 slides over plunger 11 , thus acting as a friction reducing bearing between the threaded rotatable sleeve 16 and the plunger end cap 19 . the rubber plunger tip 32 is snapped over the detent 33 of the plunger end cap 19 , as depicted in fig4 and 5 . the plunger tip assembly consists of a transducer that is seated within the plunger end cap 19 . the cavity of the plunger end cap 19 is filled with a force transmitting silicone gel which allows the transmission of forces to the transducer . other arrangements for appropriate attachment of the transducer to the plunger tip may , of course , be utilized . while a slide - lock mechanism has been illustrated and described herein , other locking mechanisms may be effectively utilized . for example , a two - piece clam - shell , spring - loaded mechanism such as that shown in fig6 a - 6c can be usefully employed . a pair of clam - shaped elements 34 and 35 are hinged at their closed end and spring - biased to be in a closed position whereby the elements 34 and 35 clamp the threaded sleeve or threaded plunger 37 . a rotatable cam 36 is positioned at the open end of the clam - shaped elements 34 and 35 , whereby rotation of the cam 36 forces the clam - shaped elements 34 and 35 into an “ open ” position whereby a threaded sleeve or plunger may slide freely . the “ open ” position is illustrated in fig6 a while fig6 b and 6c illustrate the “ closed ” position . the transducer may also be utilized in a conventional manner , as illustrated in u . s . pat . no . 5 , 004 , 472 to wallace . other mechanisms of locking a threaded sleeve or plunger in a fixed position or to provide minute pressure adjustment may be employed , including locking mechanisms disclosed in prior patents , such as u . s . pat . nos . 5 , 860 , 955 ; 5 , 433 , 707 and 5 , 685 , 848 . preferred locking mechanisms are those which are operable by the same hand which is otherwise holding or operating the syringe . preferably , the locking mechanism can be set or released by the thumb of the hand engaging one or more of the finger rings of the syringe . as stated hereinabove , having a threaded sleeve engage the locking mechanism permits minor axial adjustments of the plunger without rotation of the plunger itself which keeps a pressure readout display 39 ( fig8 a - 8c ) affixed at the proximal end of the plunger in a continuously visible position . however , if the pressure transducer and associated electronics are all incorporated as part of the plunger and the electronics send a wireless signal to a remote display , then the plunger itself may be threaded near its proximal end for engagement with a suitable locking mechanism to accomplish minute axial adjustment of the plunger which is caused by minor rotation of the plunger . a thumb ring for a thread plunger with a slightly larger open diameter may facilitate positioning of an operator &# 39 ; s thumb even though the thumb ring may be rotated slightly . also , a thumb ring which is fixed to a threaded plunger so the thumb ring freely rotates also accommodates plunger rotation . thus , a plunger which incorporates a pressure transducer and associated electronics is useful with either a threaded plunger or a threaded sleeve freely encasing the plunger . fig7 is a perspective , sectional view along a longitudinal plane encompassing the central longitudinal axis . the finger rings 15 and 15 a and thumb ring 12 are shown at the proximal end of the syringe . the open central cavity 37 ( also depicted in fig6 a ) of the plunger is exposed . it is in this space that an electronics assembly may be incorporated to connect a pressure transducer in the plunger top to a pressure readout display located in the display holder located at the proximal end of the plunger . the plunger 11 and its threaded rotatable sleeve 16 are illustrated in an inserted position in the syringe barrel . the thumbwheel 23 and sliding thread locking mechanism are also illustrated . the sleeve and plunger slide longitudinally within the syringe barrel except when the sliding thread locking mechanism engages the threads of the sleeve . the thumbwheel 23 is fixed to the sleeve so that rotation of the thumbwheel 23 rotates the sleeve threads with respect to the sliding thread locking mechanism causing the plunger 11 to advance or withdraw depending upon the direction of rotation of the thumbwheel 23 . rotation of the thumbwheel 23 while the sliding thread locking mechanism engages the threads of the sleeve causes minute longitudinal movement of the plunger , permitting minor adjustments in the fluid pressure in the barrel and attached lumen . such precise adjustment of fluid pressure is very desirable for a number of medical procedures , such as discography and angioplasty procedures . fluid pressure within the barrel may be quickly decreased to zero by unlocking the slide lock and allowing the plunger to retreat . a further embodiment of the invention incorporates a wireless transmission of pressure information from the pressure transducer to the readout display at the proximal end of the syringe . the transducer analog output may be introduced to a wireless transmitter to transmit an analog signal to the distal end of the syringe where a wireless receiver receives the signal , converts it to a digital signal , which is then introduced directly into the digital readout display . the wireless transmitter may be an infrared ( ir ) processor / transmitter which receives the analog electrical signal , converts it into an infrared analog signal which is emitted from an ir emitter . the ir analog signal is transmitted through the body of the syringe preferably through an open channel to an ir analog receiver / converter at the proximal end of the syringe . alternatively , the electrical signal may be converted into a digital ir or other digital wireless signal to be received by an appropriate receiver . an optical fiber may be advantageously used for precise ir transmission from the ir transmitter to the ir receiver . further , a digital signal may be sent via an electrical conductor between the transducer / transmitter and the receiver / display . the disclosure of u . s . pat . nos . 5 , 215 , 523 and 5 , 387 , 194 to williams / call et al . are incorporated herein by reference , especially with respect to means and systems for wireless transmission of signals produced by a pressure transducer . also incorporated herein in its entirety by this reference is u . s . pat . no . 5 , 021 , 046 to wallace , especially the disclosure relating to pressure transducers . also , wireless transmission of pressure transducer information by radio signals may be utilized within the syringe for the purposes of the invention . however , radio signals may interfere with various other equipment in an operating room - type of environment and would generally be contraindicated where such a syringe was to be utilized upon a patient having a pacemaker . fig8 a - 8c are perspective views of a syringe with a pressure display head located in a display holder having a thumb aperture located between the display and the plunger . fig8 a is a perspective view of a syringe with a pressure display head located in a display holder having a thumb aperture located between the display and the plunger . this particular syringe may incorporate the wired connection between the pressure transducer and the pressure display or a wireless transmission system such as that illustrated in fig9 . fig8 b and 8c show an elevational view and plan view , respectively , of the syringe ( infuser ) of fig8 a . the display holding portion 47 of the syringe is unique in appearance , as can be seen in fig8 a , 8 b and 8 c . additionally , the style , shape and juxtaposition of the various elements of the syringe further provide a syringe of a distinctive appearance . fig8 c shows the bottom of the display holding portion 47 , assuming that the surface in which the display is embedded is denoted the top surface , which is visible in fig8 a and 8b . the syringe of fig8 a , 8 b and 8 c has the operator &# 39 ; s thumb preferably inserted in a thumb aperture 38 from the bottom so that the display 39 will face upwards to the technician operating the syringe . this particular syringe may incorporate the wired connection between the pressure transducer and the pressure display or a wireless transmission system such as that illustrated in fig9 , described hereinbelow . an embodiment of the invention is shown in fig9 illustrating , in perspective view , a hollow plunger 11 having a pressure sensing transducer 48 located at or near the plunger tip 49 ( distal end ), which transducer 48 is electrically connected to an electronics system 40 which wirelessly transmits its output signal ( ir or rf ) to a remote receiver / pressure display 41 system . a display 42 may be located at or near the proximal end of the plunger 11 or at a remote location separate from the plunger 11 , e . g ., attached to an external surface of the syringe or entirely separate and remote from the syringe , e . g ., on a support which positions the pressure display visible 42 to one or more members of a team involved in an infusion procedure . the signal transmitted from the electronics system 40 to the display 42 may be an analog or a digital signal . if the signal is an analog signal , then the pressure display 42 includes a receiver mechanism which receives the signal and converts the analog signal to a digital signal suitable for being displayed as a pressure in millimeters of mercury , pounds per square inch , or other useful pressure units . the display 42 may further have a memory device whereby the total infusion procedure is recorded in terms of elapsed time and regular ( substantially continuously , if desired ) pressure recordings so that a history of the entire infusion procedure may be later downloaded for permanent storage . a substantially hollow plunger having an internal pressure sensing mechanism , e . g ., pressure transducer , in the tip , which is in direct or indirect contact with fluid of a syringe being pressurized , has many advantages , many of which have been enumerated herein . one such advantage is that a direct pressure reading may be displayed in a display incorporated in the proximal end of the plunger . also , in a structure such as described herein , a fluid , preferably liquid , may be contained within the hollow plunger to contact a dynamic ( diaphragm ) type - pressure influenced mechanism and conduct the received pressure through the fluid , preferably liquid , to a pressure transducer / display in the proximal end of the plunger . in such a structure , the pressure experienced at the tip of the plunger is transmitted by a fluid conductor to a pressure transducer or other pressure metering means , e . g ., an analog pressure meter , at the proximal end of the plunger . such a structure permits all the electronics necessary for a digital display , e . g ., pressure transducer , analog / digital converter and digital signal receiving display to be directly coupled to one another and located at or near the proximal end of the hollow plunger . the display at the proximal end of the syringe may be incorporated into a housing of the varying shapes and designs shown herein which accommodate functional purposes . the shape of the display housing shown in fig8 a - 8c is particularly fanciful to provide a smooth aesthetic appearance while not diminishing its attributes as a display holder and thumb engagement device . a further perspective view of the syringe of fig8 a - 8c is shown in fig1 . the view is at an oblique angle from the rear of the syringe . the above description is to aid in understanding the invention ; the full scope of which is set forth herein in the appended claims .
a device for measuring fluid pressure in the lumen of a syringe including a pressure transducer integrally mounted in the plunger of the syringe under the plunger tip , such that the force applied by the plunger to the fluid in the syringe is transmitted to the transducer and the resulting electronic signal is converted to a display value for aiding a physician . a syringe that includes such a device may be placed in communication with a tubular member attached to a needle inserted into the body of a disk found in the spinal column of the back for diagnosing diseased disks in the back . the displayed pressure value may facilitate this diagnosis . other uses of pressure applying monitoring syringes for other applications in communication with the body also benefit from the disclosed syringe construction , such as percutaneous translumenal angioplasty procedures .