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Description  |
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REFERENCE TO COPENDING APPLICATIONS
Reference is made to the following applications which are filed on even
date with this application and are assigned to the same assignee: DUAL
PORT SYRINGE, Ser. No. 08/426,149, pending; ANGIOGRAPHIC SYSTEM WITH
AUTOMATIC HIGH/LOW PRESSURE SWITCHING, Ser. No. 08/426,148, pending;
CONTINUOUSLY ADJUSTABLE VARIABLE FLOW RATE RADIOGRAPHIC CONTRAST MATERIAL
INJECTOR, Ser. No. 08/425,300, pending.
BACKGROUND OF THE INVENTION
This invention relates to angiography and more specifically, the injector
used to inject a medical fluid such as radiographic contrast material into
living organisms.
One of the major systems in the human body is the circulatory system. The
major components of the circulatory system are the heart, blood vessels,
and the blood, all of which are vital to the transportation of materials
between the external environment and the different cells and tissues of
the human body.
The blood vessels are the network of passageways through which the blood
travels in the human body. Specifically, arteries carry the oxygenated
blood away from the left ventricle of the heart. These arteries are
aligned in progressively decreasing diameter and pressure capability from
the aorta, which carries the blood immediately out of the heart to other
major arteries, to smaller arteries, to arterioles, and finally to tiny
capillaries, which feed the cells and tissues of the human body.
Similarly, veins carry the oxygen depleted blood back to the right atrium
of the heart using a progressively increasing diameter network of venules
and veins.
If the heart chambers, valves, arteries, veins or other capillaries
connected thereto are either abnormal (such as from a birth defect),
restricted (such as from atherosclerotic plaque buildup), or deteriorating
(such as from aneurism formation), then a physician may need to examine
the heart and connected network of vessels. The physician may also need to
correct any problems encountered during the examination with a catheter or
similar medical instrument.
Angiography is a procedure used in the detection and treatment of
abnormalities or restrictions in blood vessels. During angiography, a
radiographic image of a vascular structure is obtained by injecting
radiographic contrast material through a catheter into a vein or artery.
The vascular structures fluidly connected with the vein or artery in which
the injection occurred are filled with contrast material. X-rays are
passed through the region of the body in which the contrast material was
injected. The X-rays are absorbed by the contrast material, causing a
radiographic outline or image of the blood vessel containing the contrast
material. The x-ray images of the blood vessels filled with contrast
material are usually recorded onto film or videotape and are displayed on
a fluoroscope monitor.
Angiography gives the doctor an image of the vascular structures in
question. This image may be used solely for diagnostic purposes, or the
image may be used during a procedure such as angioplasty where a balloon
is inserted into the vascular system and inflated to open a stenosis
caused by atherosclerotic plaque buildup.
Currently, during angiography, after a physician places a catheter into a
vein or artery (by direct insertion into the vessel or through a skin
puncture site), the angiographic catheter is connected to either a manual
or an automatic contrast injection mechanism.
A simple manual contrast injection mechanism typically has a syringe and a
catheter connection. The syringe includes a chamber with a plunger
therein. Radiographic contrast material is suctioned into the chamber. Any
air is removed by actuating the plunger while the catheter connection is
facing upward so that any air, which floats on the radiographic contrast
material, is ejected from the chamber into the air. The catheter
connection is then attached to a catheter that is positioned in a vein or
artery in the patient.
The plunger is manually actuated to eject the radiographic contrast
material from the chamber, through the catheter, and into a vein or
artery. The user of the manual contrast injection mechanism may adjust the
rate and volume of injection by altering the manual actuation force
applied to the plunger.
Often, more than one type of fluid injection is desired, such as a saline
flush followed by the radiographic contrast material. One of the most
common manual injection mechanisms used today includes a valve mechanism
which controls which of the fluids will flow into the valving mechanism
and out to the catheter within the patient. The valve mechanism contains a
plurality of manual valves that the user operates manually to open and
close that particular fluid channel. When the user suctions or injects
contrast fluid into the chamber, the fluid is pulled from the valve
mechanism via the open valves. By changing the valve positions, another
fluid may be injected.
These manual injection mechanisms are typically hand actuated. This allows
user control over the quantity and pressure of the injection. However, all
of the manual systems are only capable of injecting the radiographic
contrast material at maximum pressure that can be applied by the human
hand (i.e., 150 p.s.i). Also, the quantity of radiographic contrast
material is typically limited to a maximum of about 12 cc. Finally, there
are no safety limits on these manual contrast injection mechanisms which
act to restrict or stop injections that are outside of reasonable
parameters (such as rate or pressure) and no active sensors to detect air
bubbles or other hazards.
Currently used motorized injection devices consist of a syringe connected
to a linear actuator. The linear actuator is connected to a motor, which
is controlled electronically. The operator enters into the electronic
control a fixed volume of contrast material to be injected at a fixed rate
of injection. The fixed rate of injection consists of a specified initial
rate of flow increase and a final rate of injection until the entire
volume of contrast material is injected. There is no interactive control
between the operator and machine, except to start or stop the injection.
Any change in flow rate must occur by stopping the machine and resetting
the parameters.
The lack of ability to vary the rate of injection during the injection
results in suboptimal quality of angiographic studies. This is because the
optimal flow rate of injections varies considerably between patients. In
the cardiovascular system, the rate and volume of contrast injection is
dependent on the size of and blood flow rate within the chamber or blood
vessel being injected. In many or most cases, these parameters are not
known precisely. Moreover, the optimal rate of injection can change
rapidly, as the patient's condition changes in response to drugs, illness,
or normal physiology. Consequently, the initial injection of contrast
material may be insufficient in flow rate to outline the structure on
x-ray imaging, necessitating another injection. Conversely, an excessive
flow rate might injure the chamber or blood vessel being injected, cause
the catheter to be displaced (from the jet of contrast material exiting
the catheter tip), or lead to toxic effects from contrast overdose (such
as abnormal heart rhythm).
At present, the operator can choose between two systems for injecting
contrast material: a manual injection system which allows for a variable,
operator interactive flow rate of limited flow rate and a preprogrammed
motorized system without operator interactive feedback (other than the
operator can start/stop the procedure).
SUMMARY OF THE INVENTION
The present invention is an apparatus and method for delivering medical
fluid (such as radiographic material) from a fluid reservoir to a patient
which features a self purging operation to eliminate air. The apparatus of
the present invention includes an inlet port for connection to a fluid
reservoir, a syringe and a valve connected in a flow path between the
supply port and the syringe. During a fill operation, the medical fluid is
drawn from the fluid reservoir through the first valve and into the
syringe by rearward movement of the syringe plunger or piston. During a
purge operation, the piston is moved forward to expel air through the
first valve to the inlet port. The first valve permits air flow through
the flow path from the syringe to the inlet port, but blocks flow of
medical fluid back to the inlet port.
The apparatus also include, and preferred embodiments, a second valve which
is connected between the syringe and the patient. The second valve is in a
closed state during the fill and air purge operation. When an injection is
to be performed, the second valve opens to permit flow of the medical
fluid under pressure from the syringe to the patient. At the same time,
the first valve prevents flow of a medical fluid from the syringe to the
inlet port.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view illustrating a preferred embodiment of the
angiographic injector system of the present invention.
FIGS. 2A-2G are diagrams illustrating operations of the system of FIG. 1.
FIG. 3 is an electrical block diagram of the control system of the injector
system of FIG. 1.
FIG. 4 illustrates front panel controls and displays of a preferred
embodiment of the injector system of the present invention.
FIGS. 5A and 5B are side and partial top perspective views of the remote
control of the system of FIG. 1.
FIG. 6 is a perspective view of a foot operated remote control.
FIGS. 7A-7D illustrate the operation of the inlet check valve and manifold
during contrast fill, air purge, and patient inject operations.
FIGS. 8A-8C illustrate operation of the inlet check valve in greater detail
.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIG. 1 shows angiographic injector system 10 for injecting radiographic
contrast material into a blood vessel under interactive physician control.
System 10 includes main console 12, hand held remote control 14, syringe
holder 16, syringe body 18, syringe plunger 20, radiographic material
reservoir (bottle) 22, one-way valve 24, manifold 26, high pressure tube
28, catheter 30, patient medication port 32, three-way stop-cock 34,
T-connector 36, pressure transducer 38, stop-cock 40, tubing 42,
peristaltic pump 44, saline check valve 46, waste check valve 48, saline
bag 50, waste bag 52, and bag support rack 54.
Console 12 houses the electrical controls for system 10, together with the
motors which drive piston 20 and peristaltic pump 44. On the front surface
of console 12, user interface 54 provides control switches 56 and display
58 through which the user may enter control settings and monitor the
operational state of system 10.
Remote control 14 is connected to console 12 by cable 60 (although in other
embodiments remote control 14 may be connected by a wireless connection
such as an RF, infrared optic, or ultrasonic link). Remote control 14 is,
in the embodiment shown in FIG. 1, a hand-held control which includes
reset and saline push button switches 62 and 64, respectively, and flow
rate control lever or trigger 66. By squeezing trigger 66, the user can
provide a command signal to console 12 to provide a continuously variable
injection rate.
Syringe holder 16 projects from the left hand side of console 12. Syringe
holder 16 is preferably a clear material, and includes a half cylindrical
back shell 68, a half cylindrical front door 70 (which is shown in open
position in FIG. 1), and reservoir holder 72.
Syringe 18 is a transparent or translucent plastic cylinder having its open
end 74 connected to console 12. Closed end 76 of syringe 18 contains two
ports: upper port 78 and lower port 80.
Plunger 20 is movable within syringe body 18. Plunger 20 is connected to,
and driven by a motor located within console 12.
Radiographic contrast material reservoir 22 is connected through one-way
check valve 24 to upper port 78. Radiographic contrast material is drawn
from reservoir 22 through check valve 24 and upper port 78 into the
pumping chamber defined by syringe body 18 and plunger 20. Check valve 24
is preferably a weighted one-way valve which permits air to flow from
syringe body 18 back into reservoir 22, but will not permit radiographic
contrast material to flow from syringe body 18 to reservoir 22. This
permits automatic purging of air from the system, as will be described in
more detail later.
Lower port 80 of syringe body 18 is connected to manifold 26. Manifold 26
includes a spring biased spool valve which normally connects
transducer/saline port 82 and patient port 84. When radiographic contrast
material is to be injected, the pressure of the radiographic material
causes the spool valve to change states so that lower port 80 is connected
to patient port 84.
High pressure tube 28 is a flexible tube which connects patient port 84 to
catheter 30. Three-way stop-cock 34 is located at the distal end of tube
28. Rotatable luer lock connector 86 is connected to stop-cock 34 and
mates with luer connector 88 at the proximal end of catheter 30. Stop-cock
34 either blocks flow between tube 28 and catheter 30, permits flow, or
connects medication port 32 to catheter 30.
In addition to injecting radiographic material into a patient through
catheter 30, system 10 also permits other related functions to be
performed. A device for delivering the patient medication (not shown in
FIG. 1) may be connected to medication port 32 when medication is to be
delivered through catheter 30 to the patient.
When catheter 30 is in place in the patient, and an injection of
radiographic contrast material is not taking place, pressure transducer 38
monitors the blood pressure through the column of fluid which extends from
catheter 30, tube 28, patient port 84, manifold 26, transducer/saline port
82, tubing 90, T-connector 36, and tubing 92. Transducer 38 has an
associated stop-cock 40 which allows transducer 38 to be exposed to
atmospheric pressure during calibration and also allows for
removal/expulsion of trapped air so the dome chamber of transducer 38 can
be flushed with saline.
Peristaltic pump 44 supplies saline solution from bag 50 through saline
check valve 46, tubing 42, T-connector 36 and tubing 90 to saline port 82.
When peristaltic pump 44 is operating to supply saline solution, the
saline solution is supplied through manifold 26 to patient port 84 and
then through tube 28 to catheter 30.
Peristaltic pump 44 also operates in an opposite direction to draw fluid
from catheter 30 and through tube 28, manifold 26, tubing 90, T-connector
36 and tubing 42 to waste check valve 48 and then into waste collection
bag 52.
In a preferred embodiment of the present invention, syringe body 18,
manifold 26, tube 28, catheter 30, T-connector 36, tubing 42, check valves
46 and 48, bags 50 and 52, and tubing 90 and 92 are all disposable items.
They must be installed in system 10 each time an angiography procedure is
to be performed with a new patient. Once system 10 is set up with all the
disposable items installed, door 70 is closed, and syringe body 18 filled
with contrast material and purged of air, the user (typically a physician)
enters into system 10 the safety parameters that will apply to the
injection of radiographic contrast material. These safety parameters
typically include the maximum amount of radiographic contrast material to
be injected during any one injection, the maximum flow rate of the
injection, the maximum | | |
