Infusion pump with tube spike holder

An infusion pump for infusing solutions from IV bags through tubing to patients. The pump comprises a housing having a compartment which receives an IV bag in a solution-dispensing position. The bag is placed over a bladder within the compartment, and the bladder is expanded by a pressurized fluid to apply a pushing force against the bag which collapses to infuse solution through the tubing. A pump in the housing pumps a fluid such as air into the bladder under influence of a control circuit. A pressure sensor indirectly senses pressure of fluid in the bladder through a pressure of pad which contacts the bladder wall. A control circuit generates a pressure signal responsive to movement of the pressure pad for operating a valve which directs fluid between the pump and bladder. A dispensing spike is provided for interconnecting a dispensing port of the bag in fluid communication with the tubing. The spike is formed with an annulus which cooperates with a wall of the housing to prevent unintended withdrawal of the spike from a dispensing port while infusion takes place. The annulus also operates a switch which is connected in the control circuit to ensure that infusion proceeds only when the bag is in its proper solution-dispensing position in the housing.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates in general to the infusion of intravenous (IV) 
solutions. In particular, the invention relates to portable IV infusion 
pumps for use by ambulatory and other patients. 
2. Description of the Related Art 
Infusion pumps are used to deliver various types of solutions intravenously 
to patients. A variety of drugs are commonly administered to patients by 
means of the intravenous solutions. Among the types of therapies requiring 
this kind of administration are chemotherapy, antibiotic therapy and 
antiviral therapy. In many cases, patients receive multiple daily 
therapies. Certain medical conditions require infusion of drugs in 
solution over relatively short periods of time, such as from 30 minutes to 
2 hours. Infusion pumps have been developed in the prior art in an effort 
to meet these needs. There has been a requirement of providing portable 
infusion pumps for use by ambulatory patients and the like. 
The different types of infusion pumps in the prior art include elastomeric 
pumps which squeeze the solution from flexible containers, such as 
balloons, into IV tubing for delivery to the patient. Spring-loaded pumps 
have also been provided to pressurize the solution containers or 
reservoirs. In certain infusion pump designs, cartridges containing 
flexible compound compartments that are squeezed by pressure rollers for 
discharging the solutions are provided, such as in U.S. Pat. No. 
4,741,736. U.S. Pat. No. 5,330,431, issued to the inventor of the present 
invention, shows an infusion pump in which standard prefilled single 
dosage IV bags are squeezed by the use of a roller. U.S. Pat. No. 
5,348,539, also issued to the inventor of the present invention, shows an 
infusion pump in which prepackaged IV bags are squeezed by a bladder which 
is actuated by a fluid pump from a reservoir. 
Dispensing spikes have been provided for interconnecting IV tubing with the 
IV bags. The spikes penetrate through dispensing ports in the bags to 
permit the fluid to infuse through the tubing to the patient. U.S. Pat. 
5,106,374 to Apperson discloses a spike having a locating flange which 
assists in locating the spike within the housing of an ambulatory infusion 
device. 
The prior art infusion devices include arrangements for sensing the 
pressure of the IV bags to control the infusion procedure, such as for 
shutting off the infusion flow. 
The need has been recognized for a portable infusion pump which controls 
the infusion process by indirectly sensing IV solution pressure without 
intrusion into the bag itself. It would also be desirable to provide such 
an infusion pump which provides a safe and reliable arrangement for 
sensing when the IV bag is in its proper solution-dispensing position 
within the compartment of the pump housing and which also ensures that the 
dispensing spike cannot be accidentally withdrawn from the bag's 
dispensing port when the infusion is in progress. 
The need has been recognized for an infusion pump which obviates the 
foregoing and other limitations and disadvantages of prior art infusion 
pumps. Despite the various infusion pumps in the prior art, there has 
heretofore not been provided a suitable and attractive solution to these 
problems. 
OBJECTS AND SUMMARY OF THE INVENTION 
It is a general object of the present invention to provide a new and 
improved infusion pump for dispensing IV solutions to patients. 
Another object is to provide an infusion pump of the type described which 
is of relatively small size and is inexpensive and simple to operate. 
Another object is to provide an infusion pump of the type described which 
ensures against accidental separation of the dispensing spike from the 
dispensing port of the IV bag during the infusion procedure. 
Another object is to provide an infusion pump of the type described which 
ensures that the IV bag is properly in its solution-dispensing position 
during the infusion procedure. 
The invention in summary provides an infusion pump having a housing which 
provides a compartment for receiving an IV bag in a solution-dispensing 
position. A bladder mounted in the housing has a flexible wall which 
expands and contracts under influence of pressurized fluid from a pump. 
The bladder expands against the IV bag so that the solution is infused out 
of the bag through a dispensing port into IV tubing to the patient. This 
provides the operating means for collapsing the bag. Fluid pressure in the 
bladder is indirectly sensed by a non-intrusive sensor which is connected 
in a circuit that controls the pump. A dispensing spike interconnects the 
IV tubing with the dispensing port in the bag, and the spike has a 
structure which actuates a switch for enabling the control system when the 
bag is in its proper solution-dispensing position. When the lid of the 
housing is closed, the spike is captured and held in place to prevent 
against unintended withdrawal during the infusion procedure. 
The foregoing and additional objects and features of the invention will 
appear from the following specification in which the several embodiments 
have been set forth in detail in conjunction with the accompanying 
drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
In the drawings, FIGS. 1 and 2 illustrate generally at 10 a portable 
infusion pump according to a preferred embodiment of the invention. 
Infusion pump 10 provides an ambulatory system which enables health care 
professionals to infuse patients directly from single dose container bags 
which are pre-filled with IV solutions. Infusion pump 10 of the invention 
is suitable for use in homes, hospitals or clinics. It is also readily 
adapted for operation in any position, such as resting on a table with the 
patient in bed, or it could be carried by the patient. 
Infusion pump 10 is comprised of a box-shaped housing 12 having a lid 14 
which pivots open and closed about a hinge 16. The interior of the housing 
is divided into an upper compartment 18 and lower compartment 20 by a 
horizontal flat plate 22. The upper compartment is sized and shaped 
commensurate with the size and shape of a standard large (115 cc) IV bag 
24, and the compartment can also contain a standard small (50 cc) IV bag. 
An inflatable bladder 26 is mounted across the upper surface of plate 22 
within the upper compartment. The opposite walls of the bladder are 
hermetically sealed together about their periphery to provide a closed 
internal volume for containing a fluid under pressure. In the present 
embodiment, the fluid is a gas, preferably air, although liquid fluids 
could also be employed, such as a low viscosity, non-toxic oil. 
Lower compartment 20 of the housing mounts an air pump 28, a two-position 
solenoid valve 30, a battery compartment 32 and a printed circuit board, 
not shown, which contains components of the electric control circuit 34 
shown schematically in FIG. 5. A pressure sensor 36 is mounted from plate 
22 and depends downwardly into the lower compartment. The pressure sensor 
includes a moveable pressure pad 38 which extends upwardly through a 
central opening 40 in plate 22 into juxtaposed relationship with the lower 
wall of bladder 26. Expansion and contraction of the bladder as its 
internal fluid pressure increases and decreases correspondingly causes up 
and down movement of the pressure pad. The pressure sensor generates an 
electric pressure signal responsive to movement of the pressure pad, and 
this signal is directed through line 42 into control circuit 34. The 
control circuit is powered by suitable dry cells, not shown, mounted in 
the battery compartment. 
Control circuit 34 is also connected through line 44 to operate the air 
pump. The pump inlet draws atmospheric air through inlet tube 46 and 
filter 48, with pressurized air being directed out through tube 50 into 
the solenoid valve 30. This valve has a normally closed inlet 52 connected 
with air pump 28, and a normally open outlet 54 is connected via tube 56 
through filter 48 and tube 58 to atmosphere. An outlet 60 leads through 
tube 62 to the bladder. In the normally open position of the valve, the 
inner volume of the bladder is opened through outlet 54 to atmospheric air 
so that the IV bag cannot be pressurized. At the same time, inlet 52 
blocks out pressurized air from the pump. When the control circuit sends a 
signal through the line 42 to the valve, inlet 52 is opened so that the 
valve directs pressurized air from the pump into the bladder while outlet 
54 is closed. 
With lid 14 in its open position shown in FIG. 1, IV bag 24 is inserted so 
that it lies flat across the upper wall of the bladder. In this 
solution-dispensing position of the bag, the bag's dispensing port 64 and 
filling port 66 extend toward the right of the compartment, as viewed in 
FIGS. 1 and 2. 
FIG. 4 illustrates dispensing spike 68 in accordance with the invention 
which provides means for releasably interconnecting the IV tubing with the 
IV bag. Dispensing spike 68 is comprised of a tubular body 70 having a 
proximal end adapted for receiving the end of IV tubing 72. The distal end 
of the tubular body is formed into a piercing spike 74 which is adapted to 
pierce through the closed end of dispensing port 64. This opens the inner 
channel of the spike to solution within the bag. The dispensing spike 
thereby interconnects the end of the IV tubing in fluid communication with 
the solution in the bag. 
Dispensing spike 68 includes an annulus 76 formed about the tubular body. 
The annulus has a diameter which is sufficiently large to enable the hand 
of the user to apply a force along the longitudinal axis of the body for 
inserting and removing the spike into and from the dispensing port. A 
diameter in the range of 0.6 " to 1.0 ", and preferably 0.8 ", is suitable 
for this purpose. 
It is another important feature of the invention that annulus 76, in 
cooperation with housing end wall 78 and lid 14, is releasably captured 
and securely held in place when the bag is in its proper 
solution-dispensing position. Toward this objective, a notch 79 (FIG. 3) 
is formed along the upper side of housing end wall 78. A U-shaped groove 
80 is formed in the notch at a position for seating about the lower 
portion of tubular body, as best shown in FIG. 4. In this position, 
annulus 76 fits within the upper compartment with its outer surface seated 
against the housing end wall. Outward forces on the tubular body, such as 
when the IV tubing is pulled, are resisted by the annulus which thereby 
holds the spike against displacement from the IV bag as long as the lid is 
closed. The corresponding end of the lid is formed with a downwardly 
projecting ridge 82 which matches the shape of the notch. U-shaped groove 
84 (FIG. 1) is formed in the lower side of the ridge, and this groove 
seats against the upper portion of tubular body 70 when the lid is closed. 
Lid 14 is releasably held in its closed position by means of a plurality, 
shown as three, of latches 86 which are mounted at spaced positions on a 
slidebar 88. The slidebar is mounted for back and forth movement across 
the upper edge of housing front wall 90. A spring 92 is mounted at one end 
of the slidebar to urge it toward the right, as viewed in FIG. 1. With the 
slidebar urged to the right, the latches engage lid notches 94 (FIG. 3) to 
hold the lid down. A manually operated latch release button 96 carried on 
the slidebar projects through an opening in the front of the housing to 
permit the user to move the slidebar to the left so that the latches 
release from the lid. 
Another important feature of the invention is the provision of an on-off 
switch 98 which, in combination with dispensing spike annulus 76, 
generates a bag-in-place signal when the bag is in its proper 
solution-dispensing position. The bag-in-place signal is directed through 
line 100 into the control circuit for controlling the infusion procedure. 
The end of horizontal plate 22 is formed with a slot 102 (FIG. 3) through 
which spike annulus 76 projects downwardly into the lower compartment. 
Switch 98 is provided with an actuating arm 104, and the switch is 
positioned in the lower compartment so that the arm projects into an 
interference relationship with the portion of annulus which extends 
downwardly through slot 102. When the dispensing spike is out of the 
position shown in FIG. 1, such as when the IV bag is either out of the 
compartment or improperly positioned, then annulus 76 cannot fit fully 
down through the slot. This permits the actuating arm to move upwardly so 
that switch 98 is operated to a position in which the bag-in-place signal 
is disabled. 
While an air filter 48 is shown for filtering air from the atmosphere into 
pump 28, the invention contemplates that the filter could be eliminated 
with the pump drawing inlet air directly from the atmosphere, and with 
exhaust air from the bladder being sent through outlet 54 directly to 
atmosphere. 
The invention also contemplates an arrangement in which the outlet from 
pump 28 directs air through a line leading directly into bladder 26. In 
such an arrangement, the solenoid valve 30 would have one inlet connected 
with the bladder and one outlet which directs air to the atmosphere either 
directly or through an air filter. The valve would be operated by a 
control circuit of the type shown in FIG. 5 between one position in which 
the valve inlet is closed while the pump fills the bladder with 
pressurized air, and in another position in which the valve inlet is 
opened so that pressurized air from the bladder is discharged through the 
valve to atmosphere. 
Housing 12 includes a control panel 106 having a power-on pushbutton 108, 
an infuse pushbutton 112. The pushbutton 112. The panel also includes a 
light 114 providing a battery low condition signal, and a light 116 
providing a check status signal. Pushbutton 108 is provided with a light 
118 for indicating a power-on condition, pushbutton 110 is provided with a 
light 120 indicating an infuse condition, and pushbutton 112 is provided 
with a light 122 for indicating a stop condition. 
The flow chart comprised of FIGS. 6A and 6B illustrates the steps in the 
method of operation of diffusion pump 10. With air pump 28 turned off, the 
IV bag is placed into its solution-dispensing position within the upper 
compartment of the housing at step 124. The lid is then closed at step 
126, which is followed by the patient, or health care professional, 
pushing the power button at step 128. This turns on the power light at 
step 130, and the control circuit runs its system checks at step 132. If 
the spike annulus properly actuates switch 98 at light step 134, a "yes" 
indication is directed into the "system okay" logic step 136. If not, the 
check status light is turned on and an automatic alarm sounds at step 139. 
If the "system okay" condition exists, the infuse button is pushed at step 
138. If the lid is accidentally opened prior to completion of infusion, 
switch 98 is deactivated at step 140. The control circuit responds and 
turns the air pump off at step 142, valve 30 is deactivated at step 144 so 
that air is exhausted from the bladder through the filter to atmosphere, 
the check status light is turned on at step 146, and the infuse light is 
turned off at step 148. 
The signal generated from the infuse button being turned on is directed 
into line 150 which: turns on pressure sensor 36 at step 152, turns the 
air pump on at step 154, activates valve 30 at step 156 which directs 
pressurized air from the pump into the bladder, and turns the infuse light 
on at step 158. Next, the logic checks whether the pressure sensor senses 
a bladder pressure of a greater than a predetermined level, for example 
greater than 6.5 psi, at step 160. If that level or above is not sensed, 
then the air pump remains on at step 162. When the bladder pressure 
reaches or exceeds that level, then the air pump is turned off at step 
164. The circuit logic next determines at step 166 whether the bladder 
pressure is below a lower predetermined level, for example 5.5 psi. If it 
is below that level, then the air pump is turned on at step 168. If not, 
then the logic at step 170 determines if the time elapsed since the pump 
was on is greater than 5 minutes. If so, then the air pump remains off at 
step 172. Next, the infuse light is turned off at step 174, valve 30 is 
deactivated to exhaust air from the bladder at step 176, the check status 
light is on and the alarm sounds at step 178. 
The method then proceeds to step 180 where the patient or health care 
professional checks the status of infusion. If the infusion is complete, 
the power button is turned off at step 182. This turns all systems off at 
step 184 so that the patient can open the lid at step 186, and remove the 
IV bag at step 188. If the infusion is not complete, then the patient can 
correct the problem at step 190 and press the infuse button at step 192. 
This turns the check status light off at step 194, and the logic proceeds 
through line 196 to repeat the infusion process. 
If at any time during the infusion process the patient presses the stop 
button at step 198, then the infuse light is turned off at step 200, the 
stop light is turned on at step 202, the solenoid valve is deactivated at 
step 204 and the air pump is turned off at step 206. The logic then 
determines at step 208 if infusion is complete. If so, the logic proceeds 
to step 182 so that the power button can be turned off. If the infusion is 
not complete, then the patient can correct the problem at step 210 and 
then press the infuse button at step 212 which turns the stop light 122 
off at step 214. The logic then proceeds through line 216 to repeat the 
infusion procedure. 
FIG. 7 illustrates another embodiment providing a modified dispensing spike 
218 for releasably holding the spike in a pump housing 220 when a lid 222 
is closed. Dispensing spike 218 is formed about its proximal end with an 
annular groove 224. The annular recess portion within the groove 
releasably fits on its lower side into a matching U-shaped seat 226 which 
is formed on the upper edge of the housing end wall. The lid has a 
downward protecting portion 227 at its front end which is formed with a 
similar U-shaped seat 228 which moves into register with and fits into the 
top side of the spike groove when the lid is closed. The sharpened end 230 
of the spike penetrates into the IV bag dispensing port 232. A tubular 
body 234 of the spike is formed with an internal bore 236 which receives 
the end of the IV tubing, not shown. An annulus 238 formed about the body 
provides a push surface against which force can be applied by the user's 
hand to insert and remove the spike into and from the dispensing port. 
With the lid closed, the upper and lower seats 226 and 228 fit about the 
spike groove so that the spike is locked against unintended removal from 
the housing during the infusion process. 
While the foregoing embodiments are presently considered to be preferred, 
it is understood that numerous variations and modifications may be made 
therein by those skilled in the art and it is intended to cover in the 
appended claims all such variations and modifications as fall within the 
true spirit and scope of the invention.