AU654571B2

AU654571B2 - Compression device

Info

Publication number: AU654571B2
Application number: AU20903/92A
Authority: AU
Inventors: John F. Dye
Original assignee: Kendall Co
Current assignee: Kendall Co
Priority date: 1991-11-12
Filing date: 1992-08-07
Publication date: 1994-11-10
Anticipated expiration: 2012-08-07
Also published as: CA2071379C; DE69225459D1; JPH05269163A; ES2115639T3; EP0542383A3; DE69225459T2; EP0542383A2; CA2071379A1; EP0542383B1; JP3431935B2; AU2090392A

Description

F Ref: 213732 S F Ref: 213732

AUSTRALIA

PATENTS ACT 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT

ORIGINAL

e e I I-

S

*5* Name and Address of Applicant: Actual Inventor(s): Address for Service: Invention Title: The Kendall Company Hampshire Street Mansfield Massachusetts 02048 UNITED STATES OF AMERICA John F. Dye Spruson Ferguson, Patent Attorneys Level 33 St Martins Tower, 31 Market Street Sydney, New South Wales, 2000, Australia Compression Device The following statement Is a full description of this invention, including the best method of performing it known to me/us:- 5845/4 TITLE: COMPRESSION DEVICE BACKGROUND OF THE INVENTION The present invention relates to a device for applying compressive pressures against a patient's limb througn means of compression sleeve enclosing the limb, and more particularly, to a means for automatically adjusting the pressure within the sleeve to maintain a preselected pressure.

Compression sleeves and devices for controlling them aie well known and illustrated in the prior art in such patents as IOU.S. Patent Nos. 4,013,069 of Hasty; 4,030,488 of Hasty; 4,091,804 of Hasty; 4,029,087 of Dye et al; 3,942,518 of Tenteris et al; and 2,145,932 of Israel, and reference may be had thereto for general background information on structure and utility.

*o Flexible compressive sleeves having a plurality of pressure compartments/chambers are wrapped around the limb of a patient and are then pressurized to apply compressive pressure t different parts of the limb. The sleeves are connected to a source of pressurized fluid which is regulated b a controller.

oThe controllers generally operate to form pressure cycles which propel the blood upwards from the ankle towards the thigh.

Such devices can be misadjusted or drift from proper adjustment so that safe and effective pressure may not be applied to the limbs.

Prior art such as U.S. Patent No. 4,396,010 of Arkans, U.S. Patent No. 4,702,232 of Gardner and U.S. Patent No.

4,013,069 of Hasty, incorporated herein by reference, manually coh-rcrol the amount'-of pressure that is- to-be supplied to a patient's limb. Furthermore, although Arkans provides a method -oof depressurizing a pressure compartment by use of a pressure release device, Arkans method of controlling the pressure applied to the limb is still provided by a manual control.

Even though the prior art has accomplished the depressurizing of chambers to reduce injury to a patient's -:51imb, the pressure supplied to the pressure compartments is still manually controlled. Thus, a nurse must remain with the unit constantly until the pressure has come up to a preselected value and then they must frequently check and recheck the pressure unit to make sure the pressure setting remains steady.

Additionally, changes in the patient's position may cause Schanges in the effective volumes of the pressure chambers resulting in undesirable changes in the pressures in the individual pressure chambers which requires. further manual adjustment.

Applicant is not aware of any prior art that discloses or 1osuggests that pressure applied to a patient's limb may be controlled by an automatic means.

Thus, a need exists for automatic control over application of pressure to the pressure chambers so that a preselected pressure value is maintained, and the time required by a person to watch over a pressure monitor is further reduced. The present invention provides such an automatic control means to control pressure exerted on a patient's limb.

SUMMARY OF THE INVENTION The object of the present invention is to provide a 2opressure generating device for applying compressive forces against a patient's limb through a flexible pressurizable sleeve which encloses the limb having a means for automatically adjusting pressure. supplied, to the pressurized sleeve to maintain a preselected pressure value.

The device has a pressure transducer and a controller which generates electrical signals in response to signals from the transducer which operate a flow control~valve that-controls the flow of fluid to a solenoid controlled valve to automatically adjust the pressure in tw sleeve.

Another object is to provide automatic pressure adjustment to eliminate the need for a nurse or similar person from having to continuously monitor the pressure sele, tion to insure it remains at a preselected pressure value.

Another object of the present invention is to provide automatic pressure adjustment i~n response to changes in the effective volumes of the pressure chambers of the sleeve caused by changes in a patient' s position other objects will become more apparent from the following description of the preferred embodiment and claims.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of the sequential compressive device as being used to apply compressive forces to the legs of to a patient; FIG. 2 is a schematic diagram, partially in block form, showing the preferred embodiment; *FIG. 3 is a timing diagram of the pressure cycles; FIG. 4 illustrates the flow control valve used to control 1 the flow of fluid to solenoid valves; and FIG. 5 is a flow vs. plunger position chart.

DESCRIPTION OF THE PREFERRED EMBODIAENTS Referring to FIG. 1 and to briefly describe the compressive device, the compression device 10 is seen as osupplying sequential compressive pressures and cooling to legs 12 a patient 14- The device .1ID includes a pressure controller 16 mounted in a case 18. The controller 16, generates controlled pressures timed as illust-rated in FIG. 3, at output ports 20A, 20B, 20C and 20D, respectively as will be Isdescribed in detail hereinafter. The output ports 20A-20D are cbnxiected -through flexible tubes 22x, 22B, 22C and 22D and are in fluid communication with input ports 24A, 24B, 24C and 24D of a manifold 26. Two sets of input ports are connected to a pair of compression sleeves 28 by a pair of flexible sets of 3otubes The compression sleeves 28 are identical to each other.

And as- shown in FIG. 1 each is wrapped around one of the patient's legs 12. Each sleeve has an ankle chamber 32A, a calf chamber 32B and a thigh chamber 32C. in addition, each 3 sleeve has one or more ventilation chambers 32D for ventilating the patient's legs 12.

The sequential compression device described above is per se old and is shown, for example, in U.S. Patent No. 4,396,010 -of Arkans, and other patents referenced therein.

Referring to FIG. 2, the pressure generator 16 functions to repetitively generate pressurne pulses to its output ports 20A-20D in the time sequence shown by wave-forms of FIG. 3. 'As seen by FIG. 3, the pressure cyclesi commence at time TA when topressure pulse A is applied to port 20A and the ankle chambers 32A are pressurized. At time TB, pressure pulse B is applied to port 20B and the calf chambers 32B are pressurized. At time- TC, pressure pulse C is applied to port 20C and the thigh chambers 32C are pressurized. At time TD, pressure pulses A, B C are terminated, chambers 32A, 32B and 32C are vented to the atmosphere, and cooling pulse D is applied to port 20D and ventilation chambers 32D. At the end of the cooling pulse, the entire sequence is repeated commencing with pressure pulse A.

Referring 'to F11G3. 2, the pressure controller 16 -has a 20compressor 74 as a generating source of pressurized fluid. In the preferred form of the invention, the pressurized fluid is air generated by an air compressor 74. The compressor 74 is connected through a conduit 70 to f luid junction 90 which is connected to solenoid valve 46D and the inlet opening 110 of low control valve 44 thriou.gh conduit 61, The discharge opening 120 of flow control valve 44 is connected through conduit 64 to the solenoid valve manifold 94. The solenoid valves 46A, 46B, 46C and 46D control the input of pressure through conduits 66A, 66B, 66C and 66D to a manifold 62 which 3oha§s ouitputf ports 20A, -20D, *20B-and 20C. The pressure transducer 34, of a commercially available type, is in fluid communication with the solenoid manifold 94 through pneumatic connection 68 and fluid junction 96.

The pressure transducer 34 senses the pressure at output 3 5port 20A through conduits 66A and 68; and then converts the pressure sensed into a first electrical signal. The f irst electrical signal is an analog electrical signal and is communicated to a signal converter 36 through lead 78. This first electrical signal is received by the signal converter 36, of a per se known and commercially available type, which converts the analog electrical signal to a digital electrical signal. The digital electrical signal generated by the signal converter 36 is then communicated to a microprocessor 38 through lead 76. The digital signal is received by the microprocessor 38, also of a per se known and commercially available type, which is programmed to monitor and to compare the digital signal to a preselected pressure value. If there lois a difference between the pressure sensed by the transducer 34 and the preselected pressure value, the microprocessor 38 then sends a second electrical signal to a driver circuit of a commercially available type, through lead 76 which in turn sends pulses of current through lead 72 to a motor 42. The imotor 42 preferably is a linear stepper motor that is commercially available, and operates the flow control valve 44 which controls the flow of fluid to solenoid valves 46A, 46B S and 46C. Thus, the pressure applied to outlet ports through solenoid valves 46A-C is dynamically regulated by .oautomatic adjustment of the flow of pressurized fluid through flow control valve 44.

Referring to FIG. 4, a flow control valve 44 for controlling and automatically adjusting pressure in pressure sleeves is depicted. The valve has a hollow body member 100 aswhich has an inlet opening 110 within which a precision orifice 112 is situated and a discharge opening 120. The body member 100 also has a chamber 130 in communication with the inlet and @discharge openings. The chamber 130 has a cylindrical central portion 132. The body member 100 may be made from any type of aomaterial such as aluminum, steel, brass, etc., although the preferred material is plastic. The flow valve also has a means for sealing against fluid flow lentering the-chamber -1-30, themeass including a plunger member i40 having -a tapered pin 141 at 4a& leading or distal end for releasably seating into the aprecision orifice 112 situated within inlet opening 110. The plunger 140 may be made of various materialF such as brass, steel, aluminum, other metals or composites, brass being preferred. Plunger 140 has a trailing or proximal sealing portion 142 in slideable fluid-tight contact with the walls of chamber 130 defining cylindrical portion 132. The taper of G2J^ the tapered pin 141 preferably is a compound taper which permits plunger 140 to precisely control 'he flow of fluid through orifice 112. Attached to the hollow body 100 is a means for moving plunger 140. This means is a linear stepper motor 42. The plunger 140 is connected to a shaft 152 of the motor 42 which extends into the hollow body 100. The motor moves the plunger 140 in a linear motion in and out of the orifice 112. The stepper motor 42 provides linear motion in increments of 0.002 (2 thousandths of an inch.) In addition, to the motor 42 has a predetermined internal stop (not shown) to prevent the plunger 140 from jamming into the body of the motor. There is also a predetermined internal stop (not shown) to prevent the tapered pin 141 from jamming into the orifice 112. Because the stepper motor 42 is calibrated to move in soo increments of 2 thousandths of an inch it can move pin 141 precisely into and out of the orifice 112 without causing it to jam. Furthermore, because the pin 141 has a compound taper, Oso* the flow of fluid through orifice 112 can be precisely controlled, thereby providing finite adjustments in the flow of aofluid to the oulenoid valves and therefore to the compression chambers.

The flow is precisely controlled due to the combination of the incremental movement of plunger 140 and the compound taper of pin 141. As pin 141 is being moved into position for ^%seating in the inlet opening 110 the compound tapered member reduces the area around the inlet opening 110 incrementally until it eventually seats in the orifice 112. This combination permits the finite pressure adjustments. As the tapered member is moved in and out of the inlet opening the area between the Sotaper and the inlet opening diminishes or expands, thus, exact control over the pressure is had, which is necessary to maintain a preselected pressure. This control -is -illustrated in FIG. 5 wherein a comparison is made of the present invention compound taper and a standard plunger commonly used within flow valves. The difference in the slopes of pressure is quite obvious. The slope of the pressure when using the standard plunger dips downward showing a drop in fluid flow has occurred. On the other hand the pressure slope of the present invention is stable and has no substantial pressure drops in 6? 40 its slope. This is important when providing pressure to a pressure sleeve that is being used on theA imL'c of a patient because any drop in pressure may cause the compressor supplying -too the pressure to over compensate and provideA-e- much pressure which may possibly cause injury to the patient. By using this new valve there are no pressure drops, thus when automatically adjusting the pressure in the sleeves, an even flow of pressure will be assured and the compressor will not provide unneeded pressure to the sleeves.

It is unknown in the art to use a linear stepper motor to move a tapered member (plunger) in a linear motion in such a precise manner. Prior art motors were of the constant rotary 1o motion type and turn the plunger down and up by screwing it into position. This has its disadvantages because if the rotary movement of the motor is not controlled, the rotary motion would exert a substantial force between the inlet and the plunger when seating the plunger so as to cause it to jam and not permit the plunger to be retracted. Although the rotary motion or movement of a rotary motor may be controlled, the cost to do so is prohibitive and thus, economically unsound for use in this art.

Referring once again to FIG. 1, the generator 16 is lomounted to a case 18, the case in its preferred from being shown to have various controls and indicators, as described hereinafter. A Setting LED (light emitting diode) 48 is shown to be provided to indicate the preselected pressure that is to be applied to the chambers 32A, 32C and 32D, of the sleeves. A 2.5cycle monitor 50 is also preferably provided to continuously display the status of the controller's compression sequence.

The cycle monitor 50 consists of four back lit panels, which when lighted read: ANKLE, CALF, THIGH and VENT. These represent the four major divisions of one complete cycle.

During operation, the ANKLE, CALF, THIGH and VENT lights will light, one at a time, -to indicate each of the major cycle divisions in turn. In addition, a ten-segment bar graph 52 is also shown to be provided. Each of the ten segments of the bar represents ten percent of a major cycle division and will light -s in sequence to indicate how much of a major cycle division is ,complete. The preferred embodiment of this invention will further include a Run LED 54 which indicates that the actual pressure is within 2mmHg of the set pressure.

After start-up, the setting LED 48 will set itself at and display as the set pressure. The setting LED 48 will light indicate that the microprocessor 38 is in the process of adjusting the actual pressure being supplied by the 6compressor 16. Within four cycles, the setting LED 48 will turn off and the Run LED 54 will come on, indicating that the actual pressure is within 3mmHg of the set pressure. The microprocessor 38 will continue to operate to make small adjustments in order to more perfectly match the set pressure.

,o The pressure generating device microprocessor 38 controls pressure to the sleeves by automatic pressure adjustment and not only sets the pressure automatically, but maintains the set pressure no matter how the patient moves or changes position.

With the advent of the present inventions automatic pressure adjustment, manual control is not required to adjust o"o the pressure to the chambers during the pressure cycle, therefore, all aspects of manual control have been removed.

The automatic adjustment feature of the present invention provides a significant advancement and a tremendous achievement 2oover the prior art, therefore an advantage over all prior art.

because the present invention automatically adjusts the pressure to pressure chambers in a sleeve, the requirement to have someone constantly watch over a pressure monitor to see the rise in pressure, and then to have them continue to monitor 1 the pressure to make sure the pressure does not exceed a preselected pressure or to make sure that the chambers have not been depressurized during the pressure cycle because of over pressurizing the chambers, has been eliminated. The nurse can start the pressure generating device, which has a preselected pressure- and go on- to other duties. The- controller- will monitor the pressure being supplied to the pressure chambers in the sleeve and will automatically adjust the pressure until the required pressure is arrived at. The controller will then continue to monitor the pressure provided throughout a pressure cycle and maintain the preselected pressure without having to manually make adjustments. The time saved by not requiring constant monitoring is substantial and makes it economically sound for use in hospitals or other health care facilities.

The present invention, even though automatically adjusting the pressure delivered to pressure chambers, also has a means, as does prior art, to depressurize the pressure chambers in the sleeves, either when the last pressure cycle has terminated, as in an earlier paragraph, or in case of an involuntary shut down or overload of the pressure system.

A description is given of the present invention for clarity and understanding and no limitations are to be considered other than those proposed by the specification and to claims thereof.

o

Claims

2. The device of claim 1 wherein the stepper motor is a linear stepper motor. .oo
3. The device of claim 1 wherein the flow control valve comprises; .0.0 25 a hollow body member having an inlet opening and a discharge opening therein, and a chamber in communication with said inlet and discharge openings; a means for sealing against fluid flow entering said chamber said means including a tapered member for releasably seating into said inlet opening; and means for moving said tapered member said means including a linear said stepper motor for moving said tapered member in a linear motion.
4. The device of claim 3 wherein said linear stepper motor is calibrated to move in a linear motion in increments of at least .002 of an inch. The device of claim 3 wherein said taper of said tapered member is a compound taper.
6. A compression device, substantially as described herein with reference to the accompanying drawings. INA\LIBHHIO0109:RLF 11 DATED this Twelfth Day of Sep tember 1994 The Kendall Company Patent Attorneys for the Applicant SPRUSON FERGUSON (NAXLHH00lOTRLF Compression Device Abstract A pressure generating device (10) for applying compressive pressures against a patient's limb (12) through means of a flexible, pressurizable sleeve (28) which encloses the limb 1 2) having a means for automatically adjusting pressure (16) within the sleeve (28) to maintain a preselected pressure applied to the limb The device (10) has a pressure transducer (34) and a controller (16) which generates electrical signals in response to signals from the transducer (34) that operate a flow control valve (44) to control the flow of fluid to the pressure chamber (32A, 32B, 32C) of the sleeve. .Figure 1 o 0. 0 Figure 1 9* 9 9o KRS/2187W