Compression Device With Pressure Determination

The present invention relates to therapeutic and prophylactic devices, and more particularly to devices for applying compressive pressures against a patient's limb.

It is known that the velocity of blood flow in a patient's extremities, particularly the legs, markedly decreases during confinement of the patient. Such pooling or stasis of blood is particularly pronounced during surgery, immediately after surgery, and when the patient has been confined to bed for extended periods of time. It is also known that stasis of blood is a significant cause leading to the formation of thrombi in the patient's extremities, which may have a severe deleterious effect on the patient, including death. Additionally, in certain patients it is desirable to move fluid out of interstitial spaces in extremity tissues, in order to reduce swelling associated with edema in the extremities.

Devices have been disclosed in U.S. Pat. Nos. 4,013,069 and 4,030,488, incorporated herein by reference, which develop and apply the desired compressive pressures against the patient's limbs. Such devices comprise a pair of sleeves which envelop the patient's limbs, and a controller for supplying fluid pressure to the sleeves through conduits which are connected in fluid communication with chambers in the sleeve. During use of the device it is desirable to know the pressure in at least one chamber of the sleeve, but prior to the invention it was necessary to connect a pressure gauge directly to the chamber, thus requiring an extra conduit leading to the sleeve which resulted in extra cost and inconvenience in use.

A principal feature of the present invention is the provision of an improved device for applying compressive pressures against a patient's limb from a source of fluid.

The device of the present invention comprises, a sleeve for placement about the patient's limb and having at least one inflatable chamber, and means for intermittently inflating and deflating the chamber. The device has first conduit means connecting the inflating means and the chamber, and second conduit means communicating with the first conduit means upstream from the chamber. The device also has means for determining pressure communicating with the second conduit means, and means for providing resistance against fluid flow passing through the second conduit means intermediate the first conduit means and the pressure determining means.

A feature of the present invention is that the pressure determining means and associated second conduit means are not connected directly to the sleeve chamber.

Another feature of the invention is that the pressure determining means and second conduit means may be connected to the first conduit means at a location adjacent the inflating means.

A further feature of the invention is that the pressure determining means, resistance providing means, and associated second conduit means determine pressure in the sleeve chamber although they are not directly connected to the sleeve chamber, thus eliminating the need for a separate conduit to the sleeve chamber.

Further features will become more fully apparent in the following description of the embodiments of this invention and from the appended claims.

In the drawings:

FIG. 1 is a fragmentary perspective view of a compression device of the present invention;

FIG. 2 is a front plan view, partly broken away, of a compression sleeve for the device of FIG. 1;

FIG. 3 is a back plan view, partly broken away, of the sleeve of FIG. 2;

FIG. 4 is a front plan view of fluid impervious sheets defining chambers in the sleeve of FIG. 2;

FIG. 5 is a back plan view of the fluid impervious sheets of FIG. 4;

FIG. 6 is a fragmentary sectional view taken substantially as indicated along the line 6--6 of FIG. 4;

FIG. 7 is a fragmentary sectional view taken substantially as indicated along the line 7--7 of FIG. 4;

FIG. 8 is a fragmentary sectional view taken substantially as indicated along the line 8--8 of FIG. 4;

FIG. 9 is a perspective view illustrating the sleeve during placement on the patient's leg;

FIG. 10 is a diagrammatic view of a pressure determining device of the present invention; and

FIG. 11 is a fragmentary perspective view of a resistance element for the pressure determing device.

Referring now to FIG. 1, there is shown an intermittent compression device generally designated 20 having a controller 22, and a pair of elongated compression sleeves 26 for enclosing a length of the patient's extremities, such as the legs as shown. The controller 22 is connected through a tube 28 to a source S of pressurized gas, and to an exhaust tube 30. Also, the controller 22 is connected to the separate sleeves 26 through separate sets of conduits 34 and 35. The controller may be of any suitable type, such as the controllers described in U.S. Pat. Nos. 4,013,069 and 4,030,488.

With reference to FIGS. 2 and 3, the sleeve 26 has an outer cover sheet 36 covering the entire outer surface of an outer fluid impervious barrier sheet 38. Also, the sleeve 26 has an inner cover sheet 40 covering an inner surface of an inner fluid impervious barrier sheet 42. The outer cover sheet 36 may comprise a relatively inelastic fabric with a brushed matte or napped finish of nylon or polyester, such as a fabric sold under the trademark Flannel/Flannel II, No. 11630, by Guilford Mills, Greensboro, N.C., which provides an attractive outer surface for the sleeve, and also defines brushed or napped fibers across the entire outer surface of the sleeve for a purpose which will be described below. In suitable form, the fabric of the sheet 36 may be warp knit from polyester yarns on a tricot machine, after which the fabric is dyed to a suitable color, and the fabric is brushed or napped on a suitable machine to raise loops from the fabric. The inner cover sheet 40 may comprise a suitable nonwoven material which provides a comfortable inner surface of the sleeve for the patient. The barrier sheets may be formed from a suitable flexible plastic material, such as polyvinylchloride. If desired, a segment of the brushed nylon fabric may be formed into a tube 44 to cover the conduits which extend from the sleeve to the controller. As shown, the conduits and covering tube 44 may extend through an opening 46 in the inner cover sheet 40.

The sleeve 26 may have a pair of side edges 48a and 48b, and a pair of end edges 50a and 50b connecting the side edges 48a and b, with the side edges 48a and b being tapered toward a lower end of the sleeve. The sleeve 26 may also have an elongated opening 52 extending through a knee region 53 of the sleeve, and defined by peripheral edges 54 extending around the opening 52. In addition, the sleeve 26 has an elongated opening or cut-out 56 in the knee region 53 extending from the side edge 48a toward a lateral central portion of the sleeve, with the opening 56 being defined by peripheral edges 58 extending from the side edge 48a around the opening 56. As shown, the inner end of the opening 56 is spaced from the opening 54, and the opening 56 defines an upper flap 60 and a lower flap 62 of the sleeve which are separated by the opening 56. Further, the sleeve 26 may have a pair of lower fastening strips 61, such as a hook material sold under the trademark Velcro, secured to the inner cover sheet 40 along the side edge 48b.

With reference to FIGS. 4-8, the inner and outer fluid impervious barrier sheets 38 and 42 have a plurality of laterally extending lines 64, such as lines of sealing, connecting the barrier sheets 38 and 42 together, and longitudinally extending lines 66, such as lines of sealing, connecting the sheets 38 and 42 together and connecting ends of the lateral lines 64, as shown. The connecting lines 64 and 66 define a plurality of longitudinally disposed chambers 68a, 68b, 68c, 68d, 68e, and 68f, which for convenience will be termed contiguous. As shown, the chambers 48 extend laterally in the sheets 38 and 42, and are disposed in the longitudinal arrangement between the end edges 50a and 50b. When the sleeve is placed on the patient's leg, the lowermost chamber 68a is located on a lower part of the leg adjacent the patient's ankle, while the uppermost chamber 68f, is located on an upper part of the leg adjacent the midthigh.

As shown, the longitudinal line 66 nearest the side edge 48b is separated intermediate the chambers 68b and c, 68c and d, and the chambers 68e and f. The lateral lines 64 define ventilation channels 70a, 70b, and 70c extending laterally in the sleeve from the longitudinal line 66 adjacent the side edge 48a toward the longitudinal lines 66 adjacent the side edge 48b, with the ventilation channels 70 being positioned at spaced locations longitudinally along the sleeve intermediate different pairs of adjoining chambers. Thus, the ventilation channel 70a is located intermediate the chambers 68b and 68c, the ventilation channel 70b is located intermediate the chambers 68c and 68d, and the ventilation channel 70c is located intermediate the chambers 68e and 68f. Moreover, the ventilation channels 70 have a width substantially less than the width of the chambers 68 such that the channels 70 do not detract from the size and volume required for the compression chambers 68. The inner and outer barrier sheets 38 and 42 also have a longitudinally extending line 72 which defines a connecting channel 74 intermediate the line 72 and the adjacent longitudinal line 66. As shown, the connecting channel 74 extends along the sides of the chambers 68c, 68d, and 68e, and communicates with the ventilation channels 70a, b, and c, such that the channel 74 connects the spaced ventilation channels 70. Further, the inner barrier sheet 42 has a plurality of openings or apertures 76 which communicate with the channels 70. Thus, when the sleeve 26 is placed on the patient's leg, the openings 76 face toward the leg.

With reference to FIGS. 4-7, the longitudinal lines 66 and 72 adjacent the side edge 48b define a pair of flaps 78a and 78b of the barrier sheets 38 and 42 which extend between the respective lines and the side edge 48b. As shown, the sheets 38 and 42 have a longitudinally extending line 79 which defines a directing channel 80 intermediate the lines 79 and 72, with the opposed longitudinal ends of the channel 80 being open. The sleeve 26 has a first connecter 82a which is commonly connected in fluid communication to the two lowermost chambers 68a and 68b, and which is connected to a conduit 34a in the illustrated conduit set 34. As shown, the conduit 34a passes through an opening 84a in the upper barrier sheet flap 78a which retains the conduit 34a at the desired position in the sleeve 26. The sleeve 26 also has a second connector 82b which is commonly connected in fluid communication to the second pair of adjoining chambers 68c and 68d, and which is connected to a second conduit 34b in the conduit set 34. The conduit 34b passes through an opening 84b in the upper flap 78a which retains the conduit 34b at the desired position. The sleeve 26 has a third connecter 82c which is commonly connected in fluid communication to the uppermost chambers 68e and 68f, and which is connected to a third conduit 34c in the conduit set 34. As shown, the conduit 34c passes through an opening 84c in the upper flap 78a, with the conduit 34c extending through the directing channel 80 in order to retain the third conduit 34c at the desired position in the sleeve. The sleeve 26 also has a fourth connector 82d which is connected in fluid communication to the connecting channel 74 in order to permit passage of air to the ventilation channels 70. As shown, the connecter 82d is connected to a fourth conduit 34d in the conduit set 34, with the conduit 34d passing through an opening 84d in the upper barrier flap 78a. Thus, the conduits 34a, 34b, and 34c are separately connected to pairs of adjoining chambers, while the conduit 34d is connected to the connecting channel 74. Of course, the other sleeve associated with the conduits 35 may be constructed in a similar manner. It will be apparent that the barrier flaps 78a and 78b, the directing channel 80, and the openings 84 cooperate to retain the conduits at the desired position within the sleeve. Further, the sleeve 26 has suitable securing means 86, such as regions of heat sealing or adhesive, bonding the flaps 78a and 78b to opposed sides of the conduits 34 adjacent the opening 46. Thus, in the event that forces are applied to the conduits 34 exterior the sleeve 26, the forces are transmitted to the flaps 78a and b rather than the connecters 82a, b, and c, in order to relieve possible strain from the connecters and prevent severance of the connecters from the sleeve.

In use, the sleeve 26 may be placed below the patient's leg preparatory to securement about the limb, as illustrated in FIG. 9. Next, the upper flap 60 and lower flap 62 may be independently passed around the patient's leg at locations above and below the knee, respectively. Thus, the opening 56 separates the flap portions of the sleeve in the region of the knee to permit independent wrapping of the upper and lower portions of the sleeve about the leg and simplify placement of the sleeve, as well as provide an improved fit. After both the upper and lower flaps 60 and 62 have been suitably wrapped about the patient's limb, the remaining part of the sleeve adjacent the side edge 48b may be wrapped over the flaps 60 and 62, and the fastening strips 61 may be pressed against the outer cover sheet 36. Thus, the hook fastening strips 61 engage with the brushed fibers of the outer cover sheet 36, such that the strips 61 and sheet 36 interengage and retain the sleeve in the wrapped configuration. Since the sheet 36 extends entirely across the outer surface of the sleeve 26, the sleeve may be readily adjusted as necessary for the desired fit according to the size of the patient's leg. Thus, the sleeve 26 may be placed in a simplified manner while accomplishing an improved fit on patients having varying leg sizes. In addition, the openings 52 and 56 greatly reduce the amount of material and bulk for the sleeve in the region of the patient's knee. Accordingly, the sleeve provides flexibility in the knee region in order to prevent binding and permit flexation of the knee during the extended periods of time while the sleeve is secured about the leg.

After placement of the sleeves on the patient's limbs, the controller 22 may be initiated in order to supply air to the sleeves 26. The controller 22 intermittently inflates the chambers 68 during periodic compression cycles, and intermittently deflates the chambers 68 through the exhaust tube 30 during periodic decompression cycles intermediate the compression cycles. The inelastic cover sheet 36 of the placed sleeve restricts the size of the inflated chambers, and greatly enchances the compressive action of the chambers to permit lower fluid volumes during the compression cycles. Further, the controller 22 supplies air through the conduits to the connecting channels 74 in the two sleeves. The air then passes from the common connecting channels 74 to the spaced ventilation channels 70 and through the openings 76 onto the patient's legs. In this manner, the device 20 ventilates a substantial portion of the patient's legs to prevent heat buildup and provide comfort for the patient during extended periods of time while the sleeves are retained in a wrapped condition about the patient's limbs. In a preferred form, the controller 22 supplies air to the ventilation channels 70 during the periodic decompression cycles. Also, the controller 22 may have suitable means, such as a switch, to selectively permit passage of air to the ventilation channels 70 or prevent passage of air to the ventilation channels 70, as desired. In addition, the switch may be utilized to control the quantity of air which ventilates the patient's limbs for maximum patient comfort.

A diagrammatic view of a pressure determining device 90 for the compression device 20 is illustrated in FIG. 10. As shown, the source S of pressurized fluid is connected to the timing circuits of the controller 22 which intermittently inflates and deflates the chambers of the sleeve 26. A first conduit 34a is connected between the controller 22 and the lowermost chamber 68a of one of the sleeves 26, although it will be understood that the conduits connected to more upwardly located chambers in either sleeve 26 may be utilized for determining pressure, if desired. A flow control valve 92 is associated with the first conduit 34a to control the flow of air through the first conduit 34a, with the flow control valve 92 being located upstream from the chamber 68a and adjacent the inflation and deflation device or controller 22.

The device 90 has a second conduit 94 which is connected to the first conduit 34a at a location upstream from the chamber 68a and downstream from the flow control valve 92, such that the second conduit 94 communicates with the first conduit 34a at a location adjacent the controller 22. The device 90 has a pressure gauge 96 of known type communicating with an end of the second conduit 94. The device 90 has a pneumatic resistance element 98 associated with the second conduit 94 at a location intermediate the connection with the first conduit 34a and the pressure gauge 96, with the resistance element 98 providing resistance against passage of air through the second conduit 94, this limiting the passage of fluid through the second conduit 94. In a suitable form, as shown in FIG. 11, the resistance element 98 comprises an insert 100 placed in a lumen 102 of the second conduit 94, with the insert 100 having an orifice 104 which is smaller in diameter than the diameter of the lumens in the second conduit 94 and the first conduit 34a.

In operation, during inflation of the chamber 68a by the controller 22 the pressure device 90 converts the pressure due to moving air in the first conduit 34a to a value on the pressure gauge 96 in accordance with the static pressure in the chamber 68a during inflation. During this time, the pressure device 90 acts to approximate integration of fluid flow in order to determine fluid pressure by the gauge 96, although the second conduit 94 is not directly connected to the chamber 68a and may be connected to the first conduit 34a at a location adjacent the controller 22, such that the gauge 96 may be included on a housing of the controller 22, as shown in FIG. 1. Thus, the pressure device 90 of the present invention eliminates the need for an extra conduit to be connected directly to the chamber 68a, although the pressure device 90 determines the static pressure in the chamber 68a. With reference to FIGS. 10 and 11, during assembly of the device 20 the size of the orifice 104 may be selected for the particular gauge 96 to obtain accurate pressure by calibrating the readings on the pressure gauge 96 with the actual static pressure in the chamber 68a. In this manner, the pressure indicated on the gauge 96 is experimentally determined according to the characteristics of the gauge 96 and the inflatable chamber 68a.

The foregoing detailed description is given for clearness of understanding only, and no unnecessary limitations should be understood therefrom, as modifications will be obvious to those skilled in the art.