Novel External Circulatory Assist Device

Abstract

Novel external pressure circulatory assist apparatus utilizing movement of a shell portion of a limb-enclosing housing as a mechanical means for applying the requisite cyclic pressure to the limbs of a patient being treated.

Description

BACKGROUND OF THE INVENTION

This invention relates to apparatus for assisting blood circulation by applying external pressure to the body. Such processes are generally known and are disclosed in, for example, U.S. Pat. No. 3,303,841 to Dennis and U.S. Pat. No. 3,654,919 to Birtwell.

As indicated in the Birtwell patent, the prior art devices usually achieved pressure by having liquid pressure cycled by a pump means attached to a liquid reservoir surrounding the legs of a patient being treated. More recently, apparatus has been developed whereby a mechanical platen rises and falls while in contact with a constrained leg-enclosing reservoir, thereby causing the pressure in the reservoir to cycle. This older apparatus is highly satisfactory in some circumstances but, as the therapeutic value of external assist apparatus becomes more apparent for various types of therapy, the known apparatus has been found to be heavier than is convenient for handling and portability.

SUMMARY OF THE INVENTION

Therefor it is an object of the invention to provide a lightweight limb-housing unit for use in external circulatory assist processes.

Another object of the invention is to provide a means to achieve the simultaneous and synchronous action of two leg units with a minimum of mechanical apparatus.

A further object of the invention is to utilize necessary superstructure of an external circulatory assist apparatus to serve the dual function of housing and pressurizing a liquid bladder.

Another object of the invention is to provide a pressurizing means having sufficient displacement capacity to provide suitable treatment for patients with a wide variety of limb sizes and without having to change water capacity of the pressurized, liquid-containing bladder wrapped about the limbs.

Other objects of the invention will be obvious to those skilled in the art on reading this application.

The above objects have been substantially achieved by using leg housing members as the means by which mechanical pressure is applied to liquid-filled blankets wrapped about the legs.

ILLUSTRATIVE EMBODIMENT OF THE INVENTION

In this application and accompanying drawings there is shown and described a preferred embodiment of the invention and suggested various alternatives and modifications thereof, but it is to be understood that these are not intended to be exhaustive and that other changes and modifications can be made within the scope of the invention. These suggestions are selected and included for purposes of illustration in order that others skilled in the art will more fully understand the invention and the principles thereof and will be able to modify it in a variety of forms, each as may be best suited in the condition of a particular case.

IN THE DRAWINGS

FIG. 1 is a view of a patient positioned for treatment in the apparatus of the invention.

FIG. 2 is a view similar to FIG. 1 excepting the apparatus is shown in an "open" position, i.e., a position wherein a relatively low pressure or no pressure is exerted by the housing apparatus on the legs of the patient.

FIG. 3 is an elevation of the actuating mechanism with the housing in the FIG. 1 position.

FIG. 4 is an elevation of the actuating mechanism with the housing in the open, i.e., the FIG. 2, position.

Referring to FIG. 1, it is seen that a patient is placed with his legs, from upper thigh to ankles, in an external pressure circulatory assist apparatus 10. Apparatus 10 is placed on a table 12 and comprises a base plate 14 on which is mounted leg housing 16 comprising two leg-holding chambers 18. Each chamber 18 consists of an upper shell 20 and a lower shell 22. Lower shells 22 are fixed to base plate 14. Upper shells 20, however, are pivotally mounted onto the outer sides of shells 22 by quick-connecting fastening means 24. The upper shell and lower shell are approximately coextensive with the legs of the patient.

FIGS. 3 and 4 show the means by which the pivotally-mounted shells 20 are moved.

Upper shells 20 are attached to generally triangular plates 26 which extend inwardly from the patient's limbs. Triangular plates 26, when in the downward position shown in FIG. 3, act as lever means for applying pressure to bladders 28 which encircle the legs of the patient. Plates 26 are integral with upper shells 20 and, as a consequence, pivot on the pin members 30 of quick-connecting fastening means 32. Pin members 30 are mounted on brackets 34 and fastened to lower shells 22. The pins extend laterally into receptacles in brackets 36 which are mounted on upper shells 20.

Lower shells 22 are rigidly positioned on base plate 12 and connected to one another by lower bracing plates 38 which extend between the two lower shells.

Referring to FIGS. 4 and 5, it is seen that base plate 14 carries mechanical actuator means 40 operably connected to pivot plates 26 upwardly and downwardly in response to the action of a hydraulic cylinder 42. Hydraulic cylinder 42 is mounted on base plate 14 by means of mounting bracket 44. A piston 46 is connected to the cylinder, thence to two bell-cranks 48 and 48a, mounted on brackets 50 and 50a respectively, through operating rods 52 and 54. When the bellcranks are rotated clockwise by a leftward movement of piston 46, they cause the downward movement of lift rods 57 and, consequently, the downward movement of plates 26 until they assume the position illustrated in FIGS. 1 and 3. Conversely, when bellcranks 48 and 48a are rotated clockwise by a rightward movement of piston 46, they cause the simultaneous upward movement of lift rods 57 and the upward movement of plates 26 to assume the position illustrated in FIGS. 2 and 4.

Lift rods 57 are connected to lift assemblies 56. Each lift assembly comprises a removable locking pin 58 which connects two pivot blocks 62. Each pivot block 62 is connected to a pivot block retainer 64 by a pivot block shaft 66. Pivot block retainer members 64 are attached directly to plates 26. In operation of lift assembly 56, it will be seen that lift rods 57 are pushed upwardly to bear against locking pins 58 and cause the lifting of pivot blocks 62. Simultaneously shafts 66 rise, and allow the pivoting of, pivot block retainers 64 which are directly connected to plates 26. This movement is reversed on the downward movement of the lift rods and an alternating pressure action is achieved by the device. In this action the generally hoop-shaped leg compartments tend to withstand and dissipate stresses with substantially no change in their shape. This allows a more predictable control of the pressurizing cycle. Moreover, the vertical thrust necessary to operate the opening and closing of the leg compartments is largely dissipated through horizontal force vectors exerted on brackets 44 and 50a. Thus this force is largely counterbalanced by the tensile strength of base plate 14 and this factor contributes substantially to the dimensional stability of the apparatus in opposing vertical distortion during operation.

The liquid containing bladders, as is known in the art, are formed of a non-distensible material and fastened to the leg unit shell members to minimize any lateral movement of the bladders along the leg.

It is also to be understood that the following claims are intended to cover all of the generic and specific features of the invention herein described and all statements of the scope of the invention which might be said to fall therebetween.

Claims

What is claimed is:

1. In an external circulatory assist apparatus comprising a liquid-containing bladder means adapted to be positioned around a patient's limbs within a limb housing, the improvement wherein said housing comprises two limb-holding chambers, each said chamber comprising an upper shell portion and a lower shell portion and each said chamber adapted to be approximately coextensive with the limb enclosed therein, means for alternately moving said upper shells with respect to said lower shells to simultaneously increase and decrease the pressure exerted on said liquid containing bladder means in each chamber.

2. Apparatus as defined in claim 1 wherein said upper shells and lower shells are hinged together along the outer edges thereof, wherein said lower shells are stationary and each said upper shell is attached to a mechanical lift means to alternately push and pull said upper shells into compressing and decompressing relationship to said bladder means.

3. Apparatus as defined in claim 2 wherein said mechanical means comprises a hydraulic piston adapted to drive two spaced, vertically reciprocating lift rods into contact with said mechanical means, said lift rods being driven by driving means so mounted as to dissipate the opposing forces thereof as tensile forces normal to the direction of lift and along a base plate on which said mechanical means is mounted.

4. Apparatus as defined in claim 1 wherein said bladder means is fully enclosed and comprises no operable connection with an exterior source of liquid.

5. Apparatus as defined in claim 2 wherein said bladder means is fully enclosed and comprises no operable connection with an exterior source of liquid.

6. Apparatus as defined in claim 3 wherein said bladder means is fully enclosed and comprises no operable connection with an exterior source of liquid.