Valve-less fluid control circuit for rhythmic action devices

Details Valve-less fluid control circuit for rhythmic action devices Valve-less fluid control circuit for rhythmic action devices

2000-09-01

2001-11-20

Yu, Justine R. (Department: 3764)

Surgery: kinesitherapy

Kinesitherapy

Device with applicator having specific movement

C601S158000, C137S809000, C137S814000

Reexamination Certificate

active

06319214

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to mechanical devices providing rhythmic action. More particularly, the invention relates to fluid control circuits providing rhythmic action for sequential compression devices, such as circulatory assist devices.
2. Description of the Related Art Various examples of fluid control circuits for sequential compression devices used to assist patients in circulating fluid around a limb or limbs are provided by U.S. Pat. Nos. 4,396,010 (to Arkans), 4,481,937 (to Arkans) and U.S. Pat. No. 4,858,596 (to Kolstedt). The contents of these patents are incorporated by reference herein as background material.
Prior art fluid control circuits utilize a series of valves and pressure relief valves, which must be periodically opened and closed, for circulating the liquid through a sleeve or cuff. Opening and closing of the valves requires either a series of solenoid controls (with sophisticated electronic controls) or cam actuators. The hardware necessary for the control of opening and closing valves uses large amounts of power and increases the bulk of such devices.
In addition, the mechanical action of the valves, solenoids and cams are prone to wear and tear, which will degrade the quality of the compression device over time, requiring high costs for maintenance and repair. Thus, there exists a need in the art for improvement in fluid control circuits.
One of the present inventors previously designed a valve-less artificial heart utilizing a dual fluid oscillator (U.S. Pat. No. 3,599,244, the content of which is incorporated by reference herein as background material), which relies on the dynamic flow properties of blood for its operation. In this device, the system provides better reliability than prior art artificial hearts using mechanical valves, which often fail.
However, the dual fluid oscillator of the prior art requires the placement of a pump at each output having a pressure, which is directly related to the input pressure, and is inversely related to the pressure head against which it is being pumped. Moreover, the fluid from one part of the dual fluid oscillator does not directly transfer the fluid to the second (or any other) oscillator, as would be required in a sequential compression device.
Finally, the prior art dual fluid oscillator also requires that the oscillator portions must be arranged contiguously with each other so that a filling of a first fluid oscillator with a working fluid increases the pressure to such a level that the pressure against a common diaphragm causes the diaphragm to press against the second fluid oscillator, emptying the second fluid oscillator.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to develop a fluid control circuit having a plurality of fluid oscillators which can circulate the working fluid successively to each particular fluid oscillator without requiring the opening and closing of a series of valves.
To this end, according to the present invention, there is provided a valve-less fluid control circuit for controlling rhythmic action devices, such as circulatory assist devices. The fluid control circuit has a plurality of pressure sensitive fluid oscillators for circulating a fluid. Each fluid oscillator includes a capacitance chamber unit for peristaltic pumping of fluid after being filled via an input conduit and a resistance conduit. A first control conduit provides an outlet of fluid from the capacitance unit during peristaltic pumping, and when the pressure of the fluid in the first control conduit reaches a certain level relative to the pressure of fluid in the input conduit, the fluid is directed through an interactive region and exits the first fluid oscillator through an exhaust conduit. A coupling unit couples the output of the first fluid oscillator to the input conduit of the successive fluid oscillator, so that the expansion and contraction of the capacitance chambers occurs successively without the need for valves and/or complicated control circuitry, such as solenoids and cams. A return conduit at the last fluid oscillator returns the fluid to a second control conduit of the first fluid oscillator to refill the first capacitance chamber.
More particularly, the present invention is directed to a fluid control circuit for controlling rhythmic action devices, the fluid control circuit comprising a plurality of pressure sensitive fluid oscillators coupled together in a ring configuration for circulating a fluid, wherein each of the fluid oscillators comprises: an input conduit having a first end for receiving a working fluid; an interactive region communicating with a second end of the input conduit; a resistance conduit having a first end communicating with the interactive region; capacitance chamber means for storing the working fluid and for providing a peristaltic pumping of the working fluid, the capacitance chamber means communicating with a second end of the resistance conduit; an exhaust conduit communicating with the interactive region; a first control conduit for controlling a direction of the flow of the working fluid entering the interactive region, the first control conduit communicating at a first end with the capacitance chamber means and at a second end with the interactive region, so as to provide an output path of the working fluid pumped from the capacitance chamber means, the first control conduit communicating with the interactive region at an angle relative to the input conduit so that when a fluid pressure of the working fluid in the first control conduit reaches a certain predetermined level relative to the fluid pressure in the input conduit, the first control conduit controls a flow direction of the working fluid entering the interactive region from the input conduit, so as to direct the flow toward the exhaust conduit; and wherein the fluid control circuit further comprises coupling means for coupling the plurality of fluid oscillators together so that an output from the exhaust conduit of each fluid oscillator is coupled to the input conduit of a successive one of the fluid oscillators in the ring configuration, so that the working fluid circulates successively through the respective capacitance chambers of the fluid control circuit without valves.
The first fluid oscillator of the plurality of fluid oscillators may further comprise a second control conduit communicating with the interactive region at an angle relative to the input conduit, so that when a fluid pressure of the working fluid in the second control conduit reaches a certain predetermined level relative to the fluid pressure in the input conduit, the second control conduit controls the direction of the working fluid to flow towards the capacitance chamber means; and a last fluid oscillator of the plurality of oscillators may comprise a return conduit having a first end communicating with the exhaust conduit of the last fluid oscillator, and a second end communicating with the second control conduit of the first fluid oscillator, so that at least a portion of the working fluid exiting the last oscillator is recirculated to the first fluid oscillator from the return conduit to the second control conduit, so as to control the direction of the fluid to flow towards the capacitance chamber means.
The capacitance chamber means of the plurality of fluid oscillators may include expandable sleeves which successively expand and contract as the working fluid is circulated successively through each of the plurality of fluid oscillators.
The device means for coupling may include venting means arranged between the exhaust conduit of one of the fluid oscillators and the input conduit of a successive one of the fluid oscillators.
At least one of the fluid oscillators may comprise a valve-less booster pump arranged at one of (i) the input conduit, (ii) the coupling means, and (iii) the exhaust conduit or at least one fluid oscillator which comprises a centrifugal pump arranged at one of (i) the input conduit, (ii) the coupling means, and

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