The present application is one of four applications being filed on the same day and bearing publication numbers 2022/0265994 and 2022/0265993, and patent numbers 11,236,741 and 11,300,119. Each of these related applications and patents, other than the present application, is hereby incorporated herein by reference in its entirety.
The present invention relates to pulsatile fluid pumps, and more particularly to pulsatile fluid pumps suitable for pumping blood.
A pulsatile fluid pump is taught in U.S. Pat. No. 7,850,593 (“our prior patent”) for an invention of Douglas Vincent and Matthew Murphy, who are co-inventors of the present invention. Our prior patent discloses a pump actuated by a linear motor configured to cause reciprocation of a flexible membrane, serving as a wall of a fluid housing, that is in turn coupled to a pair of ball valves, in a manner as to implement pulsatile fluid flow.
In accordance with one embodiment of the invention, a pulsatile fluid pump system includes a pump-valving assembly including a chamber and a set of ports; and a diaphragm assembly coupled to the chamber and including an edge-mounted flexible diaphragm having an inside surface for contacting a fluid in the chamber to be pumped and an outside surface exposed to ambient air. The diaphragm assembly and the pump-valving assembly are configured as an integral pump assembly. The pulsatile fluid pump system further includes a linear motor having a magnet and a coil, the magnet moving in relation to the coil, the coil having an electrical input. The pulsatile fluid pump system also includes a control housing rigidly coupled to the linear motor and a controller system having an electrical output coupled to the electrical input of the coil, the controller system defining an electrical waveform at the electrical output to cause desired operation of the diaphragm. The integral pump assembly is configured to be removably coupled to the control housing, and the diaphragm assembly of the integral pump assembly is configured to be removably coupled to the linear motor.
Alternatively or in addition, the pulsatile fluid pump system further includes a push rod, coupled to the linear motor, and configured for removable attachment to the diaphragm assembly. Also alternatively or in addition, the pulsatile fluid pump system further includes a force sensor coupled between the linear motor and the push rod.
In a related embodiment, the pulsatile fluid pump system further includes a flexible seal surrounding the push rod. Alternatively or in addition, the pulsatile fluid pump system further includes a set of cooling fins thermally coupled to the coil of the linear motor. Also alternatively or in addition, the push rod is slidably attached to the diaphragm assembly.
Alternatively or in addition, the controller system includes a microprocessor, and the controller system is configured to execute a waveform program defining an electrical waveform at the electrical output to cause desired operation of the diaphragm.
In a further related embodiment, the integral pump assembly has a peripheral flange, and the control housing has a channel configured to removably receive the peripheral flange if the diaphragm assembly of the integral pump assembly is removably coupled to the linear motor. Alternatively or in addition, at least one of the peripheral flange and the channel has a set of compliant members to physically bias the peripheral flange in the control housing. Also alternatively or in addition, each compliant member includes a spring,
Further alternatively or in addition, the pulsatile fluid pump system further includes a latch configured to constrain the integral pump assembly in the channel. Alternatively or in addition, the set of compliant members is included in a set of ball detents.
In a related embodiment, the diaphragm assembly further includes a coupler configured to reciprocate with the diaphragm, and the integral pump assembly includes a pump housing having a neck configured to maintain axial and rotational alignment of the coupler.
In accordance with an alternative embodiment of the invention, an integral pump assembly for a pulsatile fluid pump system includes a pump-valving assembly including a chamber and a set of ports; and a diaphragm assembly coupled to the chamber and including an edge-mount flexible diaphragm having an inside surface for contacting a fluid in the chamber to be pumped and an outside surface exposed to ambient air. The pump-valving assembly and diaphragm assembly are disposed in an integral pump assembly housing configured to be removably coupled to a control housing for the pulsatile pump system, the control housing including a linear motor having a magnet and a coil, the magnet moving in relation to the coil, the coil having an electrical input, the control housing rigidly coupled to the linear motor. The electrical input of the coil is coupled to the electrical output of a controller system defining an electrical waveform at the electrical output to cause desired operation of the diaphragm. The diaphragm assembly of the integral pump assembly is similarly configured to be removably coupled to the linear motor.
Alternatively or in addition, the integral pump assembly housing includes a peripheral flange, and the control housing has a channel configured to removably receive the peripheral flange if the diaphragm assembly of the integral pump assembly is removably coupled to the linear motor. Also alternatively or in addition, the peripheral flange has a set of compliant members to physically bias the peripheral flange in the control housing.
In a related embodiment, each compliant member includes a spring. Alternatively or in addition, the set of compliant members is included in a set of ball detents.
In accordance with yet another embodiment of the invention, a control housing is provided for removably receiving and being removably coupled to an integral pump assembly for a pulsatile fluid pump system. The integral pump assembly includes (i) a pump-valving assembly including a chamber and a set of ports; and (ii) a diaphragm assembly coupled to the chamber and including an edge-mount flexible diaphragm having an inside surface for contacting a fluid in the chamber to be pumped and an outside surface exposed to ambient air. The pump-valving assembly and diaphragm assembly are disposed in an integral pump assembly housing. The control housing includes a chassis; a linear motor, rigidly coupled to the chassis, and having a magnet and a coil, the magnet moving in relation to the coil, the coil having an electrical input; and a controller system having an electrical output coupled to the electrical input of the coil, the controller system defining an electrical waveform at the electrical output to cause desired operation of the diaphragm. The control housing is configured to be removably coupled to the integral pump assembly, and the linear motor is configured to be removably coupled to the diaphragm assembly of the integral pump assembly.
Alternatively or in addition, the integral pump assembly has a peripheral flange, and the control housing further has a channel configured to removably receive the peripheral flange if the diaphragm assembly of the integral pump assembly is removably coupled to the linear motor.
The foregoing features of embodiments will be more readily understood by reference to the following detailed description, taken with reference to the accompanying drawings, in which:
Definitions. As used in this description and the accompanying claims, the following terms shall have the meanings indicated, unless the context otherwise requires:
A “set” includes at least one member.
An “electrical waveform” is a waveform selected from the group consisting of an electrical current waveform, a voltage waveform, and combinations thereof.
The term “user-specifiable input parameter” includes a user-definable attribute pertinent to an alarm setting or calculation for a user interface, such as low flow limit 421a, high flow limit 421b, and body surface area 421c (BSA), as well as combinations of any of the foregoing attributes.
The term “user-specifiable parameter defining the performance of the linear motor” in the course of pumping includes a motor performance attribute such as stroke strength 401a, beat rate 401b, flow rate, average flow rate, stroke volume, flow index, pulse pressure, output pressure, magnet displacement, as well as combinations of any of the foregoing attributes.
The term “physical flow characteristic” includes a measured attribute such as stroke strength, beat rate, flow rate, average flow rate 411a, stroke volume 411b, flow index 411c, flow rate waveform 412, stroke volume waveform 413, duration over which the pump has been running (e.g., measured by timer 414), as well as combinations of any of the foregoing attributes. If an attribute is user-specified in a given embodiment of the present invention, then measurement of the attribute is of subsidiary importance since its value has been specified. Similarly, if an attribute being measured has primary importance a given embodiment of the present invention, then the parameter would not have been user-specified.
“Normal flow” is flow from the entrance to the inlet port 111 through the chamber 102 to the exit of the outlet port 121.
A “slight reversal of flow” past a ball in a ball check valve is a small, controlled amount of desired reverse flow past the ball before the ball is seated in a closed position.
“Diastole mode” is a phase of operation of a pulsatile pump, according to embodiments of the present invention, during which the diaphragm 202 of the pump-valving assembly 200 is pulled away from the chamber 102 so as to create negative pressure within the chamber 102, inlet ball check valve assembly 110, and third tapered tract 126, but not the fourth tapered tract 122.
“Systole mode” is a phase of operation of a pulsatile pump, according to embodiments of the present invention, during which the diaphragm 202 of the pump-valving assembly 200 is pushed towards the chamber 102, so as to create positive pressure within the chamber 102, outlet ball check valve assembly 120, and the second tapered tract 116, but not the first tapered tract 112.
In
There is growing consensus that desirable characteristics of a pulsatile pump should include both sufficient hemodynamic energy and a human-like waveform architecture. To evaluate pulsatile flow, we choose the human heart as the best model: it delivers a proper stroke volume at a natural cadence with a physiologic rest at the end of each stroke, adapting to the physiologic demands of the patient by adjusting the cardiac output, as the product of stroke volume and beat rate. Via the left ventricle, the human heart provides hemodynamic energy that results in a pressure wave that propagates fully through the elastic arterial tree. It appears that only a biomimetic stroke volume delivered in a biomimetic time frame (like the native systolic contraction produced by the heart) allows the elastic arterial tree to properly relax during the diastolic phase. Use of continuous flow devices stretches the elastic arterial wall but never allows proper relaxation, creating constant and atypical stress on the endothelial cells and interfering with natural baroreceptor sympathetic and parasympathetic signaling, thus disrupting the body's homeostatic control state.
The waveform program 511 causes the pulsatile fluid pump system 301 to replicate the ability of the left ventricle of the human heart to deliver physiological hemodynamic energy proportional to a user-specified stroke strength 401a by causing delivery of the necessary fraction of the stroke volume of a pump chamber 102 in a physiologic natural cadence at a user-specified beat rate 401b. It is a user (a perfusionist) of the pulsatile fluid pump system 301 who adjusts the stroke strength 401a (an indirect specification of stroke volume) and beat rate 401b to meet the physiologic demand of the patient. Furthermore, the waveform program 511 replicates the physiologic rest at the end of each stroke, thereby allowing natural relaxation of the arterial tree.
The structure of a pulsatile pump in accordance with various embodiments of the present invention can usefully reflect attributes of the human heart. The human heart is preload sensitive—the heart cannot “pull” blood into the left ventricle; it can only allow the blood available to flow naturally into the ventricle. The human heart is also afterload sensitive in that it is responsive to the compliance and resistance in the downstream vasculature and doesn't exert excess force on the blood, which could damage the vasculature. Lastly, the left ventricle cannot deliver blood that isn't in the ventricle when it contracts; there is a limited bolus of blood that it can deliver.
Similarly, the pulsatile fluid pump system 301 has similar attributes of inherent safety: it is preload and afterload sensitive, and it is limited in both the volume of blood it can deliver and the force at which it can deliver that bolus of blood. When filling, the pulsatile fluid pump system 301 allows gravity filling from the venous reservoir, exerting minimal negative pressure. When emptying, the linear motor 330 is inherently limited in the force that it can generate by its design. As such, it cannot overpressure the downstream tubing or vasculature, instead delivering less than the volume of blood in the pump chamber 102, thereby only delivering as much volume as the vasculature can receive.
The integral pump assembly 200 is analogous to a left ventricle of the human heart; the inlet ball check valve assembly 110 used in various embodiments hereof is analogous to a mitral valve; and the outlet ball check valve assembly 120 used in various embodiments hereto is analogous to an aortic valve. Like the human heart, the inlet 110 and outlet 120 ball check valve assemblies are passive and require a slight reversal of flow to close. This slight reversal of flow mimics the slight reversal that occurs when the aortic valve of the human heart closes.
In one embodiment, of the present invention, show in
In another embodiment of the present invention, shown in
In
The operation of the waveform programs 511, graphics program 611, and graphic display 400 is discussed in further detail in the related patent, referenced above, bearing patent number 11,300,119.
The embodiments of the invention described above are intended to be merely exemplary; numerous variations and modifications will be apparent to those skilled in the art. All such variations and modifications are intended to be within the scope of the present invention as defined in any appended claims.
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