MXPA05012337A - Air pressures-actuated driver for pneumatic ventricular assistance devices. - Google Patents

Abstract

The invention relates to a driver for a pneumatic ventricular assistance device (VAD) which is actuated by pressurised air, oxygen or any other gas that is commonly available in hospital rooms, intensive care units and operating theatres. The inventive driver can supply both blood ejection pressure (systole) and blood filling vacuum pressure (diastole) to the VAD. According to the invention, the driver is controlled by a digital/computer controller by means of pressure and volume sensors and electromechanical valves. The ventricular pumping is performed by a single spring-driven bellows or piston. Moreover, the computer can actively regulate the maximum systolic ventricular pressure, the maximum diastolic pressure drop, the rhythm of the cycles and/or the ejection volume (depending on the operating mode). The driver can also ventilate the drive conduit automatically and periodically in order to remove condensation and vitiated air therefrom. The device comprises no motor nor electrical pump and, as a result, is small, reliable, easy to manage and less expensive.

Description

AIR PRESSURE-RELATED EXCITER FOR PNEUMATIC VENTRICULAR ASSISTANCE DEVICES Field of the Invention The present invention relates to medical equipment, and, more particularly, to machines for activating pneumatic ventricular medical assistance devices.

BACKGROUND OF THE INVENTION Ventricular assist devices ("VADs") are used to help supplement the heart's pumping action both during and after certain types of surgeries, in situations in which a cardiopulmonary bypass is not required or recommended. complete (using a heart-lung machine) in view of the serious side effects associated with it. Ventricular assist devices typically comprise one per cannula or other tube and some kind of pump operably connected to the cannulas. In use, the cannulae are fixed either to the left side of the heart (a left ventricular assist device) or to the right side of the heart (a right ventricular assist device) "in parallel", that is, the pump complements the action of pumping of the heart but not drifting completely, and the pump is activated. Alternatively, a pump can be implanted directly into the body. 2 Originally, the ventricular assist devices were activated by air, where fluctuating air pressure, provided by a simple mechanical air pump machine, was applied to a bladder-type sac. The bladder had inlet and outlet valves, so that blood could enter the bladder through the inlet valve when the pressure in the bladder was low, and leave the bladder through the outlet valve when the pressure in the bladder was low. the bladder was high. Unfortunately, these pneumatic ventricular assist devices were complicated, and used expensive mechanical valves that were prone to failure, subject to "capping" and caused trauma or blood damage due to hard metal edges and the like. To overcome these problems, smaller and more reliable ventricular assist surfaces have been in use and / or development. These include axial flow pumps for temporary insertion directly into the heart, and peristaltic or centrifugal pumps. The former are based on the principle of Archimedes, where a rod with helical blades is rotated inside a tube to displace liquid. In use, a miniature axial flow pump mounted on a catheter is suitably positioned within the heart, and is operated by means of a certain kind of external magnetic exciter or other suitable mechanism. With RPM's high enough, a significant amount of 3 Blood can be pumped. In the case of peristaltic pumps, the blood is moved by the action of a rapidly rotating impeller (centrifugal cone or similar), which causes the blood to accelerate to the outside and exit both of these categories of ventricular assist devices are generally reliable and implantable, but they are very expensive, not particularly durable and are not useful in situations in which a patient requires a true pulsating blood supply. Specifically, axial and peristaltic pumps are typically left in a continuous mode of operation, in which a uniform stream of blood is delivered on a continuous basis, unlike the natural rhythm of the heart, which acts on a periodic basis and producer of impulses. In addition, these pumps are still widely in the development or test phase. Due to the inherent performance limitations of these ventricular assist devices, pneumatic devices appear to be a good option to provide a pulsating pulmonary augmentation. However, as mentioned above, pneumatic ventricular assist devices are prone to failure and can cause blood damage and coagulation. Moreover, the exciter units for operating the pneumatic ventricular assist devices are based on motors (to date, generally not mechanically reliable), and can only offer a simple 4-way mode. cyclic pressure operation, that is, a minimum and maximum repetitive pressure applied to the bladder of the VAD, which can not be adjusted for particular patient conditions. Accordingly, a principal object of the present invention is to provide an exciter for pneumatic ventricular assist devices that is more reliable, does not have an electric or motor pump, and that provides a greater degree of operational flexibility and adaptation. Brief Description of the Invention A gas actuator exciter or actuator mechanism for a pneumatic ventricular assist device (VAD) is actuated by pressurized air, oxygen or any other gas commonly available in hospital rooms, intensive care units and operating rooms. operations. The exciter can provide both blood ejection pressure (systole) and blood fill (diastole) vacuum to the VAD. The exciter is controlled by a computer / digital controller by means of pressure and volume sensors, and electromechanical valves controlled by computer. Ventricular pumping is carried out by a single piston or spring-loaded bellows inside a pump cylinder. The computer can actively regulate the maximum systolic ventricular pressure, maximum diastolic vacuum, cycle rate and / or expulsion volume (depending on the mode of operation). The exciter is also capable of 5 Automatically and periodically ventilate the excitation duct to eliminate condensation and stale air. The absence of an electric motor or pump makes the device small, reliable, easy to operate and less expensive.

BRIEF DESCRIPTION OF THE DRAWINGS These and other features, aspects and advantages of the present invention will be better understood with respect to the following description, appended claims and accompanying drawings, in which: Figure 1 is a schematic diagram of a pressure operated exciter of air for pneumatic ventricular assist devices, according to the present invention; Figures 2A and 2B are schematic diagrams of a portion of the air operated actuator in operation and Figures 3A-3C are various views of the air pressure driven exciter implemented as a portable trolley with wheels.

Detailed Description of the Invention With reference to Figure 1, a preferred embodiment of a gas pressure driven exciter or an actuator mechanism 10 for driving an assist device 6 Ventixular tire 12 (VAD) includes a console unit 14 and a pressurized air / gas unit 16, which includes one or more pressurized gas (preferably air) backup tanks 18 and a gas inlet connector 20 which is fixed to a wide pressurized air duct in installations 22. The console unit 14 includes a computer or other electronic controller 24, a pump cylinder or a positive displacement pump (e.g., piston or bellows) 2S with one element of spring-loaded, sealing gas 28 (for example, a piston or bellows), an inlet pressure valve 30 and a cylinder vent valve 32, both of which are attached to the source of pressurized air 16 and end of origin (or entrance) of the pump cylinder 26. A tubular outlet duct 34 is connected to the discharger or pump outlet 26. The duct, however, is attached to the ventricular assist device 12. In use, at the beginning of a cycle, the computer 24 opens the inlet pressure valve 30 to compress the bellows and spring 28 and raise the systolic pressure in the VAD 12 (active systole). Once the desired maximum pressure of the excitation duct, measured by an excitation duct pressure sensor 36 electrically connected to the computer 24, is achieved, the inlet pressure valve 30 is closed and the computer 24 waits (passive systole). until the desired blood volume is expelled from the VAD (limited volume mode) or time 7 stroke has elapsed (limited frequency mode). The diastole begins when opening the cylinder vent valve 32. The compressed spring inside the bellows 28 then creates a vacuum for the cycle's blood filling phase (ie, as the spring pushes the bellows outward, the pressure of gas in the excitation duct 34, connected to the VAD 12, decreases). Once the desired vacuum level, measured by the excitation duct pressure sensor 36, is reached, a vacuum regulating valve 38 (attached to the exciting duct 34) is opened to let air into the interior of the VAD / air gap. inner piston / excitation duct 34 ensuring that the desired vacuum level is not exceeded. The computer 24 then waits for the desired blood volume to fill the VAD 12 (limited volume mode) or until the diastolic time has elapsed (limited frequency mode). As indicated above, the preferred exciter mechanism 10 uses controlled pressurized air to operate the VAD 12, supplied to the console 14 from the pressurized air unit 16, and not a motor driven pump or the like. The pressurized air unit 16 may be separated from, or attached to, the console 14, for example, as part of a moving carriage or the like (see Figures 3A-3C). The main source of pressurized air is the supply of pressurized air, oxygen or other gas 22 found in the most hospital rooms, intensive care units and operating rooms, which is connected to unit 16 by connector 20. The inlet pressure has to be several times greater than the desired maximum systolic pressure, which is approximately 0.35 kg / cm2 (5 psi). Standard hospital oxygen and air supplies are regulated for 3.51 kg / cm2 (50 psi) of pressure, which can be regulated by a regulator / alarm unit 40 placed between the console 14 and tanks 18 and supply conduit 22. The tanks 18 are provided as a backup in case the main supply conduit 22 is closed, or when portability is required. A selector valve 42, either manual or computer controlled, is provided to select between the supply conduit 22 and the tanks 18. The regulator / alarm unit 40 can be configured to emit an alarm if the inlet pressure in the unit regulator / alarm 40, that is, the duct pressure or tank pressure, drops or falls below a certain level. An inlet pressure sensor 44, in fluid communication with the pressurized air inlet duct 46 of the console and electrically connected to the computer 24, can be provided to emit a signal to the computer 24 to alert the user if the pressure of input falls due to a supply failure. The computer 24 can have any design or 9 proper configuration. In an exemplary embodiment, the computer 24 comprises a microcontroller or microprocessor 50 and associated standard components (RAM, busbar I / O, etc.), a video controller 52 and visual presenter 54 operably connected to the microcontroller 50, a busbar or communications port 56 (for example, USB, Ethernet) for external access to the microcontroller, and an A / D and D / A converter 58 or other sensor / valve interface or control unit. The computer 24 also includes a horn 60 for sounding alarms or the like. The remaining components will be described with respect to the operation of the air pressure driven exciter 10. The pneumatic ventricular assist devices work by applying air pressure to a bladder or bag effectively connected in parallel to the heart of a patient. Specifically, when pressure is applied to the sac, the blood in the sac is expelled. When the air pressure against the sac is reduced, the sac expands, causing blood to enter the sac. When proper directional valves are used, this creates pulsating or cyclic blood flow. According to the present invention, with reference to Figures 2A and 2B, this action is achieved using computer controlled valves, a source of pressurized air and the pump cylinder with bellows or piston driven by spring. 10 As shown in Figure 2 ?, at the beginning of a cycle, the computer 24 opens the inlet pressure valve 30. This causes the air to enter the inlet side (e.g., intake chamber or outlet chamber). ) of the pump cylinder 26, which compresses the bellows and spring 28 (it should be noted that the cylinder intake chamber is sealed or separated from the outlet side or from the discharge chamber). Compressing the bellows 28 causes the air / gas pressure in the exciting conduit 34 to increase, which in turn compresses the bladder or sac 70 of the VAD, forcing blood out of the sac, through an outlet valve 72. of VAD, and into the patient's bloodstream. Once the desired maximum pressure in the exciting conduit 34 is achieved, as measured by the excitation duct pressure sensor 36, the inlet pressure valve 30 'is closed and the computer 24 waits (passive systole) until the desired volume of blood is expelled from VAD 12 (limited volume mode) or the systolic time has elapsed (limited frequency mode). If the diastolic vacuum has not been established or is below the desired level (i.e., the excitation duct pressure is above the desired diastolic vacuum level), the computer 24 causes the vacuum regulating valve 38 to momentarily open to let a small amount of air escape from the excitation duct 34 at the end of the systolic period. eleven As shown in Figure 2B, the diastole begins when the cylinder vent valve 32 is opened. The compressed spring within the piston cylinder or bellows will then create a vacuum for the cycle's blood fill phase. Specifically, by letting pressurized air out of the cylinder 26, there is no longer sufficient pressure to counteract the spring in the bellows 28. The spring forces the bellows / piston 28 outwards, increasing the effective volume of the exciting conduit 34 and reducing the pressure of the bellows. air in it. This causes the bladder 70 of the VAD to expand, introducing blood into the interior through a one-way VAD inlet valve 74. Once the desired vacuum level, measured by the excitation duct pressure sensor 36, is reached, the vacuum regulating valve 38 is opened to let air into the exciting duct 34 ensuring that the desired vacuum level is not exceeded. be exceeded. If the desired vacuum level is not reached, then it will be adjusted for the next cycle by opening the vacuum regulator valve 38 as described above. The computer 24 then waits for the desired volume of blood to fill the VAD (limited volume mode) or until the diastolic time has elapsed (limited frequency mode). The blood volume in the VAD 12 can be measured directly by a sensor in the chamber (not shown). The volume of blood in the VAD blood bag does not have to be 12 measured directly, however, allowing for a simpler VAD design, but can be computed directly by computer 24 (calibrated to VAD dead space and excitation duct) by using Boyle's law (assuming a constant temperature, P1.V1 = P2.V2) and measuring the volume displaced in the 2S pump cylinder and pressures in the excitation and barometric duct. The barometric pressure and the displaced volume can be measured by having, respectively: i) a barometric pressure sensor 80 operably linked to the computer 24 and ii) a distance sensor 82 (LED, another optical sensor or the like) in the cylinder pump 26 and operably connected to computer 24, which measures the distance from one end of the pump cylinder to the bellows (or other suitable measurement). A safety pressure relief valve 84 is attached to the drive conduit 34 to ensure that the maximum excitation duct / duct pressure (e.g., 0.35 kg / cm2 (5 psi)) is never exceeded, which could lead to air leaks in the VAD 12. Periodically or at times selected by the user, the exciter 10 has the ability to vent the excitation duct 34 to avoid excess condensation and remove stale air. This is achieved at the end of the diastolic period by opening an excitation duct vent valve 86, positioned between the exciting duct 34 and the duct.

Pressurized air inlet duct 46, for a short time. The VAD / inner cylinder / excitation duct space 34 is pressurized with fresh air. The excess pressure is vented by the pressure relief valve 84. Then the vacuum regulator valve 38 is opened to vent the system. Computer 24 is an electronic controller mechanism for regulating the maximum ventricular systolic pressure and maximum diastolic vacuum in a cardiac patient, through the amount of gas selectively provided to the intake pump and exhausting the chambers, wherein the computer 24 has the ability to control the entire process (mentioned in the previous paragraphs) according to parameters pre-established by the manufacturer or selectable by the user, such as desired impulse volume, velocity, VAD output, systolic to diastolic ratio, maximum diastolic volume, volume minimal systolic, maximum systolic pressure and / or maximum diastolic vacuum. The computer, through its sensors, also has autodiagnostic capabilities and can indicate warnings and alarms to the user. Finally, the computer may also have the ability to store or relieve the operational status and performance of the exciter to remote locations (nurses station, doctor's office) via network or wireless communications 56. Although the VAD pumping action is effected 14 Mainly using pressurized air, the computer, valves and sensors are electrically activated, by means of a standard power supply (connected to a wall socket), generator, battery power system, or similar (not shown). Mufflers or dampers 88 may be attached to the outlets of the valves 32, 38, to minimize noise as the pressurized air is let out periodically out of the air conduits of the exciter. An emergency foot pump or bellows 90 can be operably connected to the drive conduit 34, by means of a manual selector valve 92 and / or connector 94. In an emergency (i.e., complete loss of pressurized air and / or energy electrical), the foot bellows 90 is manually pumped, causing a variable pressure to be applied to the VAD 12. Preferably, the volume of air displaced by the bellows 90 is configured to generally coincide with the displacement volume required to operate the bag. of pumping 70 of the VAD. Figures 3A-3C show how the air pressure driven exciter 10 can be implemented as a portable carriage. Although the air pressure driven exciter has been described as having separate pump air inlet and vent valves 30, 32, respectively, it could be a unitized air distribution device, ie, a computer controlled device with three states, is used instead: i) "closed"; ii) open to the environment (possibly through a silencer) and iii) open to the air inlet duct 46. This is also the case for the valves 38, 84, 86 in the exciting duct 34. In this way, the The term "air distribution device", as used herein, refers to both: autonomous and individual valves; multi-state valves; as to a combination of the two. Although the air pressure driven exciter has been illustrated as having a spring-loaded piston or bellows in the pump, a different impulse mechanism other than a spring (polymer elements, motor units, build the bellows) may be used instead. from a deformable material with a material memory, etc.). Accordingly, the term "driven air movement element" incorporates any bellows, piston or the like, driven with a spring or other suitable device. Since certain changes can be made in the air pressure driven exciter for pneumatic ventricular assist devices described above, without departing from the spirit and scope of the invention described herein, it is intended that all of the subject matter of the above description or shown in FIG. the attached drawings is simply interpreted 16 as examples illustrating the inventive concept of the present and not considered as limiting the invention.

Claims (1)

17 CLAIMS! -! £ 3 1. An apparatus characterized in that it comprises: a) a source of pressurized air; b) a pump cylinder that is connected in fluid communication to the pressurized air source by an outlet air line, wherein the pump cylinder comprises an interior space; and a sealed element of driven air movement that is placed in the interior space and divides the interior of a pump cylinder into an inlet chamber and a discharge chamber; to a pneumatic ventricular assist device; c) a pneumatic ventricular assist device connected in fluid communication with the discharge chamber via a conduit, wherein the pneumatic ventricular assist device comprises: a bag that is selectively expandable and collapsible in response to the air pressure emanating from the vacuum chamber pump; d) a first air distribution device in fluid communication with the air inlet duct and the chamber inlet, wherein the first air distribution device can be electrically controlled to connect the inlet of the chamber to the ambient atmosphere; e) a second air distribution device in fluid communication with the duct and the air inlet duct, wherein the second air distribution device can be electrically controlled to connect the duct, and the pump cylinder to the atmosphere 18 environment and f) an electronic controller device for regulating the maximum ventricular systolic pressure and maximum diastolic vacuum of a cardiac patient, through the amount of gas selectively provided to the intake and discharge chambers, without the need for an electric motor, and wherein the controlling device comprises an electronic controller electrically connected to the first and second air distribution devices, wherein the electronic controller is configured: i) to cause the first air distribution device to connect the inlet of the chamber to the inlet duct of air, thus compressing the driven air movement element and causing the level of pressure in the duct to increase to excite the ventricular assist device during systole; ii) to cause the first air distribution device to connect the chamber inlet to the ambient atmosphere, thereby reducing the pressure against the driven air movement element and allowing the driven air movement element to move to the ambient atmosphere. its non-compressed state, wherein the level of pressure in the excitation conduit decreases to excite the ventricular assist device during the diastole and iii) to cause the second air distribution device to connect the conduit to the ambient atmosphere, with the purpose of letting air enter the conduit, when the pressure level of 19 Excitation conduit falls below a desired vacuum level for diastolic operation of the ventricular assist device. Apparatus according to claim 1, characterized in that: the second air distribution device is further configured to be electrically controlled to connect the duct to the air inlet duct; and the electronic controller is configured to vent the duct after the diastole to cause the second air distribution device to open the duct, and the pump cylinder, first to the air inlet duct to the ambient atmosphere. Apparatus according to claim 2, characterized in that the second air distribution device comprises: a vacuum regulating valve in fluid communication with the duct and the ambient atmosphere; and an excitation duct vent valve in fluid communication with the duct, the pump cylinder, and the air inlet duct. Apparatus according to claim 1, characterized in that the first air distribution device comprises: an inlet pressure valve in fluid communication with the air inlet duct and the inlet chamber of the pump cylinder; and a cylinder vent valve in fluid communication with the inlet 20 of the camera and the ambient atmosphere. Apparatus according to claim 1, further characterized by comprising a safety pressure relief valve in fluid communication with the duct to vent air from the excitation duct of the pump cylinder when the pressure of the excitation duct exceeds a maximum pressure of the ventricular assist device. Apparatus according to claim 1, further characterized in that it comprises an inlet pressure sensor in fluid communication with the air inlet duct to detect a level of pressure in the air inlet duct, where the pressure sensor The input is electrically connected to the electronic controller to alert a user when the pressure level in the air inlet duct falls below a preselected operational pressure level. Apparatus according to claim 1, further characterized in that it comprises sensors operably connected to the inlet chamber of the pump cylinder and to the conduit, and electrically connected to the electronic controller, for measuring pressure levels at the inlet of the pump cylinder and the excitation conduit of the pump cylinder. 8. Apparatus according to claim 1, further characterized in that it comprises an air unit 21. pressurized connected operably to the air inlet duct, wherein the pressurized air unit comprises: at least one pressurized air back tank; and an air inlet connector configured to be connected to a pressurized air duct of the entire installation. Apparatus according to claim 8, further characterized in that it comprises a portable carriage with. wheels, wherein the wheeled car houses the electronic controller, the first and second air distribution devices, the pump cylinder, the air inlet duct and the pressurized air unit. Apparatus according to claim 1, further characterized in that it comprises a portable trolley with wheels, wherein the trolley with wheels houses the electronic controller, the first and second air distribution devices, the pump cylinder and the inlet duct of air. Apparatus according to claim 1, characterized in that the driven air movement element is a spring-loaded bellows. 12. An apparatus characterized in that it comprises: a) a source of pressurized gas; b) a pump connected in fluid communication with the pressurized gas source, wherein the pump comprises: a housing and an air moving element driven inside the housing that divides the housing into a intake chamber and a discharge chamber, in 22 where the discharge chamber is connected to the outlet tubular conduit; c) a pneumatic ventricular assist device with the discharge chamber through the conduit, wherein the pneumatic ventricular assist device comprises: a bag that is selectively expandable and collapsible in response to the gas pressure emanating from the chamber pump discharge; d) an inlet valve in fluid communication with the pressurized gas source and the pump intake chamber, wherein the inlet valve can be electrically controlled to connect the source of pressurized gas to the inlet of the pump housing; e) a pump vent valve in fluid communication with the pump housing inlet and the ambient atmosphere, wherein the pump vent valve can be electrically controlled to expose the pump housing inlet to ambient atmosphere; f) a vacuum regulating valve in fluid communication with the output excitation duct and the ambient atmosphere, wherein the pump Ventilation valve can be electrically controlled to expose the output exciting duct to the ambient atmosphere and g) a controlling device electronic device for regulating the maximum ventricular systolic pressure and the maximum diastolic vacuum of a cardiac patient, through the amount of gas selectively provided to the pump intake and discharge chambers, wherein the electronic controller device comprising: an electronic controller electrically connected to the inlet valve and pump vent valve, wherein the computer is configured to periodically: i) open the inlet valve to compress the driven air movement element within the pump housing until a desired maximum pressure is reached in the output drive line for systolic operation of the ventricular assist device; ii) close the inlet valve for passive systolic operation of the device 10 ventricular assistance; iii) open the pump vent valve to decompress the gas-driven movement element for diastolic operation of the ventricular assist device and iv) open the vacuum regulating valve to let air from the ambient atmosphere enter. 15 inside the output excitation duct if the output excitation duct pressure drops below a desired minimum pressure in the exit excitation duct for diastolic operation. 13. Apparatus according to claim 12, Further characterized in that it comprises an excitation conduit vent valve in fluid communication with the outlet exciting conduit and the pressurized gas source, wherein the electronic controller is configured to vent the exhaust excitation conduit. 25 after the diastole when opening the valve 24 first excitation duct ventilation and then open the vacuum regulating valve. 14. Gas actuator actuator for operating a pneumatic ventricular assist device, characterized in that it comprises: a) a source of pressurized gas; b) a pump connected in fluid communication with the source of pressurized gas, wherein the pump comprises: a housing and an air moving element driven inside the housing and dividing the housing into an inlet and outlet drive duct, the Exit excitation conduit is configured to be connected to a pneumatic ventricular assist device; c) an electrically controllable input valve connected to the pressurized gas source and to the pump housing inlet d) an electrically controllable pump vent valve connected to the pump housing inlet; e) an electrically controllable vacuum control valve connected to the output excitation duct and f) an electronic control device for regulating the maximum ventricular systolic pressure and the maximum diastolic vacuum of a cardiac patient, through the amount of gas selectively provided to the patient. pump intake and discharge chambers, where the controller device comprises: a computer operably connected to the inlet valve and pump vent valve, where the computer is configured for periodically: i) T 25 open the inlet valve to compress the driven air movement element inside the pump housing until a desired maximum pressure is reached in the outlet exciting duct; ii) close the inlet valve; iii) once a desired period of time has elapsed or a desired blood volume has been expelled from the ventricular assist device, open the pump vent valve to decompress the driven air movement element to reduce the pressure at the outlet of the pump and iv) open the vacuum regulating valve if the outlet pressure of the pump falls below a minimum desired pressure at the pump outlet for diastolic operation of the ventricular assist device.