Cryogenic system with multiple immersion pumps

Abstract

To provide a cryogenic system with multiple submerged pumps.SOLUTION: The invention relates to a cryogenic system with multiple submerged pumps. An apparatus comprises a single insulated container configured to contain a cryogen. The apparatus also has a first pump and a second pump, both disposed in the single insulated container and configured to pump the cryogen from the single insulated container while immersed in the cryogen. A first probe and a second probe have respective first and second proximal ends coupled to receive concurrently the cryogen pumped by the first pump and the second pump, respectively. The first and second probes have respective first and second distal ends, which are chilled by the cryogen received through the first and second proximal ends and which are configured to be inserted into a body of a living subject.SELECTED DRAWING: Figure 2A

Description

[Technical field]

[0001] The present invention relates generally to cryogenic systems, and more particularly to systems having one or more pumps. [Background technology]

[0002] Many cryogenic systems are known in the art, some example systems are described below.

[0003] US Pat. No. 7,083,612 to Littrup et al. describes a cryotherapy system having a plurality of cryoprobes, each including a shaft having a closed distal end adapted for insertion into the body.

[0004] Baust et al., U.S. Patent No. 7,192,426, describes a cryosurgical system for supplying cryogen to a probe, which includes a container filled with cryogen having a pump bellows immersed in the cryogen.

[0005] Maurice, U.S. Patent No. 7,422,583 and U.S. Patent No. 2004 / 0210212, describe a cryosurgical device that includes a cryoprobe having a cooling portion and an electrically conductive first portion in the region of the cooling portion. The cryoprobe also has a removable sheath.

[0006] US Pat. No. 8,784,409 to Robilotto et al. describes a device that is a closed or semi-closed system in which liquid coolant is contained in both the supply and return stages.

[0007] Mackey, US Pat. No. 9,316,215, describes a multiple pump system that includes a fluid tank and a multiple pump housing connected to the fluid tank.

[0008] Baust et al., US Pat. No. 11,026,737, describes cooling an object, including living tissue, to freezing or cryogenic temperatures by placing the object in thermal communication with subcooled supercritical nitrogen.

[0009] U.S. Patent No. 11,060,778 to Jankowsky et al. describes a universal controller for integrating cryogenic equipment requiring different control mechanisms onto a single operating platform. The universal controller can include power elements configured to simultaneously drive multiple cryogenic devices having different power requirements.

[0010] Perron, US Pat. No. 11,266,458, describes a surgical cryoablation system that includes a valve having a valve inlet and a valve outlet. The valve inlet is connectable to a source of cryogenic fluid at a pressure in excess of 4000 psi, and the valve outlet is connectable to a cryoablation probe.

[0011] U.S. Patent Application 2007 / 0244474 to DeLonzor et al. describes a cryosurgery system that uses a low pressure liquid nitrogen supply. The system is stated to require only 0.5 to 15 bar of pressure to provide adequate cooling power for the treatment of typical breast lesions. Pressure can be provided by supplying lightly pressurized air into the dewar, by heating a small portion of the nitrogen in the dewar, or by using a small low pressure pump.

[0012] U.S. Patent Application Publication No. 2008 / 0125764 to Vanselette et al. describes a cryosurgery system that provides temperature control of individual cryoprobes to increase procedural flexibility and simplicity in cryoablation procedures. The cryosurgery system provides individual control of multiple cryoprobes in a closed-loop cooling circuit. The individual control allows for the simultaneous use of multiple cryoprobes in a procedure.

[0013] U.S. Patent Application No. 2015 / 0126987 to Semenov et al. describes a method of supplying cryogen to a cryogenic instrument by connecting the cryogenic instrument to a reservoir having a cryogen via a cryogenic conduit and supplying the cryogen from the reservoir to the cryogenic instrument via the cryogenic conduit.

[0014] U.S. Patent Application Publication No. 2016 / 0249970 to Yu et al. describes an intravascular near-critical fluid-based cryoablation catheter for forming elongated, longitudinally continuous lesions in tissue. The catheter includes an elongated shaft, a flexible distal tissue treatment section, and a distal end.

[0015] U.S. Patent Application Publication No. 2020 / 0121498 to Baust et al. describes a cryogenic medical device for delivering supercooled liquid coolant to various configurations of cryoprobes designed for the treatment of damaged, diseased, cancerous, or other unwanted tissue. The apparatus is a closed or semi-closed system in which the liquid coolant is contained in both the supply and return stages.

[0016] U.S. Patent Application Publication No. 2021 / 0177482 to Tegg et al. describes a medical device that may include a balloon and a movable manifold, the movable manifold including a plurality of first openings, inside the balloon, and configured to distribute a fluid within the balloon.

[0017] U.S. Patent Application Publication No. 2021 / 0244457 to Hilleli et al. describes a probe having a distal end including a lumen and configured to contact tissue of a living subject, a temperature sensor disposed at the distal end, and a pump having a pump motor coupled to deliver cryogenic fluid through the lumen to the distal end of the probe and receive cryogenic fluid back from the probe. Summary of the Invention

[0018] According to one embodiment of the present invention, there is provided an apparatus comprising: a single insulated container configured to contain a coolant; first and second pumps, both disposed within the single insulated container and configured to pump the coolant from the single insulated container while submerged in the coolant; and first and second probes, having respective first and second proximal ends coupled to simultaneously receive the coolant pumped by the first and second pumps, respectively, and having respective first and second distal ends configured to be cooled by the coolant received via the first and second proximal ends and to be inserted into a body of a living subject.

[0019] Typically, the first pump and the second pump are each selected from the group including a bellows pump, a plunger pump, and a piston pump.

[0020] In the disclosed embodiment, the first and second pumps are not connected.

[0021] In a further disclosed embodiment, the coolant pumped by the first pump is at a first flow rate and the coolant pumped by the second pump is at a second flow rate, the first and second flow rates being independent of each other.

[0022] generally, The first distal end includes a first temperature sensor and the second distal end includes a second temperature sensor, the first flow rate responsive to a first temperature measured by the first temperature sensor and the second flow rate responsive to a second temperature measured by the second temperature sensor.

[0023] In yet another disclosed embodiment, an apparatus includes a processor configured to operate a first pump and a second pump.

[0024] According to one embodiment of the invention, a method includes the steps of: providing a single insulated container configured to contain a coolant; disposing a first pump and a second pump within the single insulated container; configuring the pumps to pump the coolant from the single insulated container while submerged in the coolant; and coupling a first probe and a second probe to the first pump and the second pump, respectively, the first probe and the second probe having respective first and second proximal ends coupled to simultaneously receive the coolant pumped by the first and second pumps, respectively, and having respective first and second distal ends configured to be cooled by the coolant received via the first and second proximal ends and to be inserted into a body of a living subject. A method is provided that includes:

[0025] The present disclosure will become more fully understood from the following detailed description of the embodiments thereof, taken in conjunction with the drawings, in which: [Brief description of the drawings]

[0026] [Figure 1] FIG. 1 is a schematic diagram of an apparatus used in a multi-probe cryogenic procedure, according to one embodiment of the present invention. [Figure 2A] FIG. 2A is a schematic diagram illustrating the structure and operation of a console, according to an embodiment of the present invention. [Figure 2B] FIG. 2B is a schematic diagram of two piston pumps operating within a console, according to an embodiment of the present invention. [Diagram 3] FIG. 3 is a schematic block diagram illustrating how a processor controls the flow rate of a pump, according to one embodiment of the present invention. [Figure 4] FIG. 4 is a flowchart of actions taken by a processor in executing an algorithm for operating the pump during the procedure of FIG. 1, according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0027] overview A typical cryogenic medical procedure for treating a tumor in a patient involves inserting the distal end of a probe into the tumor. The proximal end of the probe is connected to a coolant pump system external to the patient, which then pumps coolant into the distal end of the probe, freezing and thus killing the tumor. Freezing from a single probe creates a roughly spherical ice ball around the distal end of the probe that encompasses the tumor.

[0028] For tumors that are not encompassed by the spherical ice ball, or if the ice ball encompasses non-tumorous tissue (e.g., an elongated tumor), it may be necessary to use one or more additional probes, operated independently, that allow the ice ball to be shaped according to the shape of the tumor.

[0029] However, each additional probe requires a respective external coolant pumping system, making the provision of multiple external coolant pumping systems during a medical procedure cumbersome and expensive.

[0030] An embodiment of the present invention addresses the problem of multiple pumping systems by providing a single system with multiple pumps, each of which can be connected to the proximal end of a respective probe. The distal ends of the probes can be independently inserted into the tumor, and once inserted, the distal ends can be independently cooled. In contrast to the prior art coolant pumping systems referenced above, where each pump system is held in its own insulated container, the single system of the present invention uses only one insulated container. One insulated container, typically a dewar, is configured to hold two or more cryogenic pump systems. However, like the prior art systems, each of the pump systems of the present invention can operate independently of each other.

[0031] Having only one insulated container for multiple pump systems reduces the time that needs to be spent filling and draining the coolant from the system. Additionally, with multiple pump systems in separate insulated containers, there is a problem that one of the containers may empty before the other during a procedure, which is not an issue with only one insulated container.

[0032] Detailed Description In the following description, like elements in the figures are identified by like reference numbers and, where necessary, distinguished by the addition of a letter to the reference number.

[0033] Reference is now made to Figure 1, which is a schematic diagram of an apparatus 20 being used in a multi-probe cryogenic procedure, according to one embodiment of the present invention. By way of example, the procedure envisaged in the following description is for breast tumors, although it will be understood that the apparatus 20 may be used for other procedures, such as prostate or kidney tumors, and all such procedures are considered to fall within the scope of the present invention.

[0034] The procedure is performed by physician 24 on patient 28, and the physician can observe the results of the procedure on a display 32 included in device 20. The physician can also interact with elements of device 20 via a keypad or pointing device 34. (Generally, a procedure for a breast tumor involves performing a scan, such as an ultrasound, CT (computed tomography), or MRI (magnetic resonance imaging) scan of the breast of patient 28, and presenting the results of the scan on display 32. The scan is typically performed by a professional other than physician 24. Details of the scan are not relevant to this disclosure, and for simplicity, the professional is not shown in FIG. 1.)

[0035] The device 20 comprises a console 42, described in more detail below, and the device is controlled by a processor 36 coupled to a memory 40 in which software 44 for the operation of the device is stored. The processor 36 and memory 40 are typically installed in the console 42. The software 44 in the memory 40 may be downloaded to the processor in electronic form, for example over a network. Alternatively or additionally, the software may be provided on a non-transitory tangible medium, such as an optical, magnetic, or electronic storage medium.

[0036] The console 42 houses within an outer casing 64 a plurality of substantially similar submerged cryogenic pumps 50, each connectable to a respective cryogenic probe 58 by a respective connector 54 within the console. Herein, the console 42 is assumed to house four pumps 50A, 50B, 50C, 50D attached to connectors 54A, 54B, 54C, 54D, respectively. However, it will be understood that in other embodiments there may be other numbers of pumps and connectors, so long as there are at least two of each. As shown in FIG. 1, it is assumed that the physician 24 connects three probes 58A, 58B, 58C, collectively referred to as probe 58, to connectors 54A, 54B, 54C, with no probe connected to the fourth connector 54D, and therefore a plug 59 inserted into the fourth connector to isolate that connected pump from the atmosphere.

[0037] Each probe 58 has a proximal end 62 and a distal end 66. The physician 24 inserts and manipulates the distal ends 66A, 66B, and 66C of each probe so that they are precisely positioned, generally using scanning as described above. The physician can then activate the pumps 50A, 50B, and 50C, generally using the device 34, to begin transferring cryogenic fluid to the distal ends 66A, 66B, and 66C to cool tissue proximate the distal ends. The cryogenic fluid is initially stored in the console 42 in liquid form, but during the procedure the fluid may change from a liquid to a liquid / gas mixture or even a completely gaseous state. Unless otherwise stated, cryogenic fluid is herein intended to include, by way of example, liquid nitrogen or gaseous nitrogen. However, it will be understood that other cryogenic fluids, such as cryogenic argon, may be used in the apparatus 20, and all such cryogenic fluids are contemplated to be within the scope of the present invention.

[0038] The pump 50 may include any type of submersible cryogenic pump known in the art, typically a reciprocating pump such as a bellows pump, a plunger pump, or a piston pump. In the following description, the pump 50 in the console 42 is assumed to be a piston pump, by way of example, although the description may be modified mutatis mutandis to accommodate different pumps.

[0039] The cryogenic procedure described above is generally performed in two phases: a first phase in which the temperature of the distal end 66 of the probe 58 is reduced to an initial temperature, typically between about -10°C and about -30°C, and a second phase in which the distal end temperature is further reduced to a subsequent temperature that is lower than the initial temperature. In one embodiment, the subsequent temperature is about -160±10°C. As described further below, each pump 50 may operate independently such that each pump may be in one of two phases at any time during the procedure.

[0040] Figure 2A is a schematic diagram showing the structure and operation of console 42, and Figure 2B is a schematic diagram of two piston pumps operating within the console, in accordance with an embodiment of the invention. For clarity, in Figure 2A pump 50 is shown as a rectangle with minimal detail, with details of pump 50 being shown in the drawing of pumps 50A, 50B in Figure 2B.

[0041] In FIG. 2A, the casing 64 of the console 42 is shown diagrammatically as a rectangle. As shown, the pumps 50A, 50B, 50C, 50D are disposed, i.e. mounted, within a single insulated vessel 70, typically a double-walled dewar having a vacuum between the two walls. The vessel 70 holds liquid coolant 74 within a lower region 80 of the vessel, and the pumps are mounted so as to be submerged in the coolant. Each pump is driven by a respective motor 68A, 68B, 68C, 68D secured to a pump support 78. The pump support 78 is mounted to a dewar cover 82, effectively sealing the vessel 70 from the atmosphere, except as described below. The seal allows the coolant within the vessel to be maintained at a pressure above atmospheric pressure, approximately 0.5 atmospheres above atmospheric pressure in one embodiment. Maintaining the coolant above atmospheric pressure prevents the liquid coolant from evaporating as the pumps 50 operate.

[0042] The pumps 50 are coupled to the respective connectors 54 by outflow lumens 94, which transfer the cryogenic fluid from the pumps to the connectors. The fluid then travels to a corresponding lumen 98 in the probe 58 and to the distal end 66. The cryogenic fluid returns to the vessel 70 from the distal end 66 via an inflow lumen 102 of the probe 58, the connector 54, and a lumen 106 of the console 42. The lumen 106 generally terminates in a liquid / gas separator 118. The lumens are generally formed from concentric cylinders or tubes, but for simplicity, the lumens are shown as lines in FIG. 2A. Each distal end 66 has a temperature sensor 110, and the outflow lumen also has a pressure sensor 114. The respective temperatures measured by the sensors 110 and the pressure measured by the sensors 114 are provided to the processor 36. For clarity, only the connections from the sensors 110A and 114A to the processor 36 are shown in FIG. 2A.

[0043] As shown in FIG. 2B for pumps 50A, 50B, each pump 50 includes a piston 72 that, when actuated by a motor 68, expels cryogenic fluid from region 80 through check valve 76 and into outlet lumen 94.

[0044] The casing 64 includes connectors 122 coupled to tubes 126 and, together with the tubes, used to fill or remove coolant from the vessel 70. The liquid coolant 74 vaporizes to form a gas coolant 130 in the upper region 84 of the vessel 70, which may be removed or held at a regulated pressure by a valve compressor assembly 134, which may be controlled by the processor 36. The assembly 134 is connected to the gas coolant 130 by tubes 138.

[0045] The assembly 134 generally comprises a relief valve that opens to atmosphere if the pressure of the gas coolant 130 exceeds a preset safety limit. The assembly may be used to aid in filling the vessel 70 with coolant through the connector 122 by removing the gas coolant 130 from the vessel and reducing its pressure. The assembly may also be used to aid in removing liquid coolant from the vessel 70 through the connector 122 by increasing the pressure of the gas coolant 130.

[0046] Processor 36 receives signals from temperature sensor 110 and pressure sensor 114 and, in response to these signals, the processor generates respective control signals for motor 68 to determine the flow rate of coolant from each pump 50. It will be appreciated that the processor determines the flow rate of each pump independently of the other pumps, i.e., the flow rate of pump 50A is determined by signals from sensors 110A and 114A, the flow rate of pump 50B is determined by signals from sensors 110B and 114B, the flow rate of pump 50C is determined by signals from sensors 110C and 114C and (if the pumps are connected to a probe) the flow rate of pump 50D is determined by signals from sensors 110D and 114D.

[0047] It will be appreciated that the pumps within vessel 70 are physically independent of each other, ie, the pumps and their associated probes have no common elements.

[0048] 3 is a schematic block diagram illustrating how processor 36 controls the flow rate of pump 50A, according to one embodiment of the present invention. The diagram illustrates how the elements associated with pump 50A are connected to each other, and illustrates the flow of cryogenic fluid and the transfer of signal data between the elements. The following description applies to pump 50A, but it will be understood that substantially the same description applies mutatis mutandis to the other pumps in vessel 70.

[0049] Processor 36 controls the operation of pump 50A by providing pump motor control signals to motor 68A. When in operation, the motor operates pump 50A to cause cryogenic fluid to be pumped from vessel 70 at a flow rate that is dependent on the rotational speed of the motor. Generally, the flow rate of the discharged cryogenic fluid is directly proportional to the rotational speed of the motor, such that a higher rotational speed corresponds to a higher flow rate and a lower rotational speed corresponds to a lower flow rate. Flow rate is also referred to herein as the rate of delivery.

[0050] The processor 36 operates an algorithm, described below with respect to Figure 4, that uses signals from the pressure sensor 114A and the temperature sensor 110A to enable the processor to generate an output signal that controls the pump motor 68A. The output signal transferred to the pump motor controls the motor's revolution rate and therefore the flow rate of the cryogenic fluid discharged from the vessel 70.

[0051] The exhausted cryogenic fluid flows through check valve 76A, outflow lumen 94A, lumen 98A of probe 58A, and to probe distal end 66A. From distal end 66A, the cryogenic fluid returns to vessel 70, generally as a liquid / gas mixture, via lumens 102A, 106A, and separator 118A.

[0052] FIG. 4 is a flow chart of actions taken by processor 36 in executing an algorithm for operating pump 50A during the first phase of the procedure of FIG. 1, according to one embodiment of the present invention. As mentioned above, processor 36 operates any given pump 50 independently and simultaneously with other pumps 50. Thus, processor 36 may operate any other pumps 50 according to the flow chart of FIG. 4, mutatis mutandis. Alternatively or additionally, processor 36 may operate any of pumps 50 to provide coolant to the respective pump distal end by any method known in the art for cryogenic cooling of the distal end. Further alternatively or additionally, some of the pumps may not be activated, i.e., there is no flow from these non-activated pumps. Such non-activated pumps may be present when the respective probes of the pumps are inserted or not inserted into a living subject.

[0053] In describing the flow chart, it is assumed that processor 36 includes a PID (proportional-integral-derivative) controller having an output given by equation (1):

number

[0054] Those skilled in the art will be able to adapt the flow chart description to processors other than PID controllers, mutatis mutandis, without undue experimentation.

[0055] In a first step 250, the parameters of the processor 36, which is assumed to include a PID controller, as described above, are input to the processor. In the following description, the PID controller is c =0.1, ti = 0.05, and t d = 0. That is, processor 36 operates as a PI controller, and one of ordinary skill in the art can easily follow this description without undue experimentation. c , t i , t d It would be possible to accommodate other values ​​of

[0056] In step 250, processor 36 determines a target temperature T, which is the nominal temperature to which distal end 66A is to be cooled. t Temperature T t Generally, T ranges from -10°C to -50°C, but in some embodiments, t is outside this range. The processor 36 also includes t The guard temperature T g This protection temperature T g acts as a nominal temperature limit for the distal tip. In one embodiment, T t = -20°C, T g =-23℃.

[0057] The processor also determines a minimum flow rate M, which corresponds to the minimum speed that the processor should apply to pump motor 68A. m In one embodiment, the minimum motor speed is set to 224 rpm.

[0058] In an initial step 250, the processor determines a maximum flow rate M corresponding to the maximum speed to be applied to the pump motor. u A function f(P) is also provided that the processor uses to compute M u =f(P) (2) where f is a function of the pressure P measured by pressure sensor 114A.

[0059] In one embodiment of the present invention, f(P) is the maximum flow rate M u When P decreases, Mu In an embodiment, both derivatives dM u / dP and dP / dt are negative.

[0060] In the disclosed embodiment, equation (2) is set to equation (3): M u =K1·(1-P / P arb ) (3) Here, P arb is a parametric pressure that has a fixed value set to be greater than the critical pressure of the cryogenic fluid being used by the device 20. K1 is a parametric pressure that has a fixed value set to be greater than the critical pressure of the cryogenic fluid being used by the device 20. u is the proportionality constant for converting to units of

[0061] From equation (3), the gradient (dM u ) / dP is given by equation (3a): dM u / dP=-K1 / P arb (3a)

[0062] In a procedure initialization step 254, physician 24 inserts probe 58A into patient 28 and activates pump 50A to infuse cryogenic fluid into the probe.

[0063] In a first decision step 258, the processor determines whether the temperature T measured by the sensor 110A is a protection temperature T by evaluating the following equation: g Compare with. T <T g (4)

[0064] If equation (4) returns a positive value, that is, the temperature T is equal to or greater than the protection temperature T g If so, the processor proceeds to a first flow rate setting step 262, where the processor sets the flow rate to the minimum flow rate M m Control then returns to decision step 258.

[0065] If equation (4) returns a negative value, i.e., the temperature T is greater than or equal to the protection temperature, control continues to a second decision step 266. In step 266, the processor compares the temperature T to the target temperature Tt by evaluating the following equation: T

[0066] If step 266 returns a positive result, i.e., temperature T is equal to or exceeds the target temperature T t If so, then in a flow rate decrease step 268, the processor T Calculate.

[0067] If step 266 returns a negative value, i.e., temperature T is greater than or equal to the target temperature T t If so, then in a flow increase step 270, the processor increases the target flow rate M T Calculate.

[0068] In steps 268 and 270, the processor evaluates u(t) according to equation (1) and calculates the target flow rate M according to equation (6). T Determine: M T =K2 u(t) (6) where K2 is a proportionality constant used to convert u(t) to units of flow rate.

[0069] Control from steps 268 and 270 continues to a maximum flow rate step 272 .

[0070] In step 272, the processor accesses the value of the pressure P provided by the pressure sensor 114A and uses that value to calculate the maximum flow rate M according to equation (2). u Calculate.

[0071] In a third decision step 274, the processor compares the target flow rate to the maximum flow rate by evaluating the following formula: M T <M u (7)

[0072] ​If equation (7) returns a positive value, i.e., the target flow rate M T is the maximum flow rate M u If so, the processor proceeds to a second flow rate set step 278 where the processor sets the flow rate to the target flow rate.

[0073] If equation (7) returns a negative value, i.e., the flow rate M T is the maximum flow rate M u If so, the processor proceeds to a third flow rate set step 282 where the processor sets the flow rate to the maximum flow rate.

[0074] The flow chart of FIG. 4 repeats with control returning from flow steps 262 , 278 , and 282 to decision step 258 .

[0075] 4 is for pump 50A and therefore the parameters defined in step 250, as well as the temperature, flow rate and function f(P) defined in step 250, are applied to operate this pump. As noted above, this description may be applied mutatis mutandis to operate other pumps in vessel 70 and, since the pumps operate independently of one another, one or more of the parameters, temperature, flow rate and function f(P) defined in step 250 may be different or the same for each pump.

[0076] For example, T for pump 50A t may be set to -20°C, and T of pump 50B t The pump may also be set to -20°C and the temperature of 50°C. t may be set to -25°C

[0077] As mentioned above, the processor 36 is configured to operate all of the pumps in the vessel 70, and if the processor is a PID processor, K c , t i , t d The values ​​of are generally the same. However, this is not required and the value K c , t i , td It is possible that at least one of the values ​​may differ from the values ​​of the other pumps.

[0078] As noted above, the flow chart of Figure 4 is directed to a first phase of the cryogenic procedure, which applies to any given pump 50. Once the first phase is completed, the second phase of the procedure can begin. Because the pumps 50 are operated independently, it will be appreciated that at any given time during the procedure, any given pump 50 may be in either the first or second phase of the procedure.

[0079] Although the above description assumes that processor 36 is generally a single processor, it will be appreciated that each pump may have its own processor, and those skilled in the art will be able to adapt the description, mutatis mutandis, for multiple processors.

[0080] It will be understood that the above-described embodiments have been cited by way of example, and that the present invention is not limited to what has been particularly shown and described above. Rather, the scope of the present invention includes both combinations and subcombinations of the various features described above, as well as variations and modifications thereof which will occur to those skilled in the art upon reading the foregoing description and which have not been disclosed in the prior art.

Claims

1. An apparatus comprising: a single insulated vessel configured to contain a cryogen; a first pump and a second pump, both disposed within the single insulated vessel and configured to pump the cryogen from the single insulated vessel while immersed in the cryogen; a first probe having a first proximal end and a first distal end, the first probe being coupled to the first pump; and a second probe having a second proximal end and a second distal end, the second probe being coupled to the second pump; the first proximal end and the second proximal end are respectively coupled to the first pump and the second pump to simultaneously receive the cryogen pumped by the first pump to the first probe and the cryogen pumped by the second pump to the second probe; a first probe and a second probe, the first distal end of which is cooled by the cryogen received via the first proximal end and the second distal end of which is cooled by the cryogen received via the second proximal end, the first distal end and the second distal end being configured to be inserted into a body of a living subject; Equipped with the first pump and the second pump are physically independent of one another, and the first pump and the second pump and their associated probes have no common elements; the cryogen pumped by the first pump is at a first flow rate; the cryogen pumped by the second pump is at a second flow rate; the first and second flow rates are independent of each other; Device.

2. the first pump and the second pump are each selected from the group including a bellows pump, a plunger pump, and a piston pump; 2. The apparatus of claim 1.

3. the first distal end includes a first temperature sensor and the second distal end includes a second temperature sensor; the first flow rate is responsive to a first temperature measured by the first temperature sensor, and the second flow rate is responsive to a second temperature measured by the second temperature sensor.

2. The apparatus of claim 1.

4. a processor configured to operate the first pump and the second pump; 2. The apparatus of claim 1.

5. A method comprising the steps of: providing a single insulated vessel configured to contain a cryogen; disposing a first pump and a second pump within the single insulated container; configuring the first pump and the second pump to pump the cryogen from the single insulated vessel while immersed in the cryogen; coupling a first probe to the first pump and a second probe to the second pump, the first probe having a first proximal end and a first distal end and the second probe having a second proximal end and a second distal end, the first proximal end and the second proximal end being coupled to the first pump and the second pump, respectively, to simultaneously receive cryogen pumped by the first pump into the first probe and the cryogen pumped by the second pump into the second probe, the first distal end and the second distal end being configured to be cooled by the cryogen received via the first proximal end and the second proximal end and to be inserted into a body of a living subject; Including, the first pump and the second pump are physically independent of one another, and the first pump and the second pump and their associated probes have no common elements; the cryogen pumped by the first pump is at a first flow rate; the cryogen pumped by the second pump is at a second flow rate; the first and second flow rates are independent of each other; method.

6. the first pump and the second pump are each selected from the group including a bellows pump, a plunger pump, and a piston pump; The method of claim 5.

7. the first distal end includes a first temperature sensor and the second distal end includes a second temperature sensor; the first flow rate is responsive to a first temperature measured by the first temperature sensor, and the second flow rate is responsive to a second temperature measured by the second temperature sensor. The method of claim 5.

8. further comprising operating the first pump and the second pump by a single processor. The method of claim 5.

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