Patent Description:
Cryotherapy includes variety of techniques used to treat and/or map tissue, and is commonly used for procedures involving cardiac tissue. Certain types of cryotherapy, such as cryoablation, involve the use of pressurized refrigerant, which is allowed to expand within, and thereby cool tissue adjacent to, the distal portion of the treatment device. The pressurized refrigerant is typically stored in a pressurized tank or cylinder in the console of the system. Although the tank is easily removed and replaced when the refrigerant source runs out, it would be more economical to refill the tank with a new supply of refrigerant. Additionally, the pressurized tanks are considered to be Dangerous Goods, and it would therefore be desirable to reduce the amount of transport, handling, and storage of refrigerant tanks used for cryotherapy procedures.

Many medical facilities, especially hospitals, include a native or in-facility, integrated source of nitrous oxide (N<NUM>O), which is commonly used as an anesthetic. Nitrous oxide may also be used as a refrigerant in cryotherapy systems. The expanded or used nitrous oxide must be scavenged from the system, but many medical facilities do not have adequate scavenging systems for recapture, storage, and disposal of nitrous oxide vapor.

It is therefore desirable to provide a system and method for recapturing or scavenging used refrigerant vapor for storage and disposal. It is further desired that the system be contained within a cryotreatment console for economy of space and ease of transportation. Prior art is found in <CIT>, <CIT> and <CIT>.

The present invention advantageously provides system for the recovery of expanded refrigerant from a cryotreatment system for storage and disposal according to claim <NUM>. Aspects of the disclosure are given below. The unit "psi" corresponds to <NUM> Pascals. A medical system may include: a refrigerant recovery circuit, the refrigerant recovery circuit including: a first fluid flow path having: a first compressor; and a fluid recovery reservoir, the first fluid flow path including a primary refrigerant; and a closed-loop second fluid flow path including: a thermal exchange device that is in thermal communication with the fluid recovery reservoir; a second compressor; and a condenser, the closed-loop second fluid flow path including a secondary refrigerant (for example, AZ20). The system may be configured to be in fluid communication with a medical facility. The refrigerant recovery circuit may further comprise an insulating container in the first fluid flow path, and the fluid recovery reservoir and the thermal exchange device may both be located within the insulating container. The thermal exchange device may be coiled around at least a portion of the fluid recovery reservoir. The flow of the secondary refrigerant within the closed-loop second fluid flow path may reduce the temperature of the primary refrigerant. Further, the first compressor may compress the primary refrigerant to a pressure of approximately <NUM> psi. The system may further include a cryotreatment system in fluid communication with the refrigerant recovery circuit, the cryotreatment system including: a source of the primary refrigerant; a third fluid flow path downstream of the primary refrigerant and configured to be in fluid communication with and upstream of a cryotreatment device; and a fourth fluid flow path downstream of the third fluid flow path, the fourth fluid flow path being in fluid communication with and upstream of the refrigerant recovery circuit, the fourth fluid flow path configured to be in fluid communication with and downstream of the cryotreatment device. The refrigerant recovery circuit and the cryotreatment system may be located within a cryotreatment console. The fluid recovery reservoir may be configured to be removed from the cryotreatment console. The cryotreatment system may further include a three-way solenoid valve located within the fourth fluid flow path.

A system for the recovery of a cryotreatment refrigerant may generally include: a refrigerant recovery circuit, the refrigerant recovery circuit including: a first fluid flow path having: a first compressor; and a fluid recovery reservoir, the first fluid flow path including a primary refrigerant; and a closed-loop second fluid flow path including: a thermal exchange device that is in thermal communication with the fluid recovery reservoir; a second compressor; and a condenser, the closed-loop second fluid flow path including a secondary refrigerant; and a cryotreatment system in fluid communication with the refrigerant recovery circuit, the cryotreatment system including: a source of the primary refrigerant; a third fluid flow path downstream of the primary refrigerant source and configured to be in fluid communication with and upstream of a cryotreatment device; and a fourth fluid flow path downstream of the third fluid flow path, the fourth fluid flow path being in fluid communication with and upstream of the refrigerant recovery circuit, the fourth fluid flow path configured to be in fluid communication with and downstream of the cryotreatment device. The system may be configured to be in fluid communication with a medical facility. The fluid recovery reservoir and the thermal exchange device may both be located within an insulating container. The thermal exchange device may be coiled around at least a portion of the fluid recovery reservoir. The flow of the secondary refrigerant within the closed-loop second fluid flow path may reduce the temperature of the primary refrigerant. The first compressor may compress the primary refrigerant to a pressure of approximately <NUM> psi. The system may be located within a cryotreatment console, and the fluid recovery reservoir may be configured to be removed from the cryotreatment console.

A system for recovery of expanded cryotreatment refrigerant may generally include: a refrigerant recovery conduit, the refrigerant recovery conduit including: a first fluid flow path having: a first compressor; and a fluid recovery reservoir, the first fluid flow path including a cryotreatment refrigerant; and a closed-loop second fluid flow path including: a thermal exchange device that is in thermal communication with the fluid recovery reservoir; a second compressor; a condenser; and an insulating container, the closed-loop second fluid flow path including a secondary refrigerant; a cryotreatment device; and a cryotreatment system in fluid communication with the refrigerant recovery circuit and the cryotreatment device, the cryotreatment system including: a source of the cryotreatment refrigerant; a third fluid flow path between the cryotreatment refrigerant source and the cryotreatment device, the cryotreatment refrigerant expanding within the cryotreatment device; and a fourth fluid flow path between the cryotreatment device and the refrigerant recovery circuit, expanded cryotreatment refrigerant from the cryotreatment device passing through the fourth fluid flow path and into the refrigerant recovery circuit. The expanded cryotreatment refrigerant may be compressed by the first compressor to pressure of approximately <NUM> psi and the temperature of the compressed cryotreatment refrigerant may be reduced within the fluid recovery reservoir by the flow of the secondary refrigerant within the thermal exchange device, the fluid recovery reservoir and the thermal exchange device being located within the insulating container. Further, the refrigerant recovery circuit and the cryotreatment system may be located within a cryotreatment console, and the cryotreatment console may be in fluid communication with the cryotreatment device.

The present invention advantageously provides a system for the recovery of used refrigerant for reuse or disposal. The unit "psi" used herein corresponds to <NUM> Pascals. Referring now to the drawing figures in which like reference designations refer to like elements, an exemplary schematic view of a cryotreatment system including a refrigerant recovery circuit in accordance with principles of the present invention is shown in <FIG>. The cryotreatment system, generally designated as "<NUM>," may include a refrigerant recovery circuit <NUM> and may be in fluid, electrical, and mechanical communication with a cryotreatment device <NUM>. The cryotreatment system <NUM> may be located entirely within a cryotreatment console <NUM>. The cryotreatment console <NUM> may be in fluid communication with a scavenging or recovery system of a medical facility <NUM>.

Referring now to <FIG> and <FIG>, the cryotreatment system <NUM> may include one or more fluid supply reservoirs <NUM>, such as pressurized tanks, that include a coolant, Cryogenic refrigerant, or the like in fluid communication with a fluid delivery conduit <NUM> and the cryotreatment device <NUM>. As a non-limiting example, the refrigerant may be nitrous oxide (N20), such as a native or in-facility, integrated source of nitrous oxide <NUM> in the medical facility <NUM>, in which case the fluid supply reservoir <NUM> may be located external to the cryotreatment console <NUM>. Additionally or alternatively, the fluid supply reservoir may be located within the console <NUM>, and the native refrigerant from the medical facility <NUM> may not be used. The cryotreatment system <NUM> may include a fluid recovery conduit <NUM> in fluid communication with the cryotreatment device <NUM> and a recovery reservoir <NUM> of the refrigerant recovery circuit <NUM>, which is described in more detail below.

The cryotreatment system <NUM> may also include a vacuum pump <NUM> for creating a pressure gradient to draw expanded (used) refrigerant from the cryotreatment device <NUM>, into the fluid recovery conduit <NUM> and then into the refrigerant recovery circuit <NUM>. The system's fluid flow path may include at least the fluid delivery conduit <NUM> and the fluid recovery conduit <NUM>, in addition to various other conduits and/or secondary flow paths. The cryotreatment system <NUM> may also include pumps, valves, controllers or the like to recover and/or re-circulate fluid delivered to the handle, the elongate body, and/or the fluid pathways of the cryotreatment device <NUM>, as described in more detail below.

The cryotreatment system <NUM> may include one or more controllers, processors, and/or software modules containing instructions or algorithms to provide for the automated operation and performance of the features, sequences, or procedures described herein. For example, the cryotreatment system <NUM> may include one or more computers that include one or more processors for receiving signals from one or more sensors throughout the system <NUM>, and or for the automatic, semi-automatic, and/or manual operation of the system <NUM>. The one or more computers may include one or more user input devices by which a user can program system parameters such as the inflation and deflation of one or more balloons of the cryotreatment device <NUM>, circulation of refrigerant through the fluid delivery <NUM> and recovery <NUM> conduits, and/or the operation of one or more electrodes or other thermal delivery elements. The user input devices may include keyboards, knobs, buttons, dials, foot pedals, mice, touchscreens, voice input units, and/or switches. Additionally, the user may use the user input devices to override the automatic operation of the system <NUM> either programmed into or predetermined by the cryotreatment system <NUM>. Still further, signals received by the one or more processors may be used to automatically or semiautomatically control the cryotreatment device <NUM> and/or the circulation of refrigerant therein. The one or more computers may further include one or more displays, such as computer screens or other visual elements in communication with the one or more processors and/or user input devices. Finally, the cryotreatment system <NUM> may include one or more speakers or other audio alert generators that are in communication with the one or more processors and/or the user input devices.

The system <NUM> and/or the cryotreatment device <NUM> may further include one or more sensors to monitor the operating parameters throughout the system <NUM>, including for example, pressure, temperature, flow rates, volume, or the like in the cryotreatment console <NUM> and/or the cryotreatment device <NUM>, in addition to monitoring, recording or otherwise conveying measurements or conditions within the device <NUM> or the ambient environment at the distal portion of the device <NUM>. The sensor(s) may be in communication with the cryotreatment console <NUM> for initiating or triggering one or more alerts or therapeutic delivery modifications during operation of the device <NUM>. One or more valves, controllers, or the like may be in communication with the sensor(s) to provide for the controlled dispersion or circulation of fluid through the lumens/fluid paths of the device <NUM> and system <NUM>. Such valves, controllers, or the like may be located in a portion of the cryotreatment device <NUM> and/or in the cryotreatment console <NUM>.

While the cryotreatment device <NUM> may be in fluid communication with a fluid source to cryogenically treat selected tissue, it is also contemplated that the device <NUM> may additionally include one or more electrically conductive portions or electrodes thereon coupled to a radiofrequency generator or power source as a treatment or diagnostic mechanism.

As discussed above, the system fluid flow path may include one or more valves, conduits, secondary flow paths, one or more fluid supply reservoirs <NUM>, one or more fluid recovery reservoirs <NUM>, a vacuum pump <NUM>, and other system components. The cryotreatment system <NUM> may also include one or more subcoolers <NUM> with various refrigeration components such as a compressor <NUM>, condenser <NUM>, capillary tube, thermoelectric elements, and/or thermal exchange device <NUM>. A subcooler <NUM>, such as that shown in <FIG>, may be used to further cool the refrigerant as it passes within the fluid delivery conduit <NUM> from the fluid supply reservoir <NUM> to the cryotreatment device <NUM>. The fluid delivery conduit and other fluid flow paths between the fluid supply reservoir <NUM> and the device <NUM> may further include a PID circuit <NUM> and one or more valves and/or other components (for example, solenoid valves S1, S6, and S8, pressure transducer PTI, pressure relief valve PR, pressure switch PSI, shown in <FIG>).

Expanded (used) refrigerant vapor from the cryotreatment device <NUM> may flow to the refrigerant recovery circuit <NUM> (as shown in <FIG>), scavenged by the medical facility scavenging system (as shown in <FIG>), and/or vented to the atmosphere (as shown in <FIG>). Referring to <FIG>, expanded refrigerant may, with the pressure gradient created by the vacuum <NUM>, pass through the fluid recovery conduit <NUM> from the cryotreatment device <NUM>, through check valve CV6, pressure transducer PT5, through three-way solenoid valve S9, through three-way solenoid valve S4, and into the refrigerant recovery circuit <NUM>. As a non-limiting example, three-way solenoid valve S9 may vent air to the atmosphere when the system starts and air within the system is removed before beginning a cryoablation procedure. Once a cryoablation procedure begins, S9 may allow refrigerant to pass on to the refrigerant recovery circuit <NUM>. As it enters the refrigerant recovery circuit <NUM> through a first flow path <NUM>, the expanded refrigerant vapor may be at approximately <NUM> psig. After passing through a first compressor <NUM> of the refrigerant recovery circuit <NUM>, however, the refrigerant vapor may be compressed to have a pressure of approximately <NUM> psi (±<NUM> psi). After passing through the first compressor <NUM>, the compressed refrigerant may pass into a fluid recovery reservoir <NUM> for temporary storage and later disposal. As a non-limiting example, the fluid recovery reservoir <NUM>, or the insulating container and the fluid recovery reservoir <NUM>, may be removed from the refrigerant recovery circuit <NUM> and disposed. The recovery reservoir <NUM> may be reusable after the recovered refrigerant is disposed, or the recovery reservoir <NUM> may be disposable and a new reservoir used as needed.

The refrigerant recovery circuit <NUM> may also include a second fluid flow path <NUM>, which may contain a secondary refrigerant, such as AZ20. The secondary refrigerant may flow through a thermal exchange device <NUM> that is in a thermal exchange relationship (that is, in thermal communication) with the fluid recovery reservoir <NUM>. As a non-limiting example, the thermal exchange device <NUM> may be an evaporator having a coiled configuration and may be wrapped one or more times about a circumference of the fluid recovery reservoir <NUM>. Further, the recovery reservoir <NUM> and the thermal exchange device <NUM> may together be located within an insulating container <NUM>. The insulating container <NUM> may be at least partially composed of a material or layers of materials that prevent or reduce the transmission of heat. Additionally, the insulating container <NUM> may be filled with, and the thermal exchange device <NUM> and the recovery reservoir <NUM> may be surrounded by, a nonfreezing liquid <NUM> such as methanol, propylene glycol, or other liquid having similar properties. The nonfreezing liquid <NUM> may improve heat transfer between the thermal exchange device <NUM> and the recovery reservoir <NUM>. Thus, the flow of secondary refrigerant within the thermal exchange device <NUM> may cool the refrigerant within the recovery reservoir <NUM> and the insulating container <NUM> may improve cooling efficiency. The insulting container <NUM> may have a shape and configuration similar to that of the recovery reservoir <NUM>, and may be sized just large enough to accommodate the recovery reservoir <NUM>, thermal exchange device <NUM>, and nonfreezing liquid <NUM> therein. Further, the recovery reservoir <NUM> optionally may be integrated within the insulating container <NUM>. From the thermal exchange device <NUM>, the secondary refrigerant may pass through a second compressor <NUM>, then through a condenser <NUM>, and then back into the thermal exchange device <NUM>. The secondary refrigerant may also pass through a dryer and capillary tube or expansion device before passing into the thermal exchange device <NUM>. Thus, the secondary refrigerant may be recycled through the second fluid flow path <NUM> to continue cooling the recovered refrigerant within the recovery reservoir <NUM>.

Additionally or alternatively, at least a portion of the expanded refrigerant may be scavenged by the native scavenging system <NUM> within the medical facility <NUM> (as shown in <FIG>). In this case, the expanded refrigerant vapor may, with the pressure gradient created by the vacuum <NUM>, pass through the fluid recovery conduit <NUM> from the device <NUM>, through check valve CV6, pressure transducer PT5, through three-way solenoid valve S9, through three-way solenoid valve S4, and into the medical facility scavenging line <NUM>. As shown in <FIG>, the expanded refrigerant vapor may also pass through one or more additional valves, transducers, and system components. This fluid flow path may be used if, for example, the refrigerant recovery circuit <NUM> malfunctions or if the refrigerant recovery reservoir <NUM> is full.

Claim 1:
A medical system (<NUM>), comprising:
a refrigerant recovery circuit (<NUM>), the refrigerant recovery circuit including:
a first fluid flow path (<NUM>) having:
first compressor (<NUM>); and
a fluid recovery reservoir (<NUM>),
the first fluid flow path (<NUM>) being configured to contain a primary refrigerant; and
a closed-loop second fluid flow path (<NUM>) including:
a thermal exchange device (<NUM>) that is in a direct thermal exchange relationship with the fluid recovery reservoir (<NUM>);
a second compressor (<NUM>); and
a condenser (<NUM>),
the closed-loop second fluid flow path (<NUM>) being configured to contain a secondary refrigerant;
the medical system further comprising a cryotreatment device (<NUM>), a cryotreatment system (<NUM>), and a cryotreatment console (<NUM>),
the cryotreatment system (<NUM>) being in fluid communication with the refrigerant recovery circuit (<NUM>), the cryotreatment system (<NUM>) including a source of the primary refrigerant; a third fluid flow path (<NUM>) downstream of the primary refrigerant and configured to be in fluid communication with and upstream of the cryotreatment device (<NUM>); and a fourth fluid flow path (<NUM>) downstream of the third fluid flow path, the fourth fluid flow path (<NUM>) being in fluid communication with and upstream of the refrigerant recovery circuit (<NUM>), the fourth fluid flow path (<NUM>) configured to be in fluid communication with and downstream of the cryotreatment device (<NUM>), the refrigerant recovery circuit (<NUM>) and the cryotreatment system (<NUM>) being located within the cryotreatment console, wherein the fluid recovery reservoir (<NUM>) is be configured to be removed from the cryotreatment console.