Patent ID: 12194228

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Described herein are methods and systems that relieve system pressure or limit the maximum pressure in an open loop or open insufflation system for use in open or direct access surgical procedures. It will be understood that although much of the description herein is in the context of open surgery, one or more features of the present disclosure can also be implemented in other scenarios where it is desirable to limit the output pressure of a gas, such as respiratory applications.

Insufflation gases can be used in a variety of surgical procedures. In open surgery, insufflation gases can be used in a body cavity for de-airing, which can decrease the risk of air embolism or, possibly, decrease the risk of infection of the surgical wound. In open surgical applications, the insufflation system is an open loop system that provides a generally constant flow of insufflation gas as a desired flow rate over a desirable period of time, which can encompass a portion or the entirety of the surgical procedure. Such an open loop system is in contrast to the (essentially) closed loop or feedback insufflation systems used in minimally invasive surgery, in which insufflation gas is provided discontinuously or on demand to maintain a relatively low pressure (e.g., 0.3 psi, 2 kPa) within the essentially sealed body cavity.

It has been discovered by the present inventor that, although insufflation systems for use in open surgery are open loop gas delivery systems, which deliver insufflation gas to the atmosphere, occlusion of the system can occur during normal or routine operation. Occlusion of the system can cause a rise in system pressure and, possibly, failure of or damage to components of the system. This failure or damage can cause a temporary or, in some cases, a complete interruption in the insufflation therapy. Thus, the present inventor has discovered that it can be desirable to provide for pressure relief in an open loop insufflation system.

In some configurations, the open loop surgery insufflation system incorporates a humidifier to warm and humidify the delivered insufflation gas. Body cavity environments can include cells that are susceptible to damage when exposed to relatively dry and cold gases. Insufflation gases can be relatively cold and dry and may cause damage to cells, damage that can be reduced or avoided through humidifying and warming the insufflation gas. Warming and humidifying the insufflation gas can reduce or prevent cellular desiccation. This can have a positive effect on post-operative pain that not only increases quality of care but reduces recovery time and increase department throughput. Warming and humidifying insufflation gases may reduce intra-operative hypothermia, reduce post-operative pain, and improve post-operative recovery.

Some embodiments described herein provide for a humidification system that is configured to deliver warm, humidified gas to a patient undergoing a surgical procedure. The gas is passed through a water chamber which is filled with water that is heated using a heater plate. Water evaporates in the chamber and combines with the gas which flows over it, thereby heating and/or humidifying the gas. The temperature of the gas can be maintained as it travels along a heated tube to an outlet port for delivery to the patient. The humidification system can monitor the temperature and flow rate of the gas at a chamber outlet, and control an amount of electrical power delivered to the heater plate to provide a gas having a desired temperature and humidity. Thus, surgical gas from a gas source (e.g., a gas bottle, wall source or the like) can be humidified and heated and delivered to the patient, enabling the targeted area to remain moist and warm.

Some embodiments described herein provide for a surgical humidification system that includes a humidifier control system configured to determine a mode of operation, a mode of control, a heater plate set point, or any combination of these. The humidifier control system can base this determination at least in part on feedback from components of the humidification system. The components of the humidification system can provide feedback through sensors or other electrical components, and feedback can include, for example, outlet gas temperature, heater plate temperature, heater plate power, gas flow rate, user input through user interface elements, duration of operation, and the like. Some embodiments of the humidifier control system can improve efficiency of the humidification system, provide an output gas with relatively consistent humidity and temperature, and provide greater control over temperature and humidity of the gas compared to control systems that do not incorporate system component feedback. The humidifier control system can provide at least some of these improvements through modules configured to process system component feedback and adjust output settings according to a control loop feedback mechanism. If provided, the humidifier can be controlled in any suitable manner, such as using a portion or an entirety of the control systems and methods disclosed in U.S. Provisional Patent Application No. 61/699,773, filed Sep. 11, 2012 and entitled SURGICAL HUMIDIFIER CONTROL.

FIG.1illustrates an example open surgery insufflation system10for delivering an insufflation gas to a patient12and, in particular, to an open surgical site of the patient12, which can be, for example and without limitation, an area, cavity or wound (collectively referred to as a “cavity”). The open surgery insufflation system10comprises a gas source14for supplying a flow of insufflation gas. The insufflation gas can be any suitable gas for the desired purpose; however, in some configurations the insufflation gas is carbon dioxide (CO2). As described above, CO2 is often used as a surgical insufflation gas and is well-suited for open surgery insufflation because CO2 is heavier than air and tends to displace air in an open surgical cavity.

The gas source14can be of any suitable arrangement to deliver a suitable flow of insufflation gas, which in some configurations is a constant flow of insufflation gas. In some configurations, the gas source14comprises a gas bottle16filled with a compressed insufflation gas, such as CO2. However, in other configurations, the insufflation gas could be supplied by another gas supply, such as a wall supply (i.e., gas supplied via appropriate conduit from a remote reservoir) for example and without limitation. The gas source14can also comprise a pressure regulator20if necessary or desirable to regulate the pressure of the flow of insufflation gas provided by the gas bottle16or other gas supply. In some configurations, the gas bottle16contains insufflation gas (e.g., CO2) that is pressurized to a relatively high pressure (e.g., about 5,000 kPa or about 725 psi). The pressure regulator20can reduce the pressure of gas supplied by the gas bottle16to a pressure more suitable for use by the open surgery insufflation system10, such as about 400 kPa (about 58 psi), for example. It is possible to construct a pressure regulator20that could further reduce the pressure of gas supplied by the gas bottle16; however, such a regulator would be larger and/or more complicated and may not be practical for use in a surgical setting.

In some configurations, the gas source14comprises a flow regulator or flow meter22for regulating the flow rate of the flow of insufflation gas from the gas bottle16or other gas supply. The flow meter22can be any suitable type, such as a flow meter commonly used to regulate the flow rate of medical gases (e.g., respiratory gases). The flow meter22can be adjustable to permit adjustment of the gas flow rate. The flow meter22can permit adjustment of the flow rate within any suitable range. In some configurations, the flow meter22can permit adjustment of the flow rate up to about 25 liters/minute (L/min). In some configurations, the flow meter22can permit adjustment of the flow rate to between about 1-2 L/min and about 25 L/min. More particularly, the flow meter22can permit adjustment of the flow rate between about 5 L/min to about 15 L/min. Even more particularly, the flow meter22can provide a flow rate of about 10 L/min. In some configurations, a relatively low flow rate is desired and, in some such configurations, the insufflation gas can be shielded from evacuation from the surgical site, such as with a barrier, and/or the insufflation gas level can be measured at the surgical site. If the insufflation gas level is measured, feedback control of the flow rate can be utilized. However, other suitable flow rates can also be used, which may greater than 25 L/min.

In the illustrated configuration, the gas bottle16(or other gas supply), pressure regulator20and flow meter22are separate from one another and coupled by suitable conduits24. However, in other configurations, one or more of these components could be combined in an integrated unit. Other suitable arrangements are also possible.

The open surgery insufflation system10can also include a humidifier30, which receives a flow of insufflation gas from the gas source14and outputs a warmed and humidified flow of insufflation gas. The humidifier30can be of any suitable arrangement, such as the humidifier30described below with reference toFIG.2or any other suitable arrangement.

The open surgery insufflation system10can also comprise an outlet32for dispensing the flow of insufflation gas. The outlet32can be of any suitable arrangement to deliver the flow of insufflation gas to the open surgical cavity of the patient12. In some configurations, the outlet32is configured to disperse the flow of insufflation gas as it exits the outlet32. In particular, the outlet32can comprise a gas diffuser of any suitable arrangement. The outlet32(e.g., diffuser, nozzle or other arrangement) can be referred to generally as an interface or patient interface.

The open surgery insufflation system10also comprises a pressure relief arrangement, which can comprise a pressure relief valve or check valve40(referred to hereinafter as a “pressure relief valve”). The pressure relief valve40can be configured to relieve pressure within the open surgery insufflation system10in response to system pressure above a threshold pressure level. The pressure relief valve40can be of any suitable type for use in a medical fluid system, such as a ball-and-spring valve, a diaphragm valve, a leaflet valve, etc. In some configurations, the threshold pressure level can be set to be slightly or significantly higher than system pressures that are expected to occur during normal use of the open surgery insufflation system10, which can include system pressures that occur as a result of foreseeable, but less-than-ideal use of the system10. In response to systems pressures above a threshold, the pressure relief valve40can open to vent pressure from the open surgery insufflation system10, such as to the atmosphere, and reduce the system pressure. Such an arrangement can reduce the incident of or prevent failure of a system component, such as connections (e.g., taper, luer or barb connections) between components of the system10or, in some cases, larger system components (e.g., the humidifier30).

FIG.2illustrates the open surgery insufflation system10with an example surgical humidification system100for delivering temperature- and humidity-controlled gas to a patient102shown in greater detail. As described above, open surgery insufflation system10can comprise a humidifier30, which can incorporate a humidifier control system50. The humidifier30is connected to the gas source14through a supply conduit52. The humidifier30delivers humidified gas to the patient12through a patient conduit54. The conduits52,54can be made of any suitable material, such as flexible plastic tubing, for example.

The humidifier30receives gas from the gas source14through the supply conduit52. The gas can be filtered through a filter56and delivered to the humidifier30through a humidifier inlet60. The filter56can be positioned at any suitable location within the system10, such as upstream from the humidifier30, as shown, or downstream from the humidifier30. The gas is humidified as it passes through a humidifying chamber62, which is effectively a water bath, and the gas flows out through a humidifier outlet64and into the patient conduit54. The gas then moves through the patient conduit54to the patient12. In some configurations, a filter can be disposed between the humidifier outlet64and the patient12.

The humidifier30comprises a body or base66with which the humidification chamber62can be removably engaged. In some configurations, the humidification chamber62has a metal base70and is adapted to hold a volume of water72, which can be heated by a heater plate74. The heater plate74can be in thermal contact with the metal base70of the humidification chamber62. Providing power to the heater plate74can cause heat to flow from the heater plate74to the water72through the metal base70. As the water72within the humidification chamber62is heated it can evaporate and the evaporated water can mix with gases flowing through the humidification chamber62from the filter56and gas source14. Accordingly, the humidified gases leave the humidification chamber62via outlet64and are passed to the patient12via the patient conduit54preferably to the surgical site to insufflate the surgical site.

In some configurations, the humidifier30includes the humidifier control system50configured to control a temperature and/or humidity of the gas being delivered to the patient12. The humidifier control system50can be configured to regulate an amount of humidity supplied to the gases by controlling an electrical power supplied to the heater base74. The humidifier control system50can control operation of the humidifier30in accordance with instructions set in software and in response to system inputs. System inputs can include a heater plate sensor76, an outlet chamber temperature sensor80, and a chamber outlet flow probe82. For example, the humidifier control system50can receive temperature information from the heater plate sensor76which it can use as an input to a control module used to control the power or temperature set point of the heater plate74. The humidifier control system50can be provided with inputs of temperature and/or flow rates of the gases. For example, the chamber outlet temperature sensor80can be provided to indicate to the humidifier control system50the temperature of the humidified gas as it leaves the outlet64of the humidification chamber62. The temperature of the gases exiting the chamber can be measured using any suitable temperature sensor80, such as a wire-based temperature sensor. The chamber outlet flow probe82can be provided to indicate to the humidifier control system50the flow rate of the humidified gas. The flow rate of the gases through the chamber62can be measured using any suitable flow probe82, such as a hot wire anemometer. In some embodiments, the temperature sensor80and flow probe82are in the same sensor housing. The temperature sensor80and flow probe82can be connected to the humidifier30via connector84. Additional sensors may be incorporated into the open surgery insufflation system10, for example, for sensing parameters at the patient end of the patient conduit54.

The humidifier control system50can be in communication with the heater plate74such that the humidifier control system50can control a power delivered to the heater plate74and/or control a temperature set point of the heater plate74. The humidifier control system50can determine an amount of power to deliver to the heater plate74, or a heater plate set point, based at least in part on a flow condition, an operation mode, a flow reading, an outlet temperature reading, a heater plate sensor reading, or any combination of these or other factors.

The open surgery insufflation system10can include a conduit heating wire86configured to provide heat to the gases traveling along the patient conduit54. Gases leaving the outlet64of the humidification chamber62can have a high relative humidity (e.g., about 100%). As the gases travel along the patient conduit54there is a chance that water vapor may condense on the conduit wall, reducing the water content of the gases. To reduce condensation of the gases within the conduit54, the conduit heating wire86can be provided within, throughout, and/or around the patient conduit54. Power can be supplied to the conduit heating wire86from the humidifier30and can be controlled through the humidifier control system50. In some configurations, the heating wire86is configured to maintain the temperature of the gas flowing through the patient conduit54. In some configurations, the conduit heating wire86can provide additional heating of the gas to elevate the gases temperature to maintain the humidity generated by the heated water bath in the humidifier30.

FIG.2also illustrates an example of an outlet32, which can be in the form of a surgical site insufflation gas interface32for delivering the preferably warmed and humidified flow of insufflation gas from the patient conduit54to the surgical site (e.g., surgical cavity92). The gas interface32can be of any suitable arrangement for delivering a flow of insufflation gas at a sufficient flow rate to create at least a partial protective environment or insufflation gas environment94near, at or within the surgical cavity92. In some configurations, the gas interface32(in combination with a suitable gas source14and optional humidifier30) can deliver a sufficient amount of insufflation gas to maintain an insufflation gas concentration (e.g., CO2 concentration) of at least about 80%, or at least about 90%, within a substantial portion or an entirety of the surgical cavity92. In some configurations, the gas interface32can deliver a sufficient amount of insufflation gas to maintain an insufflation gas concentration of between about 80% and about 99%, or between about 90% and about 99%, within a substantial portion or an entirety of the surgical cavity92. In some configurations, the gas interface32(in combination with a suitable gas source14and optional humidifier30) can deliver up to about 25 L/min. In some configurations, the gas interface32can deliver between about 1-2 L/min and about 25 L/min. In some configurations, the gas interface32can deliver between about 5 L/min and about 15 L/min, or between about 8 L/min to about 12 L/min. In some configurations, the gas interface32can deliver about 10 L/min.

Preferably, the gas interface32can deliver the insufflation gas in a manner that minimizes or eliminates any deleterious effects on the surrounding tissue. That is, preferably the gas interface32does not provide a jet of insufflation gas, but disperses the insufflation gas over a larger area or through multiple outlets or ports and, in at least some cases, avoids creating turbulence. In some configurations, the gas interface comprises a gas diffuser96for dispersing the insufflation gas from the system10in a diffused manner. The gas diffuser96can be of any suitable arrangement. In some configurations, the gas diffuser96is coupled to the patient conduit54by a conduit or tube100. The tube100preferably is secured to the patient conduit54by a suitable connector102, such as a luer lock connector.

In some configurations, the gas diffuser96comprises a porous body, which includes a large number of ports, flow paths or cavities that permit the insufflation gas to pass from the tube100to the atmosphere outside of the gas diffuser96. The flow paths or cavities can be inherent in the material(s) used to construct the gas diffuser96or can be created within a base material(s). In some configurations, the gas diffuser96is constructed from a porous material, such as foam or foam-like material or sponge or sponge-like material. In some configurations, the gas diffuser96can be constructed from a hydrophobic material. Suitable gas diffusers96are marketed by Cardia Innovation AB of Stockholm, Sweden (the Vita diffuser) and Temed of Bosham, England. Examples of gas diffuser are disclosed in U.S. Pat. Nos. 6,494,858 and 6,994,685, the entireties of which are incorporated by reference herein. Other suitable gas diffusers96could also be used, such as perforated tubes or catheters or other perforated dispensers, for example and without limitation.

In some configurations, the tube100can include features to inhibit or prevent accidental occlusion, such as internal support ribs, for example. In some configurations, the tube100can be deformable and can be configured to hold its shape once deformed. For example, one or more of the internal ribs, a wall of the tube100or another portion of the tube could incorporated a malleable material that would hold the tube100in a desired shape once deformed. Thus, the tube100could be bent to allow the gas diffuser96to be positioned within the surgical cavity92and a portion of the tube100to be placed in contact with the patient12at a location adjacent to the surgical cavity92. If desired, the tube100can be secured in place.

As described above, the open surgery insufflation system10preferably includes a pressure relief arrangement, which can be a pressure relief valve40. The pressure relief valve40can relieve or vent pressure from within the system10if the system pressure reaches or exceeds a threshold pressure. The system10could reach or exceed the threshold pressure as a result of the partial or complete occlusion of a passage within the system10, such as within the supply conduit52, patient conduit54, tube100or gas diffuser96, for example and without limitation. The pressure relief valve40can be positioned at any suitable location within the system10. In some configurations, the pressure relief valve40is located in a non-sterile portion of the open surgery insufflation system10when the system10is in normal use under normal circumstances. For example, a portion of the system10from the gas source14up to and including the humidifier30can be non-sterile in normal use. A sterile portion of the system10can include the gas diffuser96, tube100and connector102, which can be an integrated assembly in some cases. The patient conduit54can be sterile, non-sterile or can have portions that are within the sterile field and portions that are within the non-sterile field.

Positioning the pressure relief valve40in the non-sterile field or within a non-sterile area is advantageous because the pressure relief valve40can be re-used. In some configurations, as illustrated inFIG.2, the pressure relief valve40can be positioned upstream of the humidifier30relative to a direction of the gas flow. In some configurations, the pressure relief valve40can be positioned between the gas source14and the humidifier30. In particular, the pressure relief valve40can be positioned between the flow meter22and the humidifier30. In some configurations, the pressure relief valve40can be positioned along or integrated into the supply conduit52. For example, the pressure relief valve40can be coupled to a pair of conduit portions of the supply conduit52by a tee connection, such as an NPT threaded ¼ inch tee connection, for example and without limitation.

In other configurations, the pressure relief valve40can be positioned downstream of the humidifier30and/or within a sterile portion of the open surgery insufflation system10. One such optional arrangement is illustrated inFIG.3. In such arrangements, the pressure relief valve40can be a consumable or disposable component of the system10. In some configurations, the pressure relief valve40can be positioned between the humidifier30and the diffuser32. In some such configurations, the pressure relief valve40can be positioned along, or integrated into, the patient conduit54(e.g., as described above with respect to the supply conduit52), between the patient conduit54and the diffuser32, or integrated within the diffuser32.

In use, the components of the system10can be assembled, if necessary. Supply of insufflation gas from the gas source14can be initiated, such as by opening the valve of the gas bottle16or other gas supply, for example. If necessary, the flow meter22can be adjusted to achieve a desirable flow rate of the insufflation gas. If present, the humidifier30can be turned on and adjusted to warm and humidify the insufflation gas to a desirable level. The gas diffuser96of the gas interface32can be positioned within the surgical cavity92of the patient12to create an insufflation gas environment94, which can be maintained throughout completion of the surgical procedure. In the event of a rise in system pressure above a threshold pressure, the pressure relief valve40can activate, open or vent the flow of insufflation gas to reduce the system pressure.

It has been unexpectedly discovered by the present inventor that, although the open surgery insufflation system10is an open system that dispenses insufflation gas to a generally open atmosphere that normally results in a low system pressure, occlusions can occur within the system10during normal, or at least foreseeable, use that can cause a significant rise in the system pressure. In some cases, the rise in system pressure can be sufficient, in the absence of a pressure relief arrangement40, to cause temporary or permanent damage to components of the system10. For example, elevated system pressure can cause the disconnection of components of the system10, such as the supply conduit52with the flow meter22, for example, which may be a hose and barb connection. In some cases, the disconnection can be of a luer lock connection, taper connection or other type of connection. In some cases, elevated system pressure can cause permanent damage, such as damage to the humidifier30(e.g., the humidifying chamber62), for example. Damage to the system10, temporary or permanent, can cause an interruption or cessation of the insufflation therapy, which is undesirable at the least.

It has been discovered that some causes for occlusion of the system10include, for example and without limitation, manipulation of the gas diffuser96(e.g., depression of the diffuser material during placement or to evacuate fluid build-up in the diffuser material), manipulation (e.g., bending) of the tube100, submersion of the gas diffuser96in fluid, and the gas diffuser96being adjacent to or surrounded by an object that partially or completely blocks flow, such as a semi-solid or a solid material (e.g., gauze, organs), for example and without limitation. In some cases, these actions or activities result in modest increases of the system pressure that do not pose a significant risk of damage or interruption of the insufflation therapy. However, in some cases, such actions or activities could result in significant increases in system pressure that could create a significant risk of damage or interruption of the insufflation therapy.

The present inventor has investigated the system pressure increases caused by these and similar actions or activities, as well as the system pressures that could cause damage to the system10. For example, the connection strength of the various connections between components and conduits of the system10was evaluated. As a result, it was determined that a preferred pressure relief valve40should open or vent system pressure at a threshold pressure of no more than about 83 kPa (12 pounds per square inch (psi)). In some configurations, it is preferable for the threshold pressure for opening or venting of the pressure relief valve40to be no more than about 65.5 kPa (9.5 psi). In some configurations, it is desirable for the threshold pressure for opening or venting of the pressure relief valve40to be no more than about 34.5 kPa (5 psi). Such opening or venting threshold have been determined to be suitable to reduce or eliminate the risk of damage to the system10or interruption of the insufflation therapy.

In some configurations, it is desirable to avoid opening or venting the pressure relief valve40in response to elevations in system pressure that are not likely to be harmful to components of the system10. Thus, in some configurations, it is desirable to configure the pressure relief valve40to remain closed or not vent in response to system pressure lower than about 14 kPa (2 psi). In some configurations, it is desirable to configure the pressure relief valve40to remain closed or not vent in response to system pressure lower than about 24 kPa (3.5 psi). Thus, in some configurations, it is desirable to configure the pressure relief valve40to have an opening or venting threshold pressure of between about 14 kPa (2 psi) to about 83 kPa (12 psi), or between about 14 kPa (2 psi) to about 34.5 kPa (5 psi). In other configurations, it is desirable to configure the pressure relief valve40to have an opening or venting threshold pressure of between about 21 kPa (3 psi) to about 83 kPa (12 psi), or between about 21 kPa (3 psi) to about 65.5 kPa (9.5 psi). Any values or ranges within the above-recited ranges are also contemplated. In other configurations, or other applications, the pressure relief valve40may be configured to have a higher activation, opening or venting pressure threshold. In some configurations, the pressure threshold of the pressure relief valve40is fixed and/or preset. In other configurations, the pressure threshold could be adjustable, such as adjustable within one or more of the ranges identified herein.

With additional reference toFIGS.4aand4b, the pressure relief valve40may be provided with a protective shroud110which at least partially encloses the pressure relief valve40so that the valve40is protected from detritus, such as dust, settling on it. Without the shroud110, the valve40, when it triggers, might blast any dust from the valve40into the room, which is not desirable in a surgical environment. The shroud110also helps to prevent any unintentional disconnection of the pressure relief valve40.

FIG.4ashows an example pressure relief valve40, without the shroud110attached. InFIG.4b, the pressure relief valve40has been substantially encased in the shroud110. The shroud110in this example substantially covers the length of the pressure relief valve40, but has a gap112at one end to allow the gas to escape when the pressure relief valve40triggers. In this example, the shroud110comprises an open ended cylindrical cover inside which the valve40is received. The shroud11may be permanently mounted, or removable.

Unless the context clearly requires otherwise, throughout the description and the claims, the words “comprise”, “comprising”, and the like, are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense, that is to say, in the sense of “including, but not limited to”.

Reference to any prior art in this specification is not, and should not be taken as, an acknowledgement or any form of suggestion that that prior art forms part of the common general knowledge in the field of endeavour in any country in the world.

The invention may also be said broadly to consist in the parts, elements and features referred to or indicated in the specification of the application, individually or collectively, in any or all combinations of two or more of said parts, elements or features.

Where, in the foregoing description reference has been made to integers or components having known equivalents thereof, those integers are herein incorporated as if individually set forth.

It should be noted that various changes and modifications to the presently preferred embodiments described herein will be apparent to those skilled in the art. Such changes and modifications may be made without departing from the spirit and scope of the invention and without diminishing its attendant advantages. For instance, various components may be repositioned as desired. It is therefore intended that such changes and modifications be included within the scope of the invention. Moreover, not all of the features, aspects and advantages are necessarily required to practice the present invention. Accordingly, the scope of the present invention is intended to be defined only by the claims that follow.