WO2014163713A2

WO2014163713A2 - Gas contitioning trocar

Info

Publication number: WO2014163713A2
Application number: PCT/US2014/000033
Authority: WO
Inventors: Douglas E. Ott; Nathanial TRAN; Steven Williams; Brandon Lee MICHAL
Original assignee: Lexion Medical, Llc
Priority date: 2013-03-12
Filing date: 2014-03-11
Publication date: 2014-10-09

Abstract

A gas conditioning trocar, which is in contact with a patient, having an exterior surface that is maintained at a temperature below a temperature of the heated insufflation gas by using a portion of an unheated insufflation gas to cool the exterior surface of the trocar before the unheated insufflation gas is subsequently heated to a conditioned state suitable for insufflating the body cavity of the patient.

Description

GAS CONDITIONING TROCAR

SPECIFICATION

TO WHOM IT MAY CONCERN BE IT KNOWN, That , Douglas Ott a citizen of the United States, residing in the State of Georgia, Nathinal Tran residing in the State of Minnesota, Steven Williams residing in the State of Minnesota and Michal Brand residing in the State of Minnesota have invented new and useful improvements in GAS CONDITIONING TROCAR of which the following is a specification. CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority from provisional application 61/851 ,680 filed March 12, 2013.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR

DEVELOPMENT

None

REFERENCE TO A MICROFICHE APPENDIX

None

BACKGROUND OF THE INVENTION

The concept of a medical apparatus for humidifying or otherwise treating a gas from an insufflator during surgery is described in Douglas Ott et al. U.S. patents 5,41 1 ,474; 6,068,609 and 7,066,902. Briefly, an insufflation gas is heated and hydrated i.e. conditioned, before the gas is directed into a body cavity through a device such as a trocar. In order to hydrate the insufflation gas a charge of hydration fluid is typically injected into a device where the hydration fluid can humidify the insufflation gas and a heater can bring the insufflation gas to a temperature near body temperature. The conditioned insufflation gas is then sent to a trocar for injection into a body cavity of a patient.

One of the requirements for delivery of insufflation gas to a patient's body cavity is to maintain the proper flow of insufflation gas into the body cavity. Normally, gas flows from a high-pressure gas source, which is remote from the patient, through an insufflation device and finally into a trocar where the gas is injected into the patient's body cavity. Typically, the insufflation gas is stored in high-pressure containers and a pressure regulator reduces the pressure of the gas to a lower pressure. The low pressure gas is typically delivered to the trocar through an insufflation device containing a set of inline end connectors that couple the source of insufflation gas, the pressure regulator, a filter, a heater, or a heater and a hydrator to the trocar. During the insufflation process the insufflation gas may be conditioned by filtering, heating and or hydrating before it flows through a number of inline end connectors, which are typically connected by flexible tubing.

The conditioned gas is subsequently delivered to the patient through a trocar cannula that extends into the body cavity of the patient. Typically, during a surgical procedure the amount of insufflation gas injected into the body cavity of the patient, the flow rate of the insufflation gas as well as the velocity of the insufflation gas varies over a wide range. To avoid tissue damage to the patient the flow rate of insufflation gas as well as the gas insufflation pressure in the body cavity as well as other conditions such as the temperature of the insufflation gas used to inflate a body cavity may be monitored to ensure the insufflation gas injected into the patient is at the proper insufflation temperature. Although prior art devices can maintain the insufflation gas in a proper insufflating condition the present invention includes the capability to address environmental conditions that may cause trauma to a patient. SUMMARY OF THE INVENTION

A gas conditioning trocar having a cannula for inserting into a body cavity of a patient with the gas conditioning trocar containing a heater for in situ heating the insufflation gas within the trocar but before delivery of the heated insufflation gas to a trocar cannula. The gas conditioning trocar, which is in contact with a patient, has an exterior surface that is maintained at a temperature below a temperature of the heated insufflation gas by using a portion of an unheated insufflation gas to cool the exterior surface of the trocar before the unheated insufflation gas is subsequently heated to a conditioned state suitable for insufflating the body cavity of the patient.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 shows a gas conditioning trocar for heating an insufflation gas within the trocar; Figure 2 is a partial cross sectional view of the gas conditioning trocar of Figure 1 ;

Figure 3 is a cross sectional view taken along lines 3-3 of Figure 2;

Figure 4 is a plane view of the electrical heater with a thermistor circuit and a thermal cutoff;

Figure 5 is a side view of a multilayer gas conditioning media in an unwound condition; Figure 6 is top view of the multilayer gas conditioning media of Figure 5 arranged in a spiral configuration; and

Figure 7 is a cross sectional view taken along lines 4A-4A of Figure 5.

DESCRIPTION OF THE PREFERRED EMBODIMENT Figure 1 and Figure 2 show an example of a gas conditioning trocar 10 having a gas conditioning housing formed by a cylindrical top housing 17 and a base housing member 18. Top housing 17 includes an extension or neck 11 connected to an insufflation tube 12 that carries an insufflation gas into gas conditioning chambers located within trocar 10. A filter 13, which is located in insufflation tube 12, removes impurities from the insufflation gas as it flows therethrough. Top housing 17 includes a cylindrical section 17a which is joined to a base housing 18 that supports a cannula 19 having a conical cutting tip 20 located on a distal end. A set of fluid ports 19a in cannula 19 permit lateral flow of insufflation gas into a body cavity from the trocar 10. However, in other types of trocars the insufflation gas may be injected through an opening in conical end 20. Trocar 10 includes a hydration tube 15 connected to a fluid inlet port 17b on housing 17 to permit one to supply hydration fluid to a porous media 20 in a gas conditioning chamber occupied by porous media 20. A connector 16 on the terminal end of hydration tube 15 permits one to connect or disconnect a source of hydration fluid to the gas conditioning trocar 10 and a heater within trocar 10 heats the insufflation gas to a conditioned state before the insufflation gas is discharged through cannula 19.

In the example of Figure 1 and Figure 2 the gas conditioning trocar 10 includes a gas conditioning media 20 that provides in situ and on the go conditioning of the insufflation gas, which may include hydration or heating of the insufflation gas or both heating and hydrating of the insufflation gas within the gas conditioning media 20. To quickly heat the insufflation gas as it flows through the conditioning media 20 a heater, such as an electrical heater, transfers heat to the insufflation gas to bring the insufflation gas to a conditioned state for insufflating a body cavity of a patient. When heating the insufflation gas on the go, i.e. as the insufflation gas flows through the gas conditioning trocar, the heating element of the heater usually exceeds the temperature of the conditioned insufflation gas, which is delivered to the body cavity. Therefore, one must quickly heat the insufflation gas by having the heater element at an elevated temperature that is sufficient to rapidly transfer heat to the insufflation gas during the time interval the insufflation gas flows through the porous media 20. Unfortunately, having a heating element within the trocar that is at a temperature higher than the temperature of the conditioned insufflation gas entering a patient can create a trocar condition which has the potential to cause an external surface of the trocar, which contacts a patient, to reach a temperature that is either unsafe or could cause trauma to the patient. That is, a portion of the heat generated in the gas conditioning media may also be transferred to the housing which supports the gas conditioning media and to an exterior surface of the trocar. The present invention has been found to prevent the temperature of the external surface of the trocar from causing trauma to the patient even though the trocar contains a heater that may from time to time operate at a temperature above the temperature of the insufflation gas entering the body cavity of the patient.

Figure 2 is a cross sectional view of a portion of gas conditioning trocar 10 revealing a spiral wound conditioning media 20 located around a central instrument tube 31 , which is used for insertion of medical instruments therethrough. The gas conditioning media 20 provides a dynamic site within the trocar where the insufflation gas can be conditioned on the go, that is the insufflation gas flows axially through the conditioning media 20 where the insufflation gas may be heated or hydrated or both hydrated and heated. Typically, gas conditioning media 20 includes multiple layers i.e. a multilayer media which may include a layer of gas transfer material comprising netting or the like, a layer of a fluid transferring material comprising hydrophilic material, and an electrical heater extending therebetween for heating the insufflation gas and hydration fluid as the insufflation gas flows through the conditioning media 20. As indicated in Figure 2 the unheated or unconditioned insufflation gas enters trocar 1 1 through insufflation tube 12 with a portion of the insufflating gas flowing along an annular path 29 into a top end 20a of the conditioning media 20 and eventually exiting the lower end 20b of media 20 through a set of ports 37 located in a cylindrical media support 38. A further portion of the unheated insufflation gas may flow into a C-shaped thermal isolation chamber 44 extending substantially around the gas conditioning media 20. The gas conditioning media 20 typically includes a heater assembly or heater for heating the insufflation gas to a conditioned state and may include a temperature sensor for measuring temperature as well as a pair of electrical leads for connection of an electrical heater to an electrical power source. The number of layers and the composition of the layers of material as well as the thickness of the layers may be modified according to the specific application.

Figures 5 to Figure 7 show an example of a gas conditioning media 20, which comprises a plurality of three layers of materials wound into a spiral configuration that is inserted into an annular chamber in trocar 10. In the spiral configuration state, the hydrating liquid may be brought into proximity of an electrical heater therein through an absorbing action of a hydrophilic layer in the gas conditioning media 20. The absorbing action allows distribution of the hydrating liquid proximate the heater to enable the hydration of the insufflation gas while the heater raises the insufflation gas to the proper temperature. An example of a gas conditioning media where the insufflation gas is both heated and hydrated is shown and described in assignees pending application sn 12/381 ,978 filed 3/18/2009 which is herby incorporated by reference.

More specifically, Figure 5 shows a side view of a strip of a conditioning media 20 for bringing an insufflation gas into a conditioned state. Media 20, which is shown in an unwound state in Figure 5, comprises multiple layers. In the example shown the materials of multilayer media 20 include a layer of gas transfer material comprising netting 32 and a layer of a fluid transferring material comprising hydrophilic material 30 with a heater assembly 34 extending therebetween. Heater assembly 34 includes a heater, a

temperature sensor 22 on one end and a pair of electrical leads 14 on the opposite end for connection to a power source. Although three layers are shown the number and composition of the layers of material as well as the thickness of the layers may be modified according to the specific application. Temperature sensor 22 may be part of heater assembly 34 or may be separately mounted in trocar 20 to monitor the temperature of the heater or of the insufflation gas before the insufflation gas is discharged from the trocar 20. Additional temperature sensors 22 may be included and control circuitry to control the heater such that the insufflation gas temperature is maintained within a temperature range. The gas conditioning media 20 is concentrically positioned within the trocar 10 to allow the incoming unconditioned insufflation gas to flow over or through the media 20 before the insufflation gas enters a patient. Figure 6 shows the strip of multilayer media 20 comprising a plurality of three layers of materials 30, 32 and 34 that are wound into a spiral configuration that can be inserted into an annular chamber in trocar 10. In the spiral configuration state, as shown in Figure 6, the hydrating liquid may be brought into proximity of a heater assembly 34 through an absorbing action of a hydrophilic layer 30 in media 20. The absorbing action allows distribution of the hydrating liquid proximate the heater assembly 34. Similarly, porous netting 32 may allow the insufflation gas to flow threrethrough so the gas can be brought into proximity of the heater assembly 34 to enable the insufflation gas to be brought to a conditioned state. Figure 7 is a cross sectional view of the spirally wound media 20 taken along lines 4A- 4A of Figure 6 revealing the side by side arrangement of the multiple layers comprising the gas conditioned media 20.

In order to secure the multilayer media 20 in the trocar 10 the multilayer media 20 may be wound into a diameter slightly larger than the diameter of housing wall 12 to enable one to friction fit multilayer media 20 in the trocar 10 although other methods may be used. If frictional forces are used to hold multilayer media 20, then the multilayer media should be selected to offer sufficiently low flow resistance so that the insufflation gas flow flowing thereto will not displace the multilayer media 20.

To decrease the pressure drop through netting 32 two or more layers of netting may be placed proximate each other to increase the porosity though the netting. That is, netting 32 provides flow passages for the insufflation gas to flow from upper plenum chamber 1 la to lower plenum chamber l ib without undue but sufficient resistance so that the hydration fluid and the hydration gas can be maintained in proximity thereto to enable both heating and hydration to take place.. A suitable netting 32, for example, is a bi- planar polypropylene netting having properties that may include a density of 1 1 strands per inch and a thickness of 0.030 inches (e.g., Daystar, Middleton, DE). However, any netting capable of allowing gas flow could be used without departing from the scope of the invention. Also, in some cases the netting 32 could be omitted.

Multilayer media 20 may include at least one layer of a liquid transfer media, which for example may be a hydrophilic media 30, that readily absorbs and retains a volume of hydration fluid provided to plenum chamber 11a. While other types of materials, for example wicking materials, may be used to delver the hydration fluid into proximity of the heater assembly 34, the hydrophilic media 20 brings the hydration fluid in close proximity to both the heater assembly 34 and the insufflation gas through an absorbing action. Similarly, two or more layers of hydrophilic material may be used to bring the hydration liquid proximate the heater assembly. Hydrophilic media 20 may be thin and flexible so that it is easily wound in a spiral configuration with the other layers of multilayer media 20 as shown in Figure 4.

Although many types of hydrophilic material are useable, a typical suitable hydrophilic media 20 is cellulose which is commercially available from Knowlton, Watertown, NY having the following characteristics: a basis weight of 91-99 pounds/3000 ft² and a thickness of about 0.028-0.034 inches.

The multilayer media 20 may include a heater assembly 34, which may comprise an elongated flexible heater that has external electrical leads 44 for connecting to a source of electrical power. The heater assembly 34 may be thin and flexible such that when it is sandwiched between the hydrophilic layer 30 and the layer of netting 32 the combination can be wound into a spiral configuration that can be inserted within housing 12. An advantage of the spiraled configuration is that it provides a continuous extended area for heating and hydration of the insufflation gas, i.e., the insufflation flow path is long. In the preferred embodiment, heater assembly 34, for example, is a resistance heater made of etched copper foil coated with a layer of polyimide. Another layer of polyimide may coat the foil surface. The coating of polyimide reduces the likelihood of heater assembly 34 from contacting the hydration fluid or hydrated gas such that an electrical short results. As discussed above, however, any type of heater and any type of absorbent material may be used with the invention. One end of heater assembly 34 may terminate with a temperature sensor 22 for measuring the temperature of the heater in the gas conditioning trocar 10. In other embodiments, multiple temperature sensors may be used and may be located elsewhere to sense the temperature of the gas directly rather than sensing the temperature of the heater. The temperature sensor can be located in one of the chambers 1 lb or 1 lc or located in the cannula 26. In some cases, a remote sensor (e.g. an electronic infrared sensor) exterior to the trocar could be used. When heater assembly 34 is layered with the other materials of multilayer media 20 and friction fit into housing 12, the temperature sensor 22, for example a thermistor, detects the temperature of the heater at lower plenum chamber l ib. A heater control, not shown, can increase or decrease the power supplied to heater assembly 34 to maintain the temperature of the insufflation gas within a desirable range for injection into a body cavity. The opposite end of heater assembly 34 may terminate with electrical leads 14 which can be connected to a power source. When heater assembly 34 is layered with netting 32 and hydrophilic media 20 and assembled into a spiral configuration, electrical leads 14 may extend beyond the multilayer media 20. Thus, when the multilayer media 20 is placed in housing 18, the electrical leads 14 may extend beyond housing 18 for connection to a source of electrical power as shown in Figure 1.

In the embodiment shown, multilayer media 20 is assembled into a spiral configuration (Fig. 2, Fig. 6) although other configurations may be used. An advantage of the spiral configuration is that the hydrating fluid and insufflation gas are brought in to close proximity to the heater assembly 34 as they flow from annular plenum chamber 29, 1 lc to annular plenum chamber 35. Although an annular gas conditioning media 20 which extends from side to side is shown, the gas conditioning media 20 may take other shapes or forms which allow the insufflation gas to be conditioned within the trocar. For example, only a portion of the annular chamber in the trocar may be used for the conditioning of the gas. A further benefit and advantage of use of a multilayer media is that multilayer media 20 can more easily be assembled in a flat condition and

subsequently wound into a spiral configuration for insertion into the annular chamber of the trocar 10.

Figure 4 shows a plane view of an example of an electrical heater 50, which is part of heater assembly 34 for on-the-go heating of the hydration fluid within the trocar 10 of the gas conditioning trocar 10. The electrical heater 50 comprises an electrical heating strip 59, which is spiral wound within the media 20 and typically includes an electrically insulating backing strip 50a that may support a thermistor circuit 55 having a set of thermistors 55a responsive to a temperature of the insufflation gas flowing therepast. In this example, the thermistor circuit 55 contains a set of thermistors 55a that are connected in series and are located on opposite edges of the electrical heating strip 50. Electrical leads 51 and 52, which are connectable to an external power source also connect to an electrical heater 59 that extends in a series of back and forth U shaped pattern along an interior portion of the heating strip 50. When the electrical heating strip 50 is wound into media strip 22 the application of electrical power to electrical heater 59 heats the insufflation gas as it flows therepast while a change in resistance of the thermistors 55 provides an on-the-go indication of the temperature of the insufflation gas as it flows past the heating strip 50.

In on-the-go heating the insufflation gas within the trocar 10 it may be necessary to operate the heater 59 at a temperature that is above the temperature of insufflation gas delivered to the patient in order to heat the insufflation gas as it flows through the media 20 since the time that the insufflation gas is in contact with the heating element limits the heat transfer to the insufflation gas. While the temperature of the insufflation gas can be controlled by controlling the power to the heater the result of having the heater 59 at an elevated temperature may cause both wanted and unwanted heat transfer. That is, while the wanted heat transfer to the insufflation gas occurs due to proximity of the electrical heater the proximity of the electrical heater within the sidewalls of the trocar may cause the external surfaces of the trocar 10 to receive unwanted heat transfer, which may raise the external surface of the trocar housing to undesirable level or a level that may cause trauma to a patient since the exterior surface of the gas conditioning trocar contacts the patient. As the trocar with an internal source of heat is in direct contact with the patient one wishes to prevent the external surface temperature of the trocar from becoming elevated to a condition that may cause trauma without reducing the compactness or increasing the size of the trocar.

The invention described herein as illustrated in Figure 2 and Figure 3 prevents the external surface of the trocar 10 from unwanted temperatures through use of a portion of the incoming unheated insufflation gas to cool the trocar housing while a further portion of the insufflation gas is heated within the trocar. Using the insufflation gas as a coolant has a two-fold benefit, first the cooling of the trocar housing is beneficially but the cooling of the housing can also raise the temperature of the portion of the insufflation gas that cools the housing. Consequently, when the insufflation gas, which was used to cool, is subsequently directed into the gas conditioning media it arrives at the conditioning media in a state that requires less heating since heat has been added to the insufflation gas during the cooling of the external surface of the trocar.

To illustrate the operation of the invention reference should be made to Figure 2 which shows the top end 1 1 of gas conditioning trocar 10 includes a medical instrument inlet port 1 la and a set of radial flaps 1 lb or duck bill closure that sealing closes instrument passage 41 to prevent gas backflow therethrough but flexes when contacted by a medical instrument to permit insertion of the medical instrument therethrough and into instrument passage 41.

In the embodiment shown in Figure 2, gas conditioning media 20 includes both an electrical heater (Figure 4) and a porous material 30 capable of absorbing and holding a hydration liquid such as water. In operation of gas conditioning trocar 10, the insufflation gas and the hydration fluids are introduced into an annular chamber 29 which expand out to annular chamber 1 lc. Both the hydrating fluid and the insufflation gas enter the top of the conditioning media 20 in an axial direction. Figure 2 shows the hydration fluid flows through passage 15 and downward through connector 17b where it enters the top of gas conditioning media 20. Consequently, as the insufflation gas flows through media 20 the insufflation gas may be hydrated by the hydration fluid entering through tube 15 and heated to a temperature near body temperature for injection into the body cavity of a patient by a heater within the gas conditioning media 20. Typically, in most applications the insufflation gas is heated to a temperature ranging between 33 degrees C and 38.5 degrees C before the insufflation gas is directed into a body cavity of a patient. As the insufflation gas and hydration fluids flow through the conditioning media 20 and into annular chamber 35, the heater 50 (Figure 4) within the conditioning media 20 provides on the go heating of the insufflation gas immediately prior to injection of the insufflation gas into the body cavity of a patient. The in situ heating of the insufflation gas within the trocar 10 has the benefit of avoiding temperature degradation or humidity degradation of the insufflation gas that may occur with hydration units that are remote from the trocar. In this example the conditioned insufflation gas flows into plenum chamber 35 through a set of ports 37, which are located in the cylindrical media support 38. The conditioned insufflation gas then flows into an annular chamber 35, an annular passage 39 and out the cannula 19. A surgical instrument may be passed through instrument inlet 1 la, into passage 41 and out the end 20 of cannula 19. The instrument may be withdrawn and other instruments may be used in a similar fashion throughout the procedure. As such, the delivery of conditioned insufflation gas and the use of surgical instruments may occur simultaneously without either adversely affecting or interfering with the other. In an alternate embodiment the annular passage 39 may be omitted and the insufflation gas and the medical instruments occupy the same central passage within a cannula of the trocar. Figure 2 shows the gas conditioning trocar 10 wherein includes a first housing member 17 and a second base member 18 mateable to each other to form the thermal isolation chamber 44 therebetween. In the example shown the sidewall 45a of first member 17 is sealable engaged to base memberl8 along a circumferential lip 18 and on the end proximate electrical hub 47 the housing wall 45a engages surface 18a of base member 18. As can be seen in Figure 3 isolation chamber 44 has a C-shape with an electrical hub 47 extending from the exterior sidewall to the media sidewall to provide for power transfer to the heater within the media 20. As illustrated in Figure 2 and Figure 3 the radially inner wall 46 of the thermal isolation chamber 44 is coextensive with the gas conditioning media 20 located therein with electrical hub 47 forming a first end and a second end to the thermal isolation chamber 44.

In the embodiment shown the insufflation gas is both heated and hydrated, however, in some embodiments the hydration may be omitted. Figure 2 includes a set of arrows to visual depict the flow of hydration fluid and insufflation gas into the gas conditioning media 20 and the flow of insufflation gas into a thermal isolation chamber 44 formed by an outer sidewall 45 of a top housing 17 of trocar 10 and an inner sidewall 46 of base 18 of trocar 10. Figure 3 is a top view taken along lines 3-3 of Figure 2 that reveals the spiral wound conditioning media 20 located around tube 31 and thermal isolation chamber 44 extending substantially around the periphery of housing 17a with the isolation chamber 44 having ends that terminate at electrical hub 47 which supplies power to the heater in the conditioning media 20. In this example the upper housing 17 and the base 18 of gas conditioning trocar 10 are formed from an acrylic based polymer with the thermal isolation chamber 44 formed between the outer cylindrical wall 45 of housing 17 and the inner cylindrical wall 46 of base 18.

During the condition of the insufflation gas the insufflation gas flows through the annular condition media 20, which is located radially inward from cylindrical media wall 46. Heating of the insufflation occurs through transfer of heat to the insufflation gas from an electrical heater embedded in the gas conditioning media 30.

In order to thermally isolate the exterior surface of the trocar housing 17 and thus prevent heat discomfort or trauma to body tissue of a patient the invention describe herein, as shown in Figure 3, includes a substantial cylindrical thermal isolation chamber 44 that extends around the cylindrical sidewall 46 that extends around the periphery of gas conditioning media 30. During the heating of the insufflation gas the inner annular wall 46, which supports the gas conditioning media 20 may receive unwanted heating due to the proximity to the heating source within media while the outer wall 45 is spaced from the inner wall 46 to provide a thermal isolation chamber therebetween. The use of the thermal isolation chamber 44 disrupts heat conduction from the gas conditioning media 20 to the outer housing wall 45 thereby reducing the transfer of unwanted heat to the outer wall 45 of the housing 17. The thermal isolation chamber 44 is positioned radially outward of the gas conditioning media 20 so that the unheated insufflating gas can enter the chamber 44, as illustrated in Figure 2. Consequently, the portion of the unheated insufflation gas in chamber 44 can be used maintain the outer trocar wall 45, which may come into contact with a patient, in a condition that inhibits or prevents conductive heat transfer to a patient.

The arrows in Figure 2 reveal how the unheated insufflation gas flows into an annular inlet 29 and into isolation chamber 44 where it may circulate therein and eventually flow into and through the porous media 20. That is the porous media 20 provides a flow resistance, which cause the insufflation gas to flow into the chamber 44 before the pressure becomes sufficient to flow through the media 20. Although the thermal isolation chamber 44 is dead ended at the bottom the unheated insufflation gas circulates into and out of the thermal isolation chamber 44 as the pressure changes within the trocar. It has been found that the use of the thermal isolation chamber 44 which can receive a portion of the unheated insufflation gas can prevent the external surface of the trocar 10 from reaching a temperature that may cause trauma to a patient without increasing the bulk or heft of the gas conditioning trocar.

The temperature of the incoming unheated insufflation gas may vary depending on multiple variables, which may include the internal pressure of the insufflation gas source. Typically, the temperature of the incoming insufflation gas entering the gas conditioning trocar may range from 15 to 30 degrees C although other factors may cause the temperature to be higher or lower.

In operation of the gas conditioning trocar 10 the unheated insufflation gas may be heated to a temperature, which typically may range from 33 degrees C to 38.5 degrees C although other temperature may be selected depending on the conditions of the patient as well as the environment. While the use of an acrylic polymer in the walls of the gas conditioning trocar limits or inhibits the conduction of excess heat to the outer wall 45 it has been found that the use of a thermal isolation chamber 44, which is located between the outer wall 45 and the inner wall 46 also inhibits or prevents conductive heat transfer to the outer wall 45. In addition the direction of a portion of the unheated insufflation gas into the isolation chamber can help maintain the external surfaces of the gas conditioning trocar at safe levels even though the electrical heater 59 therein may transfer unwanted heat to cylindrical wall 46 supporting the porous media 20. Thus, in operation of gas conditioning trocar 10, the insufflation gas, which is at a temperature below an insufflating temperature when it enters the gas condition trocar, is directed into both the gas conditioning media 20 and the thermal isolation chamber 44. The unheated insufflation gas flowing into the porous media 20 is heated to an insufflation temperature while the unheated insufflation gas in the thermal isolation chamber 44 cools the cylindrical sidewall 45 and cylindrical wall 46. Thus, the insufflation gas performs a dual function with a portion of the unheated insufflation gas cooling the outer sidewall 45 and the inner sidewall 46 while a further portion of the insufflation gas is heated and hydrated as it flows through porous media 20 and into a body cavity of a patient.

Claims

I Claim ?

1. A gas conditioning trocar comprising:

a gas conditioning housing having an inlet for receiving an unconditioned insufflation gas;

an insufflation gas conditioning media therein;

a heater for conditioning the insufflation gas by heating the unconditioned insufflation gas to a conditioned state; and

a thermal isolation chamber in said gas conditioning housing with said thermal isolation chamber located outward of said gas conditioning media, said unconditioned insufflation gas flowing into both the gas conditioning media where the heater brings the insufflation gas therein into the conditioned state and into the thermal isolation chamber to maintain an external temperature of the gas conditioning housing below a temperature of the conditioned state.

2. The gas conditioning trocar of claim 1 wherein the thermal isolation chamber is located between a conditioning media side wall and an exterior sidewall of the trocar.

3. The gas conditioning trocar of claim 1 including an annular inlet passage in said housing for directing insufflation gas into both the thermal isolation chamber and into the gas conditioning media.

4. The gas conditioning trocar of claim 1 wherein the housing includes a first member and a second member mateable to each other to form the thermal isolation chamber therebetween.

5. The gas conditioning trocar of claim 4 wherein the first member and the second member are sealably engaged with each other along a circumferential lip.

6. The gas conditioning trocar of claim 2 wherein the thermal isolation chamber has a C-shape with an electrical hub extending from the exterior side wall to the media side wall.

7. The gas conditioning trocar of claim 2 wherein a radially inner wall of the thermal isolation chamber is coextensive with the gas conditioning media located therein.

8. The gas conditioning trocar of claim 1 wherein an electrical hub forms a first end and a second end to the thermal isolation chamber.

9. The gas conditioning trocar of claim 1 wherein the thermal isolation chamber is dead ended.

10. A method of conditioning an insufflation gas comprising:

directing an unconditioned insufflation gas into a trocar housing having a gas conditioning chamber and a thermal isolation chamber; heating the gas in the gas conditioning chamber while thermally isolating the heated insufflation gas from an exterior surface of the housing by directing an unconditioned insufflation gas into a thermal isolation chamber.

1 1. The method of claim 10 including the step of simultaneously directing the unconditioned insufflation gas into the gas condition media and the thermal isolation chamber.

12. The method of claim 10 including the step of heating the insufflation gas in the gas conditioning chamber with an electrical heater

13. The method of claim 10 including the step of humidifying the insufflation gas in the gas conditioning chamber.

14. The method of claim 10 including the step of directing the insufflation gas to be conditioned into an interior chamber in the gas conditioning housing.

15. The method of claim 10 including the step of directing the insufflation gas into an annular chamber located in the gas conditioning housing.

16. The method of claim 10 including the step of cooling an exterior surface the gas conditioning housing with a portion of the insufflation gas injected into the gas conditioning trocar.

17. The method of claim 10 including operating a heating element at a temperature above the temperature of the insufflation gas.

18. The method of claim 10 where the heating of the insufflation gas is done on the go.

19. The method of claim 18 where a portion of an unheated insufflation gas is directed into the isolation chamber while a further portion of the unheated insufflation gas is directed proximate a heater located in the trocar.

20. The method of claim 19 where the portion of unheated insufflation gas is subsequently heated for insertion into a patient.