Abstract:
An oral cannula for placement within the oral cavity of a patient for delivery of a treatment gas and for collecting end-tidal carbon dioxide (EtCO2) includes a treatment gas delivery lumen including at least one aperture near a distal end of the treatment gas delivery lumen; an exhaled gas sampling lumen. The cannula also includes a cap having (i) a gas diverter adapted for diverting at least a portion of the treatment gas and (ii) an exhaled gas inlet including flutes and apertures there between that are in communication with the exhaled gas sampling lumen. The oral cannula is adapted for custom bending or has a bend such that the oral cannula is insertable and retainable in a patient&#39;s mouth and functional for supplying a treatment gas and sampling gas exhaled by the patient.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation-in-part of U.S. patent application Ser. No. 14/498,006, filed Sep. 26, 2014, which claims priority to U.S. Provisional Application No. 61/886,646, filed Oct. 3, 2013, and U.S. Provisional Application No. 62/009,522, filed Jun. 9, 2014, the disclosures of which are incorporated herein by reference in their entireties. 
     
    
     BACKGROUND 
       [0002]    The present invention relates to medical devices and methods, and more particularly to medical devices and methods used while a patient is anesthetized. 
         [0003]    Continuous monitoring of exhaled carbon dioxide (CO2), referred to as capnography, is the conventional standard of care for monitoring a patient&#39;s ventilation during operating room procedures. Capnography is also often used during non-intubated procedures that use moderate or deep sedation. A popular means for capnography is the well-known nasal cannula, such as disclosed in U.S. Pat. Nos. 5,335,656 and 6,439,234, which uses one nasal tube to supply oxygen (O2) to the sedated patient and another nasal tube to draw end-tidal carbon dioxide (ETCO2) for monitoring. A conventional Nasal Cannula (Adult) Salter Style® Ref. 4707F from Salter Labs is packaged with several feet of side-by-side oxygen supply tubing and sampling lumen tubing, which terminates at individual, free tubes that are connected to opposing sides of the nasal cannula body. 
         [0004]    Typically, the tubes connected to opposing ends of the nasal cannula are looped over the patient&#39;s ears, and then the tubes merge into a side-by-side configuration that extends to the oxygen supply and capnography system. 
         [0005]    Under certain conditions, the sedated patient may receive insufficient oxygen through the nasal passages, such as when the nasal passages are blocked. An anesthetist might then place the nasal cannula in the patient&#39;s mouth, such as through a portion of a bite block (if present), and increase the oxygen flow. 
       SUMMARY 
       [0006]    As described herein, an oral cannula for delivering oxygen and sampling end-tidal carbon dioxide includes an oxygen supply lumen having plural outlets near a distal end of the oxygen supply lumen. The oral cannula also includes an end-tidal carbon dioxide (ETCO2) lumen having an inlet near a distal end of the ETCO2 lumen. The ETCO2 lumen and oxygen supply lumen form a unitary oral cannula such that the oxygen supply lumen outlet is spaced apart from the ETCO2 lumen inlet. The oral cannula is adapted for bending or has a bend such that the oral cannula is insertable and retainable in a patient&#39;s mouth. 
         [0007]    In one embodiment, a method of administering oxygen and sampling end-tidal ETCO2 for a patient includes a step of providing oxygen through an oxygen supply tube and through an outlet near a distal end of the oxygen supply tube. The method also includes a step of drawing a gas sample through an ETCO2 tube and through an inlet near a distal end of the ETCO2 tube. The ETCO2 tube is affixed to the oxygen supply tube to form a unitary oral cannula, such that the oxygen tube outlet is spaced apart from the ETCO2 inlet. 
         [0008]    Structures disclosed in parent U.S. patent application Ser. No. 14/498,006 in testing has performed adequately. The inventors have discovered unexpected aspects of the function of the structure disclosed in the parent application, which discoveries have led to the new configurations disclosed herein. The present disclosure is not intended to disclaim subject matter in the parent application, as the configurations in the parent application have merit and are operable depending on the particular application of the device. 
         [0009]    The inventors discovered that under some circumstances, with oxygen supply pressures and volumetric flow rates common to modern practice, a structure disclosed in the parent application was found to unexpectedly interfere with the collection of ETCO2. The structure and location of the O2 gas outlet apertures in the parent were designed to direct treatment gas deep into the oral cavity, a seemingly desirable effect. However, by directing the O2 to the back of the mouth so that it can be readily delivered, it was discovered that the O2 could also more readily mix with the ETCO2 being expelled from the mouth under some testing conditions. As a result, the O2 treatment gas had an unexpected dilutive effect upon the ETCO2 being collected by the ETCO2 sample lumen. The resulting gas mixture analyzed by the monitoring equipment (i.e. capnograph) did not represent the true concentration of ETCO2 being expired. This dilutive effect was further amplified when higher O2 flow rates are required, typically during deep sedation. 
         [0010]    Further, the inventors discovered that under some circumstances, the oxygen gas outlet apertures sub-optimally deliver oxygen. In this regard, in some configurations disclosed in the parent application, most of the delivered treatment gas exits from the outlet nearest the closed end of the delivery tube (where resistance is first encountered). In some configurations, as much as 90% of the volumetric flow rate occurred through the outlet nearest the distal end. This occurs despite the fact that all of the treatment gas holes are of uniform size. The magnitude of the uneven flow rates across the apertures was surprising. Thus, the outlet apertures with low flow rate more readily allow for entry of body fluids (i.e. saliva, blood, phlegm, etc.) into the lumen, possibly causing treatment gas flow disturbance. Contamination of the oxygen path (flow meter, pressure regulator, etc.) is also possible. The uneven gas flow might also affect ETCO2 sampling, described above. 
         [0011]    The inventors have also discovered that in practice, under some circumstances, the structure of the ETCO 2  sampling apertures can collect body fluids (i.e. saliva, blood, phlegm, etc.). When sufficient volume of fluid is collected, an occlusion of the sampling lumen or tubing may occur. The inventors have also discovered that in practice under some circumstances, ETCO2 sampling may be diminished by mucus and saliva and in general sought to improve the structure and function of the sampling inlet when in contact with mucosal tissue and other obstructions within the oral cavity (i.e. the tongue, palate, etc.). 
         [0012]    In general, without the explanation intending to limit the scope of the claims, the inventors addressed their observations and discoveries by employing flutes at the tip of the oral cannula, by employing a hydrophobic filter, and by employing a gas diverter. The present invention is not limited to having each of these features, as the claims are intended to define the scope of the invention. 
         [0013]    A preferred embodiment employs a single fluted tip to help redirect bodily fluids away from the sampling lumen and diminish the likelihood of blockage caused by contact with mucosal tissue and other obstructions within the oral cavity. A hydrophobic filter, is located (preferably immediately behind or proximal to) below the ETCO2 sampling aperture as an additional means for protecting the ETCO2 sampling gas line from occluding. The combination of protective flutes and hydrophobic filter offers redundant means of inhibiting obstruction of ETCO2 sampling gas flows. An end cap diverter is designed to deliver treatment gas, such as O2, flowing from the treatment gas exit apertures toward the front of the oral cavity rather than the rear. In part, the purpose of the diverter is to segregate the oxygen gas from the ETCO2 gas which is being simultaneously collected and returned to the monitoring equipment. As the treatment gas flows from the treatment gas exit apertures, its path is redirected at approximately 90 degrees from its exit direction and approximately 180 degrees from its supply direction through the lumen by the end cap diverter, and thus toward the front of the oral cavity. In this regard the gas exits the diverter in a counter-flow orientation relative to the flow through the delivery lumen. Further, the disparity in gas volume flow rates is reduced by limiting the number and changing the size of delivery gas apertures. 
         [0014]    In some embodiments, an oral cannula for placement within the oral cavity of a patient for delivery of a treatment gas and for collecting ETCO2 includes a treatment gas delivery lumen including at least one aperture near a distal end of the treatment gas delivery lumen; an exhaled gas sampling lumen. The cannula also includes a cap having (i) a gas diverter adapted for diverting at least a portion of the treatment gas and (ii) an exhaled gas inlet including flutes and apertures there between that are in communication with the exhaled gas sampling lumen. The oral cannula is adapted for custom bending or has a bend such that the oral cannula is insertable and retainable in a patient&#39;s mouth and functional for supplying a treatment gas and sampling gas exhaled by the patient. 
         [0015]    In some embodiments, the oral cannula may include a hydrophobic filter in the exhaled gas sampling lumen. The oral cannula may also include a filter housing located in the cap and housing the moisture filter. The filter housing may be rigid and thereby provide radial rigidity to the cap. In some embodiments, the gas diverter is a skirt at a periphery of the proximal end of the cap. The skirt may form a plenum into which at least one aperture in the treatment gas delivery lumen opens. The filter housing may provide rigidity to the skirt to inhibit occlusion of at least one aperture in the gas delivery lumen. In some embodiments, the skirt is continuous about the cap. The cap may include a body and a funnel that is housed within the body, and the filter housing may be mounted to the funnel. The cap may include an exhaled gas sampling channel between the exhaled gas inlets and the exhaled gas sampling lumen, the filter being disposed in the exhaled gas sampling channel. The rigid filter housing may be adapted for resisting occlusion of the exhaled gas sampling lumen channel. The cap may include a sampling recess and a delivery recess on a proximal end thereof. The exhaled gas sampling lumen may be located in the sampling recess. The treatment gas delivery lumen may be located in the delivery recess. The cap may be cylindrical. The flutes may form the distal-most portion of the cap. The filter may be at a base of the flutes. 
         [0016]    In some embodiments, the oral cannula includes a shaping wire that is adapted for repeated plastic bending by a user&#39;s hands to conform to a desired shape or contour of a patient&#39;s facial, oral cavity, or airway anatomy. The wire may be encased and is formed of a non-magnetic material. The wire may have sufficient strength to enable a user to insert the oral cannula through and past the oral cavity. At least one aperture of the gas delivery lumen may be located in a sidewall of the gas delivery lumen. The gas delivery lumen may have a sealed tip. The exhaled gas inlet may be distal relative to the gas diverter. 
         [0017]    In some embodiments, a method of administering a treatment gas and sampling exhaled gas for a patient, includes a step of inserting an oral cannula to a patient&#39;s mouth. The oral cannula includes a treatment gas delivery lumen including at least one aperture near a distal end of the treatment gas delivery lumen; an exhaled gas sampling lumen. The cannula also includes a cap having (i) a gas diverter adapted for diverting at least a portion of the treatment gas and (ii) an exhaled gas inlet including flutes and apertures there between that are in communication with the exhaled gas sampling lumen. The oral cannula is adapted for custom bending or has a bend such that the oral cannula is insertable and retainable in a patient&#39;s mouth and functional for supplying a treatment gas and sampling gas exhaled by the patient. 
         [0018]    In some embodiments, the method includes providing treatment gas through the treatment gas delivery lumen, through at least one aperture in the treatment gas delivery lumen, and via the gas diverter. The method may also include drawing exhaled gas through the exhaled gas inlet and through the exhaled gas sampling lumen. The oral cannula may also include a hydrophobic filter in the exhaled gas sampling lumen. Additionally, the oral cannula may include a filter housing located in the cap and housing the moisture filter. The filter housing may be rigid and provide radial rigidity to the cap. The gas diverter may be a skirt at a periphery of the proximal end of the cap. The skirt may form a plenum into which at least one aperture in the treatment gas delivery lumen opens, and the filter housing may provide rigidity to the skirt to inhibit occlusion of at least one aperture in the gas delivery lumen. The skirt may be continuous about the cap. The cap may include a body and a funnel that is housed within the body, and the filter housing is mounted to the funnel. The cap may include an exhaled gas sampling channel between the exhaled gas inlets and the exhaled gas sampling lumen. The filter may be disposed in the exhaled gas sampling channel. The rigid filter housing may be adapted for resisting occlusion of the exhaled gas sampling lumen channel. The cap may include a sampling recess and a delivery recess on a proximal end thereof. The exhaled gas sampling lumen may be located in the sampling recess. The treatment gas delivery lumen may be located in the delivery recess. The cap may be cylindrical. The flutes may form the distal-most portion of the cap. The filter may be at a base of the flutes. The oral cannula my include a shaping wire that is adapted for repeated plastic bending by a user&#39;s hands to conform to a desired shape or contour of a patient&#39;s facial, oral cavity, or airway anatomy. The wire may be encased and formed of a non-magnetic material. The wire may have sufficient strength to enable a user to insert the oral cannula through and past the oral cavity. At least one aperture of the gas delivery lumen may be located in a sidewall of the gas delivery lumen, and the gas delivery lumen may have a sealed tip. The exhaled gas inlet may be distal relative to the gas diverter. 
     
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         [0019]      FIG. 1A  is an illustration of an oral cannula and oxygen supply tubing and ETCO2 sampling tubing; 
           [0020]      FIG. 1B  is an enlarged illustration of the oral cannula of  FIG. 1A ; 
           [0021]      FIG. 2A  is a perspective view of a an oral cannula according to a first embodiment; 
           [0022]      FIG. 2B  is an opposite perspective view of the oral cannula of  FIG. 2A ; 
           [0023]      FIG. 3A  is a longitudinal cross sectional view of the oral cannula of  FIG. 2A ; 
           [0024]      FIG. 3B  is a transverse cross sectional view taken through lines  3 B- 3 B in  FIG. 3A ; 
           [0025]      FIG. 3C  is a transverse cross sectional view taken through lines  3 C- 3 C in  FIG. 3A ; 
           [0026]      FIG. 3D  is an enlarged view of a portion of the sidewall of the oral cannula of  FIG. 2A ; 
           [0027]      FIG. 3E  is cross sectional view taken through lines  3 E- 3 E of  FIG. 3D ; 
           [0028]      FIG. 4A  is a perspective view of a co-sheath lumen oral cannula, with hidden structure shown in dotted lines; 
           [0029]      FIG. 4B  is a perspective view of a coaxial lumen oral cannula, with hidden structure shown in dotted lines; 
           [0030]      FIG. 5A  is a perspective view of a side-by-side oral cannula; 
           [0031]      FIG. 5B  is a cross sectional view of the oral cannula of  FIG. 5A ; 
           [0032]      FIG. 6A  is a perspective view of another embodiment side-by-side oral cannula; 
           [0033]      FIG. 6B  is a cross sectional view of the oral cannula of  FIG. 6A ; 
           [0034]      FIG. 7A  is a perspective view of another embodiment side-by-side oral cannula; 
           [0035]      FIG. 7B  is a cross sectional view of the oral cannula of  FIG. 7A ; 
           [0036]      FIG. 8A  is an enlarged cross sectional view of coaxial lumens of an oral cannula; 
           [0037]      FIG. 8B  is an enlarged cross sectional view of co-sheath lumens of an oral cannula; 
           [0038]      FIG. 8C  is an enlarged cross sectional view of another configuration of co-sheath lumens of an oral cannula; 
           [0039]      FIG. 8D  is an enlarged cross sectional view of side-by-side lumens of an oral cannula; 
           [0040]      FIG. 9A  is a cross sectional view of an oral cannula illustrating another embodiment of aperture configuration; 
           [0041]      FIG. 9B  is an enlarged view of a portion of the sidewall of the oral cannula of  FIG. 9A ; 
           [0042]      FIG. 9C  is cross sectional view taken through lines  9 C- 9 C of  FIG. 9B ; 
           [0043]      FIG. 10A  is a schematic view of an oxygen supply and capnography system employing the present invention; 
           [0044]      FIG. 10B  is an enlarged schematic view of an oral cannula residing in a patient&#39;s mouth; 
           [0045]      FIG. 11  is an illustration of an oral cannula assembly and treatment gas delivery lumen and exhaled gas sampling lumen; 
           [0046]      FIG. 12  is an enlarged, perspective exploded view of the oral cannula of  FIG. 11 ; 
           [0047]      FIG. 13  is an enlarged, perspective view of a portion of the oral cannula, including the cap assembly internal parts shown in relief; 
           [0048]      FIG. 14  is a cross section, orthogonal view of the oral cannula of  FIG. 13 , taken through lines  14 - 14  of  FIG. 13 ; 
           [0049]      FIG. 15A  is a schematic view of an oxygen supply and capnography system employing the present invention. 
           [0050]      FIG. 15B  is an enlarged schematic view of a flexible intraoral cannula residing in a patient&#39;s mouth. 
       
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0051]    The oral cannula embodiments described below have a treatment gas delivery lumen and an exhaled gas sampling lumen. For convenience of illustration, the lumens are also referred to as an oxygen supply lumen and an end-tidal carbon dioxide (ETCO2) lumen to reflect the most common treatment gas and the most common target for sampling the exhaled gas. Each oral cannula is located or formed at the distal end of oxygen supply tubing and end-tidal carbon dioxide (ETCO2) sampling tubing, which tubing is connected to a conventional capnography and oxygen supply and monitoring system at the end opposite the oral cannula. Conventional luer fittings may be used. Oxygen from the oxygen source (not shown in the figures) and controlled by the anesthetist or control system flows out through the oxygen supply lumen and exits through the oral cannula. Sampling gases are pulled through the oral cannula and the ETCO2 sampling lumen to the capnography system. 
         [0052]      FIGS. 1A and 1B  illustrate an oral cannula that includes a first embodiment oral cannula  10 , oxygen supply tubing  76 , an end-tidal carbon dioxide (ETCO2) sampling tubing  86 , and (preferably) conventional fittings  77  and  87  on respective proximal ends of the tubing. Oral cannula  10  includes an oxygen supply tube lumen  70  and ETCO2 sampling tube lumen  80 . As shown in  FIG. 1A , oxygen supply tube lumen  70  is at a distal portion of oxygen supply tubing  76 ; ETCO2 sampling tube lumen  80  is at a distal portion of sampling tubing  86 . In this regard, a portion of the tubing forms the oral cannula, and another portion of the tubing is extraneous to the oral cannula and extends from the oral cannula. A connector  91  is illustrated schematically to encompass any kind of connection or structure for connecting tubing  76 ,  86  to lumens  70 ,  80 . 
         [0053]    The oxygen supply tube  76  and the ETCO2 sampling tube  86  (that is, the portions of the tubing that do not form the oral cannula  10 ) preferably are several feet long, affixed together in a side-by-side relationship, and terminate at conventional luer fittings  77 ,  87  suitable for connection to an oxygen supply and ETCO2 monitoring system. Alternatively, tubing  76  and  86  may be configured in a co-sheath or coaxial configuration. 
         [0054]    Tubing  76  and  86  preferably are formed of conventional materials, such as those used for conventional nasal cannula. Preferably, the tubing is conventional PVC. In an alternative embodiment, a plastic available from Saint-Gobain Performance Plastics Corporation under the TYGON® SE-200 and TYGON name may be used. This tubing has an inert liner and can be used as an O2 delivery line. Tubing  76  and  86  are side-by-side tubes that are affixed together along their entire length, with (preferably) the supply lumen being larger in diameter than the sampling lumen. Other embodiments of the oral cannula described below may have coaxial or other tubing configurations, but the function and materials of the supply and sampling tubing is the same for all embodiments. In this specification, the term “tubing” refers to conventional, flexible tubing (described more fully below); the term “lumen” refers to the structure or the passage formed by the structure of the inventive oral cannula. 
         [0055]    As best shown in  FIGS. 2A, 2B, and 3A through 3E , oxygen supply lumen  70  and ETCO2 sampling lumen  80  in the first embodiment are in a co-sheath configuration in which ETCO2 sampling lumen  80  is enclosed within oxygen supply lumen  70  to form a portion of oral cannula body  16 . In this regard, the term “co-sheath” as used in this description refers to a structure in which one tube is contained within another, even if the axes of the tubes do not fall on the same line, including when inner tube is attached to an inner wall of the outer tube. The term “coaxial” as used in this description refers to a structure in which tubes are oriented such that the longitudinal axes generally align, including when an inner tube is loose within the outer tube. A coaxial configuration is a subset of a co-sheath configuration. 
         [0056]    Body  16  may be integrally formed with the tubing, or body  16  may be a unitary (that is, stand-alone) piece that has openings into which oxygen supply tubing  76  and ETCO2 sampling tubing  86  fit and are attached (including by a separate connector  91  to mate the parts). The sidewall of body  16  includes plural apertures  36  that are in communication with the interior of lumen  70  and tubing  76  such that oxygen supplied by the oxygen source (illustrated in  FIG. 10A ) and controlled by the anesthetist or control system flows out of oral cannula  10  through apertures  36 . Body  16  also includes apertures  37 ,  38  that are in fluid communication with plenum  74 , sampling lumen  80 , and tubing  86 , such that sampling can be controlled by the ETCO2 monitoring system. In this regard, a distal end of oxygen supply lumen  70  is sealed by a bulkhead  72  such that a distal end of the oral cannula distal to the bulkhead forms a plenum  74 , as best shown in  FIG. 3A . The portion of the oral cannula including the bulkhead and plenum can be referred to as a tip, such as a cap, for example, a bulb. In this regard, the term “tip” in this disclosure is used broadly to refer to any end structure. The tips may be formed of rigid plastic sleeve. Alternatively, the tips may be formed of a soft plastic. 
         [0057]      FIG. 3D  is an enlarged view of a portion of the sidewall of the oxygen supply lumen  70  illustrating a configuration of apertures  36 . In this regard, apertures  36  define a centerline that forms an angle A from a longitudinal centerline, which is horizontal as oriented in  FIGS. 3D and 3E . Preferably, angle A is between 25 and 75 degrees, more preferably between 40 and 60 degrees, and most preferably between 45 and 50 degrees. Further, a distal or upper portion of apertures  36  include a scoop  92  intended to inhibit unintentional blocking of the apertures by contact with a patient&#39;s tissues. 
         [0058]      FIGS. 9A, 9B, and 9C  illustrates an oral cannula  910  having apertures  936  that are oriented perpendicular to the sidewall. Apertures  936  includes a scoop at the distal end, which are intended to inhibit unintentional blocking of the apertures by contact with a patient&#39;s tissues. Scoops  92  and  992  are optional, as the present invention encompasses straight holes without scoops. 
         [0059]      FIGS. 4A and 4B  illustrate additional configurations of co-sheathed oral cannula.  FIG. 4A  illustrates oral cannula  10 ′ having a bulkhead  72 ′ that is a barrier that seals the end of supply lumen  70 . Sampling lumen  80  protrudes through bulkhead  72 ′ such that plenum  74  is connected to sampling lumen  80  and not in communication with supply lumen  70 .  FIG. 4B  illustrates co-axial oral cannula  10 ″ having a bulkhead  72 ″, which functions the same as bulkhead  72 ′. Sampling lumen  80  protrudes through bulkhead  72 ″ at or near the centerline of lumen  70 . 
         [0060]    Each bulkhead  72 ,  72 ′, and  72 ″ defines the corresponding plenum  74 ,  74 ′, and  74 ″. The text below will employ the reference numerals  72  and  74  to refer to any embodiment of the bulkhead and plenum for ease of description, and reference numeral  10  to refer to any of the embodiment in  FIGS. 2A through 4B . Apertures  37  are formed in the plenum wall around the body of the plenum  74 . An end aperture  38  may be formed at the distal-most end of oral cannula  10 . 
         [0061]    Oxygen from oxygen supply tubing  76  flows within supply lumen  70  on the outside of sampling lumen  80  to exit from apertures  36 . Because bulkhead  72  forms the end of supply lumen  70 , oxygen does not enter plenum  74 . Rather, gas is pulled into plenum  74  through apertures  37  and  38  and through sampling lumen  80  by the action of the suction from the ETCO2 sampling system. 
         [0062]    Body  16 , as illustrated in  FIG. 1B , has a bend  13  that may be (optionally) formed by a wire  50  or may be formed upon molding body  16 , as explained more fully below. Body  16  can be formed of a rigid plastic or from a soft plastic, according to the particular design parameters of the oral cannula. 
         [0063]      FIG. 8A  illustrates a common coaxial configuration in which the axes are or can lie literally on the same axis. The configuration of  FIG. 8B  is, in the nomenclature of this specification, also coaxial if the tube of lumen  80  is not attached to the tube of lumen  70 , as the loose lumens will sometimes be coaxial. If the outside of lumen  70  is adhered to the inside of lumen  80  in  FIG. 8 , then the lumens have a co-sheath configuration.  FIG. 8C  illustrates another co-sheath configuration in which the outer sheath does not have a circulate cross section.  FIG. 8D  illustrates an oral cannula having a side-by-side (that is, not a co-sheath configuration). 
         [0064]      FIGS. 5A and 5B  illustrate an alternative embodiment oral cannula  110  including a tip  112 , such as a cap. Tip  112  is formed by an elongate, supply body  116 , such as a cylindrical or nearly cylindrical supply body, that forms an oxygen supply lumen  170  and a cylindrical, or nearly cylindrical sampling body  118  that forms an ETCO2 sampling lumen  180 . Bodies  116  and  118  preferably are unitary (that is, formed of a single piece of plastic and are not detachable from one another) and side-by-side. Preferably, tip  112  is approximately 1.0 to 3.0 inches long, preferably at least 1.5 inches long, and optionally includes a bend (not shown in  FIGS. 5A and 5B ), to house the entirety of the oxygen supply lumen and ETCO2 sampling lumens of the oral cannula. In this alternative, the tip would be connected to tubing  76  and  86 , and the tip may be formed of a pre-bent rigid plastic, a pre-bent soft plastic, or be supplied with a shaping wire  50 . 
         [0065]    Oxygen supply lumen  170  has a proximal end  132  and a distal end  172 . An opening  134  at proximal end  132  is sized to receive oxygen supply tubing  76 . Tubing  76  is inserted into opening  134  and preferably is adhered or welded by conventional means. The sidewall of the body  116  includes plural openings  134  that are in communication with the interior of lumen  170  and tubing  76  such that oxygen supplied by the oxygen source (not shown in Figure) and controlled by the anesthetist or control system flows out of oral cannula  10  through apertures  136 . In this regard, the distal end  172  terminates at a barrier and is sealed such that no oxygen flows out of the distal end of the oral cannula parallel to the longitudinal axis of oral cannula  110  or into plenum  174  (explained below). 
         [0066]    ETCO2 lumen  180  has a proximal end  142  and a distal end  148 . An opening  144  at proximal end  142  is sized to receive ETCO2 sampling tube lumen  180 . Lumen  180  is inserted into opening  144  and preferably is adhered or welded together by conventional means. The sidewall of the body  118  preferably has no apertures that open into sampling lumen  180 . Rather, sampling body  118  distally extends past the distal end of the oxygen supply lumen  170  into a plenum  174 . Sampling body  118  at plenum  174  has apertures  137  and (optionally) apertures on the distal end  139  of oral cannula  110  (not shown in  FIG. 5 ). Apertures  137  preferably are distributed around the circumference or periphery of plenum  174  such that sampling apertures  137  are distal to all of oxygen supply apertures  136 . Apertures  137  enable communication and flow through or near the end of body  118  into the interior of sampling lumen  180  and sampling tubing  86  when pulled by the ETCO2 monitoring system (not shown in the figures). Distal end  139  defines the distal end of oral cannula  110 . 
         [0067]      FIGS. 6A and 6B  illustrate another side-by-side embodiment oral cannula  210  including a tip  212 , an oxygen supply lumen  230 , and an ETCO2 sampling lumen  240 . Tip  212  is formed by a nearly cylindrical supply body  216  that forms a portion of oxygen supply lumen  230  and a cylindrical sampling body  218  that forms a portion of ETCO2 sampling lumen  240 . Bodies  216  and  218  are unitary (that is, formed of a single piece of plastic and are not mutually detachable from one another) and side-by-side. Preferably, tip  212  is between 0.5 inches and 1.5 inches long (measured parallel to the longitudinal axis). In cross section or in an end view, lumens  230  and  240  form a figure eight. 
         [0068]    In this regard, oxygen supply lumen  230  of the oral cannula  210  can be formed in part by tip  212  and oxygen supply lumen  270  (that is, a portion of tubing  76 ). The ETCO2 sampling lumen  240  of oral cannula  210  can be formed in part by tip  212  and sampling lumen  280  (that is, a portion of tubing  86 ). In other words, a portion of tubing  76  and  86  can form a portion of oral cannula  210 . And a portion of tip  212  can form a portion of oral cannula  210 . Alternatively, embodiment oral cannula  210  encompasses an oxygen supply lumen  230  that is short and/or includes only a fitting to close off the end of tubing. In the embodiment shown in  FIGS. 6A and 6B , body  216  includes an opening recess  234  sized to receive oxygen supply tube lumen  270 , which is inserted into the opening recess  234  and preferably is adhered or welded by conventional means. The sidewall of the tubing that forms supply lumen  270  includes plural apertures  236  that are in communication with the interior of lumen  270  and tubing  76  such that oxygen supplied by the oxygen source and controlled by the anesthetist or control system flows out of oral cannula  210  through apertures  236 . In this regard, the distal end of the supply lumen  270  is sealed by body  216  at a seal  272 . 
         [0069]    ETCO2 lumen  240  of tip  212  has an opening  244  at proximal end  242  that is sized to receive ETCO2 sampling tube lumen  280 . Lumen  280  is inserted into opening  244  and preferably is adhered or welded together by conventional means. Sampling body  218  distally extends past the distal end of the oxygen supply lumen  270  to form a plenum  274 . Sampling body  218  has apertures  237  near its distal end  239  and (optionally) apertures on its distal end (not shown in  FIG. 6 ). Apertures  237  preferably are distributed around the circumference or periphery of plenum  274  and the sampling apertures  237  are distal to all of oxygen supply apertures  236 . Apertures  237  enable communication and flow through or near the end of body  218 , in some circumstances making a right turn, into the interior of sampling lumen  240  and sampling tubing  86  when pulled by the ETCO2 monitoring system. Distal end  239  defines the distal end of oral cannula  210 . 
         [0070]      FIGS. 7A and 7B  illustrate another side-by-side embodiment oral cannula  310  that includes a tip  312 , such as a cap, for example a bulb, that may be formed of a unitary piece having openings into which oxygen supply tubing and ETCO2 sampling tubing fit and are attached or may formed integral with tubing  76  and  86 . 
         [0071]    Oral cannula  310  encompasses an oxygen supply lumen  330 , an ETCO2 sampling lumen  340 , a barrier  372 , and a plenum  374 . Tip  312  includes a port  346  that extends through the sidewall of a tip  312  on the distal side barrier  372  to communicate with plenum  374 . Tip  312  forms plenum  374  and includes sampling apertures  337  and end aperture  338 . 
         [0072]    The sidewall of the lumen  330  includes plural apertures  336  that are in communication with the interior of supply lumen  330  to enable oxygen to flow out of oral cannula  310 . Oxygen supply lumen  330  terminates at barrier  372 . Sampling lumen  340  extends exterior of the supply lumen  330 , through port  346 . Alternatively (not shown), port  346  can be located on the proximal side of barrier  372  such that port  346  extends through supply lumen  330  to pierce barrier  372  in a configuration like that described for embodiments having a bulkhead. In another alternative (not shown), sampling lumen  340  may extend all the way through supply lumen  330  and terminate only in an aperture at the distal-most end portion of the oral cannula. The latter alternative does not require a bulkhead. Plenum apertures  337  and  338  enable gas to be drawn through apertures  337  and  338 , plenum  374 , port  346 , sampling lumen  340 , and into sampling tubing  86  (not shown in  FIGS. 7A and 7B ). 
         [0073]    Oral cannula  310  may be pre-formed with a bend. Tip  312  can be formed of a rigid plastic or from a soft plastic, according to the particular design parameters of the oral cannula and in embodiments in which tip  312  is elongated (not shown), may include a bend, as described elsewhere in this disclosure. Tip  312  can be formed as a separate structure that is fused to lumens  330  and  340 , formed integral with lumen  330  by closing its distal end, or by other means as understood by persons familiar with tubing technology. 
         [0074]    For the side-by-side embodiments of  FIGS. 5A through 7B , the oxygen supply tube  76  and the ETCO2 sampling tube  86  (that is, the portions of the tubing that do not form the oral cannula  110 ,  210 ,  310 ) preferably are several feet long, affixed together in a side-by-side relationship, and terminate at conventional luer fittings  77 ,  87  suitable for connection to an oxygen supply and ETCO2 monitoring system. Alternatively, tubing  76  and  86  may be configured in a coaxial configuration. 
         [0075]    Tubing  76  and  86  preferably are formed of conventional materials, such as those used for conventional nasal cannula. Preferably, tubing  76  and  86  are conventional PVC, as will be understood by persons familiar with medical devices in this field. This tubing has an inert liner and can be used as an O2 delivery line. Tubing  76  and  86  are side-by-side tubes that are affixed together along their entire length, with (preferably) the supply lumen being larger in diameter than the sampling lumen. Other embodiments of the oral cannula described below may have coaxial or other tubing configurations, but the function and materials of the supply and sampling tubing is the same for all embodiments. In this specification, the term “tubing” refers to conventional, flexible tubing (described more fully below); the term “lumen” refers to the structure or the passage formed by the structure of the inventive oral cannula. 
         [0076]    Referring to  FIGS. 11 through 15B  to illustrate a preferred embodiment, an oral cannula assembly  400  includes treatment gas delivery tubing  76 , exhaled gas sampling tubing  86 , (preferably) conventional fittings  77  and  87  on respective proximal ends of the tubing, and an oral cannula  410 . Oral cannula  410  is referred to as an intraoral cannula, as a subset of an oral cannula, to refer to diverse positioning within the oral space throughout the oral cavity and beyond, including positioning the tip near or in contact with the Oropharynx. 
         [0077]    The oxygen supply tube  76  and the ETCO2 sampling tube  86  (that is, the portions of the tubing that do not form the oral cannula  410 ) preferably are several feet long, affixed together in a side-by-side relationship, and terminate at conventional luer fittings  77 ,  87  suitable for connection to an oxygen supply and ETCO2 monitoring system  925 ,  960 . Alternatively, tubing  76  and  86  may be configured in a co-sheath or coaxial configuration. 
         [0078]    Oral cannula  410  includes a treatment gas delivery lumen  470 , an exhaled gas sampling lumen  480 , a cap assembly  412 , and a shaping wire  414 . As shown in  FIG. 12 , delivery lumen  470  is at a distal portion of tubing  76 ; sampling lumen  480  is at a distal portion of sampling tubing  86 . In this regard, a portion of the tubing forms the oral cannula, and another portion of the tubing is extraneous to the oral cannula and extends from the oral cannula. A connector  491  is illustrated schematically to represent any kind of connection or structure for connecting tubing  76 ,  86  to lumens  470 ,  480 . As shown in  FIG. 11 , oral cannula assembly  400  has no connector between tubing  76  and  86 , as portions on the oral cannula are formed on the distal portions of the tubing. 
         [0079]    Cap assembly  412  includes an outer cap body  420 , a cap insert  440 , and a filter assembly  460 . Outer cap body  420  includes a flute portion  422  at its distal most region, a cylindrical middle sleeve  424 , and a cylindrical proximal sleeve  426 , which includes a skirt  474 . Flute portion  422  includes plural flutes  430  that are radially oriented gussets or webs that extend from cap middle sleeve  424  at a flute base  432  to a distal tip  434 . Preferably, flutes are joined together at the longitudinal centerline for mutual support. Flutes  430  in the embodiment shown in the figures are tapered to narrow in the direction of tip  434 . Other configurations of flutes are contemplated. The spaces between adjacent flutes  430  form apertures  436 . 
         [0080]    Cap middle sleeve  424  and cap proximal sleeve  426  are cylindrical and have the same outer diameter. Cap proximal sleeve  426  extends downwardly or proximally from the lower or proximal end of middle portion  424 . Proximal sleeve  426  has a greater internal diameter than the internal diameter of middle portion  424  and thus defines a frusto-conical shoulder  428  at the juncture of the inboard surfaces of portions  424  and  426 . 
         [0081]    Cap insert  440  includes a cylindrical upper or distal body  442 , a cylindrical lower or proximal body  444 , and a frusto-conical shoulder  446  between bodies  442  and  444 . The outer diameter of distal body  442  is greater than that of proximal body  444  such that the outboard surface of cap insert  440  forms an upwardly oriented funnel shape. The outer diameter of distal body  442  matches the inner diameter of middle sleeve  424  of the outer cap body  420 . The outer diameter of proximal body  444  matches the inner diameter of proximal sleeve  426  of the outer cap body  420 . 
         [0082]    The lower or proximal end of proximal body  444  has a recess  450  for receiving delivery lumen  470  and a recess  452  for receiving sampling lumen  480 . A gas channel  454  extends from the uppermost rim of cap insert  440  and is in fluid communication with sampling recess  452 . In this regard, channel  454  preferably is concentric with distal body  442  throughout all or most of distal body  442  and bends or angles to be deviate from the longitudinal centerline at the proximal end of proximal body  444 . Sampling recess  452  is thus in communication with channel  454 . Delivery recess  450  is shown as opening into sampling recess  452 , as delivery lumen  470  has a sealed tip  472 , as explained below. Alternatively, delivery recess  450  may be sealed (not shown in the Figures). 
         [0083]    Filter assembly  460  includes a hydrophobic filter element  462  and a filter housing  464 . Filter housing includes a circular flange  466 , and a downwardly depending skirt  468 . Hydrophobic filter element  462  is located on or radially within flange  466 . The hydrophobic filter element  462  is such that it prevents saliva and mucus from being drawn into the channel, such as channel  454 , and/or otherwise blocking or impeding the desired flow of sample gas. Preferably, filter housing  464  is rigid to provide radial rigidity to cap assembly  412 . 
         [0084]    Shaping wire  414  preferably is generally as described herein for other embodiments, and has the attributes of being able to be bent by the hands of the user, retaining a bend applied by a user upon insertion into a patient&#39;s mouth, and preferably being sufficiently rigid to enable the user to insert it into the airway of the patient (past the oral cavity and in some circumstances into the Oropharynx and beyond) if needed. The inventors have found that a 16 gauge, medical grade copper wire is sufficient for this purpose. Wires of similar gauge having the same or higher yield strength may be used. Wires (and other structures) of other materials and yield strength and/or resistance to bending moments may be employed if having the same or greater bending stiffness than a 16 gauge, medical grade copper wire. Preferably, wire  414  is encased or encapsulated within the material of lumen  470  and/or  480 . 
         [0085]    Delivery lumen  470  is a conventional tube material having a fused or blocked terminal end  472  and apertures, preferably a pair of round apertures  476   a  and  476   b  in the sidewall of delivery lumen  470 . Preferably, upper or distal aperture  476   a  has a smaller diameter (or for apertures that are not round, a smaller cross sectional area) than that of lower or proximal aperture  476   b  to encourage even or balanced airflow through the two apertures. The location of apertures  476   a  and  476   b  depends on the dimensions of skirt  474 , as explained below. Sampling lumen  480  preferably is a continuous, unbroken tube of conventional material described above that is open at its terminal proximal end  482 . 
         [0086]    Referring particularly to  FIGS. 11 through 14  to described the assembled device, filter assembly  460  is located on cap insert  440  such that circular flange  466  is in contact with a proximal rim of cap insert distal body  442 , an outboard surface of filter skirt  468  is in contact with or within the inboard surface of distal portion  442  of insert body  440 , and an outboard surface of insert channel  454  is in contact with or within an inboard surface of filter skirt  468 . Thus, sampling tubing  86  is in fluid communication with the underside of filter element  462  via sampling lumen  480 , sampling recess  452 , and insert channel  454 . 
         [0087]    As best shown in  FIG. 14 , cap insert  440  is located within cap outer body  420  such that the outboard surface of distal body  442  is in contact with or within the inboard surface of middle sleeve  424  of outer cap body  420 , the outboard surface of proximal body  444  is in contact with or within the inboard surface of proximal sleeve  426 , and shoulder  446  is in contact with shoulder  428 . In this regard, cap insert  440  may be glued or otherwise affixed to cap outer body  420 , held together in a press fit or interference fit, or have any other fixed relationship. Preferably, outer body  420  and insert body  440  are formed of flexible material similar to that of the PVC tubing material described above. Flutes  430  are formed of a firm, pliable plastic, such as a conventional plastic suitable for thermoforming or injection molding, such that the flutes resist deformation in the patient&#39;s mouth to prevent or inhibit occlusion. 
         [0088]    Outer cap proximal sleeve  426  extends below or proximal to proximal body  444  of insert  452  to form a skirt  474 . Skirt  474  is radially spaced apart from treatment gas delivery lumen  470  and exhaled gas sampling lumen  480  to form a plenum  478  about the inner circumference of the inboard surface of skirt  474 . In this regard, apertures  476  are located in or open into plenum  478 , or in other words are located distally or above the proximal or lower end of skirt  474 . Preferably, skirt  474  is a continuous circle, but other configurations (not shown) by which skirt  474  protects or covers apertures  476  from being occluded are contemplated. 
         [0089]    In operation, a user bends oral cannula  410  to a desired configuration, based on the user&#39;s oral cavity shape and size and like parameters of the application. Oxygen or other treatment gas is delivered through lumen  76  and into lumen  470 . As lumen  470  is blocked at its distal end  472 , the flow of treatment gas turns 90 degrees to exit through apertures  476   a  and  476   b  into plenum  478 . Plenum  478  may enhance diffusion circumferentially around lumens  470  and  480 . The treatment gas flow turns again 90 degrees to exit below skirt  474 , as illustrated by the arrows in  FIG. 14 . ETCO2 is drawn through apertures  436  between flutes  430 , through filter element  462 , through channel  454 , through lumen end  482  and into ETCO2 sampling lumen  480 . 
         [0090]    The oral cannula described herein can be molded with a bend that resists deformation, may be molded with a bend that is plastically deformable such that the shape of the oral cannula can be adjusted as desired by the anesthetist or other users, may be formed with a shaping wire encapsulated in the plastic, may be formed with a shaping wire exterior to and adhered or mechanically affixed to the body of the cannula, optionally with the wire protected by a protective sheath, or may include other mechanical support (as will be understood by persons familiar with deformable plastic medical devices). In embodiments in which the oral cannula is intended to be deformable, the oral cannula is intended to be deformed by a user&#39;s hands. In embodiments in which the oral cannula is intended to be rigid, the oral cannula is stiff enough to resist deformation by the force of a user&#39;s hands. 
         [0091]    For any of the embodiments in which the oxygen supply lumen and ETCO2 sampling lumen are not fixed in a concentric, coaxial configuration and which have a bend, it is preferred that the sampling lumen be near the inside radius of the bend to enhance the area of the oxygen supply lumen wall that is available for oxygen supply apertures. 
         [0092]    As illustrated schematically in  FIGS. 10A and 10B and 15A and 15B , a patient  900  can have an oral cannula  10 , which reference numeral is intended to represent any configuration herein (including oral cannula  410 ), which is shaped and placed in his mouth  915 . For convenience, only first embodiment oral cannula  10  is employed for the description of the overall system. The description of the system applies equally to other embodiments of the oral cannula. Also, while not shown in the figures, an oxygen delivery line  920  from an oxygen source  925  can be split, such as by a Y-splitter or other type of valve, into both an oral cannula line and a nasal cannula line. The nasal cannula line can run to a conventional nasal cannula (not shown), and the oral cannula can simultaneously be used as described above. Such a configuration may be advantageous for situations in which a patient stops breathing through his nose, but is still breathing through his mouth. An ETCO2 sampling line  950  can be connected to a patient monitoring system  960 . The ETCO2 sampling line  950  can also be split. 
         [0093]    As best shown in  FIGS. 2A, 2B, and 3A through 3E , oxygen supply lumen  70  and ETCO2 sampling lumen  80  in the first embodiment are in a co-sheath configuration in which ETCO2 sampling lumen  80  is enclosed within oxygen supply lumen  70  to form a portion of oral cannula body  16 . In this regard, the term “co-sheath” as used in this description refers to a structure in which one tube is contained within another, even if the axes of the tubes do not fall on the same line, including when inner tube is attached to an inner wall of the outer tube. The term “coaxial” as used in this description refers a structure in which tubes are oriented such that the longitudinal axes generally align, including when an inner tube is loose within the outer tube. A coaxial configuration is a subset of a co-sheath configuration. 
         [0094]    Body  16  may be integrally formed with the tubing, or body  16  may be a unitary (that is, stand-alone) piece that has openings into which oxygen supply tubing  76  and ETCO2 sampling tubing  86  fit and are attached (including by a separate connector  91  to mate the parts). The sidewall of body  16  includes plural apertures  36  that are in communication with the interior of lumen  70  and tubing  76  such that oxygen supplied by the oxygen source (illustrated in  FIG. 10A ) and controlled by the anesthetist or control system flows out of oral cannula  10  through apertures  36 . Body  16  also includes apertures  37 ,  38  that are in fluid communication with plenum  74 , sampling lumen  80 , and tubing  86 , such that sampling can be controlled by the ETCO2 monitoring system. In this regard, a distal end of oxygen supply lumen  70  is sealed by a bulkhead  72  such that a distal end of the oral cannula distal to the bulkhead forms a plenum  74 , as best shown in  FIG. 3A . The portion of the oral cannula including the bulkhead and plenum can be referred to as a tip, such as a cap, for example, a bulb. In this regard, the term “tip” in this disclosure is used broadly to refer to any end structure. The tips may be formed of rigid plastic sleeve. Alternatively, the tips may be formed of a soft plastic. 
         [0095]      FIG. 3D  is an enlarged view of a portion of the sidewall of the oxygen supply lumen  70  illustrating a configuration of apertures  36 . In this regard, apertures  36  define a centerline that forms an angle A from a longitudinal centerline, which is horizontal as oriented in  FIGS. 3D and 3E . Preferably, angle A is between 25 and 75 degrees, more preferably between 40 and 60 degrees, and most preferably between 45 and 50 degrees. Further, a distal or upper portion of apertures  36  include a scoop  92  intended to inhibit unintentional blocking of the apertures by contact with a patient&#39;s tissues. 
         [0096]    The structure and function of the oral cannula described in this specification are for illustration purposes and are not intended to be limiting. Rather, it is intended that the claims be limited only to the express structure and function expressly stated in the claims. Further, features of the embodiments described above are not limited to the particular embodiment. Rather, the present invention encompasses any of the features described above in any combination.