Abstract:
An apparatus and method for delivering oxygen to a nasopharynx and withdrawing exhale gas from the nasopharynx to a carbon dioxide monitor. In one embodiment, the apparatus can comprise one or more tubes and an airway fitting forming an airway. The airway fitting can be configured to engage at least one of the tubes and maintain the one or more tubes within the airway, and to provide an outlet to the atmosphere for the airway. In another embodiment, the tube might be in fluid communication with a junction that can direct oxygen from an oxygen supply through the tube and exhale gas from the tube to the carbon dioxide monitor. Further, the tube might comprise an outer tube and an inner tube.

Description:
[0001]     This application is a continuation-in-part of U.S. patent application Ser. No. 10/441,557, filed on May 20, 2003. 
     
    
     BACKGROUND  
       [0002]     1. Field of the Invention  
         [0003]     The present invention relates to the field of respiratory monitoring of carbon dioxide levels and the supplying of oxygen to a patient.  
         [0004]     2. Description of the Related Art  
         [0005]     It is often desirable or necessary to exchange gas with a subject, such as a medical patient. Using the example of a medical patient, oxygen can be supplied to the patient, and exhale gases such as carbon dioxide can be collected from the patient. When supplying oxygen to the patient, it may be efficient to transfer oxygen to the patient in a stable and controlled location. Likewise, carbon dioxide levels might be monitored more accurately if based on readings taken at a stable and controlled location. Further, when supplying oxygen to or collecting exhale gases from a patient, errors can occur in the setup of the equipment or apparatus. Therefore, gas supply and/or collection equipment or apparatus that can reduce the risk of error can make gas supply and gas collection safer and more reliable.  
         [0006]     Thus, there exists a need for a more stable, more efficient, and safer respiratory monitoring and oxygen supply method and apparatus.  
       SUMMARY  
       [0007]     In an exemplary embodiment, the transnasal ventilation apparatus can both collect carbon dioxide from a patient&#39;s nasopharynx and supply oxygen to a patient&#39;s nasopharynx through a tube inserted into the nasopharynx. The tube might fluidly communicate with a junction that can direct exhale gas and oxygen through the tube. More particularly, the junction might direct exhale gas from a patient&#39;s nasopharynx to a carbon dioxide monitor and/or the junction might direct oxygen from an oxygen supply to a patient&#39;s nasopharynx.  
         [0008]     In an alternate embodiment, the tube inserted into a patient&#39;s nasopharynx might comprise an inner tube and an outer tube. In this embodiment, the inner tube and the outer tube might fluidly communicate with a junction that can direct exhale gas and oxygen through the inner tube and the passageway formed by the inner and outer tubes. More particularly, the junction might direct exhale gas from a patient&#39;s nasopharynx to a carbon dioxide monitor and/or the junction might direct oxygen from an oxygen supply to a patient&#39;s nasopharynx.  
         [0009]     In other embodiments, the transnasal ventilation apparatus can comprise a first tube and a second tube, each in fluid communication with a patient&#39;s nasopharynx; and an airway fitting engaging the first tube and the second tube, the airway fitting also in fluid communication with a patient&#39;s nasopharynx and with the atmosphere.  
         [0010]     In still other embodiments, the transnasal ventilation apparatus can comprise one or more tubes; an airway fitting comprising a walled section forming an airway, the airway fitting being configured to engage at least one of the tubes and maintain the at least one of the tubes within the airway, and wherein the airway fitting is also configured to provide an outlet to the atmosphere for the airway.  
         [0011]     In still other embodiments, a airway fitting for use in a transnasal ventilation apparatus can comprise a walled section forming an airway; and one or more members attached to the walled section and configured to engage one or more tubes.  
         [0012]     And in still other embodiments, a method can comprise providing a first tube and a second tube, each in fluid communication with a patient&#39;s nasopharynx; and providing a airway fitting engaging the first tube and the second tube, the airway fitting also in fluid communication with the patient&#39;s nasopharynx and with the atmosphere.  
         [0013]     The design of the exemplary embodiments minimize the risk that the apparatus will become dislodged during surgery. In addition, the exemplary embodiments increase safety and control during medical procedures because they maintain oxygen delivery in a more “constant flow” state by supplying constant, passively delivered oxygen to a patient&#39;s pharynx. The constant oxygen delivery allows for deeper, more controlled sedation (anesthesia) of the patient. In addition, the exemplary embodiments minimize intrusion on the surgical field of the face.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0014]     Exemplary embodiments of the present invention are described herein with reference to the drawings, in which:  
         [0015]      FIG. 1  is an illustration of an exemplary embodiment;  
         [0016]      FIG. 2  is an illustration of a junction shown in  FIG. 1 ;  
         [0017]      FIG. 3  is an illustration of another exemplary embodiment;  
         [0018]      FIG. 4  is an illustration of another exemplary embodiment;  
         [0019]      FIG. 5  is an illustration of another exemplary embodiment;  
         [0020]      FIG. 6  is an illustration of another exemplary embodiment;  
         [0021]      FIG. 7  is an illustration of several components of an exemplary embodiment;  
         [0022]      FIG. 8  depicts an embodiment of an airway;  
         [0023]      FIG. 8A  depicts a plan view of the airway of  FIG. 8 ;  
         [0024]      FIG. 8B  depicts a cross-sectional view of the airway of  FIG. 8A ;  
         [0025]      FIG. 8C  depicts an elevation view of the airway of  FIG. 8 ;  
         [0026]      FIG. 8D  depicts a detail of the airway of  FIG. 8 ;  
         [0027]      FIG. 9  depicts an embodiment of a flow-through airway fitting;  
         [0028]      FIG. 9A  depicts an elevation view of the airway fitting of  FIG. 9 ;  
         [0029]      FIG. 9B  depicts a plan view of the airway fitting of  FIG. 9 ;  
         [0030]      FIG. 9C  depicts a cross-sectional view of the airway fitting of  FIG. 9B ; and  
         [0031]      FIG. 10  depicts an embodiment of an airway with an alternate flow-through airway fitting embodiment.  
     
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS  
     Example 1  
     1. Overview of Exemplary Embodiments  
       [0032]     Referring to  FIG. 1 , in accordance with an exemplary embodiment, a transnasal ventilation apparatus might comprise an insertion guide  10 , a first tube  20 , a inner tube  25 , a junction  30 , a second tube  40 , and a third tube  50 . The first tube  20  might comprise a first end  24  and a second end  22 . The inner tube  25  might comprise a first end  26  and a second end  28 . The second tube  40  might comprise a first end  42  and a second end  44 . And the third tube  50  might comprise a first end  52  and a second end  54 . Further, the insertion guide  10 , the first tube  20 , the inner tube  25 , the junction  30 , the second tube  40 , and the third tube  50  might comprise a single apparatus by, for example, being fused or otherwise bonded together or integral. Other embodiments are possible as well.  
         [0033]     Referring to  FIG. 1 , the insertion guide  10  might comprise a proximal end  12  and a distal end  14 . Although it need not be, insertion guide  10  might be tapered. For example, the diameter of the distal end  14  might be larger than the diameter of the proximal end  12 . The outside diameters of the proximal end  12  and the distal end  14  may also vary, for example, to accommodate various size nostrils and/or nasal airway passages. The length of the insertion guide  10  may vary as well. In an exemplary embodiment, the distal end  14  of the insertion guide  10  can be inserted into a patient&#39;s nasopharynx. In an exemplary embodiment, the insertion guide  10  might be made of a flexible material. For example, the insertion guide  10  might be made of polyvinyl chloride (“PVC”). Other materials, whether flexible or inflexible, are possible as well.  
         [0034]     Referring to  FIG. 1 , in an exemplary embodiment, the proximal end  12  of the insertion guide  10  might comprise a connector  16  and a cuff  18 . The connector  16  might receive the first end  22  of the first tube  20 . Although not necessary, the connector  16  of the insertion guide  10  might be bonded to the first end  22  of the first tube  20 . For example, the connector  16  can be bonded to the first end  22  by an adhesive or through chemical or heat fusing. Other methods of bonding are possible as well. In other embodiments, the connector  16  might be integral with the first end  22 . The cuff  18  might contact a patient&#39;s nostril and, in addition, might help seal the insertion guide  10  against the patient&#39;s nostril.  
         [0035]     The first tube  20  might comprise a flexible material, such as PVC. The first tube might also be made of the same material as the insertion guide  10  (which might occur if the insertion guide  10  is integral with or fused to the first tube  20 , for instance). Further, the first tube  20  might be made of the same material as the junction  30  (which might occur if the junction  30  is integral with or fused to the first tube  20 , for instance). Other 1.5 examples are possible as well.  
         [0036]     In an exemplary embodiment, the first tube  20  might comprise a inner tube  25 . For example, the inner tube  25  might be inside the first tube  20  such that the outer surface of the inner tube  25  and the inner surface of the first tube  20  can form a passage  23 . The passage  23  might, in turn, provide fluid communication between a patient&#39;s air passageways and the junction  30 .  
         [0037]     The junction  30  might comprise any type of three-way junction.  FIG. 2  depicts an exemplary junction  30  that might comprise seven chambers: a first chamber  31 , a second chamber  32 , a third chamber  33 , a fourth chamber  34 , a fifth chamber  35 , a sixth chamber  36 , and a seventh chamber  37 . Other embodiments of junction  30  are possible as well.  
         [0038]     In the exemplary embodiments of  FIGS. 1 and 2 , the first chamber  31  of junction  30  might receive the second end  24  of the first tube  20 , and the seventh chamber  37  might receive the first end  42  of the second tube  40 . The second chamber  32  and the sixth chamber  36  can then provide fluid communication between the passage  23  and the second tube  40 .  
         [0039]     Further, the third chamber  33  of junction  30  might receive the second end  28  of the inner tube  25 , and the fifth chamber  35  might receive the first end  52  of the third tube  50 . The fourth chamber  34  can then provide fluid communication between the inner tube  25  and the third tube  50 .  
         [0040]     Although not necessary, any combination or all of the first, second, third, or inner tubes  20 ,  40 ,  50 , and  25  might be bonded to the junction  30 . For example, tubes can be bonded to the junction  30  by an adhesive or through chemical or heat fusing. Other methods of bonding are possible as well. In other embodiments, any combination or all of the tubes might be integral with the junction  30 .  
         [0041]     Other embodiments of the junction  30  and/or the first, second, third, or inner tubes  20 ,  40 ,  50 , and  25  are possible. For example, portions of the first, second, third, or inner tubes may comprise a single tube. The inner tube  25  and the third tube  50  might comprise a single tube, for instance. In such a case, the third, fourth, and fifth chambers  33 ,  34 , and  35  of junction  30  might comprise a single chamber that can engage the single tube. Other examples are possible as well.  
         [0042]     Returning to  FIG. 1 , the second end  44  of the second tube  40  might be connected to a connector  72 . The connector  72  might then connect the second tube  40  to an oxygen supply  70 . The second end  54  of the third tube  50  might be connected to a connector  62 . The connector  62  might then connect the third tube  50  to a carbon dioxide monitor  60 .  
         [0043]     The second tube  40  can then fluidly connect the junction  30  to the oxygen supply  70 , and the third tube  50  can then fluidly connect the junction  30  to the carbon dioxide monitor  60 . The second tube  40  and the third tube  50  might each be made of a flexible material, such as PVC. Other examples are possible as well. For instance, the material of the second tube  40  and the third tube  50  might not be flexible, and the material of any of the first tube  20 , the inner tube  25 , the second tube  40 , or the third tube  50  need not be the same as the material of any other tube. Further, the first, second, third, and inner tubes might also all be made of the same material as the junction  30 , which might occur if the first, second, third, or inner tubes are integral with or fused to the junction  30 , for instance. The lengths of the first, second, third, and inner tubes might also vary.  
       2. Exemplary Operation  
       [0044]     Referring to  FIG. 1 , in an exemplary embodiment, a user such as an anesthesiologist (or any other medical or non-medical person) might insert the insertion guide  10  into a patient&#39;s nasal passage such that the distal end  14  of the insertion guide  10  extends toward the patient&#39;s nasopharynx. In such an arrangement, the proximal end  12  of the insertion guide  10  might frictionally engage the patient&#39;s nostril. In an exemplary embodiment, the distal end  14  of the insertion guide  10  might extend beyond the second end  26  of the inner tube  25 . In another embodiment, the distal end  14  might not extend beyond the second end  26 .  
         [0045]     The cuff  18  of the insertion guide  10  might provide a seal around a patient&#39;s nostril, thereby providing for more efficient oxygen supply and exhale gas withdrawal. Further, as shown in the embodiment of  FIG. 1 , the insertion guide  10 , the first, second, third, and inner tubes  20 ,  40 ,  50 , and  25 , the junction  30 , and connectors  62  and  72  might comprise a single apparatus, thereby providing for quicker assembly and easier use. The single apparatus might also provide for safer use because there are fewer parts to assemble, thereby lowering the risk of improper assembly or other errors.  
         [0046]     Referring back to the exemplary embodiment of  FIG. 1 , the second tube  40  might provide for fluid communication between the junction  30  and an oxygen supply  70 . The oxygen supply  70 , in turn, might apply a low, positive pressure through the second tube  40 , the sixth and second chambers  36  and  32  of junction  30 , and the passage  23 . The third tube  50  might provide for fluid communication between the junction  30  and a carbon dioxide monitor  60 . The carbon dioxide monitor  60 , in turn, might apply a low, negative pressure through the third tube  50 , the fourth chamber  34  of junction  30 , and the inner tube  25 .  
         [0047]     In accordance with an exemplary embodiment, the transnasal ventilation apparatus can provide for a steady state oxygen supply to/carbon dioxide collection from a patient. As the patient inhales, the patient can draw the lightly pressurized oxygen from the oxygen supply  70  through the passage  23  into the patient&#39;s nasopharynx. As the patient exhales, the patient can overcome the supply pressure of the oxygen in the passage  23  and can discharge the exhale gases from the patient&#39;s nasopharynx into the inner tube  25 . The negative pressure applied by the carbon dioxide monitor  60  can, in turn, withdraw the exhale gases to the carbon dioxide monitor  60 .  
       Example 2  
     1. Overview of Exemplary Embodiments  
       [0048]     Referring to  FIG. 3 , in accordance with an exemplary embodiment, a transnasal ventilation apparatus might comprise an insertion guide  10 , a first tube  20 , a junction  30 , a second tube  40 , and a third tube  50 . Referring to  FIG. 4 , in accordance with another exemplary embodiment, a transnasal ventilation apparatus might comprise an insertion guide  10 , a first tube  20  fixedly attached to the insertion guide  10 , a junction  30 , a second tube  40 , and a third tube  50 , the junction  30  being integral with the first, second, and third tubes.  FIG. 5  shows an exemplary embodiment similar to the exemplary embodiment of  FIG. 4 , but with the junction  30  being fused to the first, second, and third tubes. Although not shown, other embodiments are also possible. For instance, in another embodiment, the insertion guide  10  might be fixedly attached to the first tube  20 , but the junction  30  might not be integral with or fused to any or all of the first, second, or third tubes. Other examples are possible as well.  
         [0049]     Referring to  FIGS. 3, 4 , and  5 , the insertion guide  10  might comprise a proximal end  12  and a distal end  14 . Although it need not be, insertion guide  10  might be “bugle” shaped such that the proximal end  12  has a larger circumference than the distal end  14 . The outside diameters of the proximal end  12  and the distal end  14  may vary, for example, to accommodate various size nostrils and/or nasal airway passages. In an exemplary embodiment, the outside diameter of the proximal end  12  is 10 mm. In another embodiment, the outside diameter of the proximal end  12  is 8.7 mm. The length of the insertion guide  10  may vary as well.  
         [0050]     In an exemplary embodiment, the insertion guide  10  might comprise a cannula Two examples of commercially available cannulae are the Kendall Argyle™ Nasopharyngeal Airway and the Robertazzi™ Nasopharyngeal Airway. Other examples are possible as well. In an exemplary embodiment, the insertion guide  10  might be made of a flexible material. For example, the insertion guide  10  might be made of rubber latex. As another example, the insertion guide  10 ′ might be made of PVC. Other materials, whether flexible or inflexible, are possible as well.  
         [0051]     In an exemplary embodiment, the insertion guide  10  might hold within it a first tube  20 . As shown in  FIG. 3 , for example, the first tube  20  might be slidably inserted into the insertion guide  10 . As shown in the embodiments of  FIGS. 4 and 5 , the first tube  20  might be fixedly attached to the insertion guide  10 . For instance, the first tube  20  might be integral with or fused to the insertion guide  10 . Other examples are possible as well.  
         [0052]     The first tube  20  might comprise a flexible material, such as Silastic™. The first tube might also be made of the same material as the insertion guide  10  (which might occur if the insertion guide  10  is integral with or fused to the first tube  20 , for instance). Further, the first tube  20  might be made of the same material as the junction  30  (which might occur if the junction  30  is integral with or fused to the first tube  20 , for instance). Other examples are possible as well.  
         [0053]     The first tube  20  might, in turn, provide fluid communication between a patient&#39;s air passageways and the junction  30 . The junction  30  might comprise any type of three-way junction. In one embodiment, the junction  30  might comprise an Airlife™ Tri-Flo® Control Suction Catheter. As shown in the embodiment of  FIG. 4 , the junction  30  might be integral with the first tube  20 , the second tube  40 , and the third tube  50 . Further, as shown in the embodiment of  FIG. 5 , the junction  30  might be fused to the first tube  20 , the second tube  40 , and the third tube  50 . Other examples are also possible.  
         [0054]     In an exemplary embodiment, the second tube  40  might fluidly connect the junction  30  to an oxygen supply  70 , and the third tube  50  might fluidly connect the junction  30  to a carbon dioxide monitor  60 . The second tube  40  and the third tube  50  might each be made of a flexible material, such as Silastic™. Other examples are possible as well. For instance, the material of the second tube  40  and the third tube  50  might not be flexible, and the material of any of the first tube  20 , the second tube  40 , or the third tube  50  need not be the same as the material of any other tube. Further, the first, second, and third tubes might also all be made of the same material as the junction  30 , which might occur if the first, second, and third tubes are integral with or fused to the junction  30 , for instance. The lengths of the first tube  20 , the second tube  40 , and the third tube  50  might also vary.  
       2. Exemplary Operation  
       [0055]     Referring to  FIG. 3 , in an exemplary embodiment, a user such as an anesthesiologist (or any other medical or non-medical person) might insert the insertion guide  10  into a patient&#39;s nasal passage such that the distal end  14  of the insertion guide  10  extends toward the patient&#39;s nasopharynx. The user can then insert a first, open end  16  of the first tube  20  through the insertion guide  10 , such that the first end  16  extends toward the patient&#39;s nasopharynx. In such an arrangement, the proximal end  12  of the insertion guide  10  might frictionally engage the patient&#39;s nostril. The distal end  14  of the insertion guide  10  might frictionally engage the first end  16  of the first tube  20  and thereby hold the first end  16  in place. In an exemplary embodiment, the insertion guide  10  might hold the first end  16  in place beyond the distal end  14 . In another embodiment, the first end  16  might not extend beyond the distal end  14 . The first end  16  might also be held in place in other ways as well.  
         [0056]     As shown in the embodiments of  FIGS. 4 and 5 , the insertion guide  10  might be fixedly attached to the first tube  20 . The insertion guide  10  might then frictionally engage the nostril and thereby be held in place. In the embodiments of  FIGS. 4 and 5 , the insertion guide  10  and the integral or fused first tube  20  might provide a seal around a patient&#39;s nostril, thereby providing for more efficient oxygen supply and exhale gas withdrawal. Further, as shown in the embodiments of  FIGS. 4 and 5 , the insertion guide  10  and the first tube  20  might comprise a single component, thereby providing for quicker assembly and easier use. The single insertion guide  10 /first tube  20  might also provide for safer use because there are fewer parts to assemble, thereby lowering the risk of improper assembly or other errors.  
         [0057]     Referring back to the exemplary embodiments of  FIGS. 3, 4 , and  5 , the second tube  40  might provide for fluid communication between the junction  30  and an oxygen supply  70 . The oxygen supply  70 , in turn, might apply a low, positive pressure through the second tube  40 . The third tube  50  might provide for fluid communication between the junction  30  and a carbon dioxide monitor  60 . The carbon dioxide monitor  60 , in turn, might apply a low, negative pressure through the third tube  50 .  
         [0058]     In accordance with an exemplary embodiment, the transnasal ventilation apparatus can provide for a steady state oxygen supply to/carbon dioxide collection from a patient. As the patient inhales, the patient can draw the lightly pressurized oxygen from the oxygen supply  70  through the second tube  40  and through the first tube  20  into the patient&#39;s nasopharynx. As the patient exhales, the patient can overcome the supply pressure of the oxygen in the first tube  20  and can discharge the exhale gases from the patient&#39;s nasopharynx into the first tube  20 . The negative pressure applied by the carbon dioxide monitor  60  can, in turn, withdraw the exhale gases to the carbon dioxide monitor  60 .  
       Example 3  
     1. Overview of Exemplary Embodiments  
       [0059]     Referring to  FIGS. 6 and 7 , in accordance with another embodiment, a transnasal ventilation apparatus might comprise an airway, such as an insertion guide  10 , a flow-through airway fitting  80 , a first tube  20 , a second tube  25 , a third tube  40 , and a fourth tube  50 . The first tube  20  might comprise a first end  24  and a second end  22 . The second tube  25  might comprise a first end  26  and a second end  28 . The third tube  40  might comprise a first end  42  and a second end  44 . And the fourth tube  50  might comprise a first end  52  and a second end  54 . Although shown as separate components, the insertion guide  10 , the flow-through airway fitting  80 , the first tube  20 , the second tube  25 , the third tube  40 , and the fourth tube  50  might comprise a single apparatus by, for example, being fused or otherwise bonded together or integral. Other embodiments are possible as well.  
         [0060]     As shown in  FIG. 6 , the first tube  20  and the second tube  25  can be coupled, with one or more cinches  88 , for example. (In another embodiment, the tubes can be sold joined together as a pair.) In any case, the tubes can be similar to Datex-Ohmeda No. 73318 tubing, for example. As depicted in  FIG. 6 , the cinches  88  can prevent the tubing from separating, and can also provide a mount for other devices, such as for a clip  90 , for example. The clip  90  can then attach the tubing to the patient, the bed, etc., to make for a neater, safer patient environment.  
         [0061]     As shown in  FIG. 7 , the third tube  40  and the fourth tube  50  can also be coupled. In one embodiment, the tubes can be sold joined together as a pair. (In other embodiments, the tubes can be joined in other ways.) In any case, the tubes can be similar to Datex-Ohmeda No. 73318 tubing, for example. By being joined, the tubes can provide a neater, safer patient environment and can prevent the misconnecting of tubes.  
         [0062]     As shown in  FIG. 6 , the first tube  20  and the second tube  25  can each include one or more fittings on its ends to connect to other components. In one embodiment, the second end  24  of the first tube  20  can comprise a fitting  92 , such as a Female Luer Lock, for example. Likewise, the second end  28  of the second tube  25  can comprise a fitting  93 , such as a Male Luer Lock, for example. By making the fittings  92  and  93  different (such as by making one a male and one a female fitting, and/or by making the fittings different sizes, for example), the risk of interchanging the tubes is minimized.  
         [0063]     As shown in  FIG. 7 , the third tube  40  and the fourth tube  50  can each also include one or more fittings on its ends to connect to other components. In one embodiment, the first end  42  of the third tube  40  can comprise a fitting  94 , such as a Male Luer Lock, for example, and the second end  44  of the third tube  40  can comprise a fitting  96 , such as a Male Luer Lock, for example. Likewise, the first end  52  of the fourth tube  50  can comprise a fitting  95 , such as a Female Luer Lock, for example, and the second end  54  of the fourth tube  50  can also comprise a fitting  97 , which can connect to an oxygen supply or other gas source (or another tube, fitting, component, etc.).  
         [0064]     One advantage of using multiple supply and/or exhale tubes is that the length of some of the tubes can be reduced. In one embodiment, the first tube  20  and the second tube  25  can be disposable, and the cost of the disposable portion of the tubing can be reduced by reducing the length of the disposable portion. It can also be easier to pair supply and exhale tubes if multiple supply and/or exhale tubes are used. For instance, by keeping the length of the disposable first tube  20  and the second tube  25  relatively short, the length of the third tube  40  and the fourth tube  50  can be relatively long, and in one embodiment, can be prepackaged as a pair for neater and more convenient routing of the lines from the patient to the oxygen source, carbon dioxide monitor, etc. Other examples are possible as well.  
         [0065]     Referring to  FIG. 6 , the insertion guide  10  might comprise a proximal end  12  and a distal end  14 . Although it need not be, insertion guide  10  might be tapered. For example, the diameter of the distal end  14  might be smaller than the diameter of the proximal end  12 . The outside diameters of the proximal end  12  and the distal end  14  may also be sized to accommodate various size nostrils and/or nasal airway passages, for example. The insertion guide  10  may be different lengths in different embodiments, but in one embodiment, the insertion guide  10  is long enough to allow the distal end  14  to be inserted into a patient&#39;s nasopharynx. In an exemplary embodiment, the insertion guide  10  might be made of a flexible material. For example, the insertion guide  10  might be made of polyvinyl chloride (“PVC”). Other materials, whether flexible or inflexible, are possible as well.  
         [0066]      FIG. 8  depicts an exemplary insertion guide  10  around a portion of the first tube  20  and the second tube  25 .  FIG. 8A  depicts a plan view of the insertion guide  10 .  FIG. 8B  depicts a cross-section view of the insertion guide  10 , with exemplary dimensions included.  FIG. 8C  depicts an elevation view of the insertion guide  10 . And  FIG. 8D  depicts a detail of the insertion guide  10  around a portion of the first tube  20  and the second tube  25 .  
         [0067]     As shown in  FIG. 8 , the proximal end  12  of the insertion guide  10  can comprise a seat  86 . In one embodiment, the seat  86  is 10 mm long, has a 9 mm inside diameter, and has a 12 mm outside diameter.  
         [0068]     In one embodiment, the inside diameter at the seat  86  should be large enough to accommodate one or more tubes, such as the first tube  20  and the second tube  25 , for example. In one embodiment, the first tube  20  and the second tube  25  each have a 3 mm outside diameter.  FIG. 8D  depicts a cross-section of the insertion guide  10  at the seat  86 , and shows the first tube  20 , the second tube  25 , and an open space  89 . In operation, the open space  89  allows sufficient space for exhaled gas to escape, which, in turn, allows the exhale gas monitor (such as a carbon dioxide monitor) to sample the flow of exhaled gas.  
         [0069]     Referring back to  FIG. 6 , as discussed above, the proximal end  12  of the insertion guide  10  might comprise the flow-through airway fitting  80 . In one embodiment, the flow-through airway fitting  80  can engage the seat  86  (shown in  FIG. 8 ) of the insertion guide  10 . The airway fitting  80  can also engage a plurality of tubes, such as the first tube  20  and the second tube  25 , via one or more arms, such as a first arm  82  and a second arm  84 . Each arm might comprise one of any number of mechanisms for engaging one or more tubes, such as an aperture (as shown in  FIG. 9 ) or a clip, for example.  
         [0070]      FIG. 9  depicts an exemplary flow-through airway fitting  80 .  FIG. 9A  depicts a plan view of the insertion guide  10 .  FIG. 9B  depicts an elevation view of the insertion guide  10 . And  FIG. 9C  depicts a cross-section view of the insertion guide  10 . Some exemplary dimensions are included in these figures, although other examples are possible as well.  
         [0071]     As shown in  FIG. 9 , in one embodiment, the flow-through airway fitting  80  can engage the insertion guide  10  (by being slid onto the proximal end of the insertion guide  10 , for example). The airway fitting  80  might also be fixedly attached to the insertion guide  10 , such as by chemical or heat bonding or fusing, adhesives, or being integrally formed with the insertion guide  10 . Other examples are possible as well.  
         [0072]     A feature of one embodiment of the flow-through airway fitting  80  is that it can hold one or more tubes, such as the first tube  20  and the second tube  25 , in place in the insertion guide  10 , while also providing for and maintaining the opening  89  between the tubes and the inside surface of the insertion guide  10 . In one embodiment, the first tube  20  and the second tube  25  can be slid into the openings in the first arm  82  and the second arm  84  of the flow-through airway fitting  80 . Other examples are possible as well.  
         [0073]     The flow-through airway fitting  80  might also comprise a flange or a cuff  18 , which, in one embodiment, can contact a patient&#39;s nostril and can help seal the insertion guide  10  against the patient&#39;s nostril. The cuff  18  might also facilitate sliding the flow-through airway fitting  80  onto the insertion guide  10 .  
         [0074]     In one embodiment, the flow-through airway fitting  80  has a 12 mm inside diameter, a 15 mm outside diameter, and is 10 mm long. In one embodiment, the cuff  18  has a 22 mm outside diameter. As shown in  FIG. 9C , in one embodiment, the arms  82  and  84  are connected to the non-cuff end of the flow-through airway fitting  80 , and extend 5 to 8 mm longitudinally from the non-cuff end. Each arm can also extend transversely into the opening of the flow-through airway fitting  80 .  FIGS. 9A and 9B  show some example dimensions of such a construction. Each arm might also comprise an opening to accommodate a tube, and each opening might have an inside diameter of 3 mm (to accommodate a tube with a 3 mm outside diameter, for example).  
         [0075]      FIG. 10  depicts an alternate embodiment of the flow-through airway fitting  80 . In an alternate embodiment, one or more of the arms, such as the first arm  82 , of the flow-through airway fitting  80  can be oriented to bend one or more of the tubes (or to accommodate one or more bent tubes), such as the first tube  20 , at an (approximately) 90 degree angle. In this way, the bent tube or tubes can be routed in any direction, such as over a patient&#39;s ears, allowing access to a patient&#39;s face. Other examples are possible as well.  
       2. Exemplary Operation  
       [0076]     Referring to  FIG. 6 , in one embodiment, a user such as an anesthesiologist (or any other medical or non-medical person) might connect exhale and supply tubes, such as the first tube  20  and the second tube  25 , to the insertion guide  10 . For example, the first tube  20  and the second tube  25  might be threaded through the openings in each of the first arm  82  and the second arm  84  of the flow-through airway fitting  80 , as shown in  FIG. 6 . The first end  22  of the first tube  20  and the first end  26  of the second tube  25  might then each extend into the flow-through airway fitting  80  or the insertion guide  10 , and be held in place by the arms of the airway fitting  80 .  
         [0077]     To deliver oxygen to or exhale gas from a patient&#39;s nasopharynx, the user can insert the insertion guide  10  into a patient&#39;s nasal passage such that the distal end  14  of the insertion guide  10  extends toward the patient&#39;s nasopharynx. The proximal end  12  of the insertion guide  10  might then frictionally engage the patient&#39;s nostril, and might provide a seal or partial seal around the patient&#39;s nostril.  
         [0078]     To place a patient&#39;s nasopharynx in fluid communication with a gas source, such as an oxygen source, or with a gas monitor, such as a carbon dioxide monitor, the user might connect the first tube  20  directly to a gas monitor and might connect the second tube directly to a gas source. As shown in  FIG. 6 , however, the first tube  20  can be in fluid communication with the third tube  40 , and the third tube  40  might then directly connect to a gas monitor (or to other tubes, connections, etc., which might fluidly communicate with the gas monitor). Likewise, the second tube  25  can be in fluid communication with the fourth tube  50 , and the fourth tube  50  might then directly connect to a gas supply (or to other tubes, connections, etc., which might fluidly communicate with the gas supply). Other examples are possible as well.  
         [0079]     Thus, in one embodiment, the second tube  25  and the fourth tube  50  might provide for fluid communication between the patient&#39;s nasopharynx and an oxygen supply  70 . The oxygen supply  70 , in turn, might apply a low, positive pressure through the second tube  25  and the fourth tube  50 . Likewise, the first tube  20  and the third tube  40  might provide for fluid communication between the patient&#39;s nasopharynx and a carbon dioxide monitor  60 . The carbon dioxide monitor  60 , in turn, might apply a low, negative pressure through the first tube  20  and the third tube  40 .  
         [0080]     In accordance with one embodiment, the transnasal ventilation apparatus can provide for a steady state oxygen supply to/carbon dioxide collection from a patient. As the patient inhales, the patient can draw the lightly pressurized oxygen from the oxygen supply through the fourth tube  50  and through the second tube  25  into the patient&#39;s nasopharynx. As the patient exhales, the patient can discharge the exhale gases from the patient&#39;s nasopharynx into and through the first tube  20  and the third tube  40  to the carbon dioxide monitor, and through the opening  89  in the airway fitting  80  to the atmosphere. The negative pressure applied by the carbon dioxide monitor  60  can, in turn, withdraw the exhale gases to the carbon dioxide monitor  60 .  
         [0081]     Both supply gas and exhale gas flow to and from the patient&#39;s nasopharynx can be enhanced by the opening  89  in the flow-through airway fitting  80 . For example, as the patient exhales, some exhaled gas can escape through the opening  89  to the ambient air. The opening  89 , and the resultant escaped gas, can be important because some exhale gas monitors need to sample a flow of exhale gas to function properly. The opening  89  can help prevent the exhale gas flow from “dead-ending,” and can encourage and facilitate gas flow to the exhale gas monitor.  
       CONCLUSION  
       [0082]     Several exemplary embodiments of the present invention have been described above. Those skilled in the art will understand, however, that changes and modifications may be made to these embodiments without departing from the true scope and spirit of the present invention, which is defined by the claims.