Abstract:
An artificial airway device (also known as a Laryngeal Mask Assembly, “LMA,” or Disposable Laryngeal Mask Assembly, “DLMA”) used to facilitate lung ventilation in an unconscious patient and methods for using an artificial airway device. The device includes a curved but flexible airway tube and a hollow mask support at one end of the airway tube. The mask support includes a fairly rigid support base and a flexible, generally annular peripheral skirt which is attached to the support base. A distal tip of the mask support is narrowed and projects outwardly, thereby providing a nose portion which is used to easily locate the distal tip of the mask in the entrance into the esophagus. The skirt is capable of conforming to the space behind the larynx so as to form a seal around the circumference of the laryngeal inlet without penetrating into the interior of the larynx. The skirt surrounds a hollow interior space or lumen of the mask base into which the airway tube opens. During insertion of the LMA into the patient, the skirt is contracted, to make the LMA easier to insert into the patient&#39;s airway. The skirt of the mask can be selectively manipulated, e.g. expanded, to improve the sealing contact with the tissues around the circumference of the laryngeal inlet. The skirt, when expanded, and the support base form a “cup-like” shape, which enhances the stabilization and sealing of the mask in the airway.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to artificial airway devices used to facilitate lung ventilation in unconscious patients, and more specifically to devices designed for placement in the oropharynx of the patient in order to prevent airway obstruction an to permit either spontaneous or controlled ventilation. 
     2. Description of Related Art 
     To maintain open the airway of an unconscious patient under general anesthesia, it is common practice to use an endotracheal tube, which is a flexible tube of rubber or plastic which is inserted down through the trachea. Prior art endotracheal tubes frequently include an inflatable cuff around a distal end, which distal end is inserted into the trachea. The inflatable cuff is used to secure the endotracheal tube in place. 
     Typically, the endotracheal tube is introduced through nose and the larynx into the trachea or windpipe, and then the cuff is inflated through a small auxiliary tube in order to form a seal against the wall of the trachea. Introduction of the endotracheal tube into a patient is a skilled operation normally requiring use of a laryngoscope to guide the tube through the larynx, past the vocal cords and into the trachea. Intubation using an endotracheal tube is difficult or even impossible in some patients. Moreover, there is a significant risk of damage to soft tissues or to the larynx when using an endotracheal tube. Likewise, there is a risk of accidental, but highly undesirable, intubation of the esophagus or of the right or left main bronchus when using an endotracheal tube. 
     Alternatively, oro- or naso-pharyngeal airway devices may be used to maintain open the airway of a patient under general anesthesia. An oro- or naso-pharyngeal airway is a flexible tube extending from the mouth (oro-pharyngeal airway) or nose (naso-pharyngeal airway) into the patient&#39;s pharynx but not into the patient&#39;s larynx. An oro- or naso-pharyngeal airway is normally used in conjunction with a face mask over the patient&#39;s mouth and/or nose, unlike an endotracheal tube, which normally is not used with a mask. While preventing obstruction of the airway by the tongue, an oro- or naso-pharyngeal airway device cannot be used conveniently for controlled ventilation of the patient and does not prevent inhalation of extraneous matter (i.e., aspiration). For these and other reasons this type of device is less desirable in many applications. 
     Prior art artificial airways (see for example, U.S. Pat. Nos. 4,509,514; 4,995,388; 5,241,956; 5,249,571; 5,282,464; 5,297,547; 5,305,743; 5,355,879; 5,584,290; 5,632,271 and 5,682,880 to Archibald I. J. Brain—collectively, the “Brain patents”) use a curved tube and a laryngeal mask portion at one end of the tube. The mask portion includes a flexible annular inflatable collar which surrounds a hollow interior space of the mask portion. The mask portion is pre-formed with a roughly elliptical shape which is purported to be capable of conforming to, and fitting within, the space behind the larynx to form a seal around the circumference of the laryngeal inlet without penetrating into the interior of the larynx. The curved tube opens into the mask portion and provides an airway with the axis of the tube substantially aligned with the length of the elliptical formation of the mask portion. 
     In the Brain patents, the curved tube opens into a lumen of the mask through an aperture which is provided with flexible cross-bars to prevent the aperture from being obstructed by the epiglottis, while permitting passage of a second smaller tube, such as an endotracheal or endobronchial tube, a suction catheter, or an inspection tube such as a fiber-optic broncho- or layrngoscope. 
     Even with the seal achieved by the inflatable collar in the Brain patents, there is a risk in some circumstances that if the contents of the stomach are regurgitated by the patient, the regurgitated material will travel from the esophagus and enter the bronchial tubes. The introduction of such foreign matter into the lungs, known as aspiration, is undesirable and should be avoided. Some of the Brain patents (e.g., U.S. Pat. Nos. 4,995,388; 5,241,956 and 5,632,271) attempt to solve this problem using gastric drainage features adjacent the inflatable collar. 
     Prior art artificial airway devices may include a drainage tube, such as those described above in certain of the Brain patents, having one end region arranged for insertion with the mask portion and the other end capable of being positioned below the patient foi extracting fluid from the area of the mask portion by siphonic action, or alternatively, the other end may be connected to an apparatus for extracting the fluid by suction. Typically, the drainage tube is of a smaller diameter than the airway tube so that the drainage tube may be accommodated within the airway tube, with the one end region opening into the lumen of the mask portion. 
     When the mask portion has an upstanding collar surrounding the lumen of the mask portion, the one end region of the drainage tube may be forked and adhered to the outside of the collar, with openings of the forked portions being arranged to extract fluid from the area around the exterior of the mask portion. 
     Alternatively, the one end region of the drainage tube may open into the esophagus when the mask portion has been inserted into the laryngeal space. For example, the one end region of the drainage tube may extend past the distal end of the mask portion so as to pass through the upper esophageal sphincter muscle. The drainage tube bifurcates at the distal end of the mask to provide fork portions lying adjacent respective lateral posterior surfaces of the flexible annular inflatable collar. 
     SUMMARY OF THE INVENTION 
     The present invention is an artificial airway device which is designed to overcome certain shortcomings which have been discovered with the use, in practice, of artificial airways of the type described in the Brain patents. The prior art laryngeal mask devices as shown in the Brain patents have a number of shortcomings, which make them ineffective or unusable in certain situations, and also result in such airways being expensive to use and therefore inappropriate for Emergency Medical Service (EMS) use. For example, the airway devices as shown in the Brain patents can have a tendency for the uninflated collar to pleat or fold during insertion, which results in incomplete expansion of the collar during inflation. Incomplete inflation results in leakage, which prevents effective use of the artificial airway. Furthermore, the inflatable collars often do not conform well to the airway, also resulting in leakage. In addition, it is often difficult for the individual inserting the artificial airway to determine whether the inflatable collar is completely inflated. In order to overcome these inflation and leakage problems, artificial airways with inflatable collars are often overinflated by the individual inserting the airway to pressures in the range of 20-30 cmH 2 O, which pressures are sufficiently high that they can cause damage to the soft tissue against which the inflatable collar seals. 
     Another shortcoming of artificial airways using inflatable collars is that the mucous membranes which are in contact with the inflatable collar can become dried or irritated as the result of the contact pressure from the inflatable collar. Another difficulty with artificial airways using an inflatable collar is that it is often difficult for the individual inserting the airway to determine when the airway mask is properly in place over the larynx. This uncertainty of proper placement makes complete sealing more difficult, and also complicates insertion of the airway into the patient. Additionally, artificial airways with inflatable collars, because they must be completely inflated to properly seal, require a large number of sizes to accommodate the different sizes of airways of the patients to which they are administered. 
     Prior art artificial airways can also cause difficulties in ensuring that the airway does not accidentally enter the esophagus during insertion. Furthermore, these prior art artificial airways often do not have adequate mechanisms to anchor the mask in place after insertion. Finally, the prior art artificial airways often do not prevent gastric reflux, which may lead to aspiration, making them inappropriate for EMS use and make them only appropriate for controlled surgical use. 
     The present invention is an artificial airway device (also known as a Laryngeal Mask Assembly, “LMA,” or Disposable Laryngeal Mask Assembly, “DLMA”) used to facilitate lung ventilation in an unconscious patient and methods for using an artificial airway device, which overcome the shortcomings of prior art artificial airway devices. The device of the present invention includes a curved but flexible airway tube and a hollow mask support at one end of the airway tube. The mask support includes a fairly rigid support base which is, generally, pear shaped and a flexible, generally annular peripheral skirt which is attached to the support base. A distal tip of the mask support is narrowed and projects outwardly, thereby providing a nose portion which is used to easily locate the distal tip of the mask in the entrance into the esophagus. This nose portion helps ensure that the individual inserting the airway accurately positions the mask portion over the patient&#39;s laryngeal opening. The skirt is capable of conforming to the space behind the larynx so as to form a seal around the circumference of the laryngeal inlet without penetrating into the interior of the larynx. The skirt surrounds a hollow interior space or lumen of the mask base into which the airway tube opens. During insertion of the LMA into the patient, the skirt is contracted, to make the LMA easier to insert into the patient&#39;s airway. The skirt of the mask can be selectively manipulated, e.g. expanded, to improve the sealing contact with the tissues around the circumference of the laryngeal inlet. A biasing mechanism connected to the skirt automatically deploys the skirt into the expanded condition when a plunger mechanism is released by the operator. The skirt, when expanded, and the support base, form a “cup-like” shape, which enhances the stabilization and sealing of the mask in the airway. The skirt is preferably formed of a flexible sheet material which may be at least partially permeable to fluids, such as Coltran™ (manufactured by 3M and used in transdermal applications) or similar porous polyethylene or polymeric materials, thereby allowing the application of saline or other fluid substances to the tissue in contact with the skirt. This feature of the present invention prevents drying of the mucous membranes which are in contact with the skirt. 
     The shape of the deformable skirt of the mask ensures that it closely approximates the shape of the space between the laryngeal inlet and the walls of the lower part of the throat behind the laryngeal inlet. Because the skirt of the LMA of the present invention expands or “flowers” out uniformly with consistent pressure, only a few mask sizes are needed to accommodate a wide range of patient airway sizes, therefore reducing the number of sizes needed. This feature of the present invention also reduces costs, and makes the invention more amenable to EMS use, since fewer devices, and less storage space is needed by the EMS crew. In addition, the shape of the mask portion in its unexpanded or contracted position is such that it provide a good tactile indication when the mask portion is properly in place in the airway, thereby enhancing the ease and accuracy of insertion of the LMA in the patient. The mask portion includes a distal nose portion which seats in the entry to the esophagus during insertion, thereby providing an indication to the individual inserting the LMA that it is properly in place. Since the walls of tissue forming the back of the throat are relatively rigid, deformation of the mask skirt forces the skirt more tightly against the tissues surrounding the laryngeal inlet, resulting in an airtight seal while anchoring the mask in position. Moreover, because the skirt is caused to “cup” the laryngeal space, a more secure fit with greater integrity is obtained. In addition, because inflation is not used to expand the skirt, there is no risk of overinflation and the resultant potential damage to tissue, and pleating is also prevented. 
     The LMA of the present invention is designed to be easy and convenient to insert in the majority of patients. The LMA may also be inexpensively manufactured in quantity, thereby allowing it to be disposable. As a result, the LMA of the present invention may be more readily used in EMS or other non-hospital applications, as well as in surgical applications. When the distal tip of the mask portion reaches the upper end of the esophagus, a definite end-point can be felt by the individual inserting the LMA, indicating that the mask portion is correctly placed. The skirt is then manipulated by a control mechanism, passing through the airway tube and into the support base, to form the airtight seal. The mask portion does no, enter the larynx or trachea, so the risk of damage to these structures is avoided. 
     Likewise, the risk of accidental entry of the mask portion into the esophagus or one of the main bronchi is also avoided with use of the LMA of the present invention. Once in place, the LMA is generally used to allow the lungs to be ventilated by positive pressure. Alternatively, the patient may be permitted to breathe spontaneously after insertion of the LMA. 
     In addition, an inflatable bag and an attached tube may be inserted into the stomach of the patient via the tube and mask portion. The bag can be inflated and used as an anchor to secure the mask portion in position, and the attached tube may be used as a guide for inserting the mask portion into the patient&#39;s airway. The bag may also prevent gastric reflux from the stomach and aspiration into the patient&#39;s airway, making the LMA of the present invention more adaptable to emergency and EMS use, as well as adaptable to a larger variety of surgical applications than prior art artificial airways. As an alternative, a palate assist mechanism may be provided with the LMA of the present invention, to anchor the LMA in place using the patient&#39;s hard palate and tongue. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a partially broken away elevation view of one embodiment of the laryngeal mask assembly of the present invention. 
     FIG. 1 a  is a cross-sectional view of the airway tube, through line IA—IA of FIG.  1 . 
     FIG. 2 is an exploded perspective view of one embodiment of the mask support of the laryngeal mask. 
     FIG. 3 a  shows a plan view of the upper support plate of the embodiment of FIG.  2 . 
     FIG. 3 b  shows a plan view of the underside of the upper insert of the embodiment of FIG.  2 . 
     FIG. 3 c  shows a plan view of the underside of the lower insert of the embodiment of FIG.  2 . 
     FIG. 3 d  shows a plan view of the lower support plate of the embodiment of FIG.  2 . 
     FIG. 3 e  is an elevation view of a side of the upper insert of the embodiment of FIG.  2 . 
     FIG. 3 f  is a perspective view of the upper insert of the embodiment of FIG.  2 . 
     FIG. 3 g  is an elevation view of an end of the upper insert. 
     FIG. 3 h  is an elevation view of a side of the lower insert of the embodiment of FIG.  2 . 
     FIG. 3 i  is a perspective view of the lower insert of the embodiment of FIG.  2 . 
     FIG. 3 j  is an elevation view of ar end of the lower insert of the embodiment of FIG.  2 . 
     FIGS. 4 a  and  4   b  show cross-sectional elevation views of the mask portion in the contracted and expanded positions, respectively, for the embodiment shown in FIG.  1 . 
     FIGS. 5 a  and  5   b  show partial plan views of the manipulation ring for the skirt in the contracted and expanded positions, respectively, through lines IVA—IVA and IVB—IVB in FIGS. 5 a  and  5   b , respectively. 
     FIG. 5 c  is a cross-sectional view of the support device, through line VC—VC of FIG. 5 a.    
     FIG. 6 is an end view of the cylinder of the embodiment of FIG.  1 . 
     FIG. 6 a  is a cross-sectional view of the cylinder, through line VIA—VIA of FIG.  6 . 
     FIG. 7 is a plan view of the outer sleeve for the plunger cap shown in FIG.  1 . 
     FIG. 7 a  is a cross-sectional elevation view of the outer sleeve, through line VIIA—VIIA of FIG.  7 . 
     FIG. 8 is a partial plan view of the expansion ring with an attached beaded chain. 
     FIG. 8 a  is an elevation view of the control ring support of the expansion ring. 
     FIG. 9 is a partial plan view of the ring tip used in the embodiment shown in FIGS. 5 a  and  5   b.    
     FIG. 9 a  is a partial elevation view of the ring tip shown in FIG.  9 . 
     FIG. 9 b  is a sectional view of the ring tip taken along the lines IXB—IXB in FIG.  9 . 
     FIG. 10 is a partially cross-sectional view of the laryngeal mask assembly of the present invention, as inserted in the airway of a patient. 
     FIG. 11 is a cross-sectional, partial assembly, elevation view of a second embodiment of the upper support plate and upper insert of the present invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1 is a partially broken-away elevation view of one embodiment of the laryngeal mask assembly (LMA) or disposable laryngeal mask assembly (DLMA) of the present invention. In the embodiment of FIG. 1, the mask portion  100  is connected to a partially curved away tube  200  which includes a plunger cap  300 . An anchor balloon unit or fluid supply unit  400  is an optional feature for certain embodiments of the present invention. 
     In the embodiment shown in FIG. 1, the mask portion  100  includes an upper support plate  110  and an upper insert  120 . The upper insert  120  is attached to and fits into an opening in the upper support plate  110 . A flexible skirt  150 , formed of a thin, flexible, biologically-neutral material which may be at least partially permeable to fluids, such as Coltran™ (manufactured by 3M and used in transdermal applications) or similar porous polyethylene or polymeric materials, is attached to and projects from the upper support plate  110 . The use of a partially permeable material allows the application of saline or other fluids to the tissue which is in contact with the flexible skirt when the LMA of the present invention is deployed and expanded in place in the patient&#39;s P airway, thereby allowing mucous membranes to be irrigated and/or drugs to be administered to that tissue. The permeability of such a material to gases, such as air, oxygen or anesthesia, is sufficiently slow so that there is no appreciable leakage of the delivered gas through the skirt  150 . The skirt  150  is also attached to a lower support plate  140 . The skirt  150  can be expanded or contracted by the individual responsible for inserting the LMA into the patient P by operating the plunger cap  300 . The plunger cap  300  controls the operation of an expansion ring  500  within the skirt  150 , thereby controlling expansion and contraction of the mask portion  100 . 
     The airway tube  200  is fixed to the mask portion  100 . In the preferred embodiment of FIG. 1, the airway tube  200  is made of a material which is sufficiently flexible to permit it to deform so as to fit down the patient&#39;s airway (see FIG.  10 ), but is also sufficiently stiff to permit the airway tube  200  and the mask portion  100  to be accurately positioned manually in the patient P. Polyvinyl chloride (PVC), or any other known inexpensive, durable and partially flexible material may be used as the material from which the airway tube  200  is made. 
     The airway tube  200  includes a cent al bore  201  through which various fluids (e.g., anesthesia, oxygen, air) can be administered to the patient, if and when desired. In addition, the airway tube  200  includes a small conduit  202  in the tube wall. The conduit  202  may be used to pass a balloon tube  401  and a balloon  402  into the patient&#39;s P esophagus E and stomach S (FIG.  10 ). Alternatively, conduit  202  may be used to transmit a fluid to inflate a palate assist mechanism  800 . The airway tube  200  in the embodiment of FIG. 1 also includes a pair of conduits  203  formed in the wall of tube  200 . These conduits carry, in the embodiment of FIG. 1, beaded chains  304  which are attached to the inner end of the cylinder  302  of the plunger cap  300 . Although beaded chains  304  are used in the preferred embodiment, it is to be understood that any elongated flexible member, such as wires, cords, etc., may be used to contract and expand the skirt  150  in the manner described below. A balloon tube access port  303  is formed as part of an outer sleeve  301  of the plunger cap  300 , and the balloon tube access port  303  permits the balloon  402  and balloon tube  401  to be inserted into the small conduit  202 . 
     The cylinder  302  is arranged to move within the outer sleeve  301  of the plunger cap  300 . Ends of the beaded chains  304  are connected to and movable with the cylinder  302 , while the other ends of beaded chains  304  are preferably integral with the expansion ring  500  used to control the deployment of the skirt  150 . 
     In the embodiment of FIG. 1, the anchor balloon  400  is an optional feature, and is therefore shown in dashed lines. When used with the LMA of the present invention, anchor balloon  402  is attached to a balloon tube  401  which passes through the mask portion  100  (as described below with reference to FIG.  11 ), through the airway tube  200  (via small conduit  202 ) and through a portion of the plunger cap  300  to a connector  403 . The connector  403  is selectively connected to any source of moderate fluid pressure, such that pressurized fluid (such as air or water) is supplied, via tube  401 , to the balloon  402 . When the pressurized fluid is supplied to the balloon  402 , the balloon  402  expands to take the configuration shown with reference numeral  402  in FIGS. 1 and 10. In the absence of pressurized fluid, the balloon is deflated to the outline shown with reference numeral  402 A. The balloon  402  is deflated when it is passed through conduit  202 . 
     In one method of inserting the LMA of the present invention into a patient, the deflated balloon  402 A and the balloon tube  401  are inserted through the airway tube  200  and the mask  100  so that the LMA may slide along the balloon tube  401 . The balloon tube  401  and deflated balloon  402 A may thereafter be inserted down the patient&#39;s P esophagus E and into the patient&#39;s P stomach S (see FIG.  10 ). The balloon  402  is then inflated through the connector  400  (and the balloon tube  401 ) so that the inflated balloon  402  is anchored in the Patient&#39;s P stomach S and the inflated balloon  402  blocks gastric reflux from exiting into the esophagus. The LMA of the present invention is thereafter slid down the balloon tube  401  until it is in place in the patient&#39;s P airway, directly above the patient&#39;s P larynx L. The balloon tube  401  therefore assists in guiding the LMA into the patient&#39;s P airway, while the expanded balloon  402  assists in retaining the mask  100  in place within the patient P. As an alternative method of anchoring the LMA of the present invention in place, the mask portion  100  is first inserted in place in a patient P. The balloon  402  and the balloon tube  401  may then be inserted into the patient P, through the airway tube  200  and the mask  100 , into the patient&#39;s P stomach S. The balloon  402  is then inflated through the connector  400  (and tie balloon tube  401 ) so that the inflated balloon can act as an anchor to assist in retaining the mask  100  in place within the patient P and preventing gastric reflux. 
     An alternative configuration for anchoring the LMA of the present invention in place is also shown in FIGS. 1 and 10. A palate assist  800 , which is in the form of a fluid-expandable pillow, is mounted on the shaft of the airway tube  200 , in a location on the tube  200  where it is adjacent the hard palate H and the tongue T of the patient when the LMA of the present invention is in place over the larynx L. During insertion of the LMA of the present invention into the airway of the patient P, the palate assist  800  is in a contracted position  800 A. An opening (not shown) through the wall of airway tube  200  leads from the conduit  202  to the interior of the palate assist  800 . Once the LMA of the present invention is in place, fluid may be applied to connector  400 , thereby expanding the palate assist  800  to the condition shown with reference numeral  800  in FIGS. 1 and 10. The palate assist  800 , in the expanded condition, contacts the hard palate H and tongue T of the patient P, thereby anchoring the LMA of the present invention in place within the airway of the patient P. In the embodiment of the present invention which uses a palate assist, the end of the conduit  202  near the mask portion  100  is closed off by a shelf  202 A (FIGS. 4 a  and  5   a ), so that fluid applied to conduit  202  travels only to the interior of palate assist  800 . 
     Referring now to FIG. 2, there is shown an exploded perspective view of the support structure for one embodiment of the mask portion  100 . In particular, an upper support plate  110  is a generally curved component which is, typically, formed of a flexible plastic or rubber material. A shallow recess  112  is formed around the periphery of the plate  110 . The thin membrane which forms skirt  150  is affixed to the recess  112  (see FIGS. 4 a  and  4   b ) by any known attachment method, which may include the use of an adhesive, or a hot seal. The skirt  150  is preferably formed of two or more pieces of material which are adhesively connected or hot sealed together to form the three-dimensional skirt configuration as shown in FIGS. 1 and 4 b . The upper support plate  110  includes an opening  111  in an upper surface to receive the upper insert  120 . 
     The upper insert  120  is preferably formed of a fairly rigid plastic or rubber material. The upper support plate  110  and upper insert  120  are curved in a generally clamshell shape. The upper insert  120  fits securely in and engages the opening  111  in the upper support plate  110 . The upper surface of upper insert  120  passes through the opening  111  in upper support plate  110  and fits together so that the upper surfaces of upper insert  120  and upper support plate  110  are flush. A shelf or shoulder  121  is formed around the edge of upper insert  120  and engages a similar counterpart shoulder formed underneath the opening  111  on the inner surface of upper support plate  110 . An elongated nose  124  extends from one end of the upper insert  120 . A spring post  126  is located on an underside of elongated nose  124 . A spring  511  is attached at one end to the spring post  126 . 
     A generally partially cylindrical port  123  extends upwardly from the top surface, and downwardly from the bottom surface, of the upper insert  120 . The lower end of port  123  encircles the upper end of a port  133  on the lower insert  130 , and is angled downwardly. The upper end of the cylindrical port  123  includes a slot  129  into which the end of the airway tube  200  fits. 
     A lower insert  130  which may be formed of a fairly rigid plastic or rubber material fits together with upper insert  120 , and is also shaped to comfort to the curvature of a lower support plate  140  and to fit within a recess  141  in lower support plate  140 . The lower insert  130  includes an elongated nose  131 . 
     A substantially cylindrical port  133  extends upwardly from the upper surface of the lower insert  130 . The port  133  is inserted into port  123  in the upper insert  120 . A radiused portion or inset portion  136  is formed in the outer surface of port  133 . The radiused portion  136  is angled downwardly. This radiused portion  136 , together with the bottom of the port  123 , form a channel in which control rings  580  (FIG. 8) slide. A slot  138  is formed on both sides of the port  133  to allow passage of a non-beaded portion  304 A of beaded chain  304 . 
     The front of the port  133  may includes an aperture or slot  132  (shown in dashed lines in FIGS. 2,  3   h  and  3   i ). This slot  132  allows the passage  128  for balloon tube  401  to pass through the lower insert  130 , in the embodiment shown in FIG.  11 . 
     A pair of pulleys  137  are disposed at the corners of the lower insert  130 , and are mounted on the lower insert for rotation on a pair of posts  139 . The pulleys are used to guide and control the expansion and contraction of the expansion ring  500 , which expands and contracts the skirt  150 . Resilient retainers  85  (shown in dashed outline) such as rubber bands, have one end looped around posts  139  and extend around the exterior of port  133 . The retainers  85  are used in the LMA of ale present invention to control and bias the position of expansion ring  500  and skirt  150 . The opposite end of resilient retainers  85  are looped around the stems  585  of supports  506  and  507 , thereby biasing the skirt  150  into the expanded position shown in FIGS. 4 b  and  5   b . The elastic retainers  85  also extend around the outer surface of port  133 . 
     Located between upper and lower inserts  120 ,  130  is a ring tip  501 . The ring tip  501  is preferably integrally formed with the ring arms  508  and  509  as part of a composite expansion ring  500 , although as shown in FIG. 2, the ring tip  501  can include ends  560  with bores  561  for receiving ends of the ring arms  508  and  509 . 
     The ring tip  501  includes an arcuate peripheral nose piece  901 . The nose piece  901  has the arcuate (or curved) configuration to assist in positioning the mask portion  100  in the laryngeal space in a patient without causing a substantial amount of trauma, and assists in seating the mask portion  100  in place by entering into the entry to the esophagus E. The curved configuration also smoothly conforms to the shape of the other portions of the mask assembly. 
     The ring tip  501  is bowed slightly upwardly to conform to the clamshell shape of the mask portion elements shown in FIG.  2 . The periphery of the ring tip  501  includes channels  910  which cooperate with the groove  810  in the control ring support  506 ,  507  and the ring arms  508 ,  509  shown in FIG.  8 . 
     A slot  510  in ring tip  501  fits around post  134  on lower insert  130 . This slot  510 , as it interacts with post  134 , controls the movement of the ring tip  501 , and ensures that the ring tip is deployed only radially outwardly, and does not move laterally, thereby ensuring that the ring tip  501  remains in place in the entry to the esophagus E during deployment. 
     A spring  511 , preferably in the form of a rubber band, is connected at one end to spring post  126  on upper insert  120 , and spring  511  is connected at the other end to spring post  570 , including slot  571 , on ring tip  501 . The spring  511  is used to bias the ring tip  501  outwardly, to assist in the expansion or deployment of the ring tip  501  and expansion ring  500 . 
     A lower support plate  140 , which may be formed of formed of a flexible plastic or rubber material has a hollow curved configuration of a generally clamshell shape. A recess  141  is formed in the upper surface of lower support plate  140 . The recess  141  receives and secures the lower insert  130 . The lower support plate also includes a shallow recess  144  (see FIGS. 4 a  and  4   b ) which is formed around the periphery of the lower plate  150 . The thin membrane which forms skirt  150  is affixed to the recess  144  by any known attachment method, including the use of an adhesive, or by a hot seal. 
     Referring now to FIGS. 3 a  through  3   j , there are shown various views of the components in FIG.  2 . In FIG. 3 a , there is shown a plan view of the upper support plate  110 . The recess  111  is shown formed in the upper surface of upper support plate  110 . The shoulder  112  is disposed around the perimeter of plate  110 . 
     FIG. 3 b  is a plan view of the underside of the upper insert  120 , which includes the elongated nose  124 , upon which spring post  126  is mounted. The upper insert  120  is received and is held in the recess  111  of the upper support plate  110 . As shown in FIG. 11, in one embodiment, the elongated nose  124  may include an aperture  125  passing through elongated nose  124  which communicates with aperture  127 , via passage  128 , in the port  122  in order to receive the balloon  402  and the balloon tube  401 , when those components are used with the LMA of the present invention. The aperture  125 , when used, allows the balloon  402  and balloon tube  401  to pass from the conduit  202 , through the mask portion  100  and to the exterior of the mask portion  100 . 
     The shoulder  121  interacts with the inner surface of upper support plate  110  so that the upper surface of upper insert  120  and the upper surface of upper support plate  110  are flush. 
     Referring to FIG. 3 d , the lower support plate  140  has a plurality of apertures  142  disposed in and through the surface of the lower support plate  140 . These apertures  142  are used to pass air, oxygen, anesthesia or other fluid from the airway tube  200  through the mask portion  100  and into the patient&#39;s P larynx L. A recess  141  is formed in the upper surface of lower support plate  140  to receive the lower insert  130 . The recess  141  may be spade-shaped and surrounds the apertures  142 . 
     Referring now to FIG. 3 c , there is shown a plan view of the underside of the lower insert  130 . The nose  131  extends outwardly and is adapted to be inserted into the extended portion of recess  141  in lower support plate  140 . 
     The posts  139  are shown integrally formed on the upper surface of lower insert  130 . These posts  139  have looped around them one end of the resilient retainers  85 , which are used to bias and control the control rings  580  which are in turn used to expand and contract the skirt  150 . The posts  139  also have mounted upon them, for rotary movement, the pulleys  137 . The retainers  85  may be in the form of elastic or rubber bands and are located between the upper and lower inserts  120 ,  130  and encircle the port  133  so that the retainers bias the skirt into the expanded position shown in FIGS. 4 b  and  5   b.    
     The port  133  extends upwardly from the surface of lower insert  130  and includes the radiused portion  136 . In addition, a post  134  is provided to control movement of the ring tip  501 . 
     Referring now to FIGS. 4 a  and  4   b , there are shown plan views of an assembled mask portion  100 , in contracted and expanded positions, respectively. In FIGS. 5 a ,  5   b  and  5   c , the upper insert  120  is shown mounted in the upper support plate  110  which is mounted above lower support plate  140 . The lower insert  130  is mounted beneath the upper support plate  110  in lower support plate  140 . A non-beaded portion  304 A of the beaded chains  304  extends through slots  138 , as may be seen in FIG. 5 a.    
     Referring concurrently to FIGS. 4 a ,  4   b ,  5   a  and  5   b , there is shown the expansion ring  500  (which is partially broken away for clarity) and the control components used to expand and contract the expansion ring  500 . The expansion ring  500 , which includes ring tip  501  and ring arms  508 ,  509 , is disposed between plates  120  and  130  when the mask portion  100  is assembled (see FIGS. 4 a  and  4   b ). In particular, FIGS. 4 a  and  5   a  show the expansion ring  500  in the closed or contracted position. In this condition, the skirt  150  is deployed limply around the periphery of the mask portion  100 . Conversely, FIGS. 4 b  and  5   b  show the expansion ring  500  in the open or fully deployed or expanded position. In this condition, the skirt  150  is deployed around the mask portion  100  to form the seal in the space above the larynx L (FIG.  10 ). 
     As shown in FIGS. 5 a ,  5   b  and  8 , the ends of the expansion ring  500 , i.e., the ends of ring arms  508 ,  509 , are preferably integrally molded with the non-beaded portions  304 A of beaded chains  304 . Beaded chain  304  passes through conduits  203  in airway tube  200 , while non-beaded portion  304 A passes through slot  138 , over pulleys  137  and around port  133 . The opposite ends of the beaded chains  304  are connected to the inner end of cylinder  302  of plunger cap  300 . Thus, when the cylinder  302  is pulled (or otherwise positioned) axially outwardly relative to the plunger cap  300 , chains  304  pull the ends of expansion ring  500  into a relatively tightly curled or coiled configuration as shown in FIGS. 5 a  and  5   b . In this configuration, the flaccid skirt  150  hangs limply from the mask portion  100 . The contracted or coiled configuration of the expansion ring  500  is used during insertion of the mask portion  100  into the patient&#39;s P airway. 
     Conversely, when the cylinder  302  is released or otherwise moved axially inwardly, the resilient retainers  85  pull on stems  585  of expansion arms  508 ,  509 , and thus pull the ends of the expansion ring  500  to the position shown in FIG. 4 b  and  5   b , at the same time pulling the beaded chains  304  and cylinder  302  axially inwardly and sliding the control rings  580  around the port  133  in the radiused portion  136 . The expansion ring  500  is relaxed upon release of the cylinder  302 , so that it expands relative to the tightly coiled condition in FIGS. 4 a  and  5   a . When the ring  500  expands (as shown in FIGS. 4 b  and  5   b ) the skirt  150  is forced outwardly in a uniform manner around the entire periphery of the expansion ring  500 . As is seen in FIG. 4 b , the expanded skirt  150  is forced both radially outwardly and axially outwardly relative to the mask support  100 . This radially and axially outward motion creates a “cup-like” configuration C of the skirt  150  relative to the mask portion  100 , which aids in sealing the mask portion  100  against the laryngeal opening. 
     In the assembled device, the expansion ring  500  is mounted between the inserts  120  and  130  shown in FIG.  2 . In particular, the expansion ring  500  fits over the port  133  and each of the control rings  580  are looped over the port  133  in radiused portion  136  so that the control rings slide circumferentially around radiused portion  136 . Because radiused portion  136 , and the bottom of port  123 , are angled downwardly, the expansion ring  500  expands axially outwardly (i.e., downwardly) and radially outwardly, and contracts radially inwardly and radially inwardly. As a result, during expansion, the skirt  150  forms a cup-like shape C. This action and configuration provide a mask portion  100  which covers the laryngeal space L and, as well, forms a secure seal of the laryngeal space L. 
     As is seen in FIGS. 4 a  and  5   a , the ring  500  is contracted when the cylinder  302  is pulled axially outwardly. That is, the beaded chain  304  and non-beaded portions  304 A pull on the ring arms  508 ,  509 , which causes the control rings  580  to slide around port  133 , until the ring arms  508 ,  509  assume the position shown in FIGS. 4 a  and  5   a . The control ring supports  506  and  507  are integrally formed with the flexible ring arms  508  and  509 , the ring arms  508 ,  509  being contracted within the perimeter of the mask support  100 . Thus in the contracted position, the skirt  150  remains limp and flaccid (FIG. 4 a ), so that the overall mask portion  100  has a minimal radial dimension and is easily inserted down the patient&#39;s P oral cavity O and into the area above the laryngeal space L. 
     The resilient retainers  85  are looped around the stems  585  of supports  506  and  507  below the control rings  580 , and are also looped around and anchored to the posts  139 . The resilient retainers  85  provide tension to the supports  506 ,  507 , thereby biasing the supports  506 ,  507  (and as a result the expansion ring  500  which is integral with the supports  506 ,  507 ) into the expanded or deployed position shown in FIGS. 4 b  and  5   b.    
     A post  134  fits in a slot  510  in ring tip  501  to thereby control the amount of radially outward movement of ring tip, and also to prevent lateral movement of ring tip  501 . This feature assists in ensuring that ring tip  501  stays properly situated in the esophageal opening during deployment of the skirt  150 , thereby ensuring that the placement of the skirt  150  remains proper on deployment. 
     A spring post  126  on upper insert, and a spring post  570  on ring tip  501 , each have mounted on them one end of a spring  511 . A slot  571  on spring post  570  may assist in retaining spring  511  on spring post  570 . The spring  511  is preferably a rubber band, which biases the ring tip  501  into the expanded position shown in FIGS. 4 b  and  5   b . The spring  511  therefore assists in expanding the expansion ring  500  into the deployed or expanded position. 
     When the cylinder  302  is released by the operator, the resilient retainers  85  pull the non-beaded sections  304 A axially inwardly. The resilient retainers  85  retract and pull the control ring supports  506  and  507  toward the rear of the port  133  (as shown in FIGS. 4 b  and  5   b ), so that the expansion ring  500 , guided by the control rings  580 , follows the downward path of the radiused portion  136 . 
     In a preferred embodiment, the expansion ring  500  is composed of two ring arms  508  and  509  formed integrally with a ring tip  501 , control rings  580 , and control ring supports  506 ,  507 , which are also formed integrally with non-beaded portions  304 A and beaded radius  304 , thereby allowing the LMA of the present invention to be more easily assembled and less expensive to manufacture. Alternatively, the ring arms  508  and  509  could be snap-fit or otherwise attached into bores  561  in a separate ring tip  501  (see FIG.  2 ), to permit assembly of various sizes of expansion rings  500  while requiring a smaller inventory of fixed-size components. 
     Referring now to FIGS. 6 and 6 a , there is shown the cylinder  302  of plunger cap  300 . The cylinder  302  includes an outer end  310  and an inner end  311 . Inner end  311  is cylindrically shaped to fit snugly, but slidably, within the annular bore  322  of sleeve  301  (see FIGS. 1 and 7 a ). The outer end  310  may be of any convenient shape suitable for grasping by the operator, as is the collar  312  which is between the outer end  310  and the inner end  311 . The ends of the beaded chains  304  can be affixed to the cylinder  302  by a snap fit, thermal bonding, pinning or any other suitable technique. In a preferred embodiment, the outer end  310  includes apertures  315  for capturing the ends of beaded chains  304 , which ends of beaded chains  304  are otherwise secured in apertures  315 . 
     Also, in the preferred embodiment, a key or pin  307  is provided in the outer surface of the inner end  311  of cylinder  302 . The key  307  is adapted to be received in keyways  330 ,  331  in sleeve  301  to prevent allow the cylinder  302  to be locked in position when the skirt  150  is expanded, and to slide into the contracted position of the skirt  150 . The key  307  operates to lock the sleeve  301  and cylinder  302  in position when the key  307  (see FIG. 7) is located in the circumferential keyway  331  and cylinder  302  is rotated relative to sleeve  301 . Thus, the keyway arrangement provides a safety feature to control the movement of the cylinder  302  relative to the sleeve  301  and thereby retains the skirt  150  in the contracted position (FIGS. 4 a  and  5   a ) during insertion into the patient P. When it is desired to expand the skirt  150 , the key  307  is aligned with the axial keyway  330 , and the key  307  then may slide axially within keyway  330 , thereby allowing cylinder  302  to slide axially relative to sleeve  301 . 
     Referring concurrently to FIGS. 7 and 7 a , there are shown, respectively, a plan and an elevational cross-sectional view of the sleeve  301  of plunger cap  300 . The sleeve has a generally cylindrical body  301  with an optional lip  321  at one end, which lip  321  accommodates the circumferential keyway  331 . The balloon tube access port  303  for the balloon tube  401  (see FIG. 1) extends from the inner end of cylinder  301  and includes a slot  305 . 
     As seen in FIG. 7 a , slot  305  in the balloon tube access port  303  may be provided to receive the balloon tube  401  which passes through the conduit  202  in tube  200 , or to provide a source of pressure to inflate palate assist  800 . Slot  305  may be formed at an angle α to sleeve  301 . 
     In a preferred embodiment, an annular channel  322  is formed axially in sleeve  301 . The channel  322  receives the inner end  311  of cylinder  302 . The depth of the channel permits full deployment and contraction of the ring  500 . The inner bore  325  of sleeve  301  is configured to receive the tube  200 . Thus, the bore  325  includes the appropriate slots  202 A and  203 A to receive the conduits  202  and  203 , respectively—which are formed in the tube  200  for the beaded chains  304 ,  305  and the balloon tube  401 . 
     Referring now to FIG. 8, there is shown a plan view of one embodiment of the ring arm  508  or  509  and a portion of the connected beaded chain  304  with the control ring support  506  (or  507 ). The beaded chain is sufficiently long to pass through the conduit  203  in tube  200  and connect to plunger  302 . 
     The ring arms  508 ,  509  are formed of a flexible plastic material. In one embodiment, a series of slits  519  are cut into the outer perimeter of the arms  508 ,  509 . The slits  519  pass partway through the arms and permit greater flexibility, if desired. It will be readily understood that the location of the slits  519  along the length of the ring arms  508 ,  509 , and the lack of slits in certain locations along the length of the ring arms  508 ,  509 , allow the shape to which the expansion ring  500  contracts and expands to be varied and controlled. As shown in FIGS. 5A and 5B, the slits  519 , which expand to notches  519 A when the ring arms  508 ,  509  are expanded, are provided in both arms  508  and  509 . 
     As shown, arms  508 ,  509  extend and preferably integrally interconnect with the ring tip  501 . It is to be understood that in FIG. 8, two ring arms  508  and  509  would preferably be integrally molded together with a ring tip  501  and two beaded chains  304  to form a one-piece expansion ring  500  unit. 
     The control ring supports  506 ,  507  are integrally formed with the arms  508 ,  509  and chain  304 . The supports  506 ,  507  are connected to the control rings  580  by stems  585 . Resilient retainers  85  are looped around stems  585 . 
     The control rings  580  are formed on the end of stems  585  of ring arms  508 ,  509 . As described above, these rings loop around the port  133  and fit, one on top of the other, in the radiused portion  136  below the bottom of port  123 . The control rings  580  slide around the port  133  to control the movement (contraction and expansion) of the ring arms  508 ,  509 . 
     Referring to FIG. 8 a , there is shown an elevation view of the ring arms  508 ,  509  and support  506 ,  507 . The control rings  580  are joined to the supports  506 ,  507  by stems  585 . In this view, it is seen that the ring arm  508  includes a peripheral groove  810  at one edge. In a preferred embodiment, the resilient retainer  85  takes the form of a rubber band and is looped over the support  506 ,  507  at stem  585 . 
     Referring concurrently to FIGS. 9,  9   a  and  9   b , there are shown various views of the ring tip  501  shown in FIGS. 5 a  and  5   b . In particular, the ring tip  501  shown in FIGS. 9,  9   a  and  9   b  is preferably integrally formed with the ring arms  508  and  509  as part of a composite expansion ring  500 . The curved configuration of the ring tip  501  smoothly conforms to the shape of the other portions of the mask portion  100 . 
     FIG. 10 shows the LMA of the present invention in place in a patient, with the optional plate assist  800  contacting the hard palate H and tongue T, or the optional balloon  402  in place in the stomach S. As shown in FIG. 10, the LMA of the present invention seats properly in place in above the laryngeal opening L and epiglottis G. 
     FIG. 11 shows the details of a second embodiment of the mask support structure of the present invention, and in particular such a structure which includes a passage  128  for balloon  402  and balloon tube  401 . In the embodiment of FIG. 11, a port  122  is formed at the upper surface of upper insert  120  and includes an aperture  127  which passes through the upper insert  120 . The aperture  127  mates with the conduit  202 . The port  122  allows the balloon tube  401 , in the embodiment where the balloon tube  401  and balloon  402  are used, to pass through the upper insert  120 . A passage  128  leads from aperture  127  to aperture  125 , through which the balloon tube  401  may pass to the exterior of the mask portion  100 , if the balloon tube  401  is used. 
     Operation of the various embodiments and methods of their use will now be described. In any embodiment which does not include the balloon  402  and balloon tube  401 , the individual inserting the LMA of the present invention first contracts the skirt  150 . This is accomplished by pulling out (i.e., axially outwardly) the cylinder  302  relative to the sleeve  301 . Once the key  307  is aligned with the circumferential keyway  331 , the cylinder  302  is rotated to thereby lock the cylinder  302  in place relative to the sleeve  301 . Pulling out on the cylinder  302  pulls the beaded chains  304  outwardly, which in turn pulls non-beaded sections  304 A outwardly and around pulleys  137 . This movement of non-beaded sections  304 A in turn pulls control rings  580  upwardly around port  133  in the direction of nose piece  501 , against the bias of resilient retainers  85 , which in turn pulls ring arms  508 ,  509  radially and axially inwardly. Movement of ring arms  508 ,  509  inwardly also pulls ring tip  501  radially inwardly, against the bias of spring  511 . The expansion ring  500  contracts to the condition shown in FIGS. 4 a  and  5   a.    
     The patient&#39;s P mouth is then opened and the LMA is inserted down the oral cavity O, with the ring tip  501  nose piece  901  facing forward. The air tube  200  is pushed inwardly into the oral cavity O until the nose piece  901  enters into the entry to the esophagus E. Once the nose piece  901  enters the esophagus E the individual inserting the LMA of the present invention will feel the nose piece  901  seating, and therefore will know that the LMA of the present invention is properly in place. Thereafter, the cylinder  302  is rotated to align key  307  with axial keyway  330 , and then cylinder  302  may be released. The cylinder  301  slides axially into sleeve  301 , guided by key  307  in axial keyway  330 , until the skirt  150  expands sufficiently to seat against the walls of the patient&#39;s P airway. Because the key  307  is free to slide in axial keyway  330 , and inner end  311  free to slide in channel  322 , the expansion ring  500  and skirt  150  are free to expand to any size which is sufficient to accommodate the size of the patient&#39;s airway. The skirt  150  and expansion ring  500  therefore need not be of a specific size range to accommodate a wide range of patient P airway sizes. 
     Thereafter, if a palate assist  800  is part of the inserted LMA, fluid under pressure may be applied to connector  403 , which fluid travels down conduit  202  and enters the interior of palate assist  800  to expand palate assist  800  until it contacts the tongue T and hard palate H, thereby securing the LMA of the present invention in place. 
     In one embodiment of the method of use of the present invention using the embodiment which includes balloon tube  401  and balloon  402 , the above-described steps are followed. After expansion of rhe skirt  150 , the balloon tube  401  and contracted balloon  402 A are threaded down conduit  202 , aperture  127 , passage  128 , aperture  125  and esophagus E until the contracted balloon  402 A enters into stomach S. Fluid is then applied to connector  403 , expanding balloon  402 A into expanded condition  402 . The expanded balloon  402  seals the stomach S off from the esophagus E, preventing gastric reflux and aspiration, and also secures the LMA of the present invention in place. 
     In a second embodiment of the method of use of the present invention using the embodiment which includes balloon tube  401  and balloon  402 , the balloon tube  401  and contracted balloon  402 A are threaded first down conduit  202 , aperture  127 , passage  128 , and aperture  125 , and then are intubated down esophagus E until the contracted balloon  402 A enters into stomach S. Fluid is then applied to connector  403 , expanding balloon  402 A into expanded condition  402 . The expanded balloon  402  seals the stomach S off from the esophagus E, preventing gastric reflux and aspiration. Next, the skirt  150  is contracted (in the same manner as described above), and the LMA of the present invention is slid down the length of balloon tube  401  (by sliding conduit  202  down the balloon tube  401 ), until the LMA is adjacent the mouth of the patient P. The mouth of the patient P is then opened, and the LMA of the present invention is then inserted down the patient&#39;s P oral cavity O, by continuing to slide the LMA down the balloon tube  401  until the nose piece  901  seats in the entry to the esophagus E. The skirt  150  is then expanded (in the same manner as described above); as a result, the balloon tube  401  and balloon  402  secures the LMA of the present invention in place. 
     Thus, there is shown and described a unique design and concept of laryngeal mask assembly. While this description is directed to a particular embodiment, it is understood that those skilled in the art may conceive modifications and/or variations to the specific embodiments shown and described herein. Any such modifications or variations which fall within the purview of this description are intended to be included as part of the invention. It is understood that the description herein is intended to be illustrative only and is not intended to be limitative. Rather, the scope of the invention described herein is limited only by the claims.