CA2107027C - Laryngeal mask construction - Google Patents

Abstract

A shell of flexibly pliant material is in peripherally sealed engagement with the inflatable ring portion of a laryngeal mask such that when both the mask ring and the space within the shell are inflated, i.e., after patient installation of the mask in deflated condition, a back cushion is established with large-area self-adapting conformation to the back wall of the pharynx, so that inflation pressure in the back cushion not only positions back contours of the mask per se at offset from the back wall of the pharynx but in addition establishes a large area of uniformly distributed forward pressure on the mask per se, resulting in a pneumatically loaded application of the inflatable ring of the mask, into enhanced sealing conformance to and engagement with the laryngeal inlet.

Description

2 ~ 07027 Laryngeal masks, lllustratlvely of the varleties dlsclosed ln U.S. Patents 4,509,514 and 4,995,388, are artlflclal alrway devlces deslgned to facllltate lung ventllatlon ln an unconsclous patlent by formlng a low-pressure seal around the laryngeal lnlet. An lnflatable-rlng seal surrounds an approprlately shaped mask whlch flts lnto the lower pharynx and ls attached to a tube whlch emerges from the mouth, as for connectlon to medlcal gas-supply tublng.
In practlce, these devlces have been successful and are ln dally use ln hospltals throughout the Unlted Klngdom.
Such masks have been found to be effectlve ln achleving a rellable alrway, preventlng obstructlon ln an unconsclous patlent. As presently used, such masks are especlally effectlve ln cases where dlfflculty wlth the alrway ls experlenced. For example, the mask has been found to prevent contamlnatlon of the lungs by blood or debrls followlng surgery of the nose and throat. But lt has become apparent that an lmportant contralndlcatlon to lts use ls the patlent who ls at rlsk from vomltlng or regurgitatlon of stomach contents whlle unconsclous. An earlier proposal of mine (see U.S. Patent 5,241,956) deals with thls problem by provlding an evacuation tube whlch is open through the center of the distal end of the inflatable seal of the laryngeal mask, thus utllizlng the dlstal end of the inflatable rlng as in inflatable cuff formation whlch establlshes perlpherally sealed engagement to the upper sphlnctral reglon of the oesophagus and centrally supports the dlstal end of the evacuatlon tube. In addltlon, there was lncluded an addltlonal lnflatable cuff carrled by the laryngeal mask and ~ 60538-1142 ,A

by the evacuatlon tube, for referenclng inflatlon against the back wall of the pharynx, thus maklng lt posslble to establlsh the laryngeal-lnlet seal wlth reduced lnflatlon pressure, as compared wlth prlor structures not havlng such an addltlonal lnflatable cuff.
Another of my earller proposals ls concerned wlth moulding technlques for manufacture of a varlety of laryngeal masks; and, ln con~unctlon wlth one of these, an lnflatable back cushlon is dlsclosed whereby the referenclng lnflatlon agalnst the back wall of the pharynx ls wldely dlstrlbuted, over substantlally the full area of the laryngeal mask. Such a back-cushlon constructlon has been found to be mechanlcally slmple and hlghly effectlve, and lt ls deslred to speclflcally dlsclose and clalm the lnflatable cushlon ln the context of each of several representatlve constructlons.
BRIEF STATEMENT OF THE INVENTION
It ls the prlmary ob~ect of thls lnventlon to provlde lnflatable back-cushlon structure and actlon ln con~unctlon wlth representatlve laryngeal mask conflguratlons, whereby to achleve lmproved laryngeal-lnlet seallng at reduced lnflatlon pressure, and ln general to avold or materlally reduce any chance of patlent trauma by reason of lnstallatlon or use of a laryngeal mask.
In lts preferred embodlments, the lnventlon achieves the foregolng ob~ect by applylng a shell of flexlble materlal ln perlpherally sealed engagement wlth the lnflatable rlng portlon of a laryngeal mask such that when both the mask rlng and the space wlthln the shell are lnflated, l.e., after patlent lnstallatlon of the mask ln deflated condltlon, a back A

cushlon ls establlshed wlth large-area self-adaptlng conformatlon to the back wall of the pharynx, so that lnflatlon pressure ln the back cushlon not only posltlons back contours of the mask E~ se at offset from the back wall of the pharynx but ln addltlon establlshes a large area of unlformly dlstrlbuted forward pressure on the mask E~ se, resultlng ln a pneumatlcally loaded appllcatlon of the lnflatable rlng of the mask, lnto enhanced seallng conformance to and engagement wlth the laryngeal mask.

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3 21 o7027 DETAILED DESCRIPTION
The invention will be described in detail for preferred embodiments, in conjunction with the accompanying drawings, in which:
Fig. 1 is a diagrammatic view, generally in side elevation for a first embodiment of artificial airway device, having a laryngeal mask of simple construction, with the back-cushion feature of the invention but without provision for gastric drainage, the same being shown in inflated condition for use in a patient;
Fig. 2 is an enlarged and simplified view in perspective of the laryngeal mask of Fig. 1, shown for use of a single supply connection, for inflation/deflation control and actuation;
Fig. 2A is a view similar to Fig. 2, for the case of independent inflation/deflation control for the inflatable ring of the laryngeal mask and for the inflatable back cushion, respectively;
Fig. 3 is an enlarged view in longitudinal section of the laryngeal mask of Figs. 1 and 2;
Fig. 4 is a view similar to Fig. 3 for a different laryngeal mask structure, wherein a side elevation has been partly broken-away to reveal deta l of the longitudinal section; and Fig. 5 is another side elevation, partly broken-away and in longitll~;nAl section, for a further embodiment which incorporates a gastric drainage feature.
Referring first to the embodiment of Figs. 1 to 3, the invention is shown in application to an airway system comprising a laryngeal-mask unit 10 and its airway tube 11, installed through the mouth 12 of a patient. The mask unit may be generally as described in said U.S. patents and therefore need not now be described in detail. It suffices to say that mask unit 10 comprises a body or back-plate 13 having a lumen 14 (Fig. 3) through which the airway tube 11 can establish a free externally accessible ventilating passage, via the patient's mouth 12 and throat 15, and past the epiglottis 16 to the larynx 17.
The body or backplate 13 of mask 10 may be of silicone rubber and relatively stiff; and body 13 is surrounded by an inflatable ring 18 which is generally elliptical and which is circumferentially united to body 13 in essentially a single plane. The inflatable ring 18 may also be of silicone rubber, although preferably relatively soft and flexible compared to body 13. An externally accessible flexible tube 19 is the means of supplying air to the inflatable ring 18 and of extracting air from (and therefore collapsing) ring 18 for purposes of mask insertion in or removal from the patient; check-valve means 21 in tube 19 will be understood to hold a given inflation or to hold a given deflation of ring 18. In the installed position of Fig. 1, the projecting but blunted distal end 20 of ring 18 is shaped to conform with the base of the hypopharynx where it has established a locating limited entry into the upper sphinctral region of the oesophagus 24. The inflated ring establishes a peripherally sealed closure around the laryngeal inlet, orienting the axis of the distal end of the airway tube 11 at an acute angle to the general plane of ring 18 and in substantial alignment with the axis of the laryngeal inlet, for direct airway communication with the larynx 17.
For the specific laryngeal mask construction of Fig. 3, the inflatable ring 18 is a first component part, and the body or backplate 13 is a separately moulded part adhes vely assembled to ring 18. Various techniques may be employed to create ring 18, and the section shown is applicable for one of the embodiments of said application Serial No.
08/003,900, to which reference is made for further descriptive detail. It suffices to identify the socket 30 of body 12, for assembly to the airway tube 11, the inlet port formation 32 for connection to inflation/deflation tube 19, and the thin pliant bowl formation 31 which defines the lumen 14 of the mask.
In accordance with the invention, and in the case of Figs. 2A, a separately inflatable back cushion is established around and over the back side of body 13. To this end, a shell 33 of softly pliant material, inflatable to an envelope profile suggested by a phantom outline 34, is peripherally sealed and adhered to substantially the equator region 35 of ring 18, and this envelope is also open to the airway passage but at the same time peripherally sealed around the outer surface of the socket region 30 of body 13.

21 o7027 In the embodlment of Flg. 2, a local openlng 36 ln rlng 18, and wlthln the volume of the pllant envelope 34, enables lnflatlon alr vla tube 19 to concurrently lnflate (or to concurrently deflate) both rlng 18 and the back cushlon 33.
And ln the embodlment of Flg. 2A, there ls no equlvalent of the port 35, but a separate flexlble-tube connectlon 19', whlch communlcates only with the inner volume of the back cushlon, enables lndependent control of lnflatlon pressure to the respectlve lnflatable volumes.
Regardless of whether the inflatable rlng 18 and the lnflatable back cushlon are slmultaneously or lndependently lnflated, the net effect of lnflatlon wlthln both volumes, ls to enable the back cushlon 33 to establlsh referenclng contact wlth the back wall of the pharynx, and the relatlvely stlff features of the back slde of plate 12 are thereby substantlally relleved from dlrect contact wlth the wall of the pharynx. In Flg. 1, thls clrcumstance is shown by a heavy phantom proflle of the back cushlon, expanded for almost the full longltudlnal extent of the mask rlng 18 and ln elongate contlnuous contact wlth the proflle of the back wall of the pharynx, whereln ad~acent proflle features of the back slde of body 12 are offset from the back wall of the pharynx, to the extent of a clearance 37. Thls offsettlng clearance wlll be understood to extend over vlrtually the entlre back area of the mask and lts rlng 18 because pressure wlthln the back cushlon wlll be operatlve on vlrtually the entlre back area of the mask, drlving the same, l.e., lts rlng 18, lnto forwardly loaded seallng coactlon with the laryngeal inlet. Upon deflation, both inflatable volumes shrlnk, lnto conformance A

wlth features of body 12, with a floppy thin periphery of collapsed ring (18) material surroundlng the base proflle plate 12.
In the embodlment of Fig. 4, the softly pliant shell 40 of the invention is applied to another mask structure. It suffices to indicate that the entire mask structure of Fig. 4 is the product of a single moulding operation, so that both the body part 41 and its peripherally connected inflatable ring 42 are integrally related. The back cushion material at 40 may be as previously described, namely a shell sealed to substantially the full extent of equator 45 of ring 42.
Inflation/deflation within or outside the body 41 is with the same cushion-loading action on the mask for enhanced sealing around the laryngeal lnlet, and with the same backside clearance as prevlously indlcated ln connection with the offset 37 of Flg. 1.
In the embodlment of Flg. 5, the softly pllant shell 50 of the invention is applied to still another mask structure, namely, a construction which features an evacuation tube 51 which extends alongside the alrway tube 11 and the body 52 of a laryngeal mask. The evacuatlon tube 51 has sealed entry into and through the dlstal end of the inflatable ring 18 of the mask, via a re-entrant distal-end formation of ring 18; and tube 51 is thus centrally open at 53, where it is adapted to provide sealed and exclusive communication with the upper sphinctral region of the oesophagus. The evacuation tube 51 will be understood to be capable of being under applled reduced pressure, for prompt removal of a posslble gastrlc discharge from the oesophagus, and this reduced , ~
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2 t 07027 pressure wlll be addltlonally understood to draw body tlssue of the upper sphlnctral reglon lnto enhanced seallng engagement wlth the dlstal end of the laryngeal mask. The pliant shell 50 wlll be understood to have sealed perlpheral adherence to the equator reglon 55 of lnflatable rlng 18 and also to be sealed around the alrway and evacuatlon structures, whereby to complete an lnflatable back cushlon whlch can establlsh a large-area of referenclng support agalnst the back wall of the pharynx. The ablllty of the lnflated back cushlon to enhance the seallng effectlveness of rlng 18 around the laryngeal lnlet ls as descrlbed for other embodlments. And thls enhanced effectlveness ls achleved for a lesser level of lnflatlon pressure than ls posslble wlthout an lnflatable back cushlon.
Whlle lt ls preferred that the pllant shell whlch ls used to complete the lnflatable back cushlon of the varlous embodlments ls shown and descrlbed as belng perlpherally adhered to the outer or equator reglon of the lnflatable rlng 18 of the mask, lt wlll be understood that deslred large-area back-cushlon engagement wlth the back wall of the - 6a -A

2t 07027 pharynx may also be obtained if the pliant shell is sealed to a lesser profile or contour of the back side of the mask, as to the peripheral region of body 13, along the line of peripheral juncture of body 13 to ring 18. In either event, the condition is satisfied that the effective area of the inflated back cushion is at least as great as the peripheral area of the mask body 13, along the line of peripheral juncture of body 13 to ring 18.

Claims (14)

1. A laryngeal-mask construction, comprising a back-plate member providing in essentially a single plane an apertured base-mounting rim of generally elliptical configuration, an inflatable toroidal ring of flexible material surrounding and continuously connected to said base-mounting rim, and an inflatable back cushion comprising a shell of flexible material adhered generally to the perimeter of said inflatable ring to define said back cushion in conjunction with said mask construction.

2. The construction of claim 1, in which an air passage communicates between said inflatable ring and said inflatable cushion, whereby a single means of inflation and/or deflation can simultaneously serve both said ring and said back cushion.

3. The construction of claim 1, in which said inflatable ring and said inflatable back cushion have independent connections for separate inflation and/or deflation.

4. The construction of claim 1, in which said back-plate member and said inflatable toroidal ring are separate components secured to each other.

5. The construction of claim 1, in which said back-plate member and said inflatable toroidal ring are integrally connected product components of a single molding operation.

6. The construction of claim 1, in which the effective inflatable area of said back cushion is at least as great as the effective area of said back-plate member at peripheral juncture to said inflatable ring.

7. A laryngeal-mask construction, comprising a back-plate member providing in essentially a single geometric plane an apertured base mounting rim of generally elliptical configuration, said back-plate member including an airway-tube connecting formation on an inclined axis that is at an acute angle to said geometric plane, the inclined axis being in a plane which includes the major axis of the elliptical configuration and which is normal to said geometric plane, an inflatable toroidal ring of flexible material surrounding and continuously connected to said base-mounting rim, and an inflatable back cushion comprising a shell of flexible material adhered generally to the perimeter of said inflatable ring and externally sealed around said airway-tube connecting formation to define said back cushion in conjunction with said mask construction.

8. The construction of claim 7, in which an air passage communicates between said inflatable ring and said inflatable cushion, whereby a single means of inflation and/or deflation can simultaneously serve both said ring and said back cushion.

9. The construction of claim 7, in which said inflatable ring and said inflatable back cushion have independent connections for separate inflation and/or deflation.

10. The construction of claim 7, in which the effective inflatable area of said back cushion is at least as great as the effective area of said back-plate member at peripheral juncture to said inflatable ring.

11. An artificial airway device to facilitate a patient's lung ventilation, comprising an airway tube, an evacuation tube and a laryngeal mask at one end of said tubes, said mask comprising a back-plate member providing in essentially a single geometric plane an apertured base mounting rim of generally elliptical configuration extending from a proximal end to a distal end, said back-plate member including an airway-tube connecting formation on an inclined axis that diverges proximally at an acute angle to said geometric plane, the inclined axis being in a plane which includes the major axis of the elliptical configuration and which is normal to said geometric plane, an inflatable toroidal ring of flexible material surrounding and continuously connected to said base-mounting rim, the distal end of said inflatable ring being configured for entry into and insertional location of the mask by engagement with the oesophagus at the upper sphinctral region of the oesophagus when the mask is positioned for sealing the airway tube to the laryngeal inlet, said evacuation tube including a portion having sealed passage through part of said toroidal ring and having an open distal end centrally within and axially short of the distal end of said ring, and an inflatable back cushion comprising a shell of flexible material adhered generally to the perimeter of said inflatable ring and externally sealed around said airway-tube connecting formation to define said back cushion in conjunction with said mask construction.

12. The artificial airway device of claim 10, in which an air passage communicates between said inflatable ring and said inflatable cushion, whereby a single means of inflation and/or deflation can simultaneously serve both said ring and said back cushion.

13. The artificial airway device of claim 10, in which said inflatable ring and said inflatable back cushion have independent connections for separate inflation and/or deflation.

14. The artificial airway device of claim 11, in which the effective inflatable area of said back cushion is at least as great as the effective area of said back-plate member at peripheral juncture to said inflatable ring.