Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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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
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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
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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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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
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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.
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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
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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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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
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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.
