Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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BACKGROUND OF THE I~VENTION
In the administering of anaesthesic gases to
patients a m~sk is pl~ced over the nosa or mouth of the
patient and a controlled amount of the gas is permitted
to flow into the mask ~ Inhalation o anaesthetic gas
can be used to achieve a long range of predictable
responses to pain which permits medical processes such
as dental work to be perormed on the patient with less
sensation of pain.
In systems used previously a substantial amount of
the gas either escaped or was emptied into the room in
which the patient is located. Approximately ive to ten
liters of gas are clelivered to a patient under anaesthesia
or analgesia.
Some of this ~as is absorbed into the body of the
patient but the excess gas is allowed to escape înto the
surrounding environmen through a pressure relief valve.
The gas which is abs~rbed into the body during anaesthesia
also is exhaled by the patient as soon as the anaesthe~ic
gas flow has been stopped rPsulting in virtually all the
gas which has been administered to the patient under the
present process being ultimately d~mped into the room.
A growing cQ~cern or the side effects of the
escaped gases on the health of the operating personnel
has been ~oiced by many medical groups and committees~
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The high level of waste anaesthesia present in operatories
today are unnecessary and possibly harmful to the
personnel involved. : Hospitals have already started to
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make moves to effectivPly scavenye the anaesthetic gases
in their operator1es to decrease the levels ~f gas
inspired by their operating personnal. De~tal offices on -
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the other hand have had fewer regulations and levels tha-t have
been found }n dental offices have been much higher and it is
the aim of this product to help the dentist in his efforts to
scavenge waste gases in the future. Thus it is the primary
purpose of this invention to provide a process for adminis-
tering anaesthesic gases in a manner to limit the exposure of
the medical personnel to high concentrations of the gas both
during the administering pxocess and afterwards.
SUMMARY OF THE INVENTION
A method of administexing anaesthesic gas to a
patient by use of a mask which is placed over the patient's
nose and/or mouth, which mask incorporates means to administer
the anesthesic yas and also includes means to retrieve expired
anaesthesic gas and transport said expired gas and the unin-
haled gas out of the environment of the administering per-
sonnel by the employment of a vacuum s~stem.
In one aspect the present invention provides a
mask for administering gas to a patient comprising: .
(a) an inner cup-shaped wall arranged to fit over the
nose or mouth of a patient and to engage the face of the
patient along the peripheral edge thereof to form a gas
chamber between the face of the patient and the inner surface
of the inner wall;
(b) an outer wall secured to and spaced from the inner
wall to form an exhaust passage therebetween communicating ,:
with the chamber for recelving exhaust yas exhaled by the
patient into the chamber and having a peripheral edge disposed
- in the vicinity of the peripheral edge of the inner wall de-
fining means for receiving gas leaking between the peripheral
edge of the inner wall and the face of the patient;
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(c) means connect~d to the inner wall and communicating
- with the chamber for introducing gas into the chamber to be
inhaled by the patient;
(d) means connected to the outer wall and communicating
with the exhaust passage for removing the exhaust gas and the
leakage gas; and
(e) presssure control means connected between the
inner and outer walls for communicating the chamber with the
exhaust passage, the pressure control means being arranged
for gas to enter the chamber from the means for introducing
gas into the chamber when the patient inhales gas and arranged
for exhaled gas to enter the exhaust pasisage from the chamber
when the patient exhales gas.
In another aspect the present invention provides a sys-
tem for administering gas in a treatment room to a patient
which includes the mask as described in the preceding para-
graph together with means, connected to the means for intro-
ducing gas into the chamber of the mask, for supplying gas to
be inhaled by the patient and means, connected to the means
or removing exhaust gas and leakage gas, for conducting the
exhaust gas and leakage gas to an area removed from the
patient's treatment room.
~ BRIEF DESCRIPTION OF THE DRAWINGS
_
Pig. 1. shows the mask placed on a patient or
administering an anaesthesic gas;
Fig. 2, which appears on the second sheet of
drawings, is a schematlc view of an anaesthesic gas-adminis-
tering process incorporating the subject invention;
Pig. 3 is a cross-sectional view of an anaesthesic
30 mask incorporating the present invention; and -~
Fig. 4 is a bottom plan vlew of the anaesthesic
~ mask of Fig. 3. -4a-
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DESCRIPTION OF THE INVENTION
In Fig. 1 is shown a system for administering
anaesthesic gas to a p~tient. As in prior systems, an
anaesthesic gas such as oxygen and nitrous oxide is
supplied rom a pair of tanks 10 and 11 through shutsff
valves 12 and 14, respectively, to a standard mixing
valve 15. In the mixing valve the gases are mixed and
fed into a supply line 16 through a gas bag 17 for
passage through a line 18 to an anaesthesic gas mask 19.
The overall gas flow rate is con~rolled at the mixing
valve which is of a stan~ard design having flow control
means as well as means for joining the gases together.
The person administering the flow can obtain a visual
indication of the breathing volume and rate of the
patient by observing the expansion and contraction o~
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the bag 17. In addition~ such pers~n can also administer
a rapid fl~w of the gas by gr~bbing and squeezing the bag
which causes accelerated ~low through the line 18 to the :~
. mask.
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~0 As discussed previously, the patient usually breathes
~ only ~hrough the nose or mouth and it is over these organs
;: that the mask is placed. - In prior systems, the exhaled
gas and~the gas fed through the mask which iS not inhaled :~
i5 usually dumped directly into the room surrounding the
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patlent which naturally ralses the concentration of such
gas i~ that: room ~ach time the anaesthesic process is
performed. : For instance in ~ dental office th~ process
can b~ performed many tlmes a day and if the ~ir:is not.
- ~ sca~enged by passage through a non-recircula~ing air~
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; -3n / conditioning system, the concentrations of the gas can
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become quite high. Such concentrations can reach the level at which thedentist's consciousness and dexterity are actually affected by the continu-
ous breathing of the gas.
In accordance with the present invention, means are provided for
receiving substantially all of the gases supplied to the patient and con--
ducting such gases to a point exterior of the treatment room to maintain the
concentration oE the gases within the room at low levels. Thus there'is
provided a special anaesthesic mask 19 which is connected to a pump 21 such
that gas exhaled by the pa~tient, gas supplied to the mask but not inhaled
by the patient and gas escaping around the mask are collected and pumped
to a point exterior of the room by means of the pipe 20, the pump 21 and
exhaust pipe 22 leading to a point exterior of the room.
An anaesthesic mask for incorporation into the present invention
is shown in Fig. 2 and comprises an inner mask made up of an inner shell 24
which may be of thin flexible material having an opening 25 therein which
; permits entry of the nose or exit of supplied gases into the mouth. Such
inner mask has connected thereto a pair of inlet tubes 26 and 27 connecting
through the lines 28 and 29 to the supply line 18 leading from the anaes-
thesic bag 17. Thus as gas flows through the supply line under the pre-
' sure of the gases supplied from the tanks 10 and 11, it is forced to flow
into the gas cavity formed within the inner shell 24 from which it can be
inhaled by the patient to whi'ch the gas is being administered. As pointed
DUt be~ore, the p~tlent usually breathes tùroueh ths nose and ther lore
.
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the mask commonly is placed over the nose, however if the patient actually
breathes through the mouth, either the mask can be placed only over the
mouth or the mask can be made of sufficient size to fit over both the nose
and the mouth.
In the present invention the mask is provided with pressure con-
trol means as for example a pressure relief valve 30 (Figs. 2 and 3) which
valve is normally closed by the plunger 31 being spring-loaded over an
opening 32 in the inner shell. Thus the gas which enters the inlet lines
is contalned in the mask and can be readily inhaled by the patlent. Upon
exhalation by the patient, the pressure within this inner mask is imme-
diately increased suf~iciently to cause the plunger to compress the spring
34 to the position indicated in Fig. 4. Thus the exhaled gas is permitted --
to pass through the pressure relief valve and into an exhaust passage 35
formed between the inner shell 24 and an outer shell 36 which may be of thin
flexible material surrounding but spaced from that inner shell. Connect-
ing with the exhaust passage 35 are a pair of exhaust tubes 37 and 38 in
flow relationship with the exhaust lines 39 and 40 which join at the junc-
ture with the exhaust line 20 connecting with the exhaust pump 21.
In a normal mask not using an exhaust pump the exhalation by the
patient will cause a substantial increase in the flow of gas into the
inner mask such that gas will escape between the edges 25A of the mask and `~
the patient's face. Naturally this leads to a substantial leakage of
gas into the surroundings of the patient. However, by using an extract
system providing a positive exhaust flow
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by use of the pùmp 21 creating a negative pressure within
the exhaus~ lines 20, 39 and 40, the gas is scavenged
from the mask to thereby limit leakage through the
opening 25A and the patient's ~ace.
In accordance with another featuxe of the inven~ion,
the inner e~haust passage 35 opens adjacent the face of
the patient at a continuous poxt 35A surrounding the
edge 25A o~ the inner ma~k. Thus by $he creation of a
negative pressure and because the edge ~ of the outer
shell extends past the edge ~5A of the inner shell so as
to press more ti~htly against ~he patien~'s face, any gas
leaking between the juncture of the inner shell and the~
patient's face is i.mmediately scavenged through the port
. 35A to the inner passage 35 and into the exhaust lines.
~With the crea~ion of a nega~ive pressure between the
inner and outer shells there exists the possibility t~at
the mask will become pressed suf~iciently close to the
patient's face such that i* will stick to the face
because-of the negative pressure within he passage 35
.20 and the atmospheric pressure outside the mask, To
counteract this possibility means may be provided ~o
limit the negative pressure within the passage 35. One
: form of such meanB involves~the location of a series of
relief holes ~e in the outer sheI1 36 connecting the
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` inner passage 35 with atmosphexe. Such relief ho}es are
not large enough to permit total relief of the vacuum
pressure within the passage 35 but do permi~ sufficien~
air flow to limit~such vacuum pressure. Of course an
actual pressure relisf valve can also be ut.ilized if
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~ 30 necsssary which valve would control clossly the ~acuum
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pressure maintalned within the inner passaye'35.
The mask can also be provided with straps or strap
attachments 41 for attachment of the mask to the head of
the patient. In addition, the pressure xelief ~alve can
be made adjustable by the incorporation of a control
knob 42 which is threaded into the ou~er wall 44. By
tightening the thumb screw 4~ the tension on the sprill~ 34
can be increased to permit a higher buildup o~ pressure
wi~hin the inner shell 24 prior to the ope~ing of ~he
valve. Such a higher buildup might be desirable to
- cause a quick ~low of oxygen to the patient fox medical
purposes such as revLval. ~aid valve also permits the
administration of the gas to control the fullness of the
gas cavity and the breathLng reservoir.
In addition, another feature of the present invention
involves tha manufacture of the mask from material which ~ .
is transparent. Such a tra~sparent mask enables the
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administering ~ersonnel to visually obRerve the proper ~:
placement of the mask over the patient's nose and mouth. .
Also the transparent mask can be inspected e~sily to
detect the pres~nce of any foreign objects, dirt or other
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pocketing or buildup.
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