Surgery – Respiratory method or device – Respiratory gas supply means enters mouth or tracheotomy...
Reexamination Certificate
2002-07-23
2004-01-20
Lewis, Aaron J. (Department: 3761)
Surgery
Respiratory method or device
Respiratory gas supply means enters mouth or tracheotomy...
Reexamination Certificate
active
06679263
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to inflatable medical devices. More specifically, the present invention relates to protecting medical devices during sterilization by providing automatic venting at high temperatures.
The laryngeal mask airway device is a well known device that is useful for establishing airways in unconscious patients.
FIG. 1
shows a perspective view of a prior art laryngeal mask airway device
100
. Laryngeal mask airway devices such as device
100
are described for example in U.S. Pat. No. 4,509,514. Device
100
includes a hollow airway tube
110
and an inflatable mask portion
130
. Tube
110
extends from a proximate end
112
to a distal end
114
and defines an interior airway lumen that extends through the tube from the proximate end
112
to the distal end
114
. Mask portion
130
defines, at least when inflated, a central opening
136
. Mask portion
130
is coupled to the airway tube such that the lumen of the airway tube communicates with the mask portion's central opening and such that the device
100
provides a sealed internal passage that extends from the proximate end
112
to opening
136
.
In operation, the mask portion
130
is deflated, and then the mask portion is inserted through a patient's mouth into the patient's pharynx. The mask portion is preferably positioned so that a distal end
140
of mask portion
130
rests against the patient's normally closed esophagus and so that the opening
136
of the mask portion
130
is aligned with the entryway of the patient's trachea (i.e., the patient's glottic opening). After the mask portion is so positioned, the mask portion is inflated thereby forming a seal around the patient's glottic opening and this establishes a sealed airway extending from the proximate end
112
of the tube
110
to the patient's trachea. The proximate end
112
, which remains outside the patient, may be coupled to a ventilator for providing ventilation to the patient's lungs.
Referring again to
FIG. 1
, laryngeal mask airway device
100
also includes an inflation tube
138
for permitting selective inflation or deflation of mask portion
130
. An inflation valve
150
is connected to the proximate end of the inflation tube
138
and the distal end of inflation tube
138
is connected to the mask portion. The inflation valve
150
is normally closed so as to maintain the current pressure in mask portion
130
. However, valve
150
may be opened to permit inflation or deflation mask portion
130
.
FIG. 2A
shows a sectional view of inflation valve
150
, when the valve is closed (or when fluid may not freely flow between a first end
152
of the valve and a second end
154
of the valve).
FIG. 2B
shows a sectional view of inflation valve
150
, when the valve is open (or when fluid may freely flow between first and second ends
152
,
154
).
FIG. 2C
shows a view of the first end
152
of valve
150
taken in the direction of arrow
2
C—
2
C as shown in FIG.
2
A.
FIG. 2D
shows an exploded sectional view of inflation valve
150
, in which, for convenience of illustration, the space between opposite sectional views of body
160
has been artificially enlarged.
FIG. 2E
shows a more detailed sectional view of a typical prior art inflation valve
150
, when the valve is closed.
As shown, inflation valve
150
includes a hollow body
160
, which defines a central channel
169
that extends entirely through the body from end
152
to end
154
. Valve
150
also includes a movable member, or pin,
170
, and a spring
180
, both of which are disposed within the central channel
169
of hollow body
160
. One end
182
of spring
180
contacts a shoulder
162
of body
160
. The other end
184
of spring
180
contacts a shoulder
172
of pin
170
. The spring biases pin
170
away from shoulder
162
(or upwards as shown in
FIGS. 2A
,
2
B, and
2
D) such that a shoulder
174
of pin
170
normally contacts a shoulder
164
of body
160
.
In the normal resting position of valve
150
(shown in FIG.
2
A), contact between shoulder
174
(of pin
170
) and shoulder
164
(of body
160
) forms a seal and effectively prevents fluid from passing through channel
169
between the first end
152
and the second end
154
of valve
150
thereby closing the valve. The position of pin
170
shown in
FIG. 2A
may be regarded as a “closed position”. As shown in
FIG. 2B
, valve
150
may be opened by biasing pin
170
such that shoulder
174
(of pin
170
) is separated from shoulder
164
(of body
160
). Valve
150
is “open” as soon as shoulders
174
and
164
separate from one another. Once valve
150
is open, fluid may pass through channel
169
between the first end
152
and the second end
154
of valve
150
(i.e., fluid may pass from the first end to the second end or from the second end to the first end depending upon relative pressures at the valve ends). Any position of pin
170
in which shoulder
174
(of pin
170
) is separated from shoulder
164
(of body
160
) may be regarded as an “open position”. If biasing of pin
170
continues, a shoulder
176
(of pin
170
) eventually contacts a shoulder
166
(of body
160
). Shoulder
166
serves to limit the motion of pin
170
such that once shoulders
176
and
166
contact one another, further movement of pin
170
(in a direction that continues to separate shoulders
174
and
164
from one another) is prevented. Unlike shoulders
174
and
164
, the shoulders
176
and
166
do not form sealing surfaces, such that valve
150
is open even when shoulders
176
and
166
are in contact.
In laryngeal mask airway devices, the second end
154
of valve
150
is normally connected to the inflation line
138
(shown in FIG.
1
). The valve
150
is normally closed so that if the mask portion
130
is inflated or pressurized, valve
150
maintains the pressure in the mask portion, or prevents gas in mask portion
130
from passing through valve
150
and escaping to the atmosphere external to the device. In its normally closed position, valve
150
also prevents mask portion
130
from spontaneously inflating after mask portion
130
has been intentionally deflated. Although it is normally closed, valve
150
may be temporarily opened to permit selective inflation and deflation of mask portion
130
. Normally, an air syringe, or other air supply device (not shown), is coupled to end
152
of valve
150
, and in the act of coupling, the air supply device biases the pin
170
so as to separate shoulders
174
(of pin
170
) and
164
(of body
160
) and thereby open the valve. The air supply device may then inflate or deflate mask portion
130
. Once the air supply device is decoupled from valve
150
, the biasing force provided by spring
180
automatically closes valve
150
and thereby maintains the current pressure inside of mask portion
130
. End
152
of valve
150
is normally designed to comply with International Standard ISO 594-1 so that it may readily be coupled to standard air supply devices.
Although valves such as valve
150
have been in use for many years and have functioned well, there remains a need for providing improved control over the pressure in the inflatable portions of laryngeal mask airway devices as well as in other inflatable devicies.
SUMMARY OF THE INVENTION
These and other objects are provided by improved inflation valves and by inflatable devices constructed using those valves.
Several varieties of laryngeal mask airway devices are durable enough to permit them to be sterilized in an autoclave and reused. For example, the “Classic” laryngeal mask airway device sold by the Laryngeal Mask Company of Cyprus, is guaranteed to survive forty sterilizations, and in practice these devices may generally be sterilized (and reused) more than forty times before becoming too worn for reuse. The “Proseal”, also sold by the Laryngeal Mask Company of Cyprus, may also be sterilized and reused.
The sterilization process normally involves exposing the laryngeal mask airway device
Brown James
Luchetti Cynthia
Hale and Dorr LLP
LMA International, S.A.
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