Note: Descriptions are shown in the official language in which they were submitted.
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This invention relates generally to a catheter having an inflat-
able cuff balloon and more particularly to an improved inflatable catheter
having associated therewith a signal device and an inflation measurement
device to indicate and prevent overinflation of the inflatable cuff balloon.
Inflatable catheters having signal devices associated therewith
to indicate and prevent overinflation of the inflatable cuff balloon are
known and are illustrated in United States Patents Nos. 3,543,758 and
3,543,759. In both of these references, an inflatable safety sleeve, or
~ balloon, is positioned on either the catheter tube or inflation side arm and
! lo communicates with the inflation lumen and cuff balloon. When the cuff or
retention balloon reaches a predetermined pressure, such as when the balloon
is overinflated or the catheter is not properly positioned within a body ~;
cavity, the safety balloon inflates thereby indicating an overinflated con-
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dition and relieving the cuff balloon of its excess pressure.
; The problem with these prior art safety balloons is that, in each
instance, the safety balloon is upstream of the cuff balloon, i.e., inflation
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fluid, before it reaches the cuff balloon, must first pass through the
safety balloon. This construction results in expansion of the safety balloon
and false readings when, during inflation, the pressure from the inflation
source exceeds the normal inflation pressure of the cuff balloon. The cuff
balloon, however, due to the pressure drop between the safety and cuff
balloons, does not experience this increased pressure. This problem is
particularly vexatious when the safety balloon is designed to inflate at~.
pressures slightly greater (5-10 mm Hg) than the normal inflation pressure
of the cuff balloon becauseJ as the cuff balloon is inflated, particularly
with pulsatile flow, the safety balloon frequently expands indicating a false,
overpressurized condition. This false reading can be controlled by very slow-
ly inflating the cuff balloon to minimize the pressure drop between the
; safety cuff balloons. This, however, is not always a practical expedient.
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Another disadvantage of the urinary catheter construction illus-
trated in the cited prior art patents concerns application to an endotracheal
tube which should not be inflated to pressures over 50 mm Hg and preferably
not more than 20-30 mm Hg, such as illustrated in United States Patent No.
3,734,100. In this construction and during nonequilibrium, dynamic condi-
tions, such as during inflation, it is difficul* to rapidly develop a seal
by slowly inflating the cuff balloon and rapid inflation will merely lead to
expansion of the signal balloon alone.
With respect to endotracheal catheters, inflation of the cuff
balloon is a blind procedure. Cessation in passage of air about the cuff
,- balloon indicates the accomplishment of a seal; however, once sealed, it is
virtually impossible to determine the degree of overinflation. Overinflation
could produce injurious excessive pressure. This problem is further emphasiz-
ed by diffusion of certain gases into the cuff balloon during surgical
procedures, thereby increasing volume and pressure.
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It is an object of this invention to provide an inflatable catheter
having a reliable signal member positioned thereon to indicate and prevent
overinflation of the cuff balloon.
It is another object of this invention to provide a signal member
for an inflatable catheter which will not erroneously inflate during the
~; inflation of the cuff balloon.
It is a specific object of the present invention to provide a
signal member for an inflatable catheter which will not erroneously inflate
~ during rapid inflation of the cuff balloon.
,; Another object of the present invention is to provide a signal
device for an endotracheal catheter which, in combination, will facilitate
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proper placement and inflation of the cuff balloon.
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According to the invention, a catheter comprises an inflatable
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`; member and a flexible conduit having an inflation lumen, the inflatable
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member communicating with the inflation lumen, a signal member; and connector
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means for interconnecting said signal member and said inflatable memberJ
` said inflation lumen, said inflatable member, said signal member and said
connector means cooperatively defining a flowpath wherein an inflation fluid
first passes through said inflation lumen into said inflatable member and
; then passes from said inflatable member through said connector means into
said signal member, whereby said signal member is actuated after initial
expansion of said inflatable member.
; Preferably a main lumen communicates with an opening in the distal
portion of the conduit and a separate inflation lumen communicates with an
inflatable cuff member or balloon positioned proximate ~he distal portion of
the flexible conduit and inflatable at a predetermined normal inflation
pressure to either hold or seal the catheter in a body cavity.
Preferably the signal member is positioned to be outside of the
body cavity during normal use such as proximate the proximal portion of the
; flexible conduit. A separate signal lumen is provided to communicate with
the inflation lumen so that the inflation fluid need not pass through the
signal member to the cuff member.
In one embodiment, the signal member and inflatable cuff member
are interconnected by the separate signal lumen. In another embodiment, a
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separate signal or safety lumen interconnects the signal member and an inter-
; mediate point on the inflation lumen upstream of the inflatable member. In
any event, the signal member is adapted to be activated at a second pressure
; higher than the predetermined normal inflation pressure of the cuff member.
Accordingly, in one embodiment of the present invention, the signal member,
~- cuff member, safe~y lumen and inflation lumen define a flowpath wherein the
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`~ inflation fluid used to inflate the cuff member first passes from the infla-
tion lumen into the cuff member before passing through the safety lumen to
the signal member.
When inflation of the cuff member is impeded or higher inflation
pressure is imposed thereon, the signal or safety member is actuated, after
` the initial expansion of the cuff member, thereby indicating the presence of
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high pressure and the need for inflation adjustment. The advantage of the
present invention is that the safety member is effectively positioned down-
stream of the cuff member. As a consequence, the safety member will not
"see" pressures higher than the pressure seen by ~he inflatable cuff member.
This is important during inflation where, due to pressure drop through the
inflation lumen, points upstream of the cuff member are subjected to pressures
which are actually higher than the pressures actually imposed on the cuff
member.
In a particularly preferred embodiment, the signal member comprises
a flexible sleeve encircling the flexible conduit and having its edge sealed
thereto. The flexible sleeve communicates with the signal lumen through an
opening in the wall of the signal lumen. In this embodiment, the signal
member preferably has a different color than the cuff member so that the
user's attention is directed to the signal or safety member.
Similarly the signal member can comprise an edge sealed patch of
elastic material overlying an orifice communicating with the safety lumen
and a valve within the orifice, adapted to open at a fluid pressure greater
than the pressure normally required to inflate the cuff member, or a micro- -
porous body sealingly seated within the orifice, capable of wetting through
and weeping of fluid at a pressure greater than the pressure normally required
to inflate the cuff member. These latter specific features are illustrated
in United States Patent No~ 3,543,759.
Another improvement described herein comprises an inflation measure-
ment device for use in combination with the signal device. This improvement
is particularly applicable to endotracheal catheters.
The inflation measurement device includes a collar substantially
encompassing the signal member or balloon. The collar is open at one end and
preferably includes two sections having a first and second inflation indicat-
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ing dimension, respectively. The second inflation indicating dimension
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exceeds the first inflation indicating dimension. In a specific preferred
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embodiment, the collar sections are substantially cylindrical, such that the
inflation indicating dimensions are the diameters of the respective cylinders.
As the cuff member is inflated, the signal member is responsively
inflated, i.e., the signal member begins to inflate whenever the predetermined
pressure is exceeded. As inflation progresses, the signal member initially
engages the collar section having the smallest înflation indicating dimension.
Further inflation causes the signal member to expansively contact the second
collar section.
A seal between the trachea and cuff member is achieved when the
signal member begins to inflate. That is, excess inflation fluid has begun to
; fill the signal member. The collar of the inflation measurement device is
preferably dimensioned such that contact of the signal member and first collar
portion indicates a cuff balloon pressure of 60 mm Hg. Rollover of the signal
member into contact with the second collar portion indicates an overinflated
; state in the cuff member. With preferable dlmensions, contact with the second
collar portion occurs at a cuff member pressure of 90 to 100 mm Hg.
Other objects, features, advantages and embodiments of the present
invention will become apparent in the following more detailed description.
Figure 1 is a side view of a conventional Foley catheter equipped
with the signal member and pressure indicator device of the present invention.
Figure 2 is a detailed partial side sectional view of the Foley
.~ catheter illustrated in Figure 1 wherein the cuff member is inflated and the
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"r, safety member is not inflated.
Figure 3 is an end sectional view taken along section line 3-3 of
Figure 2 illustrating the main lumen, inflation lumen and safety lumen of the
Foley catheter.
- Figure 4 illustrates the safety member and cuff member in an in-
. flated condition.
'; Figure 5 is a perspective view of an endotracheal tube equipped
with the signal member and pressure indicator device of the present invention.
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Figure 6 is a detailed side sectional view of the endotracheal
tube illustrated in Figure 5, taken along section line 6-6 illustrating the
signal member in greater detail.
Figure 7 is a detailed cross sectional end view of the inflation
tube illustrated in Figure 6 taken along section line 7-7.
Figure 8 is a detailed side sectional view of another embodiment
of the present invention in an endotracheal catheter or tube.
Figure 9 is an end sectional view of the catheter tube shown in
Figure 8 taken along section line 9-9.
Figures 10 and 11 illustrate the operation of the signal member
and pressure indicator device in various states.
Figure 12 is an end view of the pressure indicator device shown
in Figure 6, illustrating the pressure indicating dimensions thereof.
Figure 13 illustrates the proper placement of an endotracheal
~ catheter with the human body.
r'"' Referring to Figures 1-4, there is illustrated a Foley urinary
, catheter tube 2 containing a safety balloon 32 according to the present inven-
^: tion. However, it should be remembered that the present invention applies to
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;~ endotracheal tubes (see Figures 5-7) and the like as illustrated in United
States Patent No. 3,734,100.
Referring first to Figures 1-4, the catheter 2 comprises a tube
;; portion 3, a tip portion 10 having a drainage opening 8 positioned in
proximity thereto and a cuff or retention balloon 20 for holding opening 8
within a body opening such as the bladder. The proximal end of the catheter
2 includes a drainage arm 4 and a bifurcated inflation arm 12 having posi-
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tioned thereon a oneway check valve 14 held in position within the arm 1? by
' a ring 15.
'~ Referring to Figures 2 and 3, a central drainage lumen 6 passes
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down the center of the tube 3. An inflation lumen 18 and a diametrically
opposed safety lumen 26 are integrally formed in the wall of the tube 3. The
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inflation lumen 18 communicates with the central lumen 16 of the inflation
arm 12 through an orifice or opening 17. Inflation fluid, such as saline
water in the case of a urinary catheter, or air in the case of an endotracheal
catheter, passes through the inflation arm 12 and orifice 17 before entering
- the inflation lumen 18. The inflation fluid, in turn, is discharged from the
inflation lumen 18 through an orifice 19 and into the free space beneath the
retention balloon 20, thereby causing the balloon 20 to expand against the
bladder wall 22 and to hold the catheter 2 within the bladder.
According to the present invention, the inflation fluid entering
the retention balloon 20 is allowed to pass through an orifice 24 into the
safety lumen 26. The safety lumen 26, as is the inflation conduit 18, is
plugged at the proximal end by an appropriate plug of material 28 to create a
defined flowpath within the tube 3. In any event, the safety conduit 26 com-
municates with the underside of the safety balloon 32 via an orifice 30.
; As illustrated in Figures 2 and 4, the signal balloon 32 comprises
a flexible sleeve encircling tube 3, and the edges of the sleeve are sealed
to the tube 3. The balloon 32 is designed to inflate at a higher pressure
,l than the retention member 20. Preferably, the safety balloon 32 is actuated
by expansion whenever the retention member 20 exceeds the normal inflation
pressure by approximately 5-10 mm mercury pressure (Hg). The inflation pres- -
sure, or actuation pressure, of the safety balloon 32 can be controlled by the
thickness and/or length of the material used to form the balloon 32 ~lone or
in combination with the length and/or diameter of the safety lumen 26. For
example, by properly selecting the length and diameter of the lum0n 26, a
; predetermined pressure drop will occur between orifice 24, exiting from the
inflation balloon 20, and orifice 30, opening into the safety indicator
balloon 32.
The balloon 32 can be manufactured from the same material as the
; retention balloon 20. When the balloon 32 is so constructed, its indication
or inflation pressure can be controlled by regulating its length. For example,
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the length of the sleeve used to form the balloon 32, when shorter than the
sleeve used to form the retention balloon 20, will cause the balloon 32 to
inflate at a higher pressure than required to inflate the balloon 20.
The retention balloon 20 and safety balloon 32 are readily con-
~ structed by means well known to those trained in the art and a detailed des-
; cription of the methods of their construction need not be set forth herein.
The balloons 20, 32 can be manufactured by coating a partially completed
catheter with a material, such as bentonite, thereby surrounding the openings
19 and 24 or 30, which are filled with an appropriate clay. The bentonite
;~ 10 coated area adheres only lightly, if at all, to subsequent dipped coats, l.e.,
latex or silicone, and causes a skin to be formed covering the holes communi-
cating with the inflation and safety lumens 18, 26. This skin, when the clay
;~ material in the holes is washed away, is inflatable because it is deposited
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on and unified with the tube material bordering the bentonite coated area.
As illustrated in Figures 1-4, the catheter of the present inven-,,;
tion advantageously positions the safety balloon 32 downstream of the infla-
tion balloon 20. During inflation, the safety balloon 32 does not experience
pressures higher than the pressures imposed upon the inflation balloon 20.
~ This is in contrast to prior art catheters wherein, during inflation, the
; 20 safety balloon can be subjected to pressures higher than the pressures seen
~:j by the inflation balloon. Accordingly, in the prior art catheters, the safety
balloon can expand and give a false reading of over-inflation. This is par-
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ticularly vexatious in the case of an endotracheal tube wherein the maximum
pressure imposed on the retention balloon is on the order of 20-30 mm Hg and,
in any event, less than 50 mm Hg. With the present invention, the cuff
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balloon 20 can be rapidly inflated against the trachea without actuating or
inflating the safety balloon 32. However, if the inflation fluid has to first
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pass through the safety balloon 32 before reaching the retention balloon 20,
then expansion of the balloon 32 would interfere with rapidly obtaining a
firm seal between the tube body and the trachea.
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Referring to Figure 5, there is illustrated an endotracheal tube
40 according to another embodiment of the present invention having an expan-
sible inflation cuff 42 positioned on the end of the endotracheal tube 40.
The cuff 42 communicates with an inflation lumen 44 whichJ in turn is inter-
connected to a double lumen tube 48 through an interconnecting splice 46. The
double lumen tube 48 comprises a main inflation lumen 50 and a smaller,
indicator or safety lumen 52, as illustrated in Figures 6 and 7.
The inflation cuff 42 is inflated by the application of inflation
fluid (air or liquid) from a syringe 68 through a one-way check valve 66 into
the inflation lumens 44, 50.
According to the present invention, which is best illustrated in
Figure 6, a portion of the fluid which exits from the inflation lumen 50 of
the double lumen tube 48 is allowed to flow upwardly through the indicator ~.lumen 52 which is plugged at one end with a suitable plug 64. An intermediate
opening 54 is positioned downstream of the plug 64. A safety balloon 60 is
positioned around a housing 56 which surrounds the double lumen tube 48. The
interior of the housing 56 is isolated from the exterior by means of a plug
62. As a result, fluid entering the interior of the housing 56 through the
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opening 54, linking the housing 56 with the safety lumen 52 in the double -
; 20 lumen tube 48, passes through an opening 58 in the housing 56 and inflates the
safety balloon 60. The exact degree of inflation of the safety balloon 60 is
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~ indicated by a pressure measurement device or monitor 70 surrounding the
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balloon 60.
The inflation lumens 44, 50 are sized, i.e., the length and dia- .-
meter are appropriately sized, such that the majority of inflation fluid flow-
ing from inflation lumen 50 passes through inflation lumen 44 and inflates
cuff 42. Sufficient pressure drop is maintained by sizing so that there is
a throttling effect through the lumen 52. The net result, during inflation,
is that the cuff 42 inflates before the safety balloon 60, so as not to give
a false indication of the degree of inflation. If the safety balloon 60
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communicated directly with the inflation lumen 50, then the balloon 60 would
inflate before the seal cuff 42 due to the pressure drop in the inflation
lumen 44, thereby producing a false reading. According to the present inven-
tion, since the inflation cuff 42 inflates first by the proper correlation
of the size of the inflation lumen 50 relative to the signal lumen 52, false
readings are substantially avoided. In other words, the pressure drop through
the signal lumen 52 is such that the signal balloon 60 does not begin to in-
~ flate until there has been inflation of the cuff balloon 42 to a predetermined
pressure threshold~ Once the cuff 42 reaches an equilibrium position, the
: 10 balloon 60 will subsequently reach an equilibrium position, that is, the
degree of expansion of the balloon 60 lags the degree of expansion of the cuff
42 until a condition of equilibrium is established.
Referring to Figures 8 and 9, another preferred embodiment of theendotracheal catheter 40 is shown. Equivalent features in Figures 6 and 8 are
similarly designated. As shown, the main inflation lumen 50 and safety lumen
52 communicate directly with a first and second channel 80, 82, respectively,
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in the endotracheal tube 40. The endotracheal tube 40 also includes a cen-
tral or primary lumen 84.
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` The channels 80, 82 are located in a reinforced portion 85 of the
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~; 20 tube 40. The lumens 50, 52 and channels 80, 82, respectively, are similarly
sized in terms of cross sectional area.
The first and second channels 80, 82 communicate with the cuff
balloon 42 through openings 86, 88, respectively. As such, the inflation
fluid is pumped into the cuff balloon 42 by the syringe 68 via the main in-
flation lumen 50, channel 80 and opening 86.
As previously discussed with respect to Figures 1-4, the safety
lumen 52 and channel 82 are sized to provide a predetermined pressure drop
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between the cuff balloon 42 and safety balloon 60. Alternatively, the thick-
ness and length of the safety balloon 60 alone or in combination with the
size of the lumen 52 and channel 82 can be used to control the inflation
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characteristics of the safety balloon 60.
Referring now to Figures 6 and 10-13, the pressure indicating
device 70 includes a retaining or securing ring 90 and a collar 92, integral
therewith. The retaining ring 90 sealingly maintains the safety balloon 60
and pressure indicating device 70 on the housing 56.
The collar 92 is open at one level and substantially encompasses
the safety balloon 60. The collar 92 includes a first and second section 94,
96 having a first and second pressure indicating dimension, respectively. The
, first and second sections 94, 96 are preferably cylindrical sections, such that
; 10 the inner diameter of the cylinder is the pressure indicating dimension. The
first and second pressure indicating dimensions are generally designated A, B,
respectively, in Figure 12.
The safety balloon 60 and pressure indicating device 70 cooperat-
` ively define means, generally designated 100, for indicating the state of
inflation of the cuff balloon 42. The cuff balloon 42 of the endotracheal
catheter 40 is shown in its proper place in the trachea in Figure 13.
! As the cuff balloon 42 is inflated and a seal is achieved, the
safety balloon 60 responsively begins to inflate. That is, the cuff balloon
42 has contacted the tracheal wall, and excess air is now entering the safety
balloon 60 over the retarding influence of the safety lumen 52 and related
structure. At this point, the cuff balloon pressure is approximately 40 mm Hg.
When the safety balloon 60 contacts the first section 94 of the collar 92,
; the pressure within the cuff balloon 42 is approximately 60 mm Hg. This is
s~fficient for normal operation of a respirator (not shown) connected to the
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endotracheal tube 40, i.e., a respiratory machine pressure of 90 ml H20.
To operate the respirator at higher pressures, it is necessary to
substantially avoid "blow-by" by increasing the volume of the cuff balloon 42. ~ --
;~ "Blow-by" is the escape of gases around the cuff balloon 42 due to the high
pressures exerted by the respirator. By inflating the cuff balloon 42 and
consequently the safety balloon 60 until the safety balloon 60 initially con-
tacts the second section 96 of the collar 92, sufficient pressure is provided
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in the cuff balloon 42. Contact of the safety balloon 60 and second section
96 indicates a cuff balloon pressure of approximately 90 to 100 mm Hg.
Referring particularly to Figure 11, overinflation of the cuff
balloon 42 and possible occlusion of the central lumen or airway 34 is in-
dicated by substantial engagement of the safety balloon 60 and second collar
section 96. In response to this visual signal, the operator, e.g., an
anesthesiologistJ would reduce the volume of air in the catheter system 40.
Overinflation may also result from diffusion ~f anesthesia gases
; into the cuff balloon 42. Upon transmission bo the safety balloon 60, the
gases diffuse into the atmosphere, such that the safety balloon 60 substan-
tially regulates cuff balloon pressure~
The safety balloon 60 and pressure indicating device 70, in com-
bination, also indicate improper placement of the cuff balloon 42. If the
safety balloon 60 does not shown any inflation after a reasonable amount of
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air has been injected into the system 40, then the cuff balloon 42 is pro-
bably improperly positioned in a large cavity such as the tracheal bifurcation
or esophagus. On the other hand, if the safety balloon 60 indicates an over-
inflated state after injection of limited inflation fluid, then the cuff
balloon 42 has probably been inserted beyond the bifurcation, as shown in
Figure 11.
For universal application, variously sized collars are provided.
- The appropriate collar is chosen based upon an examination to determine tra-
cheal size.
Several preferred embodiments of the present invention have been
disclosed herein. It is to be understood, however, that various modifications
and changes can be made without departing from the true scope and spirit of
the present invention, as defined by the following claims. For example, the
combination of the safety balloon 60 and pressure indicating device 70 is
equally applicable to the prior art catheters wherein the safety balloon
` 30 communicates directly ~ith the main inflation lumen.
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