Note: Descriptions are shown in the official language in which they were submitted.
20~1779
877-564A
GGs 590
LASBR RBSISTAN~ VENTI~ATING DBVICB
WIT~ LOC~ING ~ u~-~
Background of the Inventlon
F~eld of the In~ention
The present invention relates to 8 devlce employed
for ventilating a patient during surgical use of a la~er
in a patient' 8 airway.
De~crlptlon of the 8ac~ Art
Endotracheal tubes for controlling ventilation of a
patient during surgery are known in the art. Such
devices generally include a tubular body for conveying
the ventilation and anesthe~ia gases to and from a
patient' 8 lungs. In order to provide a tight ~eal with
the trachea for controlled ventilation, a balloon or cuff
typically i8 provided near a di~tal end of the
endotracheal tube, the cuff being inflatable from out~ide
the patient by means of an aux$1iary conduit. In order
to minimize the possibility of damaging a respiratory
tract into which a ventilation device i9 inserted, ~uch
devices usually are constructed of flexible polymeric
material.
Laser microlaryngeal surgery is increas$ngly being
employed for treatment of localized laryngeal and
tracheal lesions. There are several known types of
surgical la~ers, including ruby, argon, helium-neon, Nd-
YAG and carbon dioxide la~ers. However, the carbon
~p
7~9
dioxide laser appears best for the removal of laryngeal
papillomas, polyps, nodules, cysts and the like, since
carbon dioxide lasers produce 10.6~ lightwaves which are
absorbed by biological ti~sue, de~troying targeted cell
membranes and vaporizing cellular contents.
During laser microlaryngeal surgery, an
unobstructed, binocular view of a lesion is provided.
This provides advantages over other known types of
laryngeal surgery, such as diathermy and cryosurgery,
which utilize a probe that may obscure a surgeon's view
of the operative field. In addition, laser~ provide a
relatively bloodless field, and post-operative edema is
usually absent because the area treated by laser i~
sharply defined. Ideally, laser surgery leaves the
surrounding tissue totally unaffected, allowing rapid
healing with minimal post-operative scarring.
One con~ideration of microlaryngeal surgery is that
the operative field is shared by the anesthesiologist and
the surgeon. This can be addressed by using an
endotracheal tube having an outer diameter sufficiently
small to permit the surgery to take place while having an
inflatable cuff large enough to ma~e a seal.
Alternatively, the surgery can occur with no tube in the
airway with patient ventilation and anesthetic gas
delivery given during interruption~ in surgery via a
mask.
There are disadvantages to having no tube in the
airway. These include: lack of complete airway control,
the possibility of apnea or hypoventilation with
secondary cardiac arrythmias, laryngospasm from too light
a plane of anesthesia, non-immobilized vocal cords, and
exhalation of potent anesthetic gases through the open
mouth of the patient making scavenging of these gases
difficult.
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.
Although performing microlaryngeal surgery with no
tube in the airway is undesirable for reasons listed
above, problems also arise during laser microlaryngeal
surgery when employing an endotracheal tube. These
problems typically involve damage caused by the laser of
one or both of the endotracheal tube and inflatable cuff.
Laser damage to the ventilation device may result in loss
of airway management, burning of respiratory tis~ue, and
the production of toxic fumes.
One method which has been proposed to reduce the
risk of damaging the endotracheal tube during laser
surgery is to wrap the endotracheal tube with metallic
tape. However, wrapping a tube in metal tape is time
consuming, and rough edges of the tape may abrade and
in~ure the mucosa of the pharynx and larynx. In the
event of a poor wrapping ~ob, the possibility exists that
uncovered areas can be ignited, as does the possibility
that loose pieces of tape can be aspirated. Wrapped
metal tape increases the possibility of a kink developing
in the tube, and inadvertent mucosal damage may occur due
to reflection of the laser beam off the type.
Another proposed method for reducing the risk of
ignition of an endotracheal tube is to wrap the tube in
wet muslin. However, this also i8 time consuming, and
the muslin adds additional bulk to the tube.
Additionally, the muslin may dry out and ignite during
surgery.
Yet another proposed method for reducing the risk of
ignition of an endotracheal tube is to coat the tube with
dental acrylic. However, dental acrylic rigidifies the
tube and is not completely impenetrable by surgical
lasers. The dental acrylic further adds undesired bulk
to the tube and is time consuming to apply.
2(~01779
Metal tracheal tubes also have been utilized to
avoid ignition of the tube during laser surgery, but
problems with the use of metal tracheal tubes have been
encountered. These problems include tissue damage
brought about by insertion of rigid metal tubes, and
inadvertent mucosal damages due to reflection of the
laser beam off of the metal tube. Metal tracheal tubes
typically have large external diameters which precludes
their use with pediatric patients and patients with
tracheal stenosis, and generally have no inflatable cuff
for creating an air-tight seal. Moreover, the currently
available flexible metal tracheal tubes typically are
constructed such that the wall of the tube is not air
tight.
Venturi ventilation has been employed during laser
microlaryngeal surgery, but this may poses problems such
as pneumothorax, pneumomediastinum, stomach inflation,
aspiration of secretions, complete respiratory
obstruction, and dehydration of mucosal surfaces.
The use of metallically filled polymers for tube
construction also has been suggested to reduce the risk
of ignition of endotracheal tubes. However, proposed
metallically filled polymers provide only minimal
resistance to penetration by laser beam impact
(especially in 0~/N02 enriched atmospheres), and are
generally quite expensive.
There remains a need in the art for a surgical
ventilation device which is resistant to laser-caused
dysfunction during laser surgery.
SummAry of the Inventlon
In accordance with the present invention, a ~urgical
ventilation device resistant to laser-caused dysfunction
during laser surgery defines a continuous gas passageway
for passage of ventilation gases during surgery. The
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device includes a beveled di~tal end to facilitate
insertion into a patient's airway, the distal end
defining a portion of the continuous gas passageway. A
proximal end is also provided for connecting the
S continuous gas passageway to a source of gas. The
surgical ventilating device of this invention includes an
airtight flexible metal tube having an airtight wall
portion connecting the distal end and the proximal end of
the ventilating device. The metal tube is refiistant to
damage by a surgical laser and has a matte outer surface
for dispersing unfocused light when a surgical laser beam
is directed again~t the outer surface of the device. The
metal tube defines a substantial portion of the
continuous gas passageway. A lower, liquid-inflatable
polymeric sealing cuff and an upper, liquid-inflatable
barrier cuff are connected to and longitudinally disposed
along a lower polymeric tubing assembly at the distal end
of the device, the lower cuff being situated between the
upper cuff and the distal end. The lower polymeric
tubing assembly, with upper and lower cuffs, is connected
to the metal tube by a locking ferrule that compresses
the polymeric tubing against the metal tube so as to
prevent disengagement. The lower cuff is inflated with
liquid to bring the lower cuff into sealing contact with
a patient's airway and thereby prevent a gas leakage
between the lower cuff and the airway. The upper cuff is
inflated with liquid for bringing the upper cuff into
contact with airway to thereby shield the lower cuff from
damage caused by laser energy directed toward the lower
cuff.
Brief DescriPt~on of the Drawings
FIG. 1 is an elevation view, partly schematic, of a
laser-resistant surgical ventilation device in accordance
with the present invention.
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FIG. 2 is an enlarged elevation view, partly
schematic and in partial cross-section, of the laser-
resistant double-cuffed distal end of the surgical
ventilation device shown in FIG. 1.
FIG. 3 is a cross-sectional view along line 3-3 of
FIG. 2.
FIG. 4 i8 a perspective view in partial cross-
section and with a portion enlarged of a segment of a
metal tube of a surgical ventilating device according to
one embodiment of the invention.
FIG. 5 is a partly schematic elevation view with
portions broken away of a ventilating device according to
the invention showing interconnection of tubing elements
according to one embodiment.
FIG. 6 is a cro~s-sectional view of a connected pair
of liquid conduits for inflating elastomeric cuffs of the
surgical ventilation device shown in FIG. 1.
FIG. 7 is an enlarged, partly schematic, elevation
view with portions bro~en away and portions removed,
showing interconnection of the lower portions of a
ventilating device with a locking ferrule according to a
preferred embodiment of the invention.
FIG. 8 is an enlarged, partly schematic, elevation
view with portions broken away and portions in cross-
section, showing interconnection of the lower portions ofa ventilating device with a locking ferrule according to
another embodiment of the invention.
Detailed Description of the Preferred ~mbodiment
The endotracheal tube 10 shown in Figs. 1 and 2 is a
surgical ventilation device which i~ resistant to laser-
caused dysfunction during laser surgery. The device
defines a continuous ga~ passageway 12 for passage of
ventilation gases (including anesthetic and respiratory
ga~es) during surgery.
20Q1~779
Endotracheal tube 10 includes a distal end 14 with a
beveled tip to facilitate insertion into a human trachea,
and defines a portion of the continuous gas passageway
12.
Endotracheal tube 10 further includes a proximal end
16 for connecting the continuous gas passageway 12 to a
source of gas (not shown).
A flexible metal tube 18 having an airtight wall
portion is disposed between the distal end 14 and the
proximal end 13 of the ventilation device. The flexible
metal tube 18 is resistant to damage by a surgical laser,
and as can be seen in Fig. 1, metal tube 18 defines a
substantial portion of the continuous gas passageway 12.
The proximal end 13 of the ventilation device is
connected to the metal tube 18 by an upper polymeric
tubing 17 disposed over the proximal end of metal tube 18
to form an airtight fit.
In order to prevent inadvertent and unintended
damage to a patient' 8 tissue6 during surgery due to
reflection of a laser beam off of the metal tube, metal
tube 18 is provided with a matte outer surface for
dispersing unfocused light when a surgical laser beam is
directed against the outer surface of the metal tube.
The airtight metal tube 18 may be of any suitable
construction to permit flexibility, such as a helically
convoluted metal hose, a segmented flexible metal hose or
corrugated bellows, and is characterized by substantial
continuity from one end to another so as not to provide
laser-penetrable apertures in the sidewall of the metal
tube.
Advantageously, the flexible metal tube 18 i8
constructed of stainless steel for corrosion resistance.
The matte exterior finish of the flexible metal tubing
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reflects a highly unfocused beam, which minimizes the
potential of inadvertently damaging tissue.
One suitable construction for metal tube 18 is shown
in Fig. 4. According to this embodiment, metal tube 18
starts out as a thin stainless steel ribbon (i.e., .0035"
thick and .212" wide). This ribbon is fed through a die
set to form a helically convoluted hose or tube. The die
crimps the ribbon 19 back on to itself as shown in Fig.
4. At the same time ribbon 19 is being formed in the
die, a fine metallic filament 21 is fed into an
overlapping channel between ad~acent crimped ribbon
portions. Metallic filament 21 has a lower melting
temperature than the metallic compo~ition of ribbon 19.
The formed strip wound metal hose is heat treated in
order to melt the metallic filament 21 and thus
hermetically seal the seam.
Referring back to Figs 1-3, approximate the distal
end 14 of endotracheal tube 10 is located a lower liquid-
inflatable elastomeric sealing cuff 20 with lower
proximal cuff shoulder 21 inverted to reduce the required
intratracheal length, and an upper liquid-inflatable
barrier cuff 22 with upper proximal cuff shoulder 23
inverted to both reduce the re~uired intratracheal length
and to minimize the exposure of polymeric materials. The
ventilating device is airtight along its length from the
proximal end 13 thereof to cuffs 20 and 24.
The lower and upper cuffs 20 and 22, respectively,
are mounted on the outer surface of a lower polymeric
tubing assembly comprised of a tubular polymeric distal
tip member 24 and a tubular polymeric sleeve 24'. As
shown in Figs. 1 and 2, the lower cuff 20 is positioned
between the upper cuff 22 and the distal end 14 of the
endotracheal tube 10.
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The polymeric portions of the ventilation device,
including tubing assembly 24, 24' and upper polymeric
tubing 17, may be constructed of any suitable
biocompatible material, such as biocompatible polyvinyl
chloride, polyurethane, silicone and the like.
Tip member 42, at the distal end 14 of endotracheal
tube 10 is an atraumatic insertion tip including a
longitudinal ventilation opening lSa, and advantageously
includes a transverse ventilation opening lSb in the
event that the longitudinal opening lSa i8 blocked during
use.
In the embodiment shown in Figs. 1 and 2, the tip
member 24 is received within the polymeric sleeve 24' and
attached thereto by any suitable mean~, such as an
ultraviolet (U.V.) light-cured adhesive, chemical weld or
glue. The polymeric slee~e 24' comprises a proximal end
section of the lower polyneric assembly, within which is
received the distal end of the metal tube 18, thus
connecting the distal end 26 of metal tube 19 with the
proximal end section of the lower polymeric tubing
assembly.
By the present invention, a locking ferrule is
provided for preventing disengagement of the lower
polymeric tubing assembly from the metal tube 18. At
least a portion of the locking ferrule i~ pinched
inwardly so as to compress the proximal end section of
polymeric sleeve 24' against the metal tube 18. In the
embodiment preferred shown in Figs. 2, 5 and 7, the
locking ferrule 25 of the invention is an annular metal
collar that extends around the proximal end section of
polymeric sleeve 24~. An annular crimp 27 is provided by
compressing (i.e., crimping) the locking ferrule on its
outside diameter, which reduces the outside diameter of
the locking ferrule along the crimp and form~ a
2C~01779
mechanical bond between the proximal end section of
sleeve 24' and spirals of metal tube 18, thereby
preventing disengagement. A glue or other adhesive such
as U.V. curable adhesive 29 (shown in Fig. 8) can be used
to further connect and seal the distal end of metal tube
18 to sleeve 24'.
Although the annular crimp 27 discussed above with
reference to Figs. 2, 5 and 7 is the preferred
embodiment, other embodiments that pinch the locking
ferrule inwardly may be used. For example, in Fig. 8, a
locking ferrule 25' is disclosed which includes a
plurality of inwardly pinched depressions 27' that
"stake" the locking ferrule 25' to the metal tube 18
while compressing the proximal end section of sleeve 24'
against the metal tube 18 to prevent disengagement
therefrom. As previously discussed, a glue or other
adhesive 29 can be used to further connect and seal the
distal end of metal tube 18 to sleeve 24'. An annular
crimp as detailed in Fig. 7 is the preferred embodiment
over staking, since the annular crimp has been found to
form a stronger mechanical bond and provide a better seal
than staking.
In the embodiments shown, cuffs 20 and 22 are
polymeric, and attached to polymeric tubing 24 by any
suitable means such as by heat sealing. Suitable
materials for forming the polymeric cuffs include
polyvinyl chloride, polyurethane, silicone and the like.
Means are provided for inflating the lower sea~ ng
cuff 20 to bring the lower cuff 20 into sealing contact
with a patient's trachea and thereby prevent leakage of
gas between the lower cuff 20 and the trachea. Although
sealing cuff 20 can be inflated with a gaseous fluid, in
the preferred embodiment, sealing cuff 20 is inflated
with an aqueous liquid. To effect inflation of sealing
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cuff 20, a first inflation lumen 29 is provided in the
lower polymeric tip member 24, lumen 28 being in
communication with lower cuff 20 by means of port 30.
See Figs. 2 and 3.
S Inflation lumen 28 is connectable with a fluid
source for inflation of lower cuff 20 by means including
a first conduit 32.
Conduit 32 i8 disposed within metal tube 18 for
protection against laser damage durinq surqery, and
connects lower cuff 20 with a first valve 34 for
connecting the first conduit 32 with a liquid source ~not
~hown) and for controlling inflation and deflation of
lower cuff 20.
Means are provided for inflating the-upper barrier
cuff 22 with an aqueous liquid for bringing the upper
cuff 22 into contact with a patient's trachea to thereby
shield the lower cuff 20 from damage caused by laser
energy directed towards the lower cuff. Upper cuff 22
shields the lower cuff from damage by a surgical laser by
being positioned between an area of laser surgery (e.g.,
in an area ad~acent metal tube 18) and the fluid-filled
sealing cuff 20.
The upper barrier cuff 22 is inflated by means
including a second inflation lumen 36 in the lower
polymeric tip member 24,. The second inflation lumen 36
is in communication with the upper cuff 22 through port
38. The second inflation lumen 36 i8 connectable with a
second liquid source for inflation of upper cuff 22 by
means including a second conduit 40 disposed within metal
tube 18 for protection against laser damage. The second
conduit 40 connects the second inflation lumen 36 with a
second valve 41 in communication with a liquid source
(not shown) for controlling inflation and deflation of
upper cuff 22.
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In the embodiment shown in Fig. 1, the first and
second conduits 32 and 40 exit metal tube 18 through a
standard 15 mm connector 16 for connecting to a source of
gas. The connector 16 can be constructed of rigid or
semi-rigid biocompatible polymeric materials such as PVC
and ABS. The connector 16 is attached to metal tube 18
by any suitable means, such as glue or other adhesive.
If desired connector 16 can be attached to metal tube 18
in the same manner as lower polymeric sleeve 24'.
Conduits 32 and 40 are adhered together a~ shown in
Fig. 6 by means of a solvent or by extruding them as one.
This, along with the orientation of lumens 36 and 28,
allow easy passage of suctions and stylets through gas
passageway 12. Conduits 32 and 40 exit through a port in
connector 16. They are anchored in this port by means
such as glue.
In the embodiment shown in Fig. 5, the ends 18a and
18b of metal tube 18 are partially deconvoluted. The
increase in distance between convolutions of metal tube
18 at the ends provides a means for an adhesive to
mechanically hold onto the stainless steel tubing. The
proximal end 18a of the tube 18 has adhesive applied to
it 360 around the outer diameter thereof and tXe upper
polymeric tubing 17, such as a standard l5mm connector,
is slid over the metal tube. The distal end 18b of tube
18 has adhesive applied to it 360 around the outer
diameter thereof and lower polymeric sleeve 24' expanded
and placed on the metal tube. A plastic atraumatic tip
including ventilation openings l5a and 15b (as shown in
Fig. 2) can be solvent bonded to the internal diameter of
the lower polymeric sleeve 24~ such that it butts up
against the end of the metal tube. Locking ferrule 25 is
20Ct1779
crimped (and/or staked, if desired) about the proximal
end section of sleeve 24~ to prevent disengagement from
metal tube 18.
After tracheal tube 10 is intubated (i.e., inserted
S into a patient~s trachea), the cuffs 20 and 22 are fluid
filled with sterile isotonic saline solution. The lower
sealing cuff 20 is pressurized to maintain a tracheal
seal, and the upper bearing cuff 22 is filled, but
advantageously not to the point of creating any
substantial pres~ure (e.g., filled to near atmospheric
pressure). When fluid in the upper barrier cuff i~ at or
near atmospheric pressure, a single perforation of the
barrier cuff 22 by a surgical laser does not result in
substantial fluid drainage from barrier cuff 22.
The probability of hitting a cuff during a single
laser laryngeal surgery procedure can be determined from
Pried, M.P., "A Survey of the Complications of Laser
Surgeryn, Arch. OtolarYnqoloq~, 110:31-34 (1984). The
probabilities have been calculated as follows:
P (hitting cuff 1 time) = .06173
P (hitting cuff 2 times) = .00381
P (hitting cuff 3 times) = .00024
P (hitting cuff 4 times) = .00001
Since a single laser perforation of the barrier cuff
22 does not result in a substantial amount of fluid
drainage due to about atmospheric pressure in ~arrier
cuff 22, it can be seen that barrier cuff 22 provides a
substantial amount of protection for sealing cuff 20 and
distal end 14 of tubing 24. Further, water is an
excellent absorber of the 10.6~ wavelength of a carbon
dioxide laser such that surface molecules of the water
are boiled off and the laser energy dissipated providing
further protection for sealing cuff 20. The water in the
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barrier cuff 22 also eliminates virtually any threat of
ignition and burning of the polymeric cuffs.
According to one embodiment, the barrier cuff may be
filled with a colored aqueous solution which will leak
S out if the cuff i8 perforated and thereby visually
indicate that the cuff has been perforated. An example
of a suitable dye for coloring the aqueous ~olution i8
methylene blue. Other types of dyes may also be used.
It can be seen that the present invention provides a
stable surgical ventilation system which is highly
resistant to laser-caused dysfunction during laser
surgery. The matte-finished flexible metal tube i8
~mpenetrable by a surgical laser and reflects a highly
out-of-focus beam to preclude inadvertent damage to
tissue. The locking ferrule preventY disengagement of
the metal tube from the lower polymeric tubing carrying
the double-cuff system. The liquid-filled barrier cuff
provides protection to the tracheal sealing cuff against
damage by a laser beam impact. The double-cuff system
allows the user at least one cuff hit that will not cause
loss of protection by the barrier cuff and lead to
tracheal tube dysfunction. This, along with the very low
probability that the cuff will be hit again and the
stability of the system resulting from the locking
ferrule, provides for safe and effective airway control
during laser surgery.
Since many modifications, variations and changes in
detail may be made to the described embodiments, it is
intended that all matter in the foregoing description and
shown in the accompanying drawings be interpreted as
illustrative and not in a limiting sense.
