U.S. patent number 3,610,247 [Application Number 04/803,717] was granted by the patent office on 1971-10-05 for surface-anesthetizing medical appliance.
Invention is credited to Richard R. Jackson.
United States Patent |
3,610,247 |
Jackson |
October 5, 1971 |
SURFACE-ANESTHETIZING MEDICAL APPLIANCE
Abstract
Medical devices, endotracheal tubes, having on outside a solid
layer comprised of surface-effective anesthetic and solid substance
physically securing the anesthetic. The outer surface of the layer
has a prolonged anesthetizing effect. Semipermeable flexible
adhesive film and semipermeable sheet film across which the
anesthetic travels are specifically shown.
Inventors: |
Jackson; Richard R.
(Marblehead, MA) |
Family
ID: |
25187257 |
Appl.
No.: |
04/803,717 |
Filed: |
March 3, 1969 |
Current U.S.
Class: |
128/207.15;
604/104 |
Current CPC
Class: |
A61M
16/0445 (20140204); A61M 16/0481 (20140204); A61M
16/04 (20130101); A61M 16/0459 (20140204); A61M
19/00 (20130101); A61L 29/16 (20130101) |
Current International
Class: |
A61L
29/16 (20060101); A61L 29/00 (20060101); A61M
19/00 (20060101); A61M 16/04 (20060101); A61m
025/00 (); A61m 031/00 (); A61j 001/00 () |
Field of
Search: |
;128/260,262,265,272,351
;424/16,18,19,22 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
998,794 |
|
Jul 1965 |
|
GB |
|
215,350 |
|
Oct 1909 |
|
DD |
|
Primary Examiner: Pace; Channing L.
Claims
What is claimed is:
1. A medical tracheal tube constructed for insertion into a body
passage for prolonged exposure to mucous tissue of the patient, and
having on its outside a solid layer comprised of solid surface
effective anesthetic and solid substance physically securing the
anesthetic with respect to the tube, both said anesthetic and said
substance being solid at body temperature, the outer surface of
said layer having a nontoxic surface anesthetizing characteristic
extending over a period of at least 1 hour.
2. The tracheal tube of claim 1 wherein said solid substance is at
least in part semipermeable to secretions of mucous tissue and to
solutions of said anesthetic in said secretions whereby said
anesthetic can be gradually dissolved and flow in solution into
contact with some mucous tissue over a prolonged period of
time.
3. The tracheal tube of claim 2 wherein said solid substance
comprises an adhesive forming a coating on said tube with
anesthetic distributed therethrough.
4. The tracheal tube of claim 3 wherein said solid substance
comprises semipermeable silicone adhesive and said anesthetic is
present in said adhesive in the form of solid particles.
5. The tracheal tube of claim 2 wherein as least part of said solid
anesthetic is spaced from the outer surface of said layer by said
semipermeable solid substance.
6. The tracheal tube of claim 1 wherein said tube is formed of
resilient material, adapted to bend during insertion into the
patient, and said layer is flexible and adapted to conform to said
medical tube.
7. The tracheal tube of claim 6 wherein said layer comprises an
elastomeric substance integrally united to said tube.
8. In a tracheal tube for introducing air into the lungs of a
patient, said tube having means on its exterior surface for
applying surface effective anesthetic to the tissue of the trachea
by means of diffusion through a thickness of material having a
diffusion characteristic, the improvement wherein said exterior
surface is defined by film exposed for contact with body tissue to
be anesthetized, said film carrying substantially dry
surface-effective anesthetic spaced inwardly from said exterior
surface, said film material and said surface-effective anesthetic
being solid at body temperature and semipermeable by a liquid
compatible with said body tissue to mobilize said anesthetic to
diffuse to said exterior surface.
9. The tracheal tube of claim 8 including an inflatable cuff
secured adjacent the distal end of said tube, wherein said cuff is
formed by said film material, and at least one air passage adapted
to introduce air into said cuff to cause said cuff to seal against
tracheal tissue.
10. The tracheal tube of claim 9 wherein said film material and
said surface effective anesthetic are semipermeable by water.
11. The tracheal tube of claim 10 wherein said cuff is comprised of
semipermeable cellophane of a thickness less than 0.005 inch and
said surface-effective anesthetic is in the form of a deposit
adhered to the inner surface of said cuff, whereby said anesthetic
can diffuse through said cuff to the tracheal tissue.
12. A means for applying surface effective anesthetic by diffusion
through a thickness of material having a diffusion characteristic
wherein the material comprises a film having a surface exposed for
contact with body tissue to be anesthetized, the film carrying
substantially dry surface-effective anesthetic spaced inwardly from
said surface, said film material being permeable to and said
surface anesthetic being dissolvable by a liquid compatible with
said body tissue to mobilize said anesthetic to diffuse to said
surface.
13. The means of claim 12 wherein said film is comprised of
material from the group consisting of silicone, cellulose nitrate
an regenerated cellulose.
14. The means of claim 12 wherein said film is less than about
0.005 inch thick and said surface-effective anesthetic is in the
form of a deposit adhered to the surface of said film opposite to
said surface that is exposed for contact with body tissue.
15. The means of claim 12 wherein said surface-effective anesthetic
is dispersed through the mass of said film.
Description
This invention relates generally to medical appliances and
specifically to endotracheal tubes.
During surgical procedures the depth of general anesthetization is
often determined by the need to block the response of the patient
to the endotracheal tube that is present in his trachea. In other
words the tendency for the patient to buck (tightening of the
stomach muscles and tendency of the unconscious patient to sit up)
in response to the endotracheal tube is greater that the patient's
response to the pain at the site of the incision or the need for
maintaining a state of amnesia. This particularly so is cases where
administration of muscle relaxants is inadvisable.
Since it is desirable to maintain body functions as close as
possible to normal during surgery, and since these functions are
progressively affected with deeper levels of anesthetization, it
has long been desired to reduce the patient's reaction to
endotracheal tube throughout the surgical procedure. Prior tracheal
anesthetizing measures are objectionable for various reasons, e.g.
being effective only for short periods requiring repeated dosage,
or being complicated and introducing new steps or conditions in the
procedure of handling the patient.
It is also desirable to remove from the awakening and fully awake
patient the gag and coughing reflexes caused by the presence of the
endotracheal tube. This permits the tube to be tolerated and remain
in place in the awake patient, enabling continued support of
respiration by means of the endotracheal tube and respirator.
Likewise it permits respiratory support to be administered
immediately should this suddenly become necessary. The endotracheal
tube also gives better assurance against blockage of the airway by
tongue or tissues than do other airway devices.
More generally it has long been desirable to provide means for
decreasing sensations caused by medical tubes and similar
appliances residing in mucous passages of patients over periods in
the range of 1 to 20 hours in a manner requiring no change in the
appearance of the tubes or the steps required in their
administration.
The objects of the present invention are to meet these various
needs in a simple and practical way.
The invention employs an endotracheal or other medical tube which
may be of conventional construction in being comprised of a
flexible material such as latex rubber or polyvinyl chloride of a
thickness sufficient to ensure that the fluid passage will not be
closed by the flexing action attendant to the entubation and use of
the tube. The tube may include one or more cuffs in the form of
extensible balloons or in the form of large, highly flexible
"floppy" cuffs formed of thin film material. Featured therewith is
a solid layer or coating having a relatively thin effective
thickness and comprised of surface effective anesthetic and solid
substance physically securing the anesthetic. The outer surface of
this layer has a nontoxic (i.e. within nonharmful dosage limits)
surface anesthetizing characteristic extending over a period of at
least 1 hour, preferably over periods of 10 or 20 hours.
Advantageously the initial level of anesthetic availability is
relatively high to achieve quick onset of surface
anesthetization.
The invention also features a semipermeable membrane or securing
material disposed between the surface effective anesthetic in the
solid state and the body tissue, the anesthetic being progressively
transported thereacross.
The invention also features as the effective layer a matrix formed
by an adhesive substance containing a dispersion of solid
aggregates or crystals of surface-effective anesthetic, the
substance having a diffusion characteristic for body fluids and for
body fluids in which are dissolved minor quantities of the
anesthetic from the matrix.
The invention also features such a matrix layer and layers of other
makeups as integral with tubes and their flexible cuffs, and also
as part of flexible and distensible sleeves applied to preexisting
tube and cuff assemblies.
These and other objects and features will be revealed in the
following description of preferred embodiments taken in conjunction
with the drawings wherein:
FIG. 1 is a side view partly in cross section and partly
diagrammatic, of an endotracheal tube engaging tissue of a
patient;
FIG. 2 is a diagrammatic representation of the availability curve
of a typical device according to the invention;
FIGS. 3 and 4 are magnified cross sections taken on lines 3--3 and
4--4 of FIG. 1, respectively;
FIG. 4a is a greatly magnified view, partly diagrammatic, of a
portion of FIG. 4;
FIG. 5 is a perspective view, partly cut away of a sleeve member
according to the invention;
FIG. 6 and 7 are views of an endotracheal tube with which the
sleeve of FIG. 5 is combined;
FIG. 8 is a cross-sectioned view of a tube having a wrapping of a
diffusion membrane, securing in the inside a deposit of solid
anesthetic.
Referring to FIG. 1 an endotracheal tube 10 has a conventional air
passage 12, an angular-cut distal end 14, a proximal end provided
with a connector for the anesthetic machine, respirator or oxygen
line, and an inflatable cuff 20 together with an inflating
lumen.
The particular tube shown is made of plastic such as polyvinyl
chloride of a wall thickness t.sub.t of approximately one sixteenth
inch. The cuff is constructed of any suitable flexible film such as
extremely thin latex e.g. of less than 0.002 inch thickness and is
of a diameter substantially larger than the trachea, e.g. being
11/2 inch diameter in comparison with a trachea of 3/4 inch
diameter. Such floppy cuffs are disclosed in my copending patent
applications Ser. Nos. 427,601 and 719,994, and require very low
pressure to inflate, thus effectively combatting the necrosis
problem. Such cuffs flex to the shape shown when the lung pressure
exceeds atmospheric pressure.
Combined with this device, on the exterior surfaces exposed to the
tissue of the patient, is a layer 26 comprised on surface effective
anesthetic and bonding material physically securing the anesthetic
in place.
The layer 26 has the characteristic of presenting at its outer
surface, to tissue 28 in contact therewith, surface-effective
anesthetization of nontoxic levels extending over a period of at
least 1 hour, preferably over periods of 10 or 20 hours, in
accordance with the curve of FIG. 2 which will be discussed further
below.
In this preferred embodiment the layer comprises an elastomeric
adhesive coating applied to the outer surfaces of a previously
formed endotracheal tube and cuff assembly.
In the preferred embodiment of FIG. 5 there is shown a distensible
sleeve member 30 formed of resilient material which is supplied in
a rolled-up shape.
On its outer surface is a layer 32 similar to layer 26 of the
preceding figures, of such flexibility and resiliency to remain
coherent when the tube is convoluted in the roll 30a.
FIGS. 6 and 7 show an endotracheal tube 36 with two cuffs 38, 40
and corresponding inflation lumens 42, 44. In FIG. 6 the
distensible sleeve is shown partly applied to endotracheal tube 3,
the two dotted line positions showing progressive positions during
application. In FIG. 7 the sleeve is shown fully applied, with the
distal cuff 40 inflated, that portion of the sleeve distending
therewith and exposing its outer surface to sealing contact with
the tracheal wall.
FIG. 8 shows a section of bendable tube 50 to which has been
attached a film wrapping 52 upon the inside surface of which is
deposited solid anesthetic particles diffusable through the film
upon wetting the outside by secretions.
EXAMPLE 1
A conventional endotracheal tube with a balloon cuff similar to one
of the cuffs of FIG. 7 was coated on surfaces exposed to mucous
tissue with medical grade silicone adhesive containing a dispersion
of solid particles of a surface effective anesthetic. In
preparation, a quantity of tetracaine anesthetic in solid particle
form ("Pontocaine," Winthrop Drug Company), was ground by a mortar
and pestle until a powder of solid particles was obtained. The
particles were greenish-blue in color. 20 milligrams of the powder
were mixed with 1 cc. of medical grade silicone adhesive ("Vivosil"
medical adhesive Silicone-Type A, Becton, Dickinson and Company).
The adhesive was water-white in color, a nonflowing soft paste. The
adhesive with the 2 percent concentration of dispersed anesthetic
particles had a uniform greensh-blue cast. The prepared quantity
(i.e. 20 mg. of tetracaine) was required to provide the layer (26,
FIG. 1) over the tube and cuff. The coating was allowed to cure at
humidity conditions in excess of 20 percent at 77.degree. F.,
penetration of the atmospheric water through the silicone adhesive
causing its setup. The resulting layer was estimated to be between
a 0.003 and 0.005 inch thickness, and provided a shiny, smooth
surface. In the cured state the layer appeared clear, however under
close examination the anesthetic particles can be observed
(particles did not dissolve in the adhesive). The layer was
flexible with the underlying endotracheal tube and cuff, the layer
remaining coherent upon normal bending of the tube and distension
of the cuff.
The thus-prepared endotracheal tube was administered to an age 45
female, gall bladder excision, under a normal level of general
anesthetic. Three hours after the operation began the patient awoke
in the recovery room and looked around, with endotracheal tube in
place. There were no coughing or gaging reflexes, swallowing being
the only reaction of the patient even when the tube was jiggled by
the attending physician. When asked if she felt pain she shook her
head no. After the patient was awake 1 hour the endotracheal tube
was removed, with no spasm or coughing observed during removal,
indicating anesthetization of the upper airway as well as the
tracheal tissue in contact with the tube.
An endotracheal tube of identical construction was soaked in water
for 24 hours, after which anesthetic particles could still be seen
in the layer. After a total soaking of 72 hours the physician
placed the tube in his mouth and was able to detect numbing on the
tip of his tongue, after 5 minute exposure. Prior to soaking,
numbing of his tongue was detected with shorter exposure.
In other procedures in which the patients recovered from anesthesia
in substantially less than 4 hours, the patients tolerated the
endotracheal tubes well, but moderate coughing occurred during
initial recovery.
EXAMPLE 2
A dispersion of tetracaine particles and silicone adhesive was
prepared as in Example 1, with 30 mg. tetracaine per cc. of
adhesive (3 percent concentration). This mixture was diluted by 3
cc. of ether and the resulting dilute suspension was painted on the
endotracheal tube in two coatings to form layer 26 of FIG. 1. The
overall thickness of the layer was estimated to be between 0.002
and 0.004 inch in thickness. When setup the layer presented a
smooth, shiny surface.
This tube was placed in a patient having glaucoma, undergoing
Iridentasis. Twenty minutes after anesthetization the patient awoke
with the tube in place and with no reaction.
A similar tube was employed in a patient undergoing gall bladder
removal (cholecystectomy). The patient was maintained on a
respirator (assisted breathing) for 4 hours after awakening. After
cessation of the respirator the tube was left in the awake patient
for 1 hour. After this period the tube was jiggled by the attending
physician with no reaction whatever by the patient.
Similar tubes were employed in procedures of short duration (e.g. a
carotid arteriogram procedure) and in longer circumstances (e.g.
the tube was maintained in an unanesthetized patient for 18 hours
while his breathing was assisted by a respirator). In these cases
the tubes were well-tolerated in the awakening patient.
EXAMPLE 3
A sleeve of distensible latex rubber of 4 inch length, 3/8 inch
internal diameter, was coated on its exterior with a mixture of
silicone adhesive containing a 2 percent concentration of
tetracaine particles slightly diluted with ether. After
solidification of the adhesive layer the physician, by applying the
outer surface of the the to his tongue and lips, detected numbness
within 2 minutes.
The sleeve was slipped over an endotracheal tube having s single
balloon cuff, using liquid soap as lubricant. The tube was inserted
and the cuff inflated with air, distending he sleeve in the manner
of cuff 40 in FIG. 7.
The operation, surgery on the abdominal wall of an age 83 female,
was conducted without muscle relaxants with an unusually light
level of anesthesia:
4 liters per minute nitrous oxide
2 liters per minute oxygen
1/2 halothane (Fluothane, Ayerst Co.).
EXAMPLE 4
An endotracheal tube cuff was formed by a 19/16 inch diameter,
approximately 0.002 inch wall thickness, cellophane tube ("Weck
Sterilizing tubing," Edward Weck & Co., division of Sterling
Precision Corp.) applied over an endotracheal tube, and tied to the
endotracheal tube at opposite ends spaced approximately 2 inches
apart. An inflating lumen was connected to the cuff volume. The
cuff was filled with 10 cc. of a 2 percent solution (water base)
lidocaine hydrochloride surface-effective anesthetic ("xylocaine,"
Astra Pharamaceutical Products). The cuff was exposed to air for 4
days until the liquid had dried within the cuff, forming a deposit
of 200 milligrams solid anesthetic on the inner surfaces of the
cuff assembly. The deposit was not observable through the
cellophane and was not friable. The exterior of the cuff was
moistened with a slight amount of saline solution, to restore the
flexibility of the cellophane, and the endotracheal tube was
inserted into a patient and the cuff was inflated by introduction
of air through the lumen. The patient awoke after 4 hours. The tube
was jiggled in the trachea of the conscious patient without causing
cough.
The procedure was repeated with a number of patients with same
results.
EXAMPLE 5
A loose wrapping was formed using the cellophane tubing of example
4 along a portion of the endotracheal tube proximal to the
inflatable cuff. 20 cc. of 2 percent lidocaine hydrochloride, water
base, was dried within this wrapping forming a coating on the inner
surface of the cellophane. The cellophane wrapping was collapsed
upon the endotracheal tube in irregular folds.
The endotracheal tube was inserted with the wrapping located
proximal of the trachea. The attending physician observed that the
gas reflex of the awake patient was obtunded for 8 hours.
Referring now to FIG. 3, a magnified cross-sectional view along
line 3--3 of FIG. 1, mucous tissue 29 lying proximal of the trachea
contacts the outer surface of the layer 26. It has been observed
that the gag reflex caused by such contact is obtunded over an
extended period by anesthetic passing from the layer 26. The
physical securement of the anesthetic prevents its being washed
away by normal secretions, indeed in important instances it is
believed that the secretions play an important part in progressive
transport of the surface-effective anesthetic to the tissue. It
should be observed that the effective thickness of the layer
t.sub.e is only a small fraction of the remaining thickness of the
tube wall t.sub.t which defines the passage in a manner which
permits bending without closing-off the passage.
Referring to FIG. 4, a magnified view along line 4--4 of FIG. 1, it
is seen that the cuff 20, inflated by air 24, seals against the
tissue of trachea, with direct contact between layer 26 and the
tracheal tissue. It has been observed that the coughing and bucking
reflexes caused by such contact are obtunded over an extended
period by anesthetic passing from the layer 26. Here again the
physical securing of the anesthetic prevents its being washed away
by normal secretions, the secretions in important instances
believed to be effective in causing progressive transport of the
anesthetic to the tissue.
The relationship of the effective thickness t.sub.e of the layer
and the remaining thickness t.sub.t of the cuff corresponds to
cuffs of the balloon type such as are shown in FIG. 6. As was shown
above in example 4, however, where thinner flexible cuffs are
employed, the wall thickness of the cuff can comprise the layer in
or to which the anesthetic is secured.
Referring to FIG. 4a, a diagrammatic highly magnified
cross-sectional view of the layer 24 in action, there are shown
three anesthetic particles a, b and c. Particle a is spaced
distance t.sub.e away from the tissue, corresponding with the
distance all of the anesthetic was spaced from the tissue in
examples 4 and 5, and some of the anesthetic in the other
examples.
Secretions travel from the tissue 28 through the layer to particle
a and upon dissolving slightly, the anesthetic passes through the
semipermeable thickness to tissue 28.
Advantageously some of the anesthetic is positioned closer to the
effective surface, as for instance particles b and c. Particle c,
near or at the surface, can, with proper selection of the
anesthetic, provide immediate onset of anesthetization, or, if
relatively insoluble in water (and therefore insoluble in the
secretions) many maintain anesthetization for a substantial period.
Particle b enables an intermediate condition to be achieved.
It will be seen that choice of the particular components of the
layer will depend upon the desired characteristics of the device.
Using materials available currently, it is most preferred to employ
a solid coating in which the anesthetic is distributed from the
outer surface to a depth of at least 0.001 inch as illustrated by
each of the tiny particles a, b and c, with the inner particles
masked with semipermeable material as in the foregoing examples. By
this means rapid onset is achieved, but also the layer (being of
semipermeable material or rendered so) has an impeding effect that
ensures the availability of the anesthetic over an extended
period.
It is preferred to employ silicone adhesive diluted with ether or
the like, dilution not only enabling smoother and thinner coatings
but also believed to increase the permeability of the coating to
such anesthetics as tetracaine which, being water and not oil
soluble, has very low solubility in silicone.
Suitable semipermeable substances presently known to the inventor,
in addition to silicone adhesive and sheet films, are regenerated
cellulose (cellophane) and cellulose nitrate. The cellulose
thickness in important instances is less than 0.005 inch.
Whatever the type of construction of the layer chosen, a
requirement is that the outer surface of the layer have a nontoxic
surface anesthetizing characteristic extending over a period of at
least 1 hour and preferably over periods of 10 or 20 hours. FIG. 2
is a curve of the characteristic of a typically acceptable
embodiment. The horizontal line denotes the threshold of
anesthetizing effectiveness, established by a detectable numbness
of the tongue after contact with the surface of the layer for 5
minutes. For the examples above the nontoxicity of the quantities
of anesthetic is shown by the fact that accepted prior practice has
been to apply to the tracheal tissue at a single instant equivalent
or greater quantities of the anesthetic by means of spray or
ointment (with however only short lasting affect). No toxic
reactions were observed for the examples described above.
The required anesthetizing characteristic can be achieved through
simple tests with variation of the constituents and their
relationship to one another. For instance, for the preferred
embodiment variable parameters include the nature of the
semipermeable membrane or adhesive material, the chemical nature of
the anesthetic with regard to such factors as solubility in water
and secretions, the thickness of the membrane and the distribution
and concentration of the dry anesthetic.
Numerous variations within the spirit and scope of the claims will
occur to those skilled in the art.
* * * * *