US 3610247 A
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United States Patent Richard R. Jackson 8 Trinity Road, Marblehead, Mass. 01947 803,7 17
Mar. 3, 1969 Oct. 5, 1971 lnventor Appl. No. Filed Patented SURFACE-ANESTHETIZING MEDICAL APPLIANCE 15 Claims, 9 Drawing Figs.
U.S. Cl 128/351, 128/260, 128/272 Int. Cl A6lm 25/00, A61m 31/00, A6lj 1/00 Field of Search 128/260, 262, 265, 272, 35]; 424/16, 18, 19, 22
References Cited UNITED STATES PATENTS 10/1967 Jackson 2,803,582 8/1957 Cherney 424/19 3,363,624 l/1968 Fishman 128/260 X 3,363,629 1/1968 Kuhn 128/351 3,375,828 4/1968 Sheridan 128/351 FOREIGN PATENTS 998,794 7/1965 Great Britain 3/1 215,350 10/1909 Germany 128/3 Primary Examiner-Channing L. Pace Attorney.lohn Noel Williams 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.
PATENTEDncT 51911 1610247 FiG. 2
Illllllllllllllllllllllllll 5 IO I5 20 25 NUMBING EFFECT SURFACE-ANESTI'IETIZING MEDICAL APPLIANCE 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 patients 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 patients 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 l 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 or 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 33 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 1, 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 1% inch diameter in comparison with a trachea of inch diameter. Such floppy cuffs are disclosed in my copending patent applications Ser. Nos. 427,60l 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 ID 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 scaling 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 I 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. I) over the tube and cuff. The coating was allowed to cure at humidity conditions in excess of 20 percent at 77 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 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 lridentasis. 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 welltolerated in the awakening patient.
EXAMPLE 3 A sleeve of distensible latex rubber of 4 inch length, 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 ofcuff40 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% 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, is only a small fraction of the remaining thickness of the tube wall t, which defines the passage in a manner which permits bending without closingoff the passage.
Referring to FIG. 4, a magnified view along line 44 of FIG. 1, it is seen that the cut? 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 1, of the layer and the remaining thickness 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 0. Particle a is spaced distance I, 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 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.
What is claimed is: t
l. 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.
posite 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.