Valve for tympanic membrane ear surgery

Abstract

An air-permeable, chemically inert valve used to provide an air passage through the tympanic membrane of the ear. A thin layer of porous teflon covers the outer end of a tube lining a passageway created in the tympanic membrane. The porous teflon is impermeable to solids and liquids, but permeable to gases, thereby equalizing the air pressure between the outer and middle ear. An anti-coagulate coating may be applied to the teflon to prevent the tympanic membrane from growing over it.

Government Interests

STATEMENT OF GOVERNMENT INTEREST

The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to devices used to provide an air passage through the tympanic membrane of the ear and, more particularly, to air-permeable, chemically inert valves used to provide an air passage through the tympanic membrane of the ear.

2. Description of the Prior Art

Children born with a cleft palate condition exhibit a high likelihood of repeated ear infection as a result of deficiencies involved with the muscles associated with control of the eustachian tube. While medication eliminates the infections, the basic difficulty still remains. Consequently, an alternate method, based on surgical techniques, is utilized to insert a plastic tube between the middle and outer ear. The surgical procedure, described as a "Tympanotomy with Insertion of Tube," is designed to prevent the production of fluid in the inner ear by providing an auxiliary path for air pressure equalization between the middle and outer ear. Normally, the eustachian tube provides an airpath to equalize the air pressure between the middle and outer ear and is controlled by a muscle. When the muscle structure that controls the eustachian tube is deficient, and when infection results in closure of the eustachian tube, an air pressure differential develops between the middle and outer ear. The air pressure differential results in the production of fluid, which, if not removed, becomes increasingly viscous, and ultimately leads to deafness. Surgical procedures are utilized to remove the fluid through an incision in the tympanic membrane, and a plastic collar assembly is subsequently inserted.

The Donaldson Silastic Collar, as well as several other similar devices, provide a method of simulating the function of the eustachian tube to equalize the air pressure between the middle and outer ear by means of an air passage. However, this, as well as other existing devices also provide a passage for water and solid particles into the inner ear. Precautions must be taken, particularly in the case of small children, to prevent the entry of water into the ear when bathing or engaging in other activities in and around water.

SUMMARY OF THE INVENTION

The general purpose of the present invention is to provide a valve for providing an air passage through the tympanic membrane of the ear which will prevent the passage of solids and liquids, but will allow passage of gases. To obtain this, a specific embodiment of the present invention provides a thin-layer of porous teflon covering the outer end of a tube lining a passageway created in the tympanic membrane of the ear. The porous teflon prevents the passage of liquids or solids, but allows the passage of gases through the tube, thereby equalizing the air pressure between the outer and middle ear. An anti-coagulate coating may be applied to the teflon to prevent the tympanic membrane from growing over it.

Accordingly, one object of the present invention is to equalize the air pressure between the middle and outer ear.

Another object of the present invention is to provide a valve that passes gases but does not pass liquids or solids.

Another object of the present invention is to allow persons having valves in their ears to lead normal lives.

Another object of the present invention is to keep water out of the middle ear.

Another object of the present invention is to keep airborne particles out of the middle ear.

Another object of the present invention is to provide a chemically inert valve.

Another object of the present invention is to prevent the tympanic membrane from growing over the valve thereby rendering it useless.

Another object of the present invention is to provide an air-permeable valve.

Another object of the present invention is to equalize gaseous pressure on both sides of a membrane.

Other objects and a more complete appreciation of the present invention and its many attendant advantages will develop as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings in which like reference numerals designate like parts throughout the figures thereof and wherein.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross sectional view of the ear.

FIG. 2 is a side view of a specific embodiment of the present invention.

FIG. 3 is a rear view of the specific embodiment of FIG. 2.

FIG. 4a through e are graphs of the physical properties of a thin-layer of teflon.

DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1 illustrates the ear. Outer ear 100 is terminated by tympanic membrane 16. Eustachian tube 104 serves to equalize the air pressure between outer ear 100 and middle ear 102.

Turning now to FIG. 2, valve 10 comprises a tube 12 having a notch 14 midway between the two ends of tube 12. Notch 14 extends around the entire circumference of tube 12. Tympanic membrane 16 grows into notch 14. A passageway 18 extends through tube 12 along its longitudinal axis. A thin-layer of material 20 is affixed to and covers one end of tube 12. Valve 10 is a silastic collar with thin-layer 20 attached thereto. It is noted that valve 10 of FIG. 2 is not drawn to scale. Tube 12 is a chemically inert means for lining a passageway through tympanic membrane 16. Tube 12 serves as a conduit. Tube 12 may be made of silicon rubber or any other suitable chemically inert material that the body will not reject. It is noted that there are many different devices of varying shapes and sizes similar to tube 12 currently in medical use designed for stability in the ear. A common characteristic of all such devices is a passageway through them.

Thin-layer 20 is impermeable to solids and liquids, but permeable to gases. Thin-layer 20 is, also, chemically inert thereby restricting rejection by the body. There are a number of materials currently available with such properties including a number of metals and plastic foams which are chemically inert, air-permeable, and liquid and solid impermeable. Sintered stainless steel and sintered brass are two such metals. In addition, porous teflon plastic may be utilized. Thin-layer 20 is bonded to tube 12 using a chemically inert glue or other means. Thin-layer 20 may be made of a porous teflon material being 2.54 .times. 10.sup.-.sup.3 cm thick (0.001 inch), having a density of 0.1 gram per cubic centimeter, and water entry pressure of nominally 2 pounds per square inch. It is noted that thin-layer 20 may be attached to either end of tube 12 or anywhere in passageway 18 the only requirement being that thin-layer 20 completely cover a cross sectional area of passageway 18.

FIG. 4a through 4e graphically illustrates the physical properties of a porous teflon material. FIG. 4a graphically illustrates porosity vs. density. FIG. 4b graphically illustrates porosity vs. air permeability. FIG. 4c graphically illustrates porosity vs. thermal conductivity. FIG. 4d graphically illustrates porosity vs. size of largest pores. FIG. 4e graphically illustrates porosity vs. water enter pressure. Line 30 illustrates the specific properties of a teflon material satisfactory for use as thin-layer 20. It is noted that the material of thin-layer 20 is selectable for a wide variety of conditions that allow the optimization of pressure differential, air-flow rate and pore size requirements.

The valve 10 is inserted in a passageway or opening surgically created in tympanic membrane 16. Tympanic membrane 16 then grows aroudn valve 10 fitting into notch 14. An anti-coagulate coating may be placed in thin-layer 20 to prevent tympanic membrane 16 from growing over thin-layer 20 thereby rendering valve 10 useless.

It is noted that all of valve 10 including tube 12 and thin-layer 20 may be made of an air-permeable, solid-and-liquid-impermeable, chemically-inert material such as teflon. That is, tube 12 and thin-layer 20 may be one piece thereby eliminating the need for bonding discussed supra.

Obviously, numerous modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described herein.

Claims

I claim:

1. A gas-permeable, chemically inert valve adapted for insertion in the tympanic membrane of the ear comprising:

a. a chemically inert tubular member adapted for lining a passageway through a tympanic membrane having an external surface thereon, said external surface having a portion thereof intermediate the ends of said tubular member about which said tympanic membrane grows, said tubular member having a first opening located at one end thereof and a second opening located at the other end thereof; and

b. chemically inert means covering an entire cross-sectional area of the passageway through said tubular member, said means being impermeable to liquid and solids while being permeable to gases whereby pressure between the middle ear and the outer ear is equalized, while simultaneously preventing any passage of liquids or solids therethrough.

2. The valve of claim 1 wherein said covering is affixed to said first opening.

3. The valve of claim 1 wherein said covering means is affixed to said second opening.

4. The valve of claim 1 wherein said tubular member has means about the circumference thereof into which said tympanic membrane grows for retaining said tubular member in said tympanic membrane.

5. The valve of claim 4 wherein said tubular member has a notch around its circumference into which the tympanic membrane grows.

6. The valve of claim 1 wherein said tubular member is fabricated from a gas-permeable, solid-and-liquid impermeable, chemically inert material.

7. The valve of claim 1 wherein said covering means is a thin-layer of material made of teflon.

8. The valve of claim 1 wherein said covering means is a thin-layer of material made of sintered stainless steel.

9. The valve of claim 1 wherein said covering means is a thin-layer of material made of sintered metal.

10. The valve of claim 1 wherein said covering means is a thin-layer of material .001 inch thick, having a water entry pressure of 2 pounds per square inch and a density of 0.1 gram per cubic centimeter.

11. The valve of claim 1 further comprising an anti-coagulating coating covering said chemically inert covering means whereby said tympanic membrane is prevented from growing over said covering means.

12. A method of equalizing the gas pressure between the middle ear and the outer ear utilizing a valve assembly which simulates the eustachian tube function of the ear while preventing the inadvertent passage of both solids and liquids including water, but allowing the passage of gases through the tympanic membrane comprising:

a. surgically creating a passageway in the tympanic membrane;

b. inserting said valve assembly which incorporates a solid and liquid impermeable but gas permeable, chemically inert membrane into said passageway; and

c. allowing the tympanic membrane to grow around said valve assembly.

13. The method of claim 12, wherein immediately following the step of inserting and immediately preceding the step of allowing, a further step is inserted comprising coating said gas-permeable, chemically inert membrane with an anti-coagulating material whereby said tympanic membrane is prevented from growing over said gas-permeable, chemically inert membrane.