DISPOSABLE SPECULUM

Abstract: A sanitary protective cover or sheath for the ear canal probe of a tympanic thermometer has a generally tubular body portion and an infrared transparent membrane attached to and sealing the forward end of the tubular body portion. While the tubular body portion is being injection molded of a plastic material, a film of a similar plastic material is mated to the forward end of the tubular body portion. A portion of the film defining the membrane is thus severed from the film and thermally bonded to the tubular body portion.

Description: BACKGROUND OF THE INVENTION The present invention relates to medical instrumentation, and more particulary, to a sanitary speculum having a generally tubular body portion that fits over the ear canal probe of a tympanic infrared radiation sensing thermometer. The diagnosis and treatment of many body ailments depends upon an accurate reading of the internal or core temperature of a patient's body, and in some instances, upon a comparison to a previous body temperature reading. For many years, the most common way of taking a patient's temperature involved the utilization of a Mercury thermometer. This approach has a number of drawbacks. First of all, such thermometers are normally made of glass. They must be inserted and maintained in the patient's mouth or rectum for several minutes. This is often discomforting to the patient. Furthermore, such thermometers can break, resulting in serious lacerations or Mercury poisoning. In addition, Mercury thermometers are difficult to read, must be sterilized, and must be "shaken down" vigorously to place the Mercury at the bottom end prior to use. Because of the above drawbacks of conventional Mercury thermometers, electronic thermometers were developed and are now in widespread use. Typically, the commercialized versions of such electronic thermometers have been designed for taking a patient's temperature orally or rectally. They have a probe connected by wires to a remote unit containing an electronic circuit. The probe is inserted into a protective, disposable plastic cover or sheath before being inserted into the patient's mouth or rectum. After the patient's temperature is taken, the sheath is discarded, and the probe is inserted into another sanitary sheath for taking the next patient's temperature. In this manner, the electronic thermometer is rapidly reusable without communicating infectious organisms between patients. The foregoing type of electronic thermometer typically uses predictive techniques, by which the patient's temperature reading is taken in a significantly shorter time period, for example thirty seconds, compared to the several minutes required for the conventional Mercury thermometers. Such electronic thermometers normally have meters or other displays which enable the operator to determine the temperature much more readily than reading the position of the terminal end of a column of Mercury inside a glass tube. The probe is typically an elongated rod of small diameter. The sheath comprises a hollow tube having an open end and a closed, somewhat pointed end. It has a round cross-section of relatively small diameter and is made of a plastic material which is not toxic. The tympanic membrane is generally considered by the medical community to be superior to oral, rectal or axillary sites for taking a patient's temperature. This is because the tympanic membrane is more representative of the body's internal or core temperature and more responsive to changes in core temperature. Heretofore, efforts to provide a method and apparatus for measuring the body temperature via the external ear canal have not been successful. One approach has been to use a thermister, thermocouple or some other type of device requiring physical contact with the tympanic membrane. This approach is undesirable because of the discomfort to the patient and the danger of physical injury to the tympanic membrane. Another approach has directed air against the tympanic membrane and attempted to measure the increase in temperature in returning air in order to derive the patient's temperature. Clearly this approach has significant drawbacks in regard to accuracy. A third and better approach to tympanic temperature measurement involves sensing infrared emissions in the external ear canal. In order to accomplish this efficiently, a probe must be partially inserted into the external ear canal. A cover or sheath must be provided for enclosing the frontal portion of the probe to present a clean, sanitary surface to the patient and also to keep the probe tip free of ear wax and hair. The probe cover or sheath must be made of material which is substantially transparent to infrared radiation. As used herein, the term "speculum" shall include any type of cover or sheath adapted to fit over a probe for the purpose just described. Preferably, such a speculum is inexpensive so that it can be disposed after a temperature reading has been taken and a new speculum installed over the probe for the next patient. This eliminates any need to sterilize such speculums. EP Patent No. 180 368 of O'Hara and Phillips (published 07.05.86 and thus being a document under Article 54 (3) EPC) discloses a system of an infrared thermometer comprising such probe means including a tubular elongated waveguide having an inner end adjacent said sensor and having an outer end remote from said sensor, the outer end of said probe means being adapted for insertion into a human external ear canal to receive through the outer end of the waveguide radiation from the interior of the body opening, which radiation is guided toward said sensor for impingement thereon; and a speculum of pliant material removably telescopically disposed on said probe means, said speculum having a radiation transparent imperforate transverse wall portion extending across said open outer end of said waveguide and through which radiation can enter the waveguide. U.S. Patent No. 3,282,106 of Barnes suggests the concept of an infrared thermometer that may be placed in the ear cavity to measure body temperature. An infrared detector receives radiation through an internally polished truncated cone which acts as a shield and which is partially inserted into the ear canal. This cone is apparently a permanent part of the apparatus and is not removable or disposable. The specification of the Barnes patent indicates that this cone was not intended to actually touch any portion of the outer ear. However, Barnes indicates that the cone may lightly touch portions of the outer ear because of lack of skill of the operator. Nevertheless, no protective speculum for the cone is disclosed in Barnes. The aforementioned Barnes patent also discloses an alternate embodiment including a conventionally shaped ear plug which contacts the external ear canal but is not provided with a speculum. U.S. Patent No. 3,581,570 of Wortz discloses a tympanic temperature sensing device which has positioning means to establish a fixed relationship between the eardrum and a radiometer. A polyethylene shield fits over the probe portion to protect the radiometer. It does not appear that the shield is readily replaceable. Furthermore, the shield appears to be a cup-shaped member of uniform thickness. The very small width and length of the cup-shaped shield would make it very difficult to handle, install and replace. U. S. Patent No. 3,878,836 of Twentier discloses a disposable speculum for an infrared sensing tympanic thermometer. This speculum has the general shape of a funnel and has open forward and rearward ends. The patent indicates that preferably the speculum is formed of polyethylene. The principal drawback of this speculum is that its open forward end which is partially inserted into the ear canal may become clogged with wax or other debris and impair proper functioning. Also, the open forward end will permit germs and other foreign matter to be transferred to the thermometer instrument itself, thus presenting a risk of contamination and spreading of bacteria and viruses between patients. SUMMARY OF THE INVENTION Accordingly, it is the primary object of the present invention to provide an improved, disposable speculum. It is another object of the present invention to provide a disposable speculum for the ear canal probe of a tympanic thermometer. Another object of the present invention is to provide a disposable speculum configured for easy mounting and removal from the instrument probe. Another object of the present invention is to provide a disposable speculum which acts as a sanitary barrier between a patient's ear canal and the sensing portion of an infrared sensitive tympanic thermometer which is partially inserted into the external ear canal after having the speculum mounted over the same. The disposable speculum of the present invention comprises a sanitary protective cover or sheath for the ear canal probe of a tympanic thermometer having an infrared transparent membrane attached to and sealing the forward end of the body portion, the membrane being made of a material selected from the group consisting of polypropylene and polyethylene and having a maximum thickness of approximately 0.0254 mm (0.001 inches) and a minimum thickness of approximately 0.0127 mm (0.0005 inches), the tubular body portion being injection molded and the membrane being a film bonded to the forward end of the tubular body portion, and the film being bonded to the tubular body portion so that the speculum is capable of withstanding 0.0084 kg/qm (1.2 PSI) without rupturing or unbonding from the tubular body portion. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a side elevation view of the preferred embodiment of the disposable speculum of the present invention. Fig. 2 is a longitudinal sectional view of the speculum of Fig. 1 taken along line 2-2 of Fig. 1. Fig. 3 is a lateral sectional view of the speculum of Fig. 1 taken along line 3-3 of Fig. 1. Fig. 4 is rear end elevation view of the speculum of Fig. 1 taken from the top of Fig. 1. Fig. 5 is a front end elevation view of the speculum of Fig. 1 taken from the bottom of Fig. 1. Figs. 6a, 6b and 6c are enlarged fragmentary views illustrating further details of the preferred embodiment of the speculum. Fig. 7 is a greatly enlarged, longitudinal sectional view of the forward end of the speculum of Fig. 1 illustrating the thin film membrane bonded to the forward end of its generally tubular body. Fig. 8 is a top plan view of a tree structure which carries a plurality of the disposable speculums of the type illustrated in Figure 1. Fig. 9 is a cross-sectional view of the tree structure of Fig. 8 taken along line 9-9 of Fig. 8. DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to Figs. 1 and 2, the preferred embodiment 10 of our disposable speculum includes a generally tubular body portion 12 and an infrared transparent membrane 14 attached to and sealing the forward end of the tubular body portion. The tubular body portion has a generally frusto-conical or truncated cone configuration. Its diameter gradually reduces from its rearward end to its forward end and includes several shoulders as explained hereafter in greater detail. The frusto-conical configuration permits the speculum to be partially inserted into the ear canals of both children and adults. The tapered configuration also enables the speculum to be snugly fit over and retained on the probe of a tympanic thermometer instrument as explained hereafter in greater detail. The speculum is preferably made of a non-toxic material since it will come into contact with a patient's skin. Also, the speculum is preferably made of a material which is somewhat pliant. This allows the speculum to deform slightly to facilitate insertion into the ear canal and also to squeeze fit over the instrument probe. Most importantly, the membrane 14 must be made of a material which is substantially transparent to infrared radiation, preferably in the seven to fifteen µm wavelength range, and more preferably substantially transparent to infrared radiation having a wavelength of approximately ten µm. Clinical data has confirmed that accurate internal body temperature readings can be made by sensing infrared radiation at the foregoing wavelength which is emitted in the external ear canal. Polypropylene and polyethylene are both plastic materials which are substantially transparent to infrared radiation at the foregoing wavelength. Of course the amount of attenuation of the infrared radiation passing through this material depends upon the thickness thereof. Accordingly, the membrane 14 must be relatively thin to minimize the attenuation of infrared radiation passing therethrough so that the thermopile or other detector receiving infrared radiation through the membrane will sense the maximum amount of infrared radiation available. This enhances the accuracy of temperature measurement. Also, the membrane should have a uniform thickness, with no wrinkles or other structural characteristics that will distort the infrared radiation passing therethrough. Such distortion can introduce errors in the temperature measurement process. Accordingly, in the preferred embodiment of our speculum, the membrane 14 (Fig. 7) which serves as the IR window is made of polypropylene or polyethylene film having a maximum thickness of 0,0252 mm (0.001 inches), and preferably a thickness in the range of 0,0127 mm (0.0005 inches) to 0,0254 mm (0.001 inches). Preferably, the speculum will withstand approximately 0,0084 kg/qm (1.2 PSI) without rupturing. As explained hereafter in greater detail, the membrane 14 is thermally bonded to the forward end of the tubular body portion 12 and accordingly is able to withstand the 0,0084 kg/qm (1.2 internal PSI). The tubular body portion 12 (Fig. 2) of the speculum need not be made of an infrared transparent material. However, our speculum is more easily fabricated and the bond between the membrane and the body portion is optimized, if both the membrane and the body portion are made of a similar plastic material. The body portion must be sufficiently strong such that the speculum can be mounted over the probe, and removed from the probe, without the operator having to touch the speculum. This ensures that the speculum will be sanitary when it is introduced into the patient's ear canal. Accordingly, the thickness of the walls of the body portion 12 must be chosen to provide sufficient structural integrity to permit the foregoing mounting and removal from the instrument probe. By way of example, where the body portion is made of polypropylene or polyethylene, a wall thickness of between approximately 0,254 mm to 0,508 mm (0.01 to 0.02 inches) is adequate. The tubular body portion 12 (Fig. 1) has a forward segment 12a, an intermediate segment 12b, and a rearward segment 12c. The forward end of the segment 12a is rounded to facilitate attachment of the membrane 14 as illustrated in Fig. 7. Four circumferentially spaced, longitudinally extending flanges 16 (Figs. 1,2 and 4) project outwardly from the rear end of the segment 12c. These may engage a support well (not illustrated) at their forward ends to aid in holding the speculum stationary when the probe of the infrared thermometer is inserted into the speculum. Three circumferentially spaced ears 18 (Figs. 1,2 and 3) project inwardly from the interior of the segment 12b and mate with corresponding detents in the thermometer probe (not illustrated) for retaining the speculum on the probe. The ears 18 have a crescent shaped configuration with a convex surface as illustrated in the longitudinal sectional view of Fig. 6a, horizontal sectional view of Fig. 6b, and elevational view of Fig. 6c. By way of example, the outside diameter of the segment 12a of the tubular body portion may taper from an outside diameter of 7,9756 mm (0,314 inches) immediately aft of the curved forward end thereof to an outside diamter of 8,3566 mm (0.329 inches) at the rear end thereof. The segment 12b may extend at an angle of approximately forty-five degrees relative to the inner wall of the segment 12a. The outside wall of the segment 12c may extend at an angle of five degrees relative to the central longitudinal axis of the speculum. The tubular body portion 12 in its entirety may have a longitudinal dimension of 20,32 mm (0.8 inches). The forward curved end of the segment 12a may have an outside radius of 1,3970 mm (0.055 inches). The ears 18 may project 0,254 mm (0.010 inches) into the interior of the speculum. Preferably both the inner and outer walls of the segments diverge gradually away from the central longitudinal axis of the speculum to facilitate a snug fit on the probe of the infrared thermometer. To facilitate shipment and use, a plurality of the speculums may be connected in an array of rows and columns by a tree structure 20 (Fig. 8) of interconnected rails 22 and side walls 24 (Fig. 9) made of the same plastic as the speculum body. Small integrally formed plastic extensions 26 (Fig. 9) connect the tubular body portion of each of the speculums to the rails and side walls of the tree structure. These extensions are adapted to be easily broken to individually release a selected one of the speculums upon a predetermined amount of force being applied to the one speculum in a direction away from the tree structure while the tree structure is held in a stationary position. The side walls of the tree structure may be supported in a housing of the thermometer as illustrated in co-pending U.S. Patent Application Serial No. 663,769 identified above. Each speculum may also be seated in a corresponding well in the housing having walls which engage and support the flanges 16 when the probe of the thermometer is inserted into the rear end of the speculum and pushed downwardly toward the well. The speculum thus is squeezed over the probe and the ears 18 mate with the detents of the probe. As this is done, the extensions 26 break. The probe can then be withdrawn and the speculum is retained tightly thereon. Preferably the body portion of the speculum mates with the probe so that the membrane is stretched tightly over the probe tip, thereby removing any wrinkles in the membrane. When the ears 18 mate with the detents of the probe, the membrane is held in tight, stretched fashion thereby preventing any wrinkles that would interfere with measurement accuracy. Having described a preferred embodiment of the speculum, and a readily useable connected array of speculums, it should be apparent to those skilled in the art that our invention may be modified in both arrangement and detail. Therefore, the protection afforded our ivention should only be limited in accordance with the scope of the following claims.

Claims: A sanitary speculum having a generally tubular body portion (12) that fits over the ear canal probe of a tympanic infrared radiation sensing thermometer, characterized by an infrared transparent membrane (14) attached to and sealing a forward end of the tubular body portion (12), the membrane (14) being made of a material selected from the group consisting of polypropylene and polyethylene and having a maximum thickness of approximately 0.0254 mm (0.001 inches) and a minimum thickness of approximately 0.0127 mm (0.0005 inches), the tubular body portion (12) being injection molded and the membrane (14) being a film bonded to the forward end of the tubular body portion, and the film being bonded to the tubular body portion (12) so that the speculum is capable of withstanding 0.0084 kg/qm (1.2 PSI) without rupturing or unbonding from the tubular body portion. A speculum according to Claim 1 wherein the tubular body portion (12) is formed with a plurality of circumferentially spaced, longitudinally extending flanges (16) which project outwardly from a rear end of the tubular body portion. A speculum according to Claim 1 wherein the tubular body portion (12) is formed of an annular wall having a thickness of approximately 0.254 mm (0.01 inches) to 0.508 mm (0.02 inches). A speculum according to Claim 1 wherein the tubular body portion (12) is formed with a plurality of inwardly projecting retention ears (18). A speculum according to Claim 1 wherein the forward end of the tubular body portion (12) has rounded edges. A speculum according to Claim 1 wherein the membrane (14) has a uniform thickness. A speculum according to Claim 1 wherein the membrane (14) has no wrinkles. An array of speculums of the type set forth in Claim 1 connected in rows and columns by a tree structure (20) of interconnected rails (22) and side walls (24), the speculums being connected to the rails (22) and side walls (24) by extensions (26).

Inventors: O'HARA, GARY J., PHILLIPS, DAVID B.
Applicants: INTELLIGENT MEDICAL SYSTEMS, INC.
Application year: 1986
Main classification: G01J5
IPC codes: A61B1, G01K1, G01J5, A61B5