Patent Application
20110257521
The present invention relates generally to medical devices that use probes that come in close proximity to, or in contact with, a patient. More specifically, embodiments of the invention relate to a device for detecting the insertion of the probe into a body cavity.
A general body cavity medical probe may be inserted into the patient's body cavity for either measuring vital signs or for providing treatment. There are numerous type of general body cavity probes, such as a medical ear thermometer. General body cavity probes may contain a functional module to perform the intended medical measurement or procedure. For a medical ear thermometer, the functional module may be an infrared (“IR”) temperature sensor.
Temperature of an object, specifically of a living being such as a human or an animal, can be measured by thermal conduction or thermal radiation. For thermal conduction, a temperature sensing probe is brought into a physical contact with a surface of the living being. For thermal radiation, a temperature sensing probe is brought near the surface of a the living being and aimed at the area of interest, such as within the open space of a body cavity. Naturally emanated electromagnetic radiation in the mid and far infrared spectral ranges is detected by an appropriate sensor, whose output signal indicates the surface temperature of an object. For both thermal conduction and thermal radiation measurement methods, the temperature sensor is positioned inside or coupled to the medical probe.
Medical thermometers that operate by contact, for example, oral or rectal, may use a probe cover, for instance a sanitary probe cover. Thermal energy (i.e., heat) is transmitted through the probe cover by thermal conduction, thus at least the portion of the probe cover material overlying the thermal sensor should be highly transmissive of thermal energy. Various conventional probe covers for contact thermometers are described in, for example, in U.S. Pat. No. 4,159,766 issued to Kluge, which is hereby incorporated by reference in its entirety.
Medical thermometers that operate by radiation may also use a probe cover, because the possibility still exists of contact with the body of the patient. For example, when measuring the temperature of a tympanic membrane and the surrounding tissue inside the ear canal, the probe is inserted into the ear canal body cavity and may contact the wall of the ear canal. Before insertion, a probe cover may be installed onto the probe to envelop its parts that otherwise might come in contact with the patient's skin. Such a cover provides sanitary protection against contamination of the probe by ear wax and other soiling biological compounds, and includes properties that promote accurate temperature measurement by the detection of infrared signal. Such properties include a good transparency of the front portion of the probe cover in at least the spectral range of interest, low directional distortion of optical rays, tight manufacturing tolerances, stability of the optical properties during installation onto the probe, long term storage stability, etc. Probe covers for the IR thermometers are exemplified by U.S. Pat. No. 5,088,834 issued to Howe et al. and U.S. Pat. No. 5,163,418 issued to Fraden et al., both of which are hereby incorporated by reference in their entirety.
A probe cover may include one or more components such as polyethylene, polypropylene, and copolymers thereof. Probe cover materials may also possess relatively low absorption of electromagnetic energy over a broad spectral range from visible to the far infrared.
When a medical probe is used, either with or without a probe cover, it may be desirable to detect either a close proximity of the probe to the patient body surface, or to detect insertion of the probe into a body cavity, such as an ear canal. A shortcoming of the known art is that no medical thermometer has a capability of detecting the probe position relative to the ear canal. Therefore, a need exists to provide such a proximity measurement.
Embodiments of the invention relate generally to an apparatus and method for the proximity detection of a medical probe (e.g., a thermometer) to the surface of a living being. The embodiments should provide an accurate measurement, with or without the presence of a probe cover, by taking into account the detected proximity.
Therefore, as will be apparent from the foregoing description, embodiments of the invention include one or more of: a method or device for detection of the probe cover installation on a probe; a method or device for detecting proximity between the medical probe and a patient body surface; or a method or device to detect the insertion of a medical probe into the body cavity of a patient.
One or more embodiments of the invention provide a medical probe for insertion into a body cavity of a patient, such that the medical probe includes a probe body having a sidewall laterally circumscribing a longitudinal axis and enclosing an inner space, the sidewall having a proximal end and a distal end. Optionally, the distal end may be tapered relative to the proximal end. The medical probe also includes a sensor coupled to the probe to provide a signal relating to a condition of the body cavity of the patient, and a proximity sensor coupled to the probe, the proximity sensor configured to provide a signal indicating insertion of the probe into the body cavity. In some embodiments, the sensor may include a functional sensor or a temperature sensor, and/or the sidewall may have an elongated shape adapted for insertion into an ear canal.
Optionally, the medical probe may be designed such that the proximity sensor includes an optical transmitter and an optical receiver positioned such that, when the medical probe is positioned for insertion into the body cavity, the optical transmitter is positioned to transmit an optical signal toward an opening of the body cavity, including the edge thereof, and the optical receiver is positioned to receive the optical signal from the optical transmitter. The optical transmitter may be positioned to transmit toward a first position of the opening of the body cavity, and the optical receiver may be positioned to receive optical signals from a second position of the opening of the body cavity.
As used throughout herein, for signals related at least to the proximity sensor, signals to or from the body cavity may include signals to or from portions of the patient adjacent to the body cavity, including wall portions and/or edge portions of the cavity.
Optionally, the transmitter may have a first optical axis, and the optical receiver may have a second optical axis.
In another embodiment, the proximity sensor may further include a receiving light guide disposed within the inner space, the receiving light guide having a first end coupled to and protruding through the distal end of the sidewall, and a second end coupled to the optical receiver. Optionally, the receiving light guide may protrude through the distal end of the sidewall at an angle that is pointed away from the proximal end of the sidewall.
In another embodiment, the proximity sensor may further include a transmitting light guide disposed within the inner space, the transmitting light guide having a first end coupled to and protruding through the distal end of the sidewall, and a second end coupled to the optical transmitter. Optionally, the transmitting light guide may protrude through the distal end of the sidewall at an angle that is pointed away from the proximal end of the sidewall.
Optionally, the proximity sensor may include a translucent opto-coupler that protrudes through the sidewall, the opto-coupler including a first side disposed within the inner space, the first side being optically coupled to a light emitter and a light detector; and the opto-coupler further including a second side disposed outside the inner space, wherein the second side protrudes through the wall of the probe.
In some embodiments, the medical probe may further include an electronic circuit coupled to the sensor and to the proximity sensor, the electronic circuit including a processor and a memory coupled to the processor, the memory storing software, such that the software, when executed by the processor, is configured to execute an algorithm to process signals from the sensor and the proximity sensor. The electronic circuit may further include an output device coupled to the processor, the output device configured to output a result of the algorithm.
The medical probe may further include an ambient temperature sensor electrically coupled to the electronic circuit and positioned outside of the inner space, such that the software, when executed by the processor, is further configured to execute an algorithm to process signals from the sensor, the proximity sensor and the ambient temperature sensor.
In one or more embodiments, the medical probe may be designed such that at least one of the transmitting light guide and receiving light guide comprises a plastic optical fiber. Alternatively, at least one of the transmitting light guide and receiving light guide includes a glass rod, or a polycarbonate rod. Optionally, at least one of the transmitting light guide and receiving light guide may include a rod coated with a coating material, wherein a refractive index of the coating material is lower than a refractive index of the rod. Optionally, the first end of at least one of the transmitting light guide and receiving light guide may include a lensing bulb. Optionally, an optical barrier may be disposed in the inner space between the optical transmitter and optical receiver. Optionally, the optical receiver is disposed within the inner space.
In one or more embodiments of the invention, the proximity sensor may operate by use of ultrasonic signals.
One or more embodiments of the invention provides a method for detecting an insertion of a medical probe into a body cavity of a patient, including the steps of: transmitting, from a transmitter, a signal toward an edge portion of the body cavity; receiving, at a receiver, a return signal from an edge portion of the body cavity; and monitoring a flux of the return signal for a drop in strength, such that a path from the transmitter to the receiver is blocked when the medical probe is inserted into the body cavity such that the flux of the return signal decreases when the medical probe is inserted into the body cavity.
In another embodiment of a method for detecting an insertion of a medical probe, the medical probe having a longitudinal axis, into a body cavity of a patient along the longitudinal axis, the method includes the steps of: transmitting a signal along a first direction substantially perpendicular to the longitudinal axis; receiving a return signal from a second direction, the second direction substantially parallel to the first direction; and monitoring a flux of the return signal for an increase in strength, such that the flux of the return signal increases in strength above a predetermined threshold when the medical probe is inserted into the body cavity.
In another embodiment of a method of displaying the temperature of a body cavity of a living being, the method includes the steps of: measuring a base temperature of the cavity by use of a temperature sensor; measuring a proximity of the temperature sensor to the body cavity; measuring an ambient temperature in an area adjacent to the temperature sensor; computing a computed temperature of the body cavity in accord with a predetermined function of the base temperature, the proximity, and the ambient temperature; and displaying the computed temperature.
Optionally, the method may further detect the presence of a probe cover, and adjust the computed temperature accordingly.
Still other objects and advantages of the invention will in part be obvious and will in part be apparent from the specification. The invention accordingly includes the features of construction, combination of elements, and arrangement of parts which will be exemplified in the construction hereinafter set forth as well as the methods of construction and applying the adhesive discussed herein, and the scope of the invention will be indicated in the claims.
The above and still further objects, features and advantages of the present invention will become apparent upon consideration of the following detailed description of a specific embodiment thereof, especially when taken in conjunction with the accompanying drawings wherein like reference numerals in the various figures are utilized to designate like components, and wherein:
Embodiments of the invention achieve their objectives by adding a proximity sensor to a medical probe that may be coupled to a functional module. An example of a functional module is a temperature sensor (i.e., thermometer). The proximity sensor may be a combination of a light emitter and a light detector. In one embodiment, the light emitter and light detector are optically coupled to one another when the probe is positioned near to, but outside of the patient body cavity. However, when the probe is inserted into a body cavity, such as an ear canal, the optical coupling is modified and sensed by the light detector. In another embodiment, the light emitter and light detector are not substantially optically coupled to one another when the probe is positioned near to, but outside of the patient body cavity. However, when the probe is inserted into a body cavity, such as an ear canal, the optical coupling is modified and sensed by the light detector.
An output signal from the proximity sensor may be used by a calculation algorithm executed by a microcontroller in the medical device, for instance by adjusting a calculated and displayed temperature reading based upon measurements provided by the temperature sensor, the proximity sensor, and optionally an ambient air temperature measurement. For example, because the IR signal indicative of temperature is different when measured from the inside or outside of the ear canal, the temperature that is sent to a user display may be adjusted to account for the differing measurement positions as sensed by the proximity sensor. Alternatively, the operator may be warned about an incorrect probe position (e.g., when outside of the ear canal), or the temperature measuring and displaying process may be disabled until the medical probe is in the desired position (e.g., inside the ear canal). A display of such a warning may include a light (e.g., a red LED), an icon on an LCD panel, an audible signal (e.g., a beep or buzz), a vibration, or any combination thereof.
Some probes intended for insertion into a body cavity employ reusable or disposable probe covers. A probe cover for a medical probe is a sanitary envelope that forms a barrier between the instrument and the patient. For example, a probe cover may be coupled to an IR thermometer that is adapted to take temperature in an ear canal of a human or animal. Similar covers are applicable for use with any other body cavity or skin surface of a human or animal. Generally, the material for an infrared thermometer probe cover is selected from the group of polymers which have significant transparency in the mid and far infrared range between 3 μm and 15 μm. The same material also has a range of light transmission (about 20% to about 90%) near and below the wavelength of 1 μm, that is in the visible and near-infrared spectral ranges. Examples of the polymers are polyethylene, polypropylene, and copolymers of such. Thus, installed probe cover presents little attenuation to light over a broad spectral range.
The first rod 17 is fabricated of a material having high transparency in the wavelength used by the proximity sensor. Examples of such a material are glass and polycarbonate.
A further improvement in noise reduction and sensitivity is achieved when the emitting part of the optical proximity sensor is also moved toward the distal portion 20 of the probe 7 as illustrated in
It should be clearly understood that there can be a multitude of optical arrangements for monitoring a proximity between the probe and the body cavity. One practical embodiment is illustrated in
A “dual-mode” mode light guide (opto-coupler) 43 is shown in
To reduce possible interferences from ambient illumination and lower power consumption, the light emitter 19 preferably should be used in a pulsing mode. Then, the output from detector 21 should be gated to remove a d.c. component that is associated with the ambient illumination. These functions are performed by the electronic circuit and are of a conventional nature well known in the art.
Regardless of the actual embodiment, the light intensity is generally modulated by three external factors: installation of the probe cover, proximity to the ear canal and insertion into the ear canal. Obviously, proximity sensors of the above embodiments are not the only possible way of detecting insertion of the probe into an ear canal. Other embodiments of proximity sensors may be designed by employing physical effects of capacitance, ultrasonic and other couplings between the probe and ear canal walls. Since the coupling changes while the probe is being inserted into an ear canal, the proximity sensor responds with a change in the corresponding signal.
A proximity sensor generates a signal that is used by the electronic circuit for modifying operation of the medical device.
If a signal from the proximity sensor 44 indicates that the tip of probe 7 incorporating the IR sensor 15 is positioned inside the ear canal, the computed temperature TB is sent to display 2. However, if a signal from the proximity sensor 44 indicates that the tip of probe 7 is positioned at the entrance of the ear canal, the initial temperature TB represents the exterior skin rather than the interior of the ear canal and thus should be adjusted to compensate for a cooling effect by the ambient temperature. The cooling effect is negligible inside the ear canal but it is substantial at the entrance of the ear canal. The ambient temperature is monitored by use of the ambient sensor 50 whose signal allows circuit 49 to compute ambient temperature Ta. The adjusted temperature Td may be calculated according to the following equation:
T
d
=T
B
+k(TB−Ta), (1)
where k is a constant having a typical value of 0.017. However, the actual value of k should be experimentally determined for every practical design. The adjusted temperature Td is sent to the display 2.
In another embodiment, a signal from the proximity sensor 44 may be used to generate for the operator a warning alarm (by display 2 or by any other visual or acoustic human interface) if the probe 7 is not correctly positioned inside the ear canal.
While the invention has been particularly shown and described with reference to preferred embodiments thereof, it will be understood by those skilled in the art as described herein that various changes in form and details may be made to the disclosed embodiments without departing from the spirit and scope of the invention. Accordingly, the invention is to be limited only by the scope of the claims and their equivalents.
This application claims the priority of provisional U.S. patent application Ser. No. 61/341,715 filed on 5 Apr., 2010, the disclosure of which is hereby incorporated by reference in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 61341715 | Apr 2010 | US |
