Surgery – Diagnostic testing – Ear or testing by auditory stimulus
Reexamination Certificate
1999-03-12
2001-02-13
Hindenburg, Max (Department: 3736)
Surgery
Diagnostic testing
Ear or testing by auditory stimulus
Reexamination Certificate
active
06186959
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to biomedical instrumentation, and more particularly to portable electronic temperature measuring instruments. Still more particularly, the present invention relates to a modular sensing probe, and to systems and methods, for measuring the core body temperature of a human or animal by receiving and characterizing infrared radiation emitted by the eardrum.
BACKGROUND AND SUMMARY OF THE INVENTION
Doctors, nurses, parents, and other care providers all need to be able to rapidly and accurately measure a person's body temperature. To find out whether a person is sick, the first thing a care provider usually does is take the person's temperature. Someone running a fever is likely to have an infection. A doctor or nurse can tell a lot about how a patient is doing by monitoring the patient's temperature over time and noting how it has changed.
There are three kinds of thermometers in wide use today:
glass thermometers,
“electronic” thermometers, and
ear (“tympanic”) thermometers.
Glass thermometers are very inexpensive, very small and easy to store, and don't require batteries or other special supplies. For this reason, glass thermometers are probably the most widely used temperature measuring device in the home. However, glass thermometers have the disadvantage that they are very slow in making measurements—they typically require several minutes to reach body temperature. This is uncomfortable for the patient, and may be very troublesome when it is necessary to take the temperature of a small child or an invalid. In addition, glass thermometers are typically accurate only to within a degree, may be susceptible to errors in placement, and can be broken easily.
Because of these disadvantages, most hospitals and doctors' offices now use instruments commonly known as “electronic” thermometers. Most of us have had our temperature taken by an electronic thermometer at one time or another. The electronic thermometer includes a portable, hand-held battery powered unit with a display, and a separate probe. A wire usually connects the probe to the hand-held unit. The probe is long and thin, and has the same general shape as a glass thermometer. To use this kind of electronic thermometer, a nurse first covers the probe with a long thin disposable plastic probe cover that completely covers the probe. The disposable probe cover helps prevent the spread of disease by avoiding direct contact between the reusable probe and the germs in the patient's mouth. The nurse then puts the end of the probe under the patient's tongue. An electronic temperature sensor within the probe electrically senses the patient's temperature, and sends a signal to a microcomputer in the hand-held unit. The hand-held unit usually beeps when the temperature measurement is finished, and displays the patient's temperature on the display. The nurse can then remove the probe from the patient's mouth, strip the probe cover off the probe, and throw away the used disposable probe cover.
This type of electronic thermometer has achieved wide acceptance in hospitals because it is reasonably accurate, can be used with familiar placement techniques, and is (because of its disposable, replaceable probe covers) easily reusable for a number of different patients. Although the electronic hand-held unit is itself more expensive than most households are willing to pay, the overall cost of using this kind of electronic thermometer is relatively low because the disposable probe covers are inexpensive (two to three cents per cover, for example) and a single hand-held electronic unit may last for years and can be used to take the temperatures of many thousands of patients.
Electronic thermometers offer speed, ease of reading, and accuracy improvements over glass thermometers, and also eliminate the possibility of mercury poisoning. Although such electronic thermometers have achieved a fair degree of success, they have certain significant disadvantages. For example, they need to be constantly calibrated, are relatively easily broken, and often require a relatively long time (thirty seconds or more in many cases) to make an accurate measurement. There are also problems with taking a temperature from the patient's mouth due to breathing, keeping the thermometer under the patient's tongue, etc. Cross-contamination of infectious diseases is also a concern because the mouth is a “wet orifice.”
More recently, a new kind of electronic thermometer has appeared on the market. This new kind of thermometer works by measuring the temperature of your eardrum. Since the eardrum is also known as the “tympanic membrane,” these thermometers are sometimes called “tympanic thermometers.”
Why the eardrum? The carotid artery that supplies blood to the hypothalamus—the body's temperature control center—passes through the eardrum. For this reason, the temperature of your eardrum corresponds very closely to the core temperature of your body. Although doctors and scientists have known this fact for many years, only since the mid-1980's have commercial devices been available to measure eardrum temperature in a clinical setting.
Ear or “tympanic” thermometers work by receiving and analyzing the radiant heat (“infrared”) energy coming from the eardrum. Just as you can feel the heat when you hold your hands up in front of a warm fire, a tympanic thermometer can detect eardrum temperature without having to actually touch the eardrum by receiving the radiant heat energy coming from the eardrum.
Commercially available tympanic thermometers consist of a portable, hand-held battery powered main unit providing electronics, a display and a probe containing a special type of heat sensor such as a “thermopile” or a pyroelectric heat sensor. This special heat sensor is especially sensitive to the eardrum's radiant heat energy. Microelectronics can determine eardrum temperature from the electrical signals provided by the special heat sensor. The thermopile's sensing probe is typically an integral part of the tympanic thermometer's main unit—reducing the potential for breakage of the sensor assembly and (at least potentially) increasing reliability and accuracy.
To use the ear thermometer, a nurse or other care provider inserts a disposable probe cover onto the instrument's sensing probe. Once the disposable probe cover is in place, the nurse or other caregiver inserts the covered sensing probe into the patient's outer ear and then presses a button to command the instrument to make a measurement. The measurement time is usually very rapid—on the order of two seconds or less. The patient's temperature instantly shows on the instrument's display. The instrument may then be removed from the patient's ear, and the disposable cover can be stripped off the instrument and discarded.
Ear thermometry has advantages over other temperature measuring techniques. For example:
The measuring time is very rapid—usually less than two seconds.
The eardrum is at or near the body's core temperature, providing the most accurate location for non-invasive temperature measurement.
Because the ear is a dry orifice, cross-contamination is not much of an issue—and individual, disposable probe covers further reduce the already low cross-contamination risks.
The theoretical accuracy of the measurement is very high (for example, on the order of one tenth of one degree).
Because of the short measurement time and the use of either ear as the measuring point, it is possible to rapidly measure the temperature of children, invalids and sleeping patients—and in other situations where it is difficult to get a patient to sit still for thirty seconds with a probe under their tongue.
Despite these many clear advantages, ear thermometry has not yet achieved wide success in the medical marketplace. Even though many hospitals are believers in the concept of ear thermometry, the hospital market overall has converted less than twenty-five per cent of its temperature
Canfield Eric L.
Cheslock Edward P.
Hindenburg Max
Nixon & Vanderhye P.C.
TruTek, Inc.
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