Thermal measuring and testing – Temperature measurement – With removable cover for sensor
Reexamination Certificate
1999-02-28
2002-10-08
Gutierrez, Diego (Department: 2859)
Thermal measuring and testing
Temperature measurement
With removable cover for sensor
C374S209000
Reexamination Certificate
active
06461037
ABSTRACT:
BACKGROUND
The present invention relates generally to medical temperature probes, and more particularly to a temperature probe comprising a spring-loaded shaft for maintaining a constant force between the shaft and a temporary, disposable probe cover, and a mechanism to eject the probe cover from the probe.
Medical thermometers are useful in the diagnosis and treatment of many diseases. It is common practice in the medical arts, as in hospitals and in doctors' offices, to measure the body temperature of a patient by means of a glass bulb thermometer incorporating a heat responsive mercury column that expands and contracts adjacent a calibrated temperature scale. It is also known to use electronic thermometers that operate to sense the patient's temperature for a short period of time and then extrapolate to predict the actual patient temperature. This latter thermometer results in the determination of a patient's temperature in a much shorter time period than with mercury glass bulb thermometers.
While these thermometers have been used for many years and have been found to provide useful results in diagnosing and treating patients, some of those who use them desire a thermometer that determines a patient's temperature more rapidly. For example, a mercury thermometer typically takes at least five minutes or more to determine a patient's temperature. An electronic predictive thermometer can take one or more minutes in its predictive mode and five or more minutes in its monitoring or direct reading mode. Electronic predictive thermometers have become popular because in their predictive mode, the time for taking the temperature is much less than the mercury thermometer. For busy nursing staffs, time is of the essence. Taking a temperature in one minute is much more desirable than taking a temperature in five minutes. More patients can be served with the faster thermometer and the nursing staff can be more productive.
Additionally, the more time that a probe must be in a patient's mouth to make a temperature determination, the more likely it is that the probe will not remain in the correct location. This is particularly true with younger patients who tend to be impatient. For patients who cannot be relied upon (by virtue of age or infirmity for example) to properly retain the thermometer for the necessary period of insertion in the body, the physical presence of medical personnel during a relatively long measurement cycle is necessary. Taking a temperature of younger patients in one minute is immensely more desirable than taking the temperature in five minutes. Thus, the predictive electronic thermometer has substantially advanced the art of temperature determination.
In addition to the above, rapid reuse on other patients is also a goal. However, with reuse, precaution must be taken to avoid the possibility of cross contamination between patients. Consequently, protective covers have been designed for use with the probes of thermometers. The protective cover is designed to completely envelop the portion of the thermometer that comes into contact with the patient. Because the protective cover may then be removed and discarded after use of the thermometer, and because the protective cover has protected the thermometer from contact with the patient, the thermometer may be immediately reused by simply applying another protective cover.
Protective probe covers have been available for predictive electronic thermometers for many years making the thermometer rapidly reusable when properly used with such covers. However, a protective cover adds material between the temperature sensor in the probe of the thermometer and the heat source; i.e., the patient. Additional material between the patient and the sensor can slow down the process of determining the patient's temperature as heat from the patient must first pass through the probe cover before it reaches the sensor. Gains made in permitting immediate reuse of thermometers due to the use of a disposable probe cover may thus be offset by the increasing length of time it takes to obtain a reading, caused by that same probe cover.
In addition, given that each probe cover is used only once and then discarded, it is desirable that such probe covers be as inexpensive as possible. They should be efficiently produced from readily available, inexpensive materials utilizing common manufacturing techniques. Thus, materials offering good heat transfer characteristics and that are easily injection molded, such as thermoplastics, are desired in fabricating probe covers.
One factor in obtaining a temperature measurement in as short a time as possible is to improve the heat transfer characteristics between the probe and the probe cover. A consideration in the heat transfer characteristics of a probe cover is the contact the probe cover makes with the probe tip in which the temperature sensor is located. As is well known to those skilled in the art, air located between a probe cover and the sensor in the probe tip will act as an insulator and will slow down the transfer of patient heat to the sensor. It will then take longer to obtain a measurement of the patient's temperature. Poor contact between the probe cover and the probe will also slow down the measurement process in that heat from the patient will take longer to reach the sensor in the probe tip. Consequently, most probe and probe cover systems are designed and configured to achieve good contact between the tip of the probe, where the temperature sensor is located, and the inside surface of the probe cover so that patient heat is transferred more quickly to the temperature sensor.
Probes used with probe covers by necessity have a cover retention mechanism. A number of prior art devices relied upon the interference fit between the probe shaft distal tip and the probe cover for retaining the cover onto the probe. It is desirable in some cases where a precise interface between the probe tip and the probe cover is required to retain the probe cover onto the probe by other means.
Another design for cover retention is a split ring. In use, the probe cover is mounted over the probe shaft and pressed down over the split ring, forcing the ring to contract and thus allow the probe cover to slip over its outer periphery. The natural tendency of the ring is to return to its original shape thereby applying outward force against the probe cover, and thus retaining the cover in position over the probe. While this design has been accepted and has provided improvement to the art, in some cases a less complex design would be desired. The split ring is an extra part that must be manufactured and assembled with the probe, and thus adds to the overall complexity and cost of the probe.
Thermometers having a probe configured for receiving disposable probe covers have also been used for many years with ejection systems. In one particular design, an ejection mechanism is used to detach the probe cover from the probe after use so that the contaminated probe cover can be directly discarded without the operator having to touch it. In the typical case, the probe is held over a waste receptacle, the ejection button is pressed which detaches the probe cover from the probe and the probe cover falls into the waste receptacle. Different types of ejection mechanisms exist.
In one ejection mechanism, the probe shaft of the thermometer is coupled directly to the ejection mechanism. The probe cover is mounted over the probe and is retained in position by a retention device located at the distal end of a handle forming part of the probe. For ejection, the ejection button is pressed which causes the probe shaft to extend farther out of the probe handle pushing the probe cover also in a distal direction away from the retention device and dislodging the probe cover from a retention device. The probe cover then falls off the probe. Some improvement on this device is desired as the ejection button provides a natural resting place for the user's thumb, and in some cases, the user may inadvertently
ALARIS Medical Systems, Inc.
Fulwider Patton Lee & Utecht LLP
Guadalupe Yaritza
Gutierrez Diego
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