Patent Publication Number: US-2007107736-A1

Title: System and method for monitoring temperature while delivering anesthesia

Description:
FIELD OF THE INVENTION  
      The present invention relates generally to medical monitoring devices and artificial airway devices. In particular, but not by way of limitation, the present invention relates to devices for monitoring a patient&#39;s temperature.  
     BACKGROUND OF THE INVENTION  
      Artificial airway devices, such as an laryngeal mask airway (“LMA”) or an endotracheal tube (“ETT”), have been utilized as a tool to support a patient&#39;s breathing and to deliver oxygen and other gases into a patient&#39;s airway. For example, during medical operations requiring anesthesia, an artificial airway device may be used to deliver anesthesia and other gases, such as oxygen or nitrous oxide, to the patient&#39;s lungs.  
      During these medical operations, it is very important to maintain the patient&#39;s body temperature. It has been found, for example, that hypothermia both increases the incidence of surgical infections and inhibits the patient&#39;s blood clotting systems, which makes the patient more likely to suffer increased intraoperative blood loss. As a consequence, the practice guidelines of the American Society of Anesthesiologists and the Joint Committee of Hospital Accreditation require that, throughout such medical operations, the patient&#39;s body temperature must be monitored.  
      Because the use of an artificial airway device creates certain difficulties for measuring a patient&#39;s temperature in or through the oral cavity, other sites such as the rectum may be used, resulting in less accurate measurement, increased stress, likelihood of injury and/or embarrassment for the patient. Moreover, widely available body surface temperature monitoring devices are not reliable because the body surface sensors are exposed to either the cold operating room environment (e.g., 60 to 65 degrees Fahrenheit) or to external heating blankets that are frequently used to warm the patient during surgery.  
      The importance of being able to accurately monitor a patient&#39;s temperature during surgery, and while the patient is under anesthesia, is without question. Although currently available esophageal temperature probes are able to accurately measure a patient&#39;s temperature, these probes include a relatively large plastic tube (e.g., approximately one-quarter of an inch in diameter and about fifteen inches long) that is inserted into the patients esophagus. As a consequence, the applicability of esophageal temperature probes during surgery is generally limited to instances where the patient is under complete general anesthesia and when the patient&#39;s artificial ventilation is provided by a breathing tube (e.g., an endotracheal tube) that is concurrently inserted into the patient&#39;s windpipe.  
      In the last decade, the insertion of a breathing tube all the way into the patient&#39;s windpipe became unnecessary due to the development of the Laryngeal Mask Airway (LMA). In use, the LMA does not extend into the patients windpipe, and as a consequence, the LMA provides less irritation than the endotracheal tube while maintaining sufficient “airway control.” Out of approximately 22 to 24 million surgical procedures performed each year in the U.S.A., it is estimated that up to 50% are now performed with an LMA instead of the “classical” windpipe intubation.  
      Unfortunately, the LMA completely occludes the entrance into the patient&#39;s throat; thus the insertion of the esophageal temperature probe is physically impossible. As a consequence, up to 12 million patients are deprived of the accurate temperature monitoring and their anesthesia providers must rely on surface probes that are subject to the previously described distortions. Accordingly, a system and method are needed to address the shortfalls of present technology and to provide other new and innovative features.  
     SUMMARY OF THE INVENTION  
      To remedy the above described and other deficiencies of the current technology, an apparatus, system and method for orally monitoring a patient&#39;s temperature while an artificial airway device is in the patient&#39;s airway is disclosed. In one embodiment, the present invention includes an artificial airway device and a thermometer connected to the artificial airway device. Because the thermometer is connected to the artificial airway device, the device can be used to orally measure a patient&#39;s body temperature while delivering a gas into the patient&#39;s airway.  
      In another embodiment, the present invention encompasses a method for orally monitoring a patient&#39;s body temperature while an artificial airway device is within the patient&#39;s airway. In this embodiment an artificial airway device is first inserted, with a thermometer affixed thereto, into a patient&#39;s airway. Then, the thermometer is connected to a system capable of displaying a patient&#39;s body temperature. The thermometer then takes the patient&#39;s body temperature and the system displays the patient&#39;s body temperature.  
      In yet another embodiment, the present invention encompasses a system for orally monitoring a patient&#39;s body temperature while delivering a gas into the patient&#39;s airway. The system in this embodiment includes a thermometer affixed to an artificial airway device and a device connected to the thermometer that displays the temperature from the thermometer.  
      Accordingly, the present invention overcomes the problems with the present technology and addresses the needs of the patient care community. Exemplary embodiments of the present invention that are shown in the drawings are summarized below. These and other embodiments are more fully described in the Detailed Description section. It is to be understood, however, that there is no intention to limit the invention to the forms described in this Summary of the Invention or in the Detailed Description. One skilled in the art can recognize that there are numerous modifications, equivalents and alternative constructions that fall within the spirit and scope of the invention as expressed in the claims.  
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      Various objects and advantages and a more complete understanding of the present invention are apparent and more readily appreciated by reference to the following Detailed Description and to the appended claims when taken in conjunction with the accompanying Drawings wherein:  
       FIG. 1  is a block diagram, which illustrates a system for orally monitoring a patient&#39;s body temperature in accordance with the present invention.  
       FIG. 2  is a flow chart of one method for orally monitoring a patient&#39;s body temperature in accordance with the present invention.  
       FIGS. 3 and 3 A illustrate a schematic view and an exploded schematic view, respectively of a device according to an embodiment of the present invention.  
       FIGS. 4 and 4 A illustrates a schematic view and an exploded schematic view, respectively of a device according to another embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION  
      Referring now to the drawings, where like or similar elements are designated with identical reference numerals throughout the several views, and referring in particular to  FIG. 1 , it illustrates a system  100  for orally monitoring a patient&#39;s body temperature in accordance with the present invention. In accordance with several embodiments, the system  100  enables the temperature of a patient  108  to be orally monitored while an artificial airway device is in the patient&#39;s airway. This is accomplished by connecting a thermometer  102  to, or integrating the thermometer  102  with, the artificial airway device  104 .  
      In the exemplary embodiment depicted in  FIG. 1 , the thermometer  102  is connected to the artificial airway device  104  and to a display system  106 . As shown, the connection between the thermometer  102  and the display system  106  is represented by a solid line, but the connection is certainly not limited to wire line connections. In some embodiments for example, the thermometer  102  is connected by a wireless connection with the display system  106 . As illustrated in  FIG. 1 , it is contemplated that the system will be constructed and implemented such that the thermometer  102  and artificial airway device  104  can be inserted into a patient  108 .  
      As shown in  FIG. 1  the artificial airway device  104  is also connected to a gas delivery system  110 . In the exemplary embodiment, the gas delivery system  110  is utilized to deliver anesthesia, oxygen or other gases while the thermometer  102  is within the patient&#39;s  108  airway. Although the gas delivery system  110  and display system  106  are depicted as separate devices in the present embodiment, in another embodiment (not shown) the gas delivery system  110  and the display system  106  are incorporated into a single device.  
      By way of example only, the artificial airway device  104  in some embodiments is realized as an endotracheal tube (ETT) and in other embodiments the artificial airway device is implemented as a laryngeal mask airway (LMA). The thermometer  102  may be realized as any of a group of digital thermometers, electric thermometers, wireless thermometers, infrared thermometers, thermoscan thermometers, temperature sensors, thermal sensors, contact thermometers, thermocouple thermometers, temperature transducers, thermistors, temperature probes, radiation thermometers/pyrometers, analog thermometers and thermal diodes.  
      While referring to  FIG. 1 , simultaneous reference will be made to  FIG. 2 , which is a flowchart depicting steps carried out by the system  100  of  FIG. 1  when orally monitoring a patient&#39;s body temperature in accordance with an exemplary embodiment of the present invention. As shown, the artificial airway device  104 , with thermometer  102  connected thereto, is inserted into the patient  108  (Block  202 ), and once inserted, the thermometer  102  is connected to the display system  106  (Block  204 ). This may involve connecting a physical wire to the display system  106 , or the thermometer  102  may be wirelessly connected. Next, the thermometer  102  measures the patient&#39;s  108  body temperature (Block  206 ), and the patient&#39;s  108  body temperature is then displayed on the display system  106  (Block  208 ). It should be recognized that the order of steps depicted in  FIG. 2  may be varied without departing from the scope of the present invention. In another embodiment, for example, the thermometer  102  is connected to the display system  106  before the artificial airway device  104  (with thermometer  102  connected thereto) is inserted into the patient  108 .  
      Although not depicted in  FIG. 1  or  2 , after the artificial airway device  104  is inserted into a patient&#39;s  108  airway, it can be connected to the gas delivery system  110 . The exemplary embodiment of the present invention will therefore allow for the simultaneous delivery of gas, such as anesthesia or oxygen, into the patient  108  and the oral monitoring of a patient&#39;s body temperature with a single device. As used herein, oral or orally monitoring and oral or orally measuring are intended to encompass any monitoring or measuring that is done in or through the oral cavity of the patient, including but not limited to measuring or monitoring done at a patient&#39;s pharyngeal area and any other similar or surrounding area.  
      Referring next to  FIG. 3 , shown is a schematic view of a device where the artificial airway device  104  of  FIG. 1  is realized as a laryngeal mask airway (LMA)  304 . The LMA  304  in this embodiment, is depicted inside of a human patient  308  for purposes of example. In  FIG. 3 , and in an exploded view in  FIG. 3A , the thermometer  302  is shown affixed to the LMA  304  at a location that allows the thermometer  302  to be in physical contact with the surface of the oropharyngx so as to enable the thermometer  302  to measure the patient&#39;s  308  core body temperature.  
      As depicted in  FIG. 3 , the LMA  304  is configured to be inserted into the patient&#39;s  308  throat, and the thermometer  302  is disposed relative to the LMA  304  so as to be capable of measuring a temperature at the patient&#39;s pharynx when the LMA  304  is inserted in the patient&#39;s throat. Given the relative proximity of an area like the pharynx to the patient&#39;s heart, if the patient&#39;s core body temperature changes, then such a change is prone to be quickly picked up by the thermometer  302 , which makes a location like the pharynx a good location for measuring a patient&#39;s core body temperature. The core body temperature is considered by many to be to most appropriate temperature of a patient to measure due to the accuracy of the measurements and the insight, which the core body temperature provides into the patient&#39;s condition. As a consequence, several embodiments of the present invention provides a convenient and accurate measurement of arguably the most pertinent temperature of the patient—the core body temperature.  
      The thermometer  302  in the exemplary embodiment is also shown placed away from the tip of the LMA  304  to help make sure any temperature differential between the gases in the LMA  304  and the surrounding tissue does not affect the temperature read by the thermometer  302 . For this reason the artificial airway device  104 ,  304 , could also be insulated in order reduce or eliminate any errors caused by a temperature differential between the artificial airway device  104 ,  304 , or the gases passing through it, and the part of the patient  308  the thermometer is measuring. The present embodiment is only exemplary, however, and it is contemplated that there are locations on the LMA  304  where the thermometer  302  may be placed.  
       FIG. 3  also shows a wire  306  that runs from the thermometer through the inside of the body of the LMA. As discussed earlier, this wire  306  is only one potential, but not the only, means for connecting the thermometer  302  to a display system  106 . The wire  306  may be imbedded in the structure of the LMA  304 , inside or outside of the LMA  304 , or there may be no wire at all, but one skilled in the art will be aware of other alternative embodiments that are well within the scope of the present invention. Furthermore, although  FIGS. 3 and 4  depict a human patient  308 , this is done for purposes of explanation and description, there is nothing that should suggest the present invention is limited to human patients or artificial airway devices used on human patients and it is contemplated that the present invention is applicable in other embodiments to non-human patients.  
      Referring next to  FIG. 4 , shown is a schematic diagram depicting a device according to another embodiment of the present invention. As shown in  FIG. 4 , the artificial airway device  104  of  FIG. 1  is realized as an endotracheal tube (ETT)  404 . In this embodiment, the thermometer  402  is located at a location where it can contact part of the patient&#39;s  308  pharynx. Although the thermometer  402  is located at the lower part of the pharynx in  FIG. 4 , this is just by way of example and not a limitation to the present invention.  
      In conclusion, the present invention provides, among other things, a system and method for orally monitoring a patient&#39;s temperature while an artificial airway device is in the patient&#39;s airway. Those skilled in the art can readily recognize that numerous variations and substitutions may be made in the invention, its use and its configuration to achieve substantially the same results as achieved by the embodiments described herein. Accordingly, there is no intention to limit the invention to the disclosed exemplary forms. Many variations, modifications and alternative constructions fall within the scope and spirit of the disclosed invention as expressed in the claims.