Accuracy of Body Temperature Measurements Using the Esophageal Temperature Probe Inserted Through the Gastric Lumen of Supraglottic Airway Device
Condition: Core Temperature
Study type: Observational

Summary: 
      In general, 50-90% of patients undergoing surgery under general anesthesia are known to
      develop hypothermia during surgery. Due to hypothermia during surgery, the patient may cause
      coagulation disorders, wound infections, increased ventricular tachycardia, prolonged
      anesthesia drug effects, and electrification, resulting in delayed recovery after surgery,
      extended recovery room exit, and extended hospital stay. Therefore, unless intentional
      hypothermia is needed, active body temperature management during surgery is necessary.

      Pulmonary artery, distal esophagus, tympanic membrane, nasopharynx, oral cavity, axillary
      cavity, rectum, and bladder can be measured. The most accurate method for measuring deep body
      temperature in general anesthesia is esophageal body temperature, nasopharyngeal body
      temperature, It is known as tympanic body temperature. 3,4 However, the tympanic body
      temperature has the disadvantage that it cannot be continuously measured. Considering these
      points, esophageal thermometers that can be continuously measured in patients with general
      anesthesia and have few side effects are commonly used. The esophageal thermometer is usually
      inserted through the oral cavity. When the supraglottic airway device is inserted, the space
      in the oral cavity is filled with the supraglottic airway device, making it difficult to
      mount the esophageal thermometer. However, most second-generation supraglottic airway devices
      have gastric lumens, and gastric lumens are connected to the esophagus, allowing esophageal
      thermometers to be mounted through this space. Since the esophageal temperature probe is
      inserted in all general anesthesia patients using the supraglottic airway device in this
      application, the body temperature measured by the temporal artery at the same time is how
      accurate the body temperature measured at this time is as a reference value using the
      tympanic membrane. I would like to analyze the transient comparison. We will also analyze
      whether the esophageal thermometer mounted through the gastric lumen of the supraglottic
      airway device reflects the rapidly decreasing body temperature change when the pneumatic
      tourniquet is decompressed.
    

Detailed description: 
      Basic anesthesia management is the same as for patients undergoing general anesthesia using
      all supraglottic airway devices.

      Fasting from midnight the day before surgery, and when the patient enters the operating room,
      a blood pressure monitor, electrocardiogram, pulse saturator is mounted, and baseline blood
      pressure, oxygen saturation, and heart rate are recorded. As an anesthesia-inducing facial
      mask, it provides 100% of 4-6L/min of oxygen. Propofol is administered at 2 mg/kg, and after
      the patient's self-breathing is lost, 5% sevoflurane is supplied for 3 minutes to deepen the
      depth of anesthesia. After inserting the appropriate size of supraglottic airway (i-gel)
      according to the patient's weight, the esophageal temperature probe is inserted through the
      gastric lumen to the end of the supraglottic airway device i-gel. After 10 minutes, when the
      body temperature measurement measured in the esophagus stabilizes, the body temperature is
      measured at the tympanic membrane and temporal artery at 10-minute intervals. For the
      objectivity of body temperature measurement, the same operator performs it, and the left and
      right sides of the tympanic membrane can be measured differently, so both sides are measured
      and averaged. After Tourniquet deflation, body temperature is measured and recorded every 10
      minutes from 10 minutes.
    

Observational model: Case-Control
Time perspective: Prospective
Sampling method: Non-Probability Sample
Study population: 
        Among patients undergoing knee surgery using tourniquet for more than 1 hour, patients
        undergoing general anesthesia using the Supraglottic airway device
      
Keywords: core temperature, tympanic membrane, esophageal temperature, temporal artery temperature