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Completed

NCT Number: NCT05552092

Optimal Depth for Esophageal Stethoscope

The purpose of the present study was to evaluate the optimal insertion depth of an esophageal stethoscope with a thermistor for core temperature monitoring.

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Key information

Conditions

Surgery

Age range

20 year–65 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

Chosun University Hospital

Gwangju, 61453, South Korea

About this study

Monitoring core temperature is crucial for maintaining normothermia during general anesthesia. During anesthesia, an esophageal stethoscope with a thermistor for monitoring esophageal temperature is frequently used.

There are several researches on the depth or position of the esophageal stethoscopes, but there is only limited information (known as about 40-45 cm or T8-T9).

The purpose of the present study was to evaluate the optimal insertion depth of an esophageal stethoscope with a thermistor for core temperature monitoring.

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • The patients with ASA class 1-2 (20-65 years old) who are undergoing elective surgery with supine or lithotomy position, without position change scheduled to last more than 90 min.

Exclusion criteria

  • anatomical abnormality with the upper airway
  • risks of a difficult airway
  • abnormal central anatomical structures such as airway, diaphragm, or spine on the chest X-ray
  • history of disease or surgery on the stomach or esophagus
  • risks of bleeding or coagulopathy on the preoperative laboratory results
  • obese patients with BMI over 30
  • contraindication to insertion of ES for the surgery
  • who did not take a standing chest PA X-ray before surgery
  • position change during the surgery
  • open chest surgery

Treatment and study plan

Esophageal temperature monitoring according to the depth

Device

Core temperatures will be measured with a tympanic thermometer as a reference. When the tympanic membrane (TM) temperature is constant after measuring three consecutive times at 10 seconds intervals, the temperature will be assumed as the core body temperature.

Initially, the esophageal stethoscope (ES) will be inserted to a depth of 45 cm from the incisor. After 30 minutes of monitoring, when the changes in the body temperatures stabilized, initial temperatures of the TM and ES thermistor will be assessed.

After 5 minutes, ES will be taken out 2 cm back, and the temperatures of each site will be measured when the temperature change of the ES thermistor stabilized below 0.1°C. Eventually, the depth of ES will be changed from 45 to 27 cm with a 2 cm interval, and the temperature at each position will be measured.

Anatomical landmark

Other

For the further evaluation of the optimal insertion depth of GDT, anatomical landmarks such as distance from the cricoid cartilage to the carina (CCD) and distance from the carina to the intervertebral disc between T8 and T9 (CDD) will be measured using an electronic caliper on a preoperative chest X-ray.

Primary outcomes

  1. Desired insertion depth of ES thermistor

    Time frame: 1 day

    To evaluate the desired insertion depth, we will assess the accuracy of temperatures of the ES thermistor at each location by estimating the difference between the esophageal temperature using ES thermistor and the core body temperatures of TM.

Secondary outcomes

  1. Correlation analysis

    Time frame: Through study completion, 1 year

    The secondary outcome of the study is to assess the correlation between the characteristics of patients including gender, height, weight, BMI, CCD, or CDD, and the actual insertion depth of the ES which showed the most minor difference in temperature between TM and ES thermistor.

    Radiographic landmarks On the preoperative chest radiograph, the cricoid-to-carina distance (CCD) and the carina-to-T8/9-intervertebral-disc distance (CDD) will be measured.

  2. Optimal depth analysis

    Time frame: Through study completion, 1 year

    We will calculate a mathematical model to predict the optimal insertion depth of ES for the esophageal temperature monitoring, and further analysis for the accuracy and correlation will be done.

    To quantify tolerance to positioning error, the difference was modeled as a quadratic function of the offset from the MHS position (depth - MHS) using a linear mixed-effects model with a random intercept per patient. From the fixed-effect curve and the total (within- plus between-patient) standard deviation, the probability that a single reading fell within ±0.5 °C of core was computed across offsets to define ≥90% and ≥85% "safe zones."

Sponsors and collaborators

Lead sponsor

Chosun University Hospital

Other

Registry information

Official study title

Optimal Depth for Esophageal Stethoscope for the Monitoring of Core Temperature

Important dates

Study start
2022
Primary completion
2026
Study completion
2026
First posted
Sep 23, 2022
Registry last updated
Jul 21, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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