Optimal Depth for Esophageal Stethoscope

Optimal Depth for Esophageal Stethoscope for the Monitoring of Core Temperature

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

Study Overview

• Status: Completed
• Conditions: Surgery
• Intervention / Treatment: Device: Esophageal temperature monitoring according to the depth; Other: Anatomical landmark

Detailed Description

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.

• Study Type: Interventional
• Enrollment (Actual): 40
• Phase: Not Applicable

Contacts and Locations

Study Locations

• South Korea
  • Gwangju, South Korea, 61453
    • Chosun University Hospital

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 20 years to 65 years (Adult, Older Adult)
• Accepts Healthy Volunteers: No

Description

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

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Other
• Allocation: N/A
• Interventional Model: Single Group Assignment
• Masking: None (Open Label)

Number of Arms

1

Arms and Interventions

Participant Group / Arm

Intervention / Treatment

Experimental: Experimental; 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.

Device: Esophageal temperature monitoring according to the depth; 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.; Other: Anatomical landmark; 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.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Desired insertion depth of ES thermistor	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.	1 day

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Correlation analysis	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.	Through study completion, 1 year
Optimal depth analysis	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."	Through study completion, 1 year

Collaborators and Investigators

• Sponsor: Chosun University Hospital
• Investigators: Study Director: Ki Tae Jun, M.D., Ph.D., Chosun University Hospital

Publications and helpful links

General Publications

• Wang M, Singh A, Qureshi H, Leone A, Mascha EJ, Sessler DI. Optimal Depth for Nasopharyngeal Temperature Probe Positioning. Anesth Analg. 2016 May;122(5):1434-8. doi: 10.1213/ANE.0000000000001213.

Study record dates

Study Major Dates

• Study Start (Actual): November 26, 2022
• Primary Completion (Actual): July 13, 2026
• Study Completion (Actual): July 13, 2026

Study Registration Dates

• First Submitted: September 14, 2022
• First Submitted That Met QC Criteria: September 20, 2022
• First Posted (Actual): September 23, 2022

Study Record Updates

• Last Update Posted (Actual): July 21, 2026
• Last Update Submitted That Met QC Criteria: July 19, 2026
• Last Verified: March 1, 2026

More Information

Terms related to this study

• Keywords: Monitoring, Intraoperative; Body Temperature; Anatomic Landmarks
• Other Study ID Numbers: ET_Position

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No