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.

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.

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