This prospective observational study aims to identify simple external anatomical landmarks that allow reliable prediction of correct esophageal probe insertion depth. Accurate placement in the lower third of the esophagus is essential for reliable core temperature monitoring. Transesophageal echocardiography (TEE) will be used as the reference standard to confirm correct probe position. The study will evaluate the agreement between landmark-based insertion depth and TEE-confirmed placement in adult ICU patients undergoing clinically indicated TEE.

Correct placement of esophageal probes is essential for accurate core temperature measurement. Misplacement can lead to clinically relevant errors. Existing placement strategies based on fixed insertion depths or patient height show limited accuracy.

This study investigates whether combinations of simple external anatomical landmarks can predict the correct insertion depth. During clinically indicated TEE, probe position will be verified, and multiple anatomical measurements will be recorded. Agreement between predicted and TEE-confirmed insertion depth will be assessed using Bland-Altman analysis and intraclass correlation coefficients.

Inclusion Criteria:

• Adult (≥18 years) patients admitted to the ICU
• Clinical indication to perform a transesophageal echocardiography

Exclusion Criteria:

• <18 years

Adult ICU patients undergoing clinically indicated transesophageal echocardiography