Introduction: Confirmation of endotracheal tube (ETT) position is of prime importance immediately after insertion of ETT. Currently, end-tidal CO2 measurement, auscultation of lung-stomach fields and chest x-rays are recommended for this purpose. All these are indirect methods. We hypothesized that if the ETT is in the airway, thermal energy will spread from blood-rich pulmonary circulation to the Alveolae- distal and proximal airway including inserted ETT. This study aimed to evaluate the role of direct physiological thermo-imaging during ETT placement. Methods: Between Jan 1, 2025 and Aug 6, 2025, after approval of local ethical committee, we prospectively evaluated the pattern of thermo-image during elective ETT insertion in the anesthesia induction using hand-held thermo- scanner mounted on a cellphone. The thermo-imaging was obtained without interruption of the procedure. The images were viewed on site and stored for reviewing. The staff anesthesiologist completed the whole ETT insertion procedure and employed conventional methods to guide all procedures. The pattern of ETT thermo-imaging was viewed and analyzed by an independent physician in this team. Results: A total of 35 patients were enrolled into this study including 20 males and 15 females. The mean ages were 47.4±20.3 YO. The anesthesiologist successfully inserted at 1st attempt for all ETT placements. Immediately after insertion, the anesthesiologist checked the end-tidal CO2 and auscultation was also performed. The tube was connected to the anesthetic machine circuit. The color of the ETT turned to higher temperature (>28.5°C) among all cases within 5 seconds(0.2±0.63), almost concomitantly with the steep rise of end-tidal CO2. Conclusions: We have shown that the novel thermo-imaging of ETT was as good as current gold standard of confirmation of ETT position. Considering its advantage, the thermo-imaging of ETT did provide preliminary evidence that if ETT was in the airway, its temperature will be closer to body temperature compared to the nearby objects. More studies are currently undertaken to further test this hypothesis.
Hsieh et al. (Sun,) studied this question.