METHODS: After induction of anesthesia, tracheal intubation was performed in each patient. In the CC method, the depth of tube insertion was measured when the cuff had passed through the glottis, and again when breath sounds changed in quality; the depth of tube insertion was determined from these values. In the marker method, the depth of tube insertion was measured and determined when the marker of the tube had reached the glottis, using insertion depth according to the marker as an index.
RESULTS: Insertion depth by the marker method was 26.6 ± 1.2 cm and by the CC method was 28.0 ± 1.2 cm (P < 0.0001). The CC method indicated a significantly greater depth than the marker method.
CONCLUSIONS: This study determined the safe range of tracheal tube placement. Tube positions determined by the CC method were about 1 cm deeper than those determined by the marker. This information is important to prevent accidental one-lung ventilation and accidental extubation.
BACKGROUND: UMIN No. UMIN000011375.