Tracheal shortening during laparoscopic gynecologic surgery.

Background: During laparoscopic gynecologic surgery, pneumoperitoneum combined with the Trendelenburg position moves the carina towards the tip of the endotracheal tube (ETT), decreasing the margin of safety for the ETT position and increasing accidental endobronchial intubation. However, it remains to be established whether the tracheal length itself is actually changed. We conducted a prospective observational study to measure the change in the length of the trachea and the distance between the ETT tip and the carina in patients undergoing gynecologic laparoscopic surgery.
Methods: Twenty-three patients scheduled for laparoscopic gynecologic surgery were enrolled. In the neutral position, the tracheal length was measured using a fiberoptic bronchoscope. The distance between the ETT tip and the carina was also measured. The tracheal length and the distance between the ETT tip and the carina were measured again 10 min after carbon dioxide (CO(2)) pneumoperitoneum (12-14 mmHg) combined with the Trendelenburg position (15 degrees ).
Results: In the neutral position, the tracheal length was 11.09 +/- 0.90 cm and the distance between the ETT tip and the carina was 3.36 +/- 1.04 cm. After pneumoperitoneum combined with the Trendelenburg position, the distance between the ETT tip and the carina had decreased by 0.85 +/- 0.28 cm. The tracheal length had also decreased by 0.42 +/- 0.19 cm, which was equivalent to 49.7% of the decrease in the distance between the ETT tip and the carina.
Conclusions: These results suggest that tracheal shortening may contribute to a decrease in the distance between the ETT tip and the carina, increasing the risk of accidental endobronchial intubation during laparoscopic gynecologic surgery.