小兒 endo 要插多深？

Best Method for Placing Pediatric Tubes to the Correct Depth

Positioning of the tip too close to the carina results in endobronchial intubation when the neck is flexed.

Endotracheal tubes ideally are placed with the tip near the midtrachea, thereby minimizing the likelihood that either endobronchial intubation or accidental extubation will occur when the patient's neck is flexed or extended. In pediatric patients, tube positioning is challenging because of variations in the length of both the tube and the trachea. Investigators in Korea randomized 107 children (aged 2–8 years) who were undergoing general anesthesia to one of three methods for initially positioning the tube at the correct depth.

In group I, the tube was inserted deliberately into a mainstem bronchus and then withdrawn 2 cm (in children aged 2–5 years) or 3 cm (in children older than 5) farther than the point at which bilateral breath sounds were heard. In group II, the tube was placed with the recommended centimeter marking aligned with the vocal cords ( i.e., the 4-cm mark for tubes with an internal diameter of 4 or 4.5 cm and the 5-cm mark for tubes with a diameter 5 cm). In group III, the tube was manipulated until its tip could be palpated in the suprasternal notch (anatomically near the midtrachea). The position of the tip relative to the carina and vocal cords was then measured using a fiber-optic bronchoscope, with the neck in neutral position, full flexion, and full extension.

In groups II and III, the tip of the tube initially was placed near the midtrachea (at positions 46.5% and 43.4%, respectively, of the distance from the carina to the vocal cords), whereas in group I, the tube was placed significantly closer to the carina ( 21.4% of the distance). Flexion brought the tube very close to the carina (9.5% of the distance) in group I, but not in groups II and III (38.3 and 32.4% of the distance, respectively). Extension brought the tube tip near the midtrachea in group I ( 44.3% of the distance) and into the upper third for groups II and III (71.7% and 67.9% of the distance, respectively). Flexion produced endobronchial intubation in 5 of 35 patients in group I (most aged 2 to 5 years), but not in any patients in the other groups. No patient was extubated by extension.

Comment: This study strongly affirms the importance of placing endotracheal tubes in children in the midtrachea, where neither endobronchial intubation nor accidental extubation will occur through the entire range of motion of the neck. The often- recommended method that was used for group I is clearly inferior for correct placement and should not be used.

— Ron M. Walls, MD, FRCPC, FACEP, FAAEM
Published in Journal Watch Emergency Medicine October 5, 2007

Citation(s): Yoo S-Y et al. A comparative study of endotracheal tube positioning methods in children: Safety from neck movement. Anesth Analg 2007 Sep; 105:620.