Complications of the endotracheal tube (ETT) displacement during head and neck positional changes are related to not only the tip position but also the cuff pressure against the larynx. Here, we evaluated movement of the ETT cuff relative to laryngeal structures as well as tip displacement from the carina.

Sixty-two patients scheduled for thyroidectomy were recruited. The distance from the cricoid cartilage to the upper margin of the cuff (CC) and that from the ETT tip to the carina (TC) were measured using ultrasonography and fiberoptic bronchoscopy, respectively, during flexion and extension. The total tracheal length (TTL) was defined as the combination of CC, TC, and the distance from the upper margin of the cuff to the tip.

During flexion, the CC and TC were 1.5 ± 0.6 and 2.9 ± 1.0 cm respectively. Seven patients (11.7%) exhibited excessively deep intubation. After adjusting the cuff position under ultrasonography (CC = 0), the tip position was corrected in 96.7%. While the TC increased by 2.1 ± 1.0 cm after the positional change in extension, the CC decreased by 0.6 ± 0.7 cm because the TTL lengthened (1.4 ± 1.1 cm). Four patients (6.7%) exhibited excessive cuff displacement beyond the cricoid cartilage, which could have been corrected under ultrasonography.

In conclusion, the ETT cuff displaced toward the larynx in a less degree than the tip did from the carina due to the tracheal lengthening during head and neck extension. Nevertheless, we suggest that ultrasonographic assessment of cuff position may avoid ETT misplacement.

Trial registration https://cris.nih.go.kr/ (approval no. KCT0005319); registered on May 14, 2019.

头部和颈部位置变化期间气管导管 (ETT) 移位的并发症不仅与尖端位置有关，还与对喉部的套囊压力有关。在这里，我们评估了 ETT 套囊相对于喉结构的运动以及尖端从隆突的位移。

招募了 62 名计划进行甲状腺切除术的患者。在屈曲和伸展过程中，分别使用超声检查和纤维支气管镜测量从环状软骨到袖带上缘 (CC) 的距离以及从 ETT 尖端到隆突 (TC) 的距离。气管总长度 (TTL) 定义为 CC、TC 以及从袖带上缘到尖端的距离的组合。

在屈曲过程中，CC 和 TC 分别为 1.5 ± 0.6 和 2.9 ± 1.0 cm。7 名患者 (11.7%) 表现出插管过深。在超声检查下调整袖带位置后 (CC = 0)，尖端位置被纠正了 96.7%。虽然 TC 在扩展位置变化后增加了 2.1 ± 1.0 cm，但由于 TTL 延长 (1.4 ± 1.1 cm)，CC 减少了 0.6 ± 0.7 cm。4 名患者 (6.7%) 表现出超出环状软骨的过度袖带位移，这本可以在超声检查下得到纠正。

总之，由于头部和颈部伸展过程中气管延长，ETT 套囊向喉部的位移小于尖端从隆突的位移。尽管如此，我们建议对袖带位置进行超声评估可以避免 ETT 错位。

试用注册https://cris.nih.go.kr/（批准号：KCT0005319）；于 2019 年 5 月 14 日注册。