Endotracheal Tube Displacement during Neck Extension in Thyroid Surgery

Abstract

Objectives:Evaluate how much the endotracheal tube moves on neck extension in patients undergoing elective thyroid surgery and whether this is affected by body mass index (BMI) or neck length.Methods:Prospective study of 20 patients undergoing thyroidectomy during a 4‐month period in 2013‐2014. Patient demographics, BMI, collar size, sterno‐mental distance, and sterno‐cricoid distance were recorded. The electromyography endotracheal tubes used in thyroid surgery were marked at 1 cm, and the distance was noted in the neutral and extended (30° as tolerated) neck positions.Results:The mean age of patients was 46.4 years (range 26‐68 years). There were 18 female and 2 male patients. The mean BMI was 28.2 (range, 20.1‐32.6) and mean sterno‐mental distance was 15.2 cm (range, 9.8‐20.4 cm). The mean upward displacement of the endotracheal tube during neck extension was 22.2 ± 7.6 mm. Patients with a larger BMI (>25) had a significantly smaller amount of tube displacement than patients with a smaller BMI (<25; 17.1 ± 7.3 mm vs 24.5 ± 8.1 mm, P =. 02) and patients with a smaller neck length (sterno‐mental <12 cm) had a significantly smaller amount of tube displacement than those with a larger neck length (sterno‐mental distance >12 cm; 18.2 ± 6.9 mm vs 24.6 ± 7.1 mm, P =. 04).Conclusions:Neck extension results in upward displacement of the endotracheal tube. The amount of displacement is significantly lower in patients with a larger BMI or shorter neck length, possibly due to the limitation of neck extension in these patients. This has particular relevance for thyroidectomy patients in whom accurate positioning of the tube is essential for nerve monitoring.