Effect of head position changes on the depth of tracheal intubation in pediatric patients: A prospective, observational study

The purpose of this study was to evaluate the effect of head rotation in adults and children on endotracheal tube (ETT) position and to confirm previous results regarding the influence of head flexion and extension on ETT position. After inducing anesthesia in 24 young adults and 22 children (aged 1-9 yr), ETTs were secured on the right corner of each of their mouths. Using a fiberoptic bronchoscope, the distance from the carina to the tip of the ETT was measured with each patient's head and neck placed in a neutral position, flexed, extended, rotated to the right, and rotated to the left. In all patients, flexing the head resulted in the ETT moving towards the carina, and extension resulted in the tube being displaced in the opposite direction. In adults, head rotation to the right resulted in withdrawal of the ETT in all but one patient; displacement was 0.8 +/- 0.5 cm (mean +/- SD) (P < 0.001). Head rotation to the left resulted in the endotracheal tube being displaced in an unpredictable direction by 0.1 +/- 0.6 cm. In children, head rotation to the right resulted in withdrawal of the ETT in all patients; displacement was 1.1 +/- 0.6 cm (P < 0.001). Head rotation to the left also resulted in partial withdrawal in all patients; displacement measured 0.6 +/- 0.4 cm (P < 0.001). In adult patients under general anesthesia, head rotation towards the side of ETT fixation resulted in partial withdrawal of the tube tip away from the carina, whereas head rotation to the opposite side displaced the tube in an unpredictable manner. In children, head rotation to either side resulted in withdrawal of the ETT away from the carina.

True vocal cord paralysis may follow endotracheal intubation and be the result of peripheral nerve damage. This damage can occur as the result of compressing the nerve between an inflated endotracheal tube cuff and the overlying thyroid cartilage. A series of anatomic dissections defined the likely site of injury to be at the junction of the vocal process of the arytenoid cartilage and the membranous true vocal cord approximately 6 to 10 mm below the level of the cord. Cuff pressures were monitored during anesthetics. Analysis of the results indicated that nitrous oxide diffuses into endotracheal tube cuffs causing a substantial increase in the intracuff pressure. We have concluded that true vocal cord paralysis which follows endotracheal intubation is usually temporary. The solution to the problem lies in its prevention and several methods are described whereby it may be avoided.