Fig. 1

The image was obtained and labeled by our team to illustrate the measurement details of RTD maneuver. An example demonstration of how the potential displacement angle, distance and required force of the right trachea displacement were measured. The displacement distance of thyroid cartilage was the distance between the Adam’s apple and the sagittal midline. The displacement angle was the angulation between sagittal midline and the tie line between suprasternal fossa and the Adam’s apple. The force required by RTD maneuver was measured by a dynameter