Mechanical properties of the human trachea in vivo

Abstract

In the field of head and neck surgery, it is important to know the resectable length of the trachea in order to perform cricohyoidpexia or end to end anastomosis of the trachea successfully. The resectable length' depends closely upon extensibility of the trachea. ‘Extensibility’ also depends upon its elasticity. As previously reported by Yahara, evaluation of “Yerzly's Resilience” of the resected canine trachea could well express its elasticity.In the present study, a clinical investigation was performed for assessing “Yerzley's Resilience” of the human trachea in vivo using the same manner as Yahara's. A single rectangular mechanical impulse was given to the human trachea. Then, the vibration pattern of the trachea was recorded by ultrasonic pulse variant M-mode display. Resilience values were estimated by assessing the freely decrementing vibration curve described above using a given formula. Twenty-one men and 15 women ranging in age from 13 to 78 were investigated in the ordinary supine position at first and, then, in the extended neck position. In addition, the relationship between elasticity of the trachea and the neck extensibility was investigated.The results were as follows;1. Resilience values of the trachea become higher in proportion to the age when examined in the ordinary supine position.2. No positive relationship was obtained between aging and resilience values in the extended neck position.3. In persons above the age of 40, resilience values of the trachea in the ordinary supine position were lower if the neck extensibility was good, while higher if it was not.4. In persons below 39, resilience values were low regardless of the neck extensibility.In conclusion, the results suggest that “Yerzley's Resilience” of the human trachea in vivo can also well express the elasticity of the trachea.